CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/350,675, filed on June 9, 2022, the entire contents of which are fully incorporated herein by reference.

FIELD

[0002] The present disclosure relates to systems, methods and techniques for synthesis and production of aryltriazole compounds. Exemplary aryltriazole compounds may be of high purity and reduced discoloration.

INTRODUCTION

[0003] Triazole compounds are a versatile group of compounds, having both pharmacological and industrial applicability. In particular, aryltriazoles such as benzo- and tolyltriazoles, have found use as efficient corrosion inhibitors, UV stabilizers, and as intermediates in various syntheses, such as in the manufacture of dyes. Particularly preferred compounds for this use include benzotriazole (hereinafter “BT”), tolyltriazole (hereinafter “TT”) and alkylsubstituted analogs of both. The term “tolyltriazole” is meant to refer to 4-methylbenzotriazole, 5 -methylbenzotri azole and mixtures of the two.

[0004] While methods for the preparation of aryltriazoles was first described in 1876, these and subsequent methods of preparation produce an aryltriazole product that is darkened and discolored by various impurities. Some processes even produce aryltriazole products that are black. The free aryltriazole (that is, an aryltriazole that is not in its anionic form) is insoluble in aqueous solutions and is often isolated from aqueous solutions as a solid or a melt. Such solids or melts often contain most of the colorizing impurities initially present in the aqueous solution.

[0005] These impurities are typically generated during the diazotization reaction processes that convert ortho-aryldiamines to aryltriazoles and are caused by oxidation, dimerization, or oxidative dimerization of the starting materials as a by-product of the synthesis process, and/or by impurities in the starting materials themselves. These impurities are disfavored in the finished product, since many of the applications for which these compounds are useful require solid aryltriazoles of considerably high purity, and preferably of a lighter color, such as a white, or off- white color. [0006] Purification methods of aryltriazoles from colored impurities include crystallization, acidic and basic aqueous extraction with or without filter aids, distillation, and membrane filtration. For example, benzotriazole and/or tolyltriazole have been crystallized from alcohols, benzene, cyclohexane, and xylenes. However, there may be colored contaminants in the aryltriazoles which cannot be removed by crystallization of the free aryltriazole. Furthermore, crystallization is inherently a low yield process, with loss of product resulting. Though aryltriazoles are poorly soluble in cold and ambient temperature water, they have some solubility in hot water. Unfortunately, the colored impurities share the same property. Attempts to recrystallize free aryltriazoles from aqueous media typically precipitate the product with the colored impurities included. Generally, the aryltriazole separates as a melt, rather than a solid, and again, includes the colored impurities with it. The aryltriazole may be rendered soluble at ambient temperature by conversion to the aryltriazole anion with aqueous base. In this case, the colored impurities are also solubilized, generating a dark aqueous solution. Neutralization to a pH of about 5 or 6 regenerates the free aryltriazole, which precipitates as a solid or an oil. However, the colored impurities are usually partially solubilized.

[0007] Another major method of purification of aryltriazoles from colored bodies is the aqueous extraction from an acidic or basic solution with and without adsorption onto decolorizing media. Activated carbon, kieselguhr, diatomacious earth, clays, alumina, fuller's earth, pumice and sodium dithionite have been used to remove colored impurities from solutions of aryltriazoles. Once the aryltriazole is sufficiently purified, it is generally recovered by adjusting the solution to a pH of about 5-5.5 at room temperature (25 C or colder) using a calculated amount of an inorganic acid or base. Filter aids generally improve the removal of colored bodies, but they also adsorb an appreciable amount of the triazole. Filter aids need to be used in large quantities which makes it difficult to handle and to remove from the final purified product

[0008] Fractional distillation to separate the triazoles from the higher boiling point-colored bodies was also adopted. High vacuum distillation was necessary because of the high boiling point of triazole (higher that 200 °C at 0.137 MPa) and the possibility of partial decomposition at higher temperatures. Additives such as NaOH, formaldehyde and polyethylene glycol have been used for various reasons during distillation. It was not clearly indicated in the previous patents, how the purity of triazoles was improved and how purification by distillation impacted the % recovery of the pure triazole. The fractional distillation column and conditions were not clearly described and obviously expected to be variable based on the advances in the fractional distillation column design. Membrane filtration in the ultra- and nanofiltration range was also adopted and used under strict pore size, molecular weight (200- 1000 Daltons) and pressure conditions to partially separate the higher molecular weight-colored impurities from the triazole in a cross-flow filtration design. The final permeate was relatively purer and contained roughly 1-8% of colored impurities compared to the feed (10% colored impurities). The process was designed to keep the triazole in an anionic form and hence applying a caustic to increase the pH before passing the feed through the spiral or tubular nanofiltration membrane and required a multistage nanofiltration in the presence of a liquid carrier selected from a group of hydroxy aliphatic compounds or glycols. The partially purified alkaline permeate was then used to make 50% Na-TT solution.

SUMMARY

[0009] In one aspect, a method of synthesizing an aryltriazole is disclosed. An exemplary method may comprise: mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; mixing a strong acid into the fourth mixture; heating the fourth mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a reacted fourth mixture; providing the reacted fourth mixture to a purification unit, thereby generating a permeate stream and a retentate; adjusting a pH of the permeate stream to be no less than 5 and no greater than 5.5 to generate a fluid comprising precipitate; providing the fluid comprising precipitate to a filtration unit; and obtaining an aryltriazole from the filtration unit.

[0010] In another aspect, a method of synthesizing an aryltriazole is disclosed. An exemplary method may comprise mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; separating an oily phase from the fourth mixture; distilling, in a distillation unit, the oily phase at a temperature no less than 180 °C and no greater than 230 °C and at a pressure no less than 0.0008 MPa and no greater than 0.0012 MPa; and condensing a vapor phase from the distillation unit, thereby generating the aryltriazole.

[0011] In another aspect, a method of synthesizing an aryltriazole is disclosed. An exemplary method may comprise mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; distilling, in a first distillation unit, the fourth mixture at a temperature no less than 68 °C and no greater than 78 °C and at a pressure no less than 0.0038 MPa and no greater than 0.0048 MPa; obtaining a liquid phase from the first distillation unit; distilling, in a second distillation unit, the liquid phase at a temperature no less than 213 °C and no greater than 222 °C and at a pressure no less than 0.0006 MPa and no greater than 0.0014 MPa; and condensing a vapor phase from the second distillation unit, thereby generating the aryltriazole.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0013] FIG. 1 shows an exemplary method for synthesizing an aryltriazole.

[0014] FIG. 2 shows another exemplary method for synthesizing an aryltriazole. [0015] FIG. 3 shows another exemplary method for synthesizing an aryltriazole. [0016] FIG. 4 shows an exemplary system for synthesizing an aryltriazole.

[0017] FIG. 5 shows another exemplary system for synthesizing an aryltriazole.

[0018] FIG. 6 shows reversed-phase high-performance liquid chromatography (RP-HPLC) experimental results for benzotri azole.

[0019] FIG. 7 shows reversed-phase high-performance liquid chromatography (RP-HPLC) experimental results for tolyltri azole.

[0020] FIG. 8 A is a photograph showing experimentally generated solid TT using microfiltration. FIG. 8B is a photograph showing the experimentally generated 50% Na-TT. [0021] FTG. 9A is a photograph of experimental distillate. FIG. 9B is a photograph showing the TT cold melt after cooling the distillate shown in FIG. 9A. FIG. 9C is a photograph showing TT powder after grinding the distillate shown in FIG. 9B. FIG. 9D is a photograph showing the ground TT powder of FIG. 9C. FIG. 9E is a photograph showing 50% Na-TT after combining the TT powder of FIG. 9D with 50% NaOH and DI water.

DETAILED DESCRIPTION

[0022] Generally, the present disclosure is directed to systems and methods for synthesizing an aryltriazole, such as benzotri azole, tolyltriazole, or salts thereof. Exemplary systems and methods may be capable of generating aryltriazole in high yield and substantially free of colored contaminants. By “substantially free” is meant that the aryltriazole is produced at a purity (relative to colored contaminants) of about 90 wt% or greater, or about 95 wt% or greater, or about 97 wt% or greater, or about 99 wt% or greater.

I. Definitions

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0024] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The singular forms “a,” “an” and “the” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of’ and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0025] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5-1.4. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.”

[0026] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are contemplated. For another example, when a pressure range is described as being between ambient pressure and another pressure, a pressure that is ambient pressure is expressly contemplated.

II. Exemplary Methods

[0027] Exemplary methods disclosed and contemplated herein relate to synthesis of an aryltriazole, such as BT, TT or salts thereof. Broadly, exemplary methods may be characterized as without acidification or distillation, with acidification, or with distillation. Exemplary methods involving acidification may comprise microfiltration operations or media filtration operations. The following sections discuss exemplary reaction schemes and exemplary methods.

A. Exemplary Reaction Schemes

[0028] Without being bound by a particular theory, it appears that the purity of the final product may be affected by both the quality (purity) of the starting materials as well as the degree of completion of the diazotization and ring closure reactions in the synthesis reaction. Exemplary reaction mechanisms are summarized in the chemical equations Scheme 1 (synthesis of BT) and Scheme 2 (synthesis of TT) below. aNH

NH

Scheme 1 and

Scheme 2

[0029] Previous work has shown reaction conditions based upon these reaction schemes that usually utilize equimolar amounts of the aryldiamine and nitrite reactants to generate the aryltriazole product.

B. Exemplary Methods without Acidification or Distillation

[0030] FIG. 1 shows an exemplary method 100 for synthesizing an aryltriazole. As shown, example method 100 comprises mixing a first molar amount of a water-soluble alkali nitrite, to yield a first solution (operation 102). The exemplary method may also include: dissolving a second molar amount of said ortho-aryldiamine in an aqueous solution of a weak acid to yield a second solution (operation 104); mixing said first solution with second solution over a period of time to form a reaction mixture having a pH of 4.0 to 5.0 (operation 106); mixing the reaction mixture at a temperature for a period of time (operation 108); separating said aryltriazole from other reagents in the reaction mixture (operation 110); and drying said aryltriazole to yield a dried aryltriazole product (operation 112). Each exemplary operation is discussed in greater detail below, and other embodiments may include more or fewer operations.

[0031] Exemplary water-soluble alkali nitrites may include sodium nitrite, potassium nitrite, their salts, and combinations thereof. Exemplary first molar amounts are described in greater detail below in relation to molar amounts of ortho-aryldiamine. Generally, each mole of an ortho-aryldiamine is reacted with greater than one mole of an alkali nitrite.

[0032] An exemplary method may include dissolving a second molar amount of ortho- aryldiamine in an aqueous solution of a weak acid to yield a second solution (operation 104). Exemplary ortho-aryldiamines may be alkyl substituted. For instance, an ortho-aryldiamine may be an optionally alkyl -substituted ortho-toluene diamine (TDA) or an optionally alkyl-substituted ortho-phenylenediamine (PDA).

[0033] In some instances, the first molar amount of a water-soluble alkali nitrite may be in excess of the second molar amount of ortho-aryldiamine. In various instances, a ratio of the molar amount of ortho-aryldiamine to the molar amount of a water-soluble alkali nitrite may be between 1 : 1.02 to 1 :1.05; between 1 :1.02 to 1: 1.04; or between 1 :1.03 to 1 :1.05. In various instances, a ratio of the molar amount of ortho-aryldiamine to the molar amount of a water- soluble alkali nitrite may be no less than 1: 1.02; no less than 1: 1.03; no less than 1: 1.04; or no less than 1 : 1.05. In various instances, a ratio of the molar amount of ortho-aryldiamine to the molar amount of a water-soluble alkali nitrite may be no greater than 1 : 1.05; no greater than 1 : 1.04; no greater than 1 : 1.03; or no greater than 1 : 1.02.

[0034] Weak acids may be used as catalysts. Examples of weak acids may include acetic acid, citric acid, carbonic acid, glycolic acid, dihydrogen phosphate, oxalic acid, malonic acid, succinic acid, diglycolic acid, alkali metal bisulfates, alkanoic acids, benzoic acid, and phthalic acid.

[0035] Some embodiments drive the reaction to completion more effectively by increasing the molar ratio of the nitrite reactant to the ortho-aryldiamine reactant in the reaction mixture. In these embodiments, the nitrite ion reactant is provided at a molar excess relative to the ortho- aryldiamine. This methodology may more completely consume the aryldiamine reactant in the reaction, increasing the yield of the desired aryltriazole.

[0036] After preparation, the first solution and the second solution are mixed over a period of time to form a reaction mixture (operation 106). The first solution and the second solution are combined such that a temperature of the reaction mixture is below a given threshold, such as no greater than 85 °C; no greater than 90 °C; or no greater than 95 °C. In some instances, the second solution is added to the first solution over a period of time. In some instances, the first solution is added to the second solution over a period of time.

[0037] In some instances, the period of time for mixing the first solution and the second solution may be between 30 minutes and 90 minutes. Longer periods of time are possible but typically not industrially advantageous. Shorter periods of time may be possible depending upon system components, such as the use of cooled vessels. In various instances, the period of time for mixing the first solution and the second solution may be between 30 minutes and 90 minutes; between 30 minutes and 60 minutes; between 60 minutes and 90 minutes; between 45 minutes and 75 minutes; or between 45 minutes and 90 minutes. In various instances, the period of time for mixing the first solution and the second solution may be at least 30 minutes; at least 45 minutes; at least 60 minutes; at least 75 minutes; or at least 90 minutes. In various instances, the period of time for mixing the first solution and the second solution may be no greater than 90 minutes; no greater than 75 minutes; no greater than 60 minutes; no greater than 45 minutes; or no greater than 30 minutes.

[0038] In some instances, a volume of the second solution may be greater than a volume of the first solution. In various implementations, a volume of the second solution may be between 1.1 and 3 times; between 1.1 and 2 times; between 1.5 and 2 times; between 1.5 and 3 times; or between 2 and 3 times greater than a volume of the first solution. In various implementations, a volume of the second solution may be at least 1.1 times greater; at least 1.5 times greater; at least 2 times greater; or at least 2.5 times greater than a volume of the first solution. In various implementations, a volume of the second solution may be no greater than 3 times; no greater than 2.5 times; no greater than 2 times; or no greater than 1.5 times more than a volume of the first solution.

[0039] After forming the reaction mixture (operation 106), the reaction mixture is mixed at a reaction temperature for a period of time (operation 108). In various instances, the reaction temperature may be between 25 °C and 85 °C; between 25 °C and 70°C; between 35°C and 85°C; between 45°C and 75°C; between 60 °C and 75°C; between 65°C and 75°C; or between 68°C and 72°C. In various instances, the reaction temperature may be no greater than 85 °C; no greater than 80°C; no greater than 75°C; no greater than 70°C; no greater than 65°C; no greater than 60°C; no greater than 55°C; no greater than 50°C; no greater than 45°C; no greater than 40°C; no greater than 35°C; or no greater than 30°C.

[0040] In various instances, the reaction mixture may be mixed for various time periods. For instance, the reaction mixture may be mixed for at least 45 minutes; at least 60 minutes; at least 75 minutes; at least 90 minutes.

[0041] In various instances, a pH of about 4 to about 5.5 is maintained during the reaction. [0042] After mixing the reaction mixture, the aryltriazole may be separated from other reagents in the reaction mixture (operation 110). In some instances, the mixture may be filtered after activated charcoal is used. Tn some instances, the mixture may be fdtered without adding activated charcoal to the reaction mixture.

[0043] After separating and washing the aryltriazole, it may be dried to yield a dried aryltriazole product (operation 112). Certain embodiments result in synthesis of an aryltriazole yielding a product free or substantially free of dark colored impurities. The aryltriazole may be “high yield” and/or “high purity.”

C. Exemplary Methods Including Acidification

[0044] FIG. 2 shows an exemplary method 200 for synthesizing an aryltriazole. As shown, example method 200 comprises converting a triazole to acid salt form (operation 202), heating a low pH mixture (operation 204), passing a mixture through a microfdtration unit (operation 206) or passing a mixture through media filtration unit (operation 208), adjusting a pH of the permeate (operation 210), filtering, washing, and drying (operation 212), and making an aryltriazole solution (operation 214). Each exemplary operation is discussed in greater detail below, and other embodiments may include more or fewer operations.

[0045] An exemplary method may begin by converting a triazole to acid salt form (operation 202). In some instances, operation 202 may comprise mixing water and weak acid and optionally heating the mixture of water and weak acid. In some instances, operation 202 may comprise adding an ortho-aryldiamine to a mixture of water and weak acid. In some instances, operation 202 may comprise adding a water-soluble alkali nitrite to a mixture of water, weak acid, and ortho-aryl di amine .

[0046] Water and weak acid may be mixed in various ratios. In some implementations, a molar ratio of water to weak acid may be between 5 : 1 and 25 : 1. In various instances, a molar ratio of water to weak acid may be no less than 5:1; no less than 8: 1; no less than 10: 1; no less than 12: 1; no less than 15:1; no less than 18:1; no less than 20: 1; no less than 22:1; or no less than 25:1. In various instances, a molar ratio of water to weak acid may be no greater than 25: 1; no greater than 23 : 1 ; no greater than 20 : 1 ; no greater than 17 : 1 ; no greater than 15: 1; no greater than 13 : 1 ; no greater than 10 : 1 ; no greater than 7 : 1 ; or no greater than 5:1.

[0047] One or more weak acids may be mixed with water to generate an aqueous solution comprising weak acid. Examples of weak acids may include acetic acid, citric acid, carbonic acid, glycolic acid, dihydrogen phosphate, oxalic acid, malonic acid, succinic acid, diglycolic acid, alkali metal bisulfates, alkanoic acids, benzoic acid, and phthalic acid.

[0048] In some implementations, the aqueous solution comprising weak acid may optionally be heated before any additional components are added. For instance, the aqueous solution comprising weak acid may be heated to a temperature of no less than 30 °C; no less than 35 °C; no less than 40 °C; no less than 45 °C; no less than 50 °C; no less than 55 °C; no less than 60 °C; or no less than 65 °C. For instance, the aqueous solution comprising weak acid may be heated to a temperature of no greater than 30 °C; no greater than 35 °C; no greater than 40 °C; no greater than 45 °C; no greater than 50 °C; no greater than 55 °C; no greater than 60 °C; or no greater than 65 °C.

[0049] Operation 202 may include adding a predetermined molar amount of orthoaryldiamine in an aqueous solution of a weak acid. Exemplary ortho-aryldiamines may be alkyl substituted. For instance, an ortho-aryldiamine may be an optionally alkyl-substituted ortho- TDA or an optionally alkyl-substituted ortho-PDA.

[0050] Ortho-aryldiamine may be added in various molar ratios to weak acid. In some implementations, a molar ratio of weak acid to ortho-aryldiamine may be between 1.00:1 and 2.00:1. In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no less than 1.00:1; no less than 1.2:1; no less than 1.4: 1; no less than 1.6: 1; no less than 1.8: 1; or no less than 2.00:1. In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no greater than 2.00:1; no greater than 1.8 : 1 ; no greater than 1.6 : 1 ; no greater than 1.4 : 1 ; no greater than 1.2: 1; or no greater than 1.00: 1.

[0051] An aqueous mixture comprising weak acid and ortho-aryldiamine may be heated for a predetermined amount of time. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated for at least 15 minutes; at least 25 minutes; at least 30 minutes; at least 35 minutes; at least 45 minutes; or at least 60 minutes, n some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated for no more than 180 minutes; no more than 150 minutes; no more than 120 minutes; no more than 90 minutes; no more than 60 minutes; no more than 45 minutes; no more than 35 minutes; no more than 30 minutes; or no more than 20 minutes. [0052] In some implementations, an aqueous mixture comprising weak acid and orthoaryldiamine may be heated to a temperature no less than 50 °C; no less than 55 °C; no less than 60 °C; or no less than 65 °C. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated to a temperature no greater than 35 °C; no greater than 40 °C; no greater than 45 °C; no greater than 50 °C; no greater than 55 °C; no greater than 60 °C; or no greater than 65 °C.

[0053] In some implementations, an aqueous mixture comprising weak acid and ortho- aryldiamine may be heated and/or mixed for a time period of no less than 15 minutes; no less than 20 minutes; no less than 25 minutes; no less than 30 minutes; no less than 45 minutes; no less than 60 minutes; or no less than 90 minutes. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated and/or mixed for a time period of no greater than 180 minutes; no greater than 120 minutes; no greater than 90 minutes; no greater than 60 minutes; no greater than 45 minutes; no greater than 30 minutes; no greater than 25 minutes; no greater than 20 minutes; or no greater than 15 minutes.

[0054] Operation 202 may comprise adding a water-soluble alkali nitrite to a mixture of water, weak acid, and ortho-aryldiamine. In some instances, the mixture of water, weak acid, and ortho-aryldiamine is at a temperature no greater than 35 °C; no greater than 30 °C; no greater than 28°C; no greater than 25°C; no greater than 22°C; or no greater than 20°C when the water- soluble alkali nitrite is added. Exemplary water-soluble alkali nitrites may include sodium nitrite, potassium nitrite, their salts, and combinations thereof. Exemplary first molar amounts are described in greater detail below in relation to molar amounts of ortho-aryldiamine. Generally, each mole of an ortho-aryldiamine is reacted with greater than one mole of an alkali nitrite.

[0055] In some instances, a molar amount of a water-soluble alkali nitrite may be in excess of the molar amount of ortho-aryldiamine. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be between 1.01 : 1 and 1.1 :1; between 1.01 :1 and 1.05:1; between 1.05: 1 and 1.1 : 1; between 1.02: 1 and 1.06:1; or between 1.02: 1 and 1.04: 1. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be no less than 1.01 : 1; no less than 1.02:1; no less than 1.03: 1; no less than 1.04: 1; no less than 1.05: 1; no less than 1.06: 1; no less than 1.07: 1; no less than 1.08: 1; no less than 1.09: 1; or no less than 1.1 :1. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be no greater than 1.01 : 1 ; no greater than 1 .02: 1 ; no greater than 1 03 : 1 ; no greater than 1.04:1; no greater than 1.05: 1; no greater than 1.06:1; no greater than 1.07: 1; no greater than 1.08:1; no greater than 1.09: 1; or no greater than 1.1 :1.

[0056] In various instances, a molar ratio of ortho-aryldiamine to weak acid to water-soluble alkali nitrite may be between 1 :1 : 1.01 and 1:2: 1.05.

[0057] In some instances, water-soluble alkali nitrite may be added to a mixture of water, weak acid, and ortho-aryldiamine such that a temperature of the mixture is no greater than a predetermined temperature. In some instances, one or more temperature control units may be used to maintain a mixture of water, weak acid, and ortho-aryldiamine while adding water- soluble alkali nitrite to a temperature no greater than a predetermined temperature. In various implementations, the predetermined temperature may be 90 °C; 85°C; 80 °C; 75 °C; or 70°C. [0058] A mixture of water, weak acid, ortho-aryldiamine, and water-soluble alkali nitrite may be reacted for a predetermined period of time and at a predetermined temperature. In various instances, method 200 may include reacting a mixture of water, weak acid, ortho- aryldiamine, and water-soluble alkali nitrite for no less than 15 minutes; no less than 30 minutes; no less than 45 minutes; no less than 60 minutes; no less than 75 minutes; no less than 90 minutes; no less than 120 minutes; no less than 150 minutes; no less than 180 minutes; no less than 210 minutes; or no less than 240 minutes. In various instances, method 200 may include reacting a mixture of water, weak acid, ortho-aryldiamine, and water-soluble alkali nitrite for no greater than 300 minutes; no greater than 240 minutes; no greater than 210 minutes; no greater than 180 minutes; no greater than 150 minutes; no greater than 120 minutes; no greater than 90 minutes; no greater than 60 minutes; or no greater than 30 minutes.

[0059] In various instances, method 200 may include reacting a mixture of water, weak acid, ortho-aryldiamine, and water-soluble alkali nitrite at a temperature of no less than 75 °C; no less than 80 °C; no less than 83 °C; no less than 86 °C; no less than 89 °C; no less than 90 °C; no less than 93 °C; or no less than 96°C. In various instances, method 200 may include reacting a mixture of water, weak acid, ortho-aryldiamine, and water-soluble alkali nitrite at a temperature of no greater than 97 °C; no greater than 94 °C; no greater than 91 °C; no greater than 90 °C; no greater than 88 °C; or no greater than 85 °C.

[0060] In some instances, one or more strong acids may be added after reacting the water, weak acid, ortho-aryldiamine, and water-soluble alkali nitrite, thereby generating a low-pH mixture. Exemplary strong acids may include nitric acid (HNO3), hydrochloric acid (HC1), and sulfuric acid (H2SO4). Exemplary strong acids may have various molarities. For instance, strong acid added to the mixture may have a molarity of no less than IM; no less than 2M; no less than 3M; no less than 4M; no less than 5M; or no less than 6M.

[0061] One or more strong acids may be added until a pH of the resulting mixture is no greater than 2; no greater than 1.5; no greater than 1.25; no greater than 1.0; no greater than 0.9; no greater than 0.8; no greater than 0.7; no greater than 0.6; or no greater than 0.5.

[0062] After adding strong acid, the resulting mixture may be reacted at a predetermined temperature for a predetermined amount of time (operation 204). In various instances, the reaction mixture may be heated during operation 204 to a temperature of no less than 80 °C; no less than 83 °C; no less than 86 °C; no less than 89 °C; no less than 90 °C; no less than 93 °C; or no less than 96°C. In various instances, the reaction mixture may be heated during operation 204 to a temperature of no greater than 97 °C; no greater than 94 °C; no greater than 91 °C; no greater than 90 °C; no greater than 88 °C; or no greater than 85 °C.

[0063] In various instances, the reaction mixture may be heated during operation 204 for a time period of no less than 90 minutes; no less than 120 minutes; no less than 150 minutes; or no less than 180 minutes; no less than 210 minutes; no less than 240 minutes. In various instances, the reaction mixture may be heated during operation 204 for a time period of no greater than 270 minutes; no greater than 240 minutes; no greater than 210 minutes; no greater than 180 minutes; no greater than 150 minutes; or no greater than 120 minutes.

[0064] After reacting the low pH mixture (operation 204), the resulting fluid is subjected to one or more purification operations (operation 206 or 208). The one or more purification operations may be arranged to remove impurities, such as colored impurities. Typically, the resulting fluid is purified while at a temperature of at least 70 °C; at least 75 °C; at least 80 °C; at least 85 °C; or at least 90 °C.

[0065] In some instances, the resulting fluid is passed through a microfiltration unit (operation 206). Various types of microfiltration units may be used. “Microfiltration” as used herein, is a process to separate suspended solids from dissolved substances in a process stream. Microfiltration membranes generally separate or reject particles from about 0.05-0.1 micron to about 1 micron. On a molecular weight basis, microfiltration membranes can reject macromolecules in the 100,000 MW to 500,000 MW range. Exemplary microfiltration membranes typically allow solubilized TT acid salt to pass through and reject color-causing suspended matter. In some instances, the resulting fluid may be provided to a microfiltration unit in a crossflow configuration.

[0066] Exemplary microfiltration units may be filtration columns. Exemplary microfiltration units may be tubular. Exemplary microfiltration units may be made of various materials, such as metals. For instance, exemplary microfiltration units may be stainless steel. In some implementations, exemplary microfiltration units may be coated metals. For example, exemplary microfiltration units may be titanium coated stainless steel.

[0067] In some instances, the resulting fluid is passed through a media filtration unit. “Media filtration” as used herein, is a process where an aqueous stream passes through filtration media to remove suspended solids. In some instances, an acidified aqueous TT solution, including suspended color-forming matter, is passed through a column packed with adsorption media, where color forming matter is selectively adsorbed and held on the surface of the adsorption media, and allowing purified TT acidic aqueous solution through. Various types of media may be used. As an example, adsorption media may comprise silanized glass wool filter media.

[0068] A permeate from the microfiltration and/or media filtration units may be further processed to precipitate the triazole. For instance, a pH of the permeate may be adjusted (operation 210). In some implementations, a pH is adjusted (operation 210) to be no less than 5 and no greater than 5.5.

[0069] Various basic materials may be used to adjust the pH of the permeate (operation 210). In some instances, a strong base may be used to adjust the pH. As an example, sodium hydroxide (NaOH) may be used. Various concentrations of basic materials may be used. In some instances, the basic materials may be dissolved in water. For example, a 50 weight percent (wt%) solution of NaOH may be used to adjust the pH, where the remaining 50 wt% is water.

[0070] After adjusting the permeate pH (operation 210), the resulting mixture may be filtered, washed, and dried (operation 212). Various filters known in the art may be used to separate triazole from the liquid. As an example, vacuum filtration through a filter media may be used.

[0071] One or more washing operations may be performed after filtering. Typically, water is used to wash the precipitate. Typically, deionized water is used to wash the precipitate. In some instances, at least two washing operations or at least three washing operations may be performed after filtering.

[0072] One or more drying operations may be performed after washing. Drying operations may be conducted at room temperature or at a temperature greater than room temperature. In some instances, an oven or similar apparatus may be used to dry the washed precipitate.

[0073] After drying, the resulting triazole material may comprise no, or trace amounts, of various impurities. For instance, the resulting triazole material may comprise no more than 0.01 wt%; no more than 0.005 wt%; or no more than 0.001 wt% nitrite material. For instance, the resulting triazole material may comprise no more than 0.01 wt%; no more than 0.005 wt%; or no more than 0.001 wt% nitrate material. For instance, the resulting triazole material may comprise no more than 0.01 wt%; no more than 0.005 wt%; or no more than 0.001 wt% chloride material.

[0074] In some instances, the washed and dried precipitate may be used to make a triazole solution (operation 214). For instance, the washed and dried precipitate may be used to make a 50% Na-tri azole solution.

D. Exemplary Methods Including Distillation

[0075] FIG. 3 shows an exemplary method 300 for synthesizing an aryltriazole. As shown, example method 300 comprises forming an acidic reaction mixture (operation 302 or 304), adjusting a pH (operation 306), optionally two-stage distilling (operation 308), separating an oily phase (operation 310), distilling (operation 312), obtaining an aryltriazole melt (operation 314), cooling and grinding the melt (operation 316), and making an aryltriazole solution (operation 318). Each exemplary operation is discussed in greater detail below, and other embodiments may include more or fewer operations.

[0076] Example method 300 begins by forming an acidic reaction mixture (operation 302 or 304). In some implementations, the acidic reaction mixture may have a pH between 4.3 and 4.7 (operation 302). In some implementations, the acidic reaction mixture may have a pH between 5.3 and 5.7 (operation 304).

[0077] In some instances, operation 302 or 304 may comprise mixing water and weak acid and optionally heating the mixture of water and weak acid. In some instances, operation 302 may comprise adding an ortho-aryldiamine to a mixture of water and weak acid. In some instances, operation 302 may comprise adding a water-soluble alkali nitrite to a mixture of water, weak acid, and ortho-aryldiamine. [0078] Water and weak acid may be mixed in various molar ratios. In some implementations, a molar ratio of water to weak acid may be between 5 : 1 and 25 : 1. In various instances, a molar ratio of water to weak acid may be no less than 5:1; no less than 8: 1; no less than 10: 1; no less than 12: 1; no less than 15:1; no less than 18:1; no less than 20: 1; no less than 22:1; or no less than 25:1. In various instances, a molar ratio of water to weak acid may be no greater than 25: 1; no greater than 23 : 1 ; no greater than 20 : 1 ; no greater than 17 : 1 ; no greater than 15 : 1 ; no greater than 13:1; no greater than 10 : 1 ; no greater than 7 : 1 ; or no greater than 5: 1.

[0079] One or more weak acids may be mixed with water to generate an aqueous solution comprising weak acid. Examples of weak acids may include acetic acid, citric acid, carbonic acid, glycolic acid, dihydrogen phosphate, oxalic acid, malonic acid, succinic acid, diglycolic acid, alkali metal bisulfates, alkanoic acids, benzoic acid, and phthalic acid.

[0080] In some implementations, the aqueous solution comprising weak acid may optionally be heated before any additional components are added. For instance, the aqueous solution comprising weak acid may be heated to a temperature of no less than 30 °C; no less than 35 °C; no less than 40 °C; no less than 45 °C; no less than 50 °C; no less than 55 °C; no less than 60 °C; or no less than 65 °C. For instance, the aqueous solution comprising weak acid may be heated to a temperature of no greater than 30 °C; no greater than 35 °C; no greater than 40 °C; no greater than 45 °C; no greater than 50 °C; no greater than 55 °C; no greater than 60 °C; or no greater than 65 °C.

[0081] Operation 302 or operation 304 may include adding a predetermined molar amount of ortho-aryldiamine in an aqueous solution of a weak acid. Exemplary ortho-aryldiamines may be alkyl substituted. For instance, an ortho-aryldiamine may be an optionally alkyl-substituted ortho-TDA or an optionally alkyl-substituted ortho-PDA.

[0082] Ortho-aryldiamine may be added in a various molar ratios to weak acid. In some implementations, a molar ratio of weak acid to ortho-aryldiamine may be between 1.00: 1 and 2.00:1. In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no less than 1.00:1; no less than 1.2:1; no less than 1.4: 1, no less than 1.6: 1; no less than 1.8: 1; or no less than 2.00:1. In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no In various instances, a molar ratio of weak acid to ortho-aryldiamine may be no greater than 2.00:1; no greater than 1.8 : 1 ; no greater than 1.6 : 1 ; no greater than 1.4 : 1 ; no greater than 1.2: 1; or no greater than 1.00: 1. [0083] An aqueous mixture comprising weak acid and ortho-aryl di amine may be heated for a predetermined amount of time. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated for at least 15 minutes; at least 25 minutes; at least 30 minutes; at least 35 minutes; at least 45 minutes; or at least 60 minutes, n some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated for no more than 180 minutes; no more than 150 minutes; no more than 120 minutes; no more than 90 minutes; no more than 60 minutes; no more than 45 minutes; no more than 35 minutes; no more than 30 minutes; or no more than 20 minutes.

[0084] In some implementations, an aqueous mixture comprising weak acid and ortho- aryldiamine may be heated to a temperature no less than 50 °C; no less than 55 °C; no less than 60 °C; or no less than 65 °C. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated to a temperature no greater than 35 °C; no greater than 40 °C; no greater than 45 °C; no greater than 50 °C; no greater than 55 °C; no greater than 60 °C; or no greater than 65 °C.

[0085] In some implementations, an aqueous mixture comprising weak acid and ortho- aryldiamine may be heated and/or mixed for a time period of no less than 15 minutes; no less than 20 minutes; no less than 25 minutes; no less than 30 minutes; no less than 45 minutes; no less than 60 minutes; or no less than 90 minutes. In some implementations, an aqueous mixture comprising weak acid and ortho-aryldiamine may be heated and/or mixed for a time period of no greater than 180 minutes; no greater than 120 minutes; no greater than 90 minutes; no greater than 60 minutes; no greater than 45 minutes; no greater than 30 minutes; no greater than 25 minutes; no greater than 20 minutes; or no greater than 15 minutes.

[0086] Operation 302 or 304 may comprise adding a water-soluble alkali nitrite to a mixture of water, weak acid, and ortho-aryldiamine. In some instances, the mixture of water, weak acid, and ortho-aryldiamine is at a temperature no greater than 35 °C; no greater than 30 °C; no greater than 28°C; no greater than 25°C; no greater than 22°C; or no greater than 20°C when the water- soluble alkali nitrite is added. Exemplary water-soluble alkali nitrites may include sodium nitrite, potassium nitrite, their salts, and combinations thereof. Exemplary first molar amounts are described in greater detail below in relation to molar amounts of ortho-aryldiamine. Generally, each mole of an ortho-aryldiamine is reacted with greater than one mole of an alkali nitrite. [0087] In some instances, a molar amount of a water-soluble alkali nitrite may be in excess of the molar amount of ortho-aryldiamine. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be between 1.01 :1 and 1.1 :1; between 1.01 :1 and 1.05:1; between 1.05: 1 and 1.1 : 1; between 1.02: 1 and 1.06:1; or between 1.02: 1 and 1.04: 1. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be no less than 1.01 : 1; no less than 1.02:1; no less than 1.03: 1; no less than 1.04: 1; no less than 1.05: 1; no less than 1.06: 1; no less than 1.07: 1; no less than 1.08: 1; no less than 1.09: 1; or no less than 1.1 :1. In various instances, a ratio of the molar amount of a water-soluble alkali nitrite to a molar amount of ortho-aryldiamine may be no greater than 1.01: 1; no greater than 1.02: 1; no greater than 1.03:1; no greater than 1.04:1; no greater than 1.05: 1; no greater than 1.06:1; no greater than 1.07: 1; no greater than 1.08:1; no greater than 1.09: 1; or no greater than 1.1 :1.

[0088] In various instances, a molar ratio of ortho-aryldiamine to weak acid to water-soluble alkali nitrite may be between 1 : 1.3: 1.01 and 1:2: 1.05.

[0089] In some instances, water-soluble alkali nitrite may be added to a mixture of water, weak acid, and ortho-aryldiamine such that a temperature of the mixture is no greater than a predetermined temperature for a predetermined time. In some instances, one or more temperature control units may be used to maintain a mixture of water, weak acid, and ortho-aryldiamine while adding water-soluble alkali nitrite to a temperature no greater than a predetermined temperature.

[0090] In various implementations, the predetermined temperature may be no less than 70 °C; no less than 75 °C; no less than 80 °C; no less than 83 °C; no less than 86 °C; no less than 89 °C; no less than 90 °C; no less than 93 °C; or no less than 96°C. In various instances, the predetermined temperature may be no greater than 97 °C; no greater than 94 °C; no greater than 91 °C; no greater than 90 °C; no greater than 88 °C; no greater than 85 °C; no greater than 80 °C; no greater than 75 °C; or no greater than 70 °C.

[0091] In various instances, the predetermined time may be no less than 15 minutes; no less than 30 minutes; no less than 45 minutes; no less than 60 minutes; no less than 75 minutes; no less than 90 minutes; no less than 120 minutes; no less than 150 minutes; no less than 180 minutes; no less than 210 minutes; or no less than 240 minutes. In various instances, the predetermined time may be no greater than 300 minutes; no greater than 240 minutes; no greater than 210 minutes; no greater than 180 minutes; no greater than 150 minutes; no greater than 120 minutes; no greater than 90 minutes; no greater than 60 minutes; or no greater than 30 minutes. [0092] In some instances, exemplary method 300 includes adjusting a pH of the acidic reaction mixture (operation 306). In some instances, the pH of the acidic reaction mixture may be adjusted by adding a strong base until a pH of the acidic reaction mixture is a predetermined pH. In some instances, the predetermined pH is no less than 5.2; no less than 5.3; no less than 5.4; or no less than 5.5.

[0093] Various strong bases may be used during operation 306. As an example, sodium hydroxide (NaOH) may be used. Various concentrations of basic materials may be used. In some instances, the basic materials may be dissolved in water. For example, a 50 weight percent (wt%) solution of NaOH may be used to adjust the pH, where the remaining 50 wt% is water.

[0094] In some instances, exemplary method 300 optionally includes two-stage distillation (operation 308) after either operation 304 or operation 306. In some instances, exemplary method 300 includes separating an oily phase (operation 310) after either operation 304 or operation 306.

[0095] Broadly, during a first stage of two-stage distillation (operation 308), a vapor phase may be generated that comprises water and low boiling volatiles. During a second stage of two- stage distillation (operation 308), a liquid phase obtained during the first stage may be distilled to generate a vapor phase that comprises triazole. Vapor phase generated by the one or more distillation units is provided to one or more condensers.

[0096] A first stage of two-stage distillation (operation 308) may be performed at various temperatures and pressures. In various implementations, a first stage of two-stage distillation (operation 308) may be performed at a temperature no less than 68 °C; no less than 70 °C; no less than 73°C; no less than 75°C; or no less than 78°C. In various implementations, a first stage of two-stage distillation (operation 308) may be performed at a temperature no greater than 78 °C; no greater than 76 °C; no greater than 75 °C; no greater than 72 °C; or no greater than 70 °C. [0097] In various implementations, a first stage of two-stage distillation (operation 308) may be performed at a pressure no less than 0.0035 MPa; no less than 0.0038 MPa; no less than 0.004 MPa; no less than 0.0043 MPa; no less than 0.0045 MPa; or no less than 0.0048 MPa. In various implementations, a first stage of two-stage distillation (operation 308) may be performed at a pressure no greater than 0.0048 MPa; no greater than 0.0046 MPa; no greater than 0.0045 MPa; no greater than 0.0042 MPa; no greater than 0.004 MPa; or no greater than 0.0037 MPa.

[0098] A distillation vessel may be rotated during the first stage of two-stage distillation (operation 308). In various implementations, a distillation vessel may be rotated at a speed of 100 rotations per minute (rpm) to 250 rpm. In various implementations, a distillation vessel may be rotated at a speed of no less than 100 rpm; no less than 150 rpm; no less than 175 rpm; no less than 200 rpm; no less than 225 rpm; or no less than 250 rpm. In various implementations, a distillation vessel may be rotated at a speed of no greater than 250 rpm; no greater than 225 rpm; no greater than 215 rpm; no greater than 200 rpm; no greater than 175 rpm; or no greater than 150 rpm.

[0099] A condenser may be operated at various temperatures during the first stage of two- stage distillation (operation 308). In various implementations, a condenser may be operated at a temperature of no less than 8 °C; no less than 10 °C; no less than 12 °C; no less than 14 °C; no less than 16 °C; no less than 18 °C; no less than 20 °C; or no less than 22 °C. In various implementations, a condenser may be operated at a temperature of no greater than 22 °C; no greater than 20 °C; no greater than 18 °C; no greater than 16 °C; no greater than 14 °C; no greater than 12 °C; or no greater than 10 °C.

[00100] A second stage of two-stage distillation (operation 308) may be performed at various temperatures and pressures. In various implementations, a second stage of two-stage distillation (operation 308) may be performed at a temperature no less than 212 °C; no less than 215 °C; no less than 218 °C; no less than 220 °C; or no less than 222 °C. In various implementations, a second stage of two-stage distillation (operation 308) may be performed at a temperature no greater than 222 °C; no greater than 220 °C; no greater than 218 °C; no greater than 215 °C; or no greater than 212 °C.

[00101] In various implementations, a second stage of two-stage distillation (operation 308) may be performed at a pressure no less than 0.6 kPa; no less than 0.8 kPa; no less than 0.9 kPa; no less than 1.0 kPa; no less than 1.1 kPa; no less than 1.2 kPa; or no less than 1.4 kPa. In various implementations, a second stage of two-stage distillation (operation 308) may be performed at a pressure no greater than 1.4 kPa; no greater than 1.2 kPa; no greater than 1.1 kPa; no greater than 1.0 kPa; no greater than 0.9 kPa; no greater than 0.8 kPa; or no greater than 0.6 kPa. [00102] A distillation vessel may be rotated during the second stage of two-stage distillation (operation 308). In various implementations, a distillation vessel may be rotated at a speed of 100 rotations per minute (rpm) to 275 rpm. In various implementations, a distillation vessel may be rotated at a speed of no less than 100 rpm; no less than 150 rpm; no less than 175 rpm; no less than 200 rpm; no less than 225 rpm; no less than 250 rpm; or no less than 275 rpm. In various implementations, a distillation vessel may be rotated at a speed of no greater than 275 rpm; no greater than 250 rpm; no greater than 225 rpm; no greater than 215 rpm; no greater than 200 rpm; no greater than 175 rpm; or no greater than 150 rpm.

[00103] A condenser may be operated at various temperatures during the second stage of two- stage distillation (operation 308). In various implementations, a condenser may be operated at a temperature of no less than 88 °C; no less than 90 °C; no less than 92 °C; no less than 94 °C; no less than 96 °C; no less than 98 °C; no less than 100 °C; or no less than 102 °C. In various implementations, a condenser may be operated at a temperature of no greater than 102 °C; no greater than 100 °C; no greater than 98 °C; no greater than 96 °C; no greater than 94 °C; no greater than 92 °C; or no greater than 90 °C.

[00104] After operation 304 or operation 306, an oily phase may be separated (operation 310) for further processing. An oily phase may be termed “triazole crude” because the oily phase includes a majority of triazole material but also one or more impurities or contamination. In some instances, the triazole crude may include up to 10 wt% impurities; up to 8 wt% impurities; or up to 5 wt% impurities.

[00105] In some instances, separating an oily phase (operation 310) may include settling operations. In some instances, separating an oily phase (operation 310) may include draining an oily phase from a valve positioned near a bottom portion of a reaction vessel. An aqueous phase left after separating the oily phase may be discarded or further processed.

[00106] After separating the oily phase (operation 310), a triazole concentrate may be distilled (operation 312). In some instances, the triazole concentrate may be in a melt state when distillation (operation 312) begins. One or more distillation units may be used during operation 312. In some implementations, one or more distillation units may be rotated during operation 312. [00107] During distillation (operation 312), a vapor phase is generated that comprises tri azole. Vapor phase generated by the one or more distillation units is provided to one or more condensers.

[00108] Distillation (operation 312) may be conducted at various temperatures and pressures. In various implementations, distillation (operation 312) is performed at a temperature no less than 180 °C; no less than 185 °C; no less than 190 °C; no less than 195 °C; no less than 200 °C; no less than 205 °C; no less than 210 °C; no less than 215 °C; no less than 220 °C; no less than 225 °C; or no less than 230 °C. In various implementations, distillation (operation 312) is performed at a temperature no greater than 235 °C; no greater than 230 °C; no greater than 225 °C; no greater than 220 °C; no greater than 215 °C; no greater than 210 °C; no greater than 205 °C; no greater than 200 °C; no greater than 195 °C; no greater than 190 °C; or no greater than 185 °C.

[00109] In various implementations, distillation (operation 312) is performed at multiple different pressures. In various implementations, distillation (operation 312) may be performed at vacuum for a first period of time and at a second pressure for a second period of time. In some instances, a second pressure may be between 0.0008 MPa and 0.0012 MPa.

[00110] A distillation vessel may be rotated during distillation (operation 312). In various implementations, a distillation vessel may be rotated at a speed of 100 rotations per minute (rpm) to 300 rpm. In various implementations, a distillation vessel may be rotated at a speed of no less than 100 rpm; no less than 150 rpm; no less than 175 rpm; no less than 200 rpm; no less than 225 rpm; no less than 250 rpm; or no less than 275 rpm. In various implementations, a distillation vessel may be rotated at a speed of no greater than 300 rpm; no greater than 275 rpm; no greater than 250 rpm; no greater than 225 rpm; no greater than 200 rpm; no greater than 175 rpm; or no greater than 150 rpm.

[00111] Method 300 also includes obtaining a triazole melt (operation 314). Triazole melt may include be obtained in a condenser that is in fluid communication with a distillation vessel. Obtaining a triazole melt (operation 314) may include operating a condenser at a temperature no less than 75 °C; no less than 80 °C; no less than 85°C; no less than 90 °C; no less than 95°C; or no less than 100 °C. Obtaining a triazole melt (operation 314) may include operating a condenser at a temperature no greater than 100 °C; no greater than 95 °C; no greater than 90 °C; no greater than 85 °C; no greater than 80 °C; or no greater than 75 °C. [00112] After obtaining a triazole melt (operation 314), the material may be cooled into solid flakes and ground into powder (operation 316). Cooling may be performed at room temperature.

[00113] In some instances, after obtaining a triazole melt (operation 314) a triazole solution is made (operation 318). In some instances, the triazole melt may be solubilized to make a 50 wt% triazole solution. For example, the triazole melt may be solubilized in an aqueous basic solution. An exemplary aqueous basic solution is 50 wt% sodium hydroxide (NaOH).

IV. Exemplary Systems

[00114] Various systems may be used to implement the methods disclosed and contemplated herein. Broadly, exemplary systems may be characterized as not including distillation apparatus and including distillation apparatus. Exemplary systems may be configured for batch or continuous operation. Various aspects of exemplary systems are discussed below.

[00115] FIG. 4 schematically shows exemplary system 400 for synthesizing an aryltriazole.

As shown, system 400 includes reaction vessel 402, temperature control apparatus 404, reactant sources 406, filtration apparatus 408, precipitation vessel 410, pH adjusting material sources 412, and finishing units 414. Other embodiments may include more or fewer components.

[00116] System 400 includes reaction vessel 402 configured to receive various reactants. In some instances, reaction vessel 402 may include temperature control apparatus 404 configured to control a temperature within vessel 402. Temperature control apparatus 404 may include various sensors and computing units, not shown, configured to monitor and adjust a temperature of the reaction vessel 402 contents. Temperature control apparatus 404 may include one or more heating units configured to heat the reaction vessel 402 contents above room temperature.

[00117] In some implementations, vessel 402 may include components for mixing and/or promoting mixing of the vessel contents. For instance, vessel 402 may include one or more baffles. For instance, vessel 402 may include one or more agitation devices.

[00118] Reaction vessel 402 may be in fluid communication with one or more reactant sources 406. Typically, reactant sources 406 comprise a plurality of vessels, each of which are in fluid communication with vessel 402. One or more fluid conveying apparatus, such as pumps, may be used to provide reactants from reactant sources 406 to reaction vessel 402.

[00119] Reaction vessel 402 may be in fluid communication with a weak acid source. Example weak acids are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 402 may be in fluid communication with an ortho-aryl di amine source. Example ortho-aryldiamines are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 402 may be in fluid communication with a water-soluble alkali nitrite source. Example water-soluble alkali nitrites are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 402 may be in fluid communication with a strong acid source. Example strong acids are discussed in greater detail above with reference to the exemplary methods.

[00120] Filtration apparatus 408 separates various impurities from fluid components. In some instances, fdtration apparatus 408 is in fluid communication with vessel 402.

[00121] In some implementations, filtration apparatus 408 may comprise microfiltration components. Various aspects of exemplary microfiltration units are discussed in greater detail above with reference to example method 200.

[00122] In some implementations, filtration apparatus 408 may comprise media filtration components. Various aspects of exemplary media filtration units are discussed in greater detail above with reference to example method 200.

[00123] System 400 may also include precipitation vessel 410 configured to precipitate aryltriazole. In some instances, precipitation vessel 410 may be in fluid communication with filtration apparatus 408.

[00124] Precipitation vessel 410 may receive pH adjusting material from pH adjusting material sources 412. Exemplary pH adjusting material is described in greater detail above with respect to the exemplary methods.

[00125] Finishing units 414 may be configured to perform various operations to complete the final aryltriazole product. For example, finishing units 414 may include one or more filtration units configured to separate triazole from the liquid. For example, finishing units 414 may include one or more washing units configured to wash the solid triazole product. For example, finishing units 414 may include one or more drying units configured to dry washed, solid triazole product. For example, finishing units 414 may include one or more grinding units configured to grind the solid triazole product into a powder. For example, finishing units 414 may include one or more solution-generating units configured to generate a triazole solution using the solid triazole product.

[00126] FIG. 5 schematically shows exemplary system 500 for synthesizing an aryltriazole. As shown, system 500 includes reaction vessel 502, temperature control apparatus 504, reactant sources 506, distillation apparatus 508, condenser 510, and finishing units 514. Other embodiments may include more or fewer components.

[001271 System 500 includes reaction vessel 502 configured to receive various reactants. In some instances, reaction vessel 502 may include temperature control apparatus 504 configured to control a temperature within vessel 502. Temperature control apparatus 504 may include various sensors and computing units, not shown, configured to monitor and adjust a temperature of the reaction vessel 502 contents. Temperature control apparatus 504 may include one or more heating units configured to heat the reaction vessel 502 contents above room temperature.

[00128] In some implementations, vessel 502 may include components for mixing and/or promoting mixing of the vessel contents. For instance, vessel 502 may include one or more baffles. For instance, vessel 502 may include one or more agitation devices.

[00129] Reaction vessel 502 may be in fluid communication with one or more reactant sources 506. Typically, reactant sources 506 comprise a plurality of vessels, each of which are in fluid communication with vessel 502. One or more fluid conveying apparatus, such as pumps, may be used to provide reactants from reactant sources 506 to reaction vessel 502.

[00130] Reaction vessel 502 may be in fluid communication with a weak acid source. Example weak acids are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 502 may be in fluid communication with an ortho-aryl di amine source. Example ortho-aryldiamines are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 502 may be in fluid communication with a water-soluble alkali nitrite source. Example water-soluble alkali nitrites are discussed in greater detail above with reference to the exemplary methods. Reaction vessel 502 may be in fluid communication with a strong base source. Example strong bases are discussed in greater detail above with reference to the exemplary methods.

[00131] Various components, not shown, may be used to separate an oily phase from an aqueous phase. For instance, reaction vessel 502 may include one or more valves positioned near a bottom portion of the reaction vessel 502, and oily phase may be obtained via the one or more valves. In some instances, a commercial decanter or centrifuge may be used to separate an oily phase from an aqueous phase.

[00132] Distillation apparatus 508 separates triazole components from other components in the fluid generated in reaction vessel 502. In some instances, distillation apparatus 508 may be in fluid communication with reaction vessel 502. Tn some implementations, distillation apparatus 508 may include a plurality of distillation units operating in serial and/or parallel.

[001331 Generally, distillation apparatus 508 generates a liquid stream and a gas/vapor stream. The gas/vapor stream is provided to condenser 510. In some instances, the liquid stream may be discarded. In some instances, the liquid stream may be recycled back to the distillation apparatus. [00134] In some implementations, distillation apparatus 508 may include components configured to rotate distillation apparatus during operation. For example, distillation apparatus 508 may be rotatable at a speed of at least 100 rpm; at least 150 rpm; at least 175 rpm; at least 200 rpm; at least 225 rpm; or at least 250 rpm.

[00135] Distillation apparatus 508 may include one or more pressure regulation components. Exemplary pressure regulation components may selectively control a pressure within distillation apparatus 508. In some instances, distillation apparatus may operable at or near vacuum conditions.

[00136] In some implementations, various angles between distillation apparatus 508 and condenser 510 may be used. In some instances, an angle between an outlet of distillation apparatus 508 and an inlet of condenser 510 may be between 150° and 160°; between 155° and 160°; between 150° and 155°; or between 152° and 158°. In various implementations, an angle between an outlet of distillation apparatus 508 and an inlet of condenser 510 may be no less than 150°; no less than 151°; no less than 152°; no less than 153°; no less than 154°; no less than 155°; no less than 156°; no less than 157°; no less than 158°; or no less than 159°. In various implementations, an angle between an outlet of distillation apparatus 508 and an inlet of condenser 510 may be no greater than 150°; no greater than 151°; no greater than 152°; no greater than 153°; no greater than 154°; no greater than 155°; no greater than 156°; no greater than 157°; no greater than 158°; or no greater than 159°.

[00137] Condenser 510 receives and condenses gas and vapor from distillation apparatus 508. Condenser 510 may include temperature control components configured to monitor and/or control a temperature within condenser 510. Condenser 510 may include pressure regulation components configured to monitor and/or control a pressure within condenser 510.

[00138] Triazole generated in condenser 510 may be provided to finishing units 514. Finishing units 514 may be configured to perform various operations to complete the final triazole product. [00139] For example, finishing units 514 may include one or more filtration units configured to separate triazole from the liquid. For example, finishing units 514 may include one or more washing units configured to wash the solid triazole product. For example, finishing units 514 may include one or more drying units configured to dry washed, solid triazole product. For example, finishing units 514 may include one or more grinding units configured to grind the solid triazole product into a powder. For example, finishing units 514 may include one or more solution-generating units configured to generate a triazole solution using the solid triazole product.

V. Experimental Examples

[00140] Various experimental examples were conducted, and the results are discussed below.

Example 1: Synthesis of High Purity Benzotriazole in Acid Form

Table 1

Procedure:

[00141] 22 g of sodium nitrite was dissolved in deionized water to a final weight of 150 g, then transferred into a 4-neck reaction flask. A mixture containing 32.75 g of o- phenylenediamine (o-PDA) and 36.4 g acetic acid, 80.9 g of water and 0.3 g of sodium dithionite was prepared and transferred into the 4-neck reaction flask slowly over a period of 30 min. at room temperature (20.7 °C), An exotherm was observed and the temperature spiked from 20.7 °C to 79.4 °C. The reaction was allowed to proceed at 79.4 °C for Ihour. The heater was turned off and the reaction mixture was permitted to cool down to 26.7 °C where a yellowish white precipitate of BT started to form. The cake was then fdtered and washed several times with ice cold water (meaning water at a temperature between 3 °C and 10°C) until the pH of washings was around 6.5. BT was then further purified to a snow-white solid by mixing with water and charcoal at 43.3-60 °C followed by filtration and washing with ice cold water. BT not treated with charcoal was yellow in color.

[00142] Purity of the BT and TT products was determined by reversed phase high performance liquid chromatography (RP-HPLC) using a Waters Cis reversed-phase column (3.0 x 150 mm x 3.5 pm particle) at a flow rate of 0.5 ml/minute and a step gradient of an eluant mixture comprising 0.05 wt% formic acid in deionized water to acetonitrile in 50 minutes. Samples were weighed, dissolved, and diluted in deionized water to make a 0.01 wt% solution of the sample. 0.025 pL of each 0.01 wt% sample solution was automatically injected as each experimental sample. The column temperature was maintained at 40° C throughout the analytical assay.

[00143] FIG. 6 shows the RP-HPLC results for BT. FIG. 7 shows the RP-HPLC results for TT. The area under the BT or TT peaks was calculated as the weight of the sample. The identity of the putative BT and TT peaks in the experimental chromatography traces were confirmed by comparison to BT and TT analytical standards of > 99 wt% purity.

Example 2: Synthesis of High Purity Tolyltriazole through Acidification to pH 0-1

Followed by Microfiltration

Procedure:

[00144] 1091.1 g of deionized water was mixed with 236.8 g of glacial acetic acid inside a 3- necked 5-liter reaction flask equipped with a mixer, heating mantle and temperature controller, and heated up to 60 °C. 238.2 g of o-toluene diamine (o-TDA, previously melted at 100 °C)) was added into the reaction flask and the mixture was kept at 60 °C for 30 minutes. The reaction mixture was allowed to cool down to room temperature (22-25 °C). 349.6 g of 40% sodium nitrite was slowly added to the reaction mixture at a controlled rate to keep the temperature below 90 °C. An exotherm was observed and the temperature was spiked from 22°C to 80 °C. The heater was then turned on and set at a temperature of 90 °C. The reaction mixture was allowed to react at 90 °C for 1 hour. 2017 g of 1 M nitric acid was added to the finished reaction mixture and allowed to mix for 3 hrs. at 90 °C. The entire batch was then transferred while hot into the feeding tank of a JMark microfiltration unit equipped with a tubular, titanium (Ti)- coated stainless steel membrane column, with dimensions of 3 meter (6 tubes 0.5 m each) and pore size of 0.3-1 micron. The feed tank was kept at 90 °C along the filtration process and a pressure of 0.69-0.76 MPa was applied to push the acidified mixture through the membrane filter. The TT rich permeate was separately collected without recirculation through the membrane. The acidic, purified filtrate was then adjusted to a pH of 5.5 with 50% NaOH, where TT was precipitated, filtered out, washed and dried to give nitrite, nitrate and chloride free pure solid TT. The retentate/concentrate was separately collected and found to be rich in the colored bodies with minimum amount of TT.

[00145] Sample purity was determined and calculated as described in Example 1, above. Solid purity was determined to be 100.1%. The purity of the 50% Na-TT was determined to be 98.6%. [00146] FIG. 8A is a photograph showing the experimentally generated solid TT and FIG. 8B is a photograph showing the experimentally generated 50% Na-TT. Example 3: Synthesis of High Purity Tolyltriazole through acidification to pH 0-1 followed by glass wool media filtration

Procedure:

[00147] 160.2 g of deionized water was mixed with 46.1 g of glacial acetic acid inside a 4- necked 0.5-liter reaction flask (at room temperature) equipped with a mixer, heating mantle and temperature controller. 37.4 g of molten o-toluene diamine (o-TDA) was added into the reaction flask and the mixing was continued for 30 minutes where the reaction mixture was allowed to cool down around 26.7 °C . 54.2 g of 40% sodium nitrite was slowly added to the reaction mixture at a controlled rate to keep the temperature below 79.4 °C. An exotherm was observed and the temperature was spiked from 26.7 °C to 73.9 °C. The heater was then turned on and set at a temperature of 79.4 °C. The reaction mixture was allowed to react at 79.4 °C for 1 hour or until the TT concentration reached the calculated stochiometric amount or the nitrite concentration dropped down to minimum. 100 g of 5 M nitric acid was added to the reaction mixture and allowed to mix for 3 hrs. at 79.4 °C or until the concentration of TT reaches a maximum in the aqueous layer. The entire acidified mixture was then vacuum filtered through silane modified (treated with a dimethyldichlorosilane) borosilicate glass wool with a fiber diameter of 8 micron, where the dark bodies were selectively adsorbed on the fibers allowing a purified TT to pass through. The acidic, purified filtrate was then adjusted to a pH of 5.5 with 50% NaOH, where TT was precipitated, filtered out, washed and dried to give nitrite, nitrate and chloride free pure solid TT. Example 4: Synthesis of High Purity Tolyltriazole through adjustment to pH 5.5 followed by rotary evaporator distillation

Procedure:

[00148] 59.29 g of deionized water was mixed with 8.05 g of glacial acetic acid inside a 4- necked 0.5-liter reaction flask (at room temperature) equipped with a mixer, heating mantle and temperature controller. 13.22 g of molten o-toluene diamine (o-TDA) was added into the reaction flask and the mixing was continued for 30 minutes where the reaction mixture was allowed to cool down to around 26.7 °C. 19.44 g of 40% sodium nitrite was slowly added to the reaction mixture at a controlled rate to keep the temperature below 79.4 °C. An exotherm was observed and the temperature was spiked from 26.7 °C to 73.9 °C. The heater was then turned on and set at a temperature of 79.4 °C. The reaction mixture was allowed to react at 79.4 °C for 1 hour or until TT concentration reached the calculated stochiometric amount or the nitrite concentration dropped down to minimum. The mixer was stopped to allow the TT concentrate to settle at the bottom of the flask, while the heater was kept on at a temperature of 79.4 °C or higher to keep TT in a melt state. The top acidic aqueous layer was decanted off, and the TT concentrate was transferred into the evaporation flask of a rotary evaporator (Buchi R-300), for colored bodies removal by distillation at high temperature and vacuum. The distillation flask was heated up to 200-220 °C and rotated at a speed of 200 rpm in an oil bath. The vacuum was lowered to a pressure of 800-1200 kPa and the condenser was constantly kept at 95 °C to keep the distilled TT in a clear yellow melt state. The TT melt was either poured off and left to cool down into solid flakes and ground into a powder. Alternatively, the TT clear yellow melt is then solubilized in a calculated amount of 50% NaOH and water to make 50% Na-TT solution of light-yellow color.

[00149] Sample purity was determined and calculated as described in Example 1, above. Solid purity was determined to be 98.7%. The purity of the 50% Na-TT was determined to be 100.7%. [00150] FIG. 9A is a photograph of the distillate. FIG. 9B is a photograph showing the TT cold melt after cooling the distillate. FIG. 9C is a photograph showing TT powder after grinding. FIG. 9D is a photograph showing the ground TT powder. FIG. 9E is a photograph showing 50% Na-TT after combining the TT powder with 50% NaOH and DI water.

Example 5: Synthesis of High Purity Tolyltriazole through solid crude TT distillation by rotary evaporator

Procedure:

[00151] 173.3 g of deionized water was mixed with 36.3 g of glacial acetic acid inside a 4- necked 0.5-liter reaction flask (at room temperature) equipped with a mixer, heating mantle and temperature controller. The mixture was heated up to 60 °C. 37.4 of molten o-toluene diamine (o-TDA) was added into the reaction flask and the mixing was continued for 30 minutes at 60 °C. The reaction mixture was then allowed to cool down to around 26.6 °C. 55.4 g of 40% sodium nitrite was slowly added to the reaction mixture at a controlled rate to keep the temperature below 79.4 °C. An exotherm was observed and the temperature was spiked from 26.7 °C to 73.9 °C. The heater was then turned on and set at a temperature of 90 °C. The reaction mixture was allowed to react at 90 °C for 1 hour or until TT concentration reached the calculated stochiometric amount or the nitrite concentration dropped down to minimum. 47.63 g of 50% NaOH was added to the reaction mixture and allowed to mix for 30 minutes to fully solubilize TT. The sample was then stored for a period of 3 months. Later on, the entire batch was treated with 70% nitric acid to achieve a pH of 5.5 and allowed to cool down, where TT crude got solidified, and the aqueous layer was decanted. The solid TT crude was then transferred into the evaporation flask of a rotary evaporator (Buchi R-300), for colored bodies removal by distillation at high temperature and vacuum. The distillation flask was heated up to 200-220 °C and rotated at a speed of 200 rpm in an oil bath. The vacuum was lowered to a pressure of 800-1200 kPa and the condenser was constantly kept at 95 °C to keep the distilled TT in a clear yellow melt state. The TT melt was either poured off and left to cool down into solid flakes and ground into a powder. Alternatively, the TT clear yellow melt is then solubilized in a calculated amount of 50% NaOH and water to make 50% Na-TT solution of light-yellow color.

[00152] Sample purity was determined and calculated as described in Example 1, above.

Example 6: Synthesis of High Purity Tolyltriazole through adjustment to pH 5.5 followed by rotary evaporator distillation

Procedure:

[00153] 295.8 g of deionized water was mixed with 196 g of glacial acetic acid inside a 4- necked 5-liter reaction flask (at room temperature) equipped with a mixer, heating mantle and temperature controller. 311 .8 g of molten o-toluene diamine (o-TDA) was added into the reaction flask and the mixing was continued for 30 minutes where the reaction mixture was allowed to cool down to around 26.7 °C. 451 g of 40% sodium nitrite was slowly added to the reaction mixture at a controlled rate to keep the temperature below 79.4 °C. An exotherm was observed and the temperature was spiked from 26.7 °C to 73.9 °C. The heater was then turned on and set at a temperature of 79.4 °C. The reaction mixture was allowed to react at 79.4 °C for 1 hour or until TT concentration reached the calculated stochiometric amount or the nitrite concentration dropped down to minimum. The mixer was stopped to allow the TT concentrate to settle at the bottom of the flask, while the heater was kept on at a temperature of 79.4 °C or higher to keep TT in a melt state. The top acidic aqueous layer was decanted off, and the TT concentrate/crude was checked for pH(around 5.2-5.5) and then transferred into the evaporation flask of a rotary evaporator (Buchi R-300), for colored bodies removal by distillation at high temperature and vacuum. The distillation flask was heated up to 200-220 °C and rotated at a speed of 200-250 rpm in an oil bath. The vacuum was lowered to a pressure of 800-1200 kPa and the gas phase TT was kept under a temperature of 80 °C by careful adjustment of the rotary drive unit. The condenser was constantly kept at 95 °C to keep the distilled TT in a clear yellow melt state. The TT melt was either poured off and left to cool down into solid flakes and ground into a powder. Alternatively, the TT clear yellow melt is then solubilized in a calculated amount of 50% NaOH and water to make 50% Na-TT solution of light-yellow color.

Embodiments

[00154] For reasons of completeness, the following embodiments are provided.

Embodiment 1. A method of synthesizing an aryltriazole, the method comprising: mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; mixing a strong acid into the fourth mixture; heating the fourth mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a reacted fourth mixture; providing the reacted fourth mixture to a purification unit, thereby generating a permeate stream and a retentate; adjusting a pH of the permeate stream to be no less than 5 and no greater than 5.5 to generate a fluid comprising precipitate; providing the fluid comprising precipitate to a filtration unit; and obtaining an aryltriazole from the filtration unit.

Embodiment 2. The method according to Embodiment 1, wherein the weak acid is acetic acid.

Embodiment 3. The method according to Embodiment 1 or Embodiment 2, wherein a molar ratio of water to weak acid is no less than 5 : 1 and no greater than 25 : 1.

Embodiment 4. The method according to any one of Embodiments 1-3, wherein a molar ratio of water to weak acid is about 5: 1.

Embodiment 5. The method according to any one of Embodiments 1-4, wherein the orthoaryldiamine is an alkyl-substituted ortho- toluene diamine (TDA).

Embodiment 6. The method according to any one of Embodiments 1-5, wherein a ratio of a molar amount of ortho-aryldi amine to a molar amount of the water-soluble alkali nitrite is between 1 : 1.02 to 1 : 1.05.

Embodiment 7. The method according to any one of Embodiments 1-6, wherein the water- soluble alkali nitrite is sodium nitrite, potassium nitrite, or a salt thereof.

Embodiment 8. The method according to any one of Embodiments 1-7, wherein the purification unit is a microfiltration unit. Embodiment 9. The method according to any one of Embodiments 1-8, wherein the purification unit is a media filtration unit.

Embodiment 10. The method according to any one of Embodiments 1-9, wherein the aryltriazole is benzotriazole.

Embodiment 11. The method according to any one of Embodiments 1-10, wherein the aryltriazole comprises 4-methylbenzotriazole, 5-methylbenzotriazole, or a mixture thereof.

Embodiment 12. The method according to any one of Embodiments 1-11, wherein the strong acid is nitric acid (HNO3).

Embodiment 13. The method according to any one of Embodiments 1-12, wherein heating the second mixture is performed for at least 15 minutes and no more than 180 minutes.

Embodiment 14. The method according to any one of Embodiments 1-13, wherein heating the third mixture is performed for at least 15 minutes and no more than 300 minutes.

Embodiment 15. The method according to any one of Embodiments 1-14, wherein heating the fourth mixture is performed for at least 90 minutes and no more than 270 minutes.

Embodiment 16. The method according to any one of Embodiments 1-15, further comprising filtering, washing, and drying the aryltriazole; and either generating an aryltriazole powder or generating a sodium aryltriazole solution.

Embodiment 17. A method of synthesizing an aryltriazole, the method comprising: mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; separating an oily phase from the fourth mixture; distilling, in a distillation unit, the oily phase at a temperature no less than 180 °C and no greater than 230 °C and at a pressure no less than 0.0008 MPa and no greater than 0.0012 MPa; and condensing a vapor phase from the distillation unit, thereby generating the aryltriazole.

Embodiment 18. The method according to Embodiment 17, wherein separating the oily phase comprises settling and/or decanting.

Embodiment 19. The method according to Embodiment 17 or Embodiment 18, wherein the weak acid is acetic acid; wherein the ortho-aryldiamine is an alkyl-substituted ortho- toluene diamine (TDA); and wherein the water-soluble alkali nitrite is sodium nitrite, potassium nitrite, or a salt thereof.

Embodiment 20. The method according to any one of Embodiments 17-19, wherein a molar ratio of water to weak acid is no less than 5 : 1 and no greater than 25: 1; and wherein a ratio of a molar amount of ortho-aryldiamine to a molar amount of the water- soluble alkali nitrite is between 1: 1.02 to 1:1.05.

Embodiment 21. The method according to any one of Embodiments 17-20, wherein the aryltriazole is (i) benzotriazole or (ii) 4-methylbenzotriazole, 5-methylbenzotriazole, or a mixture thereof.

Embodiment 22. The method according to any one of Embodiments 17-21, further comprising generating an aryltriazole powder. Embodiment 23. The method according to Embodiment 22, further comprising generating a sodium aryltri azole solution.

Embodiment 24. A method of synthesizing an aryltriazole, the method comprising: mixing a weak acid with water to generate a first mixture; mixing an ortho-aryldiamine into the first mixture to generate a second mixture; heating the second mixture to a temperature no less than 35 °C and no greater than 65 °C; after heating the second mixture, mixing a water-soluble alkali nitrite into the second mixture to generate a third mixture; heating the third mixture to a temperature no less than 75 °C and no greater than 96 °C to generate a fourth mixture; distilling, in a first distillation unit, the fourth mixture at a temperature no less than 68 °C and no greater than 78 °C and at a pressure no less than 0.0038 MPa and no greater than 0.0048 MPa; obtaining a liquid phase from the first distillation unit; distilling, in a second distillation unit, the liquid phase at a temperature no less than 213 °C and no greater than 222 °C and at a pressure no less than 0.0006 MPa and no greater than 0.0014 MPa; and condensing a vapor phase from the second distillation unit, thereby generating the aryltriazole.

Embodiment 25. The method according to Embodiment 24, wherein the second distillation unit is the first distillation unit.

Embodiment 26. The method according to Embodiment 24 or Embodiment 25, wherein the weak acid is acetic acid; wherein the ortho-aryldiamine is an alkyl-substituted ortho- toluene diamine (TDA), and wherein the water-soluble alkali nitrite is sodium nitrite, potassium nitrite, or a salt thereof. Embodiment 27. The method according to any one of Embodiments 24-26, wherein a molar ratio of water to weak acid is no less than 5 : 1 and no greater than 25: 1; and wherein a ratio of a molar amount of ortho-aryldiamine to a molar amount of the water- soluble alkali nitrite is between 1: 1.02 to 1:1.05.

Embodiment 28. The method according to any one of Embodiments 24-27, wherein the aryltriazole is (i) benzotriazole or (ii) 4-methylbenzotriazole, 5-methylbenzotriazole, or a mixture thereof.

Embodiment 29. The method according to any one of Embodiments 24-28, further comprising generating an aryltriazole powder.

Embodiment 30. The method according to any one of Embodiments 24-29, further comprising generating a sodium aryltriazole solution.