ANALYSIS

FIELD OF THE INVENTION

[0001] The invention relates to an analytical technique for the quantitative determination of an analyte, in particular to an on-line analytical technique for the quantitative determination of carbonyl content in alcohols produced by the hydrogenation of aldehydes.

BACKGROUND OF THE INVENTION

[0002] Hydro formylation is a well-known process in which an olefin is reacted with carbon monoxide and hydrogen in the presence of a catalyst to form aldehydes and/or alcohols containing one carbon atom more than the feed olefin. It is also known as the Oxo process, or as the oxonation process. The commercially important Oxo process produces such alcohols, which find uses in plastics, soaps, lubricants, and other products. Thus, hydro formylation of ethylene yields propionaldehyde and propylene yields a mixture of n- and iso-butyraldehyde (with the n- isomer usually predominating), followed by catalytic hydrogenation to the corresponding alcohols, e.g. n-propanol and n-butanol. Synthetic alcohols, particularly those in the range of about 8 to 13 carbon atoms (C8-C13), are used as plasticizers for poly(vinyl chloride) and the like. By way of example, the important plasticizer alcohol, 2-ethylhexanol, is made by alkali-catalyzed condensation of n-butyraldehyde to yield the unsaturated aldehyde, 2-ethyl-hex-2-enal, which is then hydrogenated to yield the desired 2-ethylhexanol.

[0003] The Oxo process and variations thereon are the subject of numerous patents and patent applications, recent examples of which are U.S. Patent Nos. 8,288,595; 8,049,043; and 8,022,256.

[0004] Synthetic alcohols are typically plagued with the problem of undesirable color and color forming impurities, e.g., aldehydes and ketones. Many methods have been tried to mitigate the problem, for example, treatment with reducing agents, such as hydrogen in the presence of a catalyst such as zinc and copper catalyst, Raney nickel catalyst, zirconium promoted nickel-kieselguhr catalyst, or the like, treatment with borohydrides such as sodium borohydride, and also ozone treatments. See, for instance, U.S. Patent Nos. 3,642,915 and 3,232,848.

[0005] As an example of a commercial process, the crude alcohol product from the hydrogenation section of the Oxo Process, containing color and color-forming impurities, is passed through a finishing section, where it is treated with sodium borohydride. The reactivity of sodium borohydride towards aldehydes and ketones (if present) is much greater than the reactivity of sodium borohydride with the active hydrogen of the alcohol or the ester carbonyl. Sodium borohydride reduces aldehydes and ketones to the corresponding alcohols.

[0006] The amount of agent to use in the finishing section will depend on the amount of aldehydes and ketones in the crude product. Excess sodium borohydride leads to the formation of particulates in the product alcohol. It can also slow down the reaction to form plasticizers in the next production step. It may also lead to a decrease in resistivity in products used for wire and cable insulation. In the case where hydrogen is used in the finishing section, excess use of hydrogen is disadvantageous at least because of the expense.

[0007] Accordingly, analysis of the crude product for carbonyl content is important to avoid over- or under-treatment in the finishing section, and prompt analysis results are important in order to accurately control the treatment process. However, analysis of trace carbonyl impurities in the manufacture of Oxo alcohols and many other organic compounds has been by laboratory testing. This generally involves transport of the samples, analysis at the lab and reporting the data back to the manufacturing unit.

[0008] The amount of residual aldehydes and ketones may be expressed as a carbonyl number. The theoretical carbonyl number (TCBN) of a material is traditionally reported in mg

KOH per gram of sample. This originated from the fact that historically KOH was used to titrate the HCL liberated when the carbonyl compound reacted with hydroxylamine hydrochloride. The theoretical value for a pure carbonyl compound is expressed by the following formula:

TCBN = (FWKOH/FW CARBONYL COMPOUND) X (NCARBONYL COMPOUND) X 1000 mg/g where FW is the formula weight of the species specified in the equation. N is the number of active carbonyl groups in the carbonyl compound. The TCBN for pure 2-octanone, typically used as a calibration standard, is 438. The carbonyl number (CBN) for a standard is expressed by the following formula:

CBN=(W x TCBN x P)/T

where W the weight of carbonyl compound; P is the percent purity of carbonyl compound; T is the total weight of standard. The CBN for 98% pure 2-octanone is 429 (W/T=l). The units for both TCBN and CBN is mg KOH/g, which are typically omitted in reporting the respective numbers.

[0009] The CBN value for an unknown sample may be obtained via direct titration, by way of example, with hydroxylammoniumchloride to form an oxime and free hydrochloric acid followed by pontentiometric titration of the free hydrochloric acid with an alcoholic solution of tetra-n-butyl ammonium hydroxide or an inferential technique using, by way of example, an extractive method followed by spectrophotometric determination as set forth, for instance, by Lohman, Spectroscopic Determination of Carbonyl Oxygen, Analytical Chemistry, Vol. 30, No. 5, May 1958, pp. 972-974, or a non-extractive technique using spectrophotometric determination as set forth, for instance, by Bartkiewicz and Kenyon, in Anal. Chem. Vol. 35, No. 3, March 1963. These methods are laborious and at best the results are obtained on the order of one hour after the sample is taken. While the analysis is going on, the commercial process continues with possible wasteful use of treating chemicals and/or poor quality control of the product alcohol, as previously discussed.

[0010] A reagent comprising an alcoholic solution of 2,4-dinitrophenylhydrazine (DNPH) and sulfuric acid has previously been described for qualitative analysis using Thin Layer Chromatography (TLC). See Organikum, pp. 70-71, 16, VEB Verlag, Berlin 1986. This technique, however, is inapplicable to quantitative determination.

[0011] Another existing wet chemical technique is described in the document BRCP 4589, available from ExxonMobil Chemical Company, Baton Rouge, Louisiana, and suffers from several disadvantages. Among these are: large quantities of chemicals are needed to run continuously operating instruments; instrument capabilities limit the practical range of the carbonyl number that can be measured; the initial cost and maintenance costs of the instrumentation are high; required calibrations are frequent and time consuming; and the analysis results for samples take no less than 45 minutes after sample preparation. Thus, existing laboratory analysis to determine the carbonyl content of Oxo alcohols is labor- intensive and time-consuming, reducing the economies of the process.

[0012] A subsequent technique described in U.S. Patent App. Pub. No. 2006/0145065 similarly suffers from several disadvantages. That publication describes a fast analysis method in which a sample to be analyzed is combined with a strong reagent solution of DNPH and sulfuric acid and subsequently reacted with a KOH mixture before undergoing analysis by a spectroscopic technique to determine the carbonyl content of the sample. This technique utilizes unstable reagents necessitating frequent replacement, and requires manual laboratory filtration due to precipitation of an insoluble salt requiring regular filter replacement.

[0013] One problem identified with this technique was the instability of the required KOH mixture reagent. It has been found that the KOH mixture comprising ethanol, water, and KOH, catalyzes carbonyl growth over time. The KOH slowly catalyzes oxidation of ethanol into acetaldehyde. This slow change in the KOH mixture causes uncontrolled variation in measurement results unless the KOH mixture is changed regularly and frequently.

[0014] Another problem identified was that the neutralization of sulfuric acid with KOH forms a large amount of insoluble K ₂ SO ₄ salt precipitant requiring filtration before a colorimetric measurement can be taken. Such burdensome filtration needs make an unmanned on-line process infeasible. The filter would need to be changed often either manually or by the action of an automated filter changing device that would be difficult and expensive to develop and maintain.

SUMMARY OF THE INVENTION

[0015] The present inventors surprisingly have found a new process that overcomes the noted drawbacks of existing methods including the carbonyl analysis process described in U.S. Patent App. Pub. No. 2006/0145065, thus providing a wet chemical method adapted to run in an on-line analyzer, potentially in conjunction with an Oxo alcohol finishing process. The inventive process greatly improves response time for unit operations, helps insure product quality, and reduces necessary manpower. On-line analysis additionally allows for carbonyl treatment processes to be controlled in real time, thereby reducing the usage and corresponding cost of treatment reagents, such as sodium borohydride, and preventing product overtreatment which can result in unsafe levels of free hydrogen or require additional hydrogen removal processes.

[0016] The invention is in part directed to a process for quantitative analysis of an analyte (species of interest, e.g., carbonyl containing species) in a sample which includes (1) mixing the sample with a first reagent to form a reaction mixture, wherein the first reagent mixture comprises a phenylhydrazine and an acid catalyst, and wherein the acid catalyst catalyzes a reaction of the analyte and the phenylhydrazine faster than HC1; (2) mixing a portion of the reaction mixture with a second reagent and a third reagent to form a final mixture containing a measurable species corresponding to the analyte, wherein the second reagent comprises a strong base and water, and the third reagent comprises an alcohol and water; (3) determining the quantity of the measurable species in the final mixture using a non- extractive spectrophotometric technique; and (4) determining the quantity of analyte present in the sample by correlation to the determined quantity of the measurable species.

[0017] The phenylhydrazine may be 2,4-dinitrophenylhydrazine. The strong base may be NaOH. The third reagent may comprise ethanol and water. The acid catalyst is H ₂ SO ₄ . The second and third reagents may be stored separately until mixing with the reaction mixture. The final mixture does not need to be filtered before the quantity of the measurable species is determined using the non-extractive spectrophotometric technique.

[0018] It is an object of this invention to provide a simple and effective process of quantitative analysis, particularly adaptable to the quantitative analysis of carbonyl content, and even more particularly adaptable to the finishing process of synthetic alcohols so as to improve their color and remove impurities therefrom while preventing overtreatment. Such impurities may cause undesirable color and quality issues with downstream products.

[0019] The embodiments listed above are not mutually exclusive and may be combined. These and other embodiments, objects, features, and advantages will become apparent as reference is made to the following detailed description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Described herein are systems and methods for quantitative determination of an analyte, particularly for on-line carbonyl analysis. Various specific aspects of the invention will now be described, including definitions that are adopted herein for purposes of understanding the claimed invention. While the following detailed description illustrates specific aspects, those skilled in the art will appreciate that the invention can be practiced in other ways. For purposes of determining infringement, the scope of the invention will refer to any one or more of the appended claims, including their equivalents, and elements or limitations that are equivalent to those that are recited. Any reference to the "invention" may refer to one or more, but not necessarily all, of the inventions defined by the claims.

[0021] The invention is in part directed to a process for quantitative analysis of an analyte in a sample which includes (1) mixing the sample with a first reagent to form a reaction mixture, wherein the first reagent mixture comprises a phenylhydrazine and an acid catalyst, and wherein the acid catalyst catalyzes a reaction of the analyte and the phenylhydrazine faster than HCl; (2) mixing a portion of the reaction mixture with a second reagent and a third reagent to form a final mixture containing a measurable species corresponding to the analyte, wherein the second reagent comprises a strong base and water, and the third reagent comprises an alcohol and water; (3) determining the quantity of the measurable species in the final mixture using a non-extractive spectrophotometric technique; and (4) determining the quantity of analyte present in the sample by correlation to the determined quantity of the measurable species. To avoid misunderstanding, as used herein the term "analyte" means the species that is being quantitatively analyzed, i.e. a carbonyl containing species including but not limited to aldehydes and/or ketones in a sample comprising C3-C20 alcohols.

[0022] The quantitative analytical technique according to the invention is conveniently and advantageously adapted to a commercial hydro formylation process (i.e., oxonation process, or "Oxo Process") finishing section. The sample may be taken from an alcohol mixture containing alcohol and optionally carbonyl-containing compounds. The alcohol may be a branched or linear C3-C20 alcohol, aromatic or cyclic alcohol, or various mixtures thereof. The carbonyl containing compounds, which are the analyte in the alcohol mixture, may be ketones, aldehydes, or mixtures thereof. The sample may be taken from an unfinished alcohol stream, for example from downstream of a hydrogenation step and distillation step, but upstream from a hydro finishing step. The sample may alternatively be taken downstream from a hydro finishing step, or even parallel to a hydro finishing step. Such hydro finishing may entail catalyzed hydrogenation or chemical treatment such as treatment with sodium borohydride.

[0023] However, it is to be understood that the process according to the invention is useful for quantitative analysis, e.g., carbonyl number determination on any sample by the addition of the reagents according to the present invention followed by potentiometric titration or spectrophotometric techniques using extractive or non-extractive methods, and is also useful for the determination of other analytes, i.e., those analytes which react with the reagent according to the present invention to form a moiety which may be quantitatively analyzed by spectroscopic (or spectrophotometric; the terms are used interchangeably herein), chromatographic, or other quantitative techniques.

[0024] The first reagent may include a phenylhydrazine and an acid catalyst in solution. The phenylhydrazine may form a colored entity with the analyte, which may comprise aldehydes and ketones, whereby the analyte may be quantitatively determined by quantitative determination of the entity, either alone without further reaction (e.g., by non-extractive or extractive analysis such as set forth in Bartkiewicz et al, or Lohman, respectively, referred to above) or by reaction of the entity with yet another compound, e.g., a strong base, to generate a measurable species which may subsequently be quantitatively determined by techniques such as any spectroscopic method. The phenylhydrazine may have electron-withdrawing substituents, e.g., a nitro group, such as a dinitrophenylhydrazine, including without limitation 2,4-dinitrophenylhydrazine. As used herein "DNPH" refers specifically to the species 2,4- dinitrophenylhydrazine. DNPH will form a colored entity with aldehydes and ketones which will then react with a strong base, such as NaOH, to form a species that may be analyzed by spectrophotometric techniques, including without limitation the yellowness color index measure according to ASTM E-313. The yellowness color index is per se well-known; see, for instance, U.S. Patent No. 3,972,854. Other techniques such as those in ASTM D1500 and ASTM D6045 may also be applicable.

[0025] The acid catalyst present in the first reagent catalyzes the reaction between the phenylhydrazine and the analyte faster than HC1. A DNPH-HCl complex has been used in the prior art but the present inventors have discovered that a more robust reaction is necessary in order to provide for an on-line analysis. Sulfuric acid is a suitable acid.

[0026] The first reagent may be a highly concentrated solution of acid catalyst and DNPH. The reagent may comprise a solution containing 10 vol. % or more acid and about 1 part by weight DNPH to about 5 parts by volume concentrated acid. The acid may be an acid that catalyzes the reaction of the analyte, if present, and the DNPH faster than HC1. Thus, the reagent may comprise 10 vol. % or more concentrated (i.e., between 90-100%) sulfuric acid and about 1 g DNPH per 5 mL sulfuric acid in an aqueous alcoholic solvent, which may comprise ethanol. Other useful acids include HCIO ₃ , HNO ₃ , HCIO ₄ , trifluoromethylsulfonic acid, and the like. The solvent for the first reagent may comprise a mixture of water and ethanol. The alcohol may be denatured alcohol and the water may be deionized water. A mixed solvent useful in the present invention may be a solution having a ratio of ethanohwater of from about 4: 1 to about 1 : 1, or the solvent may comprise about 3 parts ethanol to about 1 part water. A suitable denatured alcohol is available from EMD Millipore as product AX0445E-1 OmniSolv®, a high purity solvent consisting of approximately 95 parts by volume of specialty denatured ethyl alcohol formula 3A (200 proof), methanol (in the amount of about 4.3 vol. % in the final high purity solvent) and 5 parts by volume isopropyl alcohol (IP A). In one embodiment, the first reagent solution comprises 2-3 wt% DNPH; 20-30 wt% H ₂ S0 ₄ ; 20-30 wt% H ₂ 0; and 40-60 wt% denatured ethanol. The exact amounts of each component used in preparing the first reagent may be determined by one of ordinary skill in the art in possession of the present disclosure.

[0027] With regard to preparation of the first reagent, it will be understood by one of ordinary skill in the art wishing to follow safe laboratory practice that a small amount of the acid stronger than HC1 is slowly added to the aqueous alcohol solution. The phenylhydrazine, e.g., DNPH, is typically then added and the mixture is well stirred. This first reagent solution is of high color and becomes darker in the presence of the sample. This reagent solution may be prepared well ahead of the time at which the analysis will occur. Note that the first reagent solution is light sensitive and will typically degrade over time. It has been found that, for instance, wrapping a bottle containing the solution in aluminum foil will prolong the useful life of the reagent solution for several months. This DNPH solution should be predominately free of particulates before use.

[0028] The second reagent solution may comprise a strong base in aqueous solution. The strong base does not form an abundant amount of precipitant when in contact with the acid catalyst of the first reagent solution, and may be, by way of non-limiting example NaOH. The second reagent may comprise 1.8M NaOH solution in water. This base is used to neutralize the acid of the first addition and thereby reduces the high color of the DNPH sample solution. The resulting solution's carbonyl chromophore becomes the desired measureable species.

[0029] The third reagent solution may include alcohol and water. The third reagent solution is used to insure solubilization of the neutralized acid species and dilutes the mixture to the spectroscopically desired concentration. Specifically, the third reagent may comprise 70% alcohol and 30% water. The alcohol may be denatured ethanol. Alternatively, the third reagent may be the same as the alcohol solvent for the first reagent solution. The exact amounts used in preparing the second and third reagents may be determined by one of ordinary skill in the art in possession of the present disclosure.

[0030] An aspect of the inventive process is carried out by first combining the sample containing the analyte with the first reagent. When the first reagent is mixed with the sample, a highly colored entity is formed due to the reaction between the carbonyl containing compounds, if any are present in the sample, and the DNPH in the first reagent. The first reagent is combined with the sample in a ratio so that there is a reasonable excess of DNPH to the expected carbonyl content, with which the DNPH will react. It is necessary to have at least a 100% stoichiometric amount of DNPH in order to get an accurate reading of carbonyl content, however a large excess of DNPH may negatively impact the signal to noise ratio and variability of the analysis results. For samples with a carbonyl number of 1 or less, a volume ratio of first reagent solution to sample between 1 : 1 and 0.4: 1 provides an excess of DNPH, with a volume ratio of 0.4: 1 providing the best reduction in result variability. For example, 4 ml of first reagent solution may be combined with 10 ml of sample. After combining the first reagent with the sample, the resultant reaction mixture is well-mixed. For example, the reaction mixture may be mixed for 1-5 minutes. [0031] A portion of the reaction mixture is then combined with the second and third reagents to form a final mixture. When combined with the reaction mixture, the second and third reagents together cause a reaction with the species formed from the reaction of the DNPH and the aldehyde and/or ketone, to form an ionic species that may be analyzed by spectrophotometric techniques. Before being combined with the reaction mixture, the second and third reagents are stored separately and not combined. The reaction mixture, second reagent, and third reagent may be combined in a volume ratio of about 1 : 16:48. For example, 0.125 ml of reaction mixture may be combined with 2 ml of second reagent and 6 ml of third reagent. The resulting final mixture is again well-mixed. For example, the final mixture may be mixed for 1-5 minutes.

[0032] In the case where the sample contains a carbonyl- containing species and the first reagent includes DNPH, the final mixture comprises a measurable species, which (without wishing to be bound by theory) is believed to be the "chinoidal anion" shown below:

Chinoidal Anion

where Ri and R ₂ are groups that were attached to the carbonyl in the carbonyl-containing compounds present in the sample. This species may be analyzed by spectrophotometric techniques, including without limitation by colorimetry, uv spectroscopy, infrared spectroscopy, near-infrared spectroscopy, or by the yellowness color index measure according to ASTM E-313. Once the quantity of measurable species is found, the quantity of carbonyl- containing species may be correlated by well-known methods. For example, the final mixture may be measured using a spectrometer at a specified wavelength window appropriate for the carbonyl chromophore. The window is chosen based on its sensitivity to the carbonyl- hydrazine moiety. Quantitation is determined by comparison to known standards using methods typically used for spectrometric methods. [0033] The process described above may be performed in an on-line analyzer in connection with a commercial hydro formylation finishing system. The sample may be provided to the analyzer by use of a fast transfer loop from the finishing system. The on-line analyzer may be of the flow injection type. This allows the addition of the reagents sequentially and at appropriate timing.

[0034] It will be recognized by one of skill in the art in possession of the present disclosure that a color- forming entity, i.e., the phenylhydrazine, may be caused to react with an analyte comprising a moiety of interest other than an aldehyde or ketone and which may also be analyzed by a spectroscopic technique, e.g., carboxylic acid groups by IR spectroscopy, and the like. In particular, carbonyl derivatives having the formula X-C(0)-Y (where X and Y, which may be the same or different, are independently selected from H, F, CI, Br, I, OR, SR, SeR, NRR, PRR, CRR'R", SiRR'R', BRR, A1RR', where R, R ^* , and R", which may be the same or different, are independently selected from H, B, Al, C, Si, N, P, O, S, Se, F, CI, Br, I) will react with DNPH, to form derivatives that can be analyzed using extraction or non-extractive quantitative analysis by chromatographic (e.g., GC, HPLC, or Super Critical Fluid Chromatography (SFC)) and/or spectroscopic techniques (e.g., IR, UV- vis, Raman, NMR, or colorimetry). The structure X-C(0)-Y will be recognized by the ordinary artisan to mean an X and Y substituent independently bonded to the carbon atom of the carbonyl group C(O), otherwise indicated by the structure C=0.

[0035] The use of NaOH as opposed to KOH as described in U.S. Patent App. Pub. No. 2006/0105465 provides a surprising solution to a problem identified by the present inventors. In the process described in U.S. Patent App. Pub. No. 2006/0105465, KOH neutralizes sulfuric acid during the process reaction, producing copious quantities of insoluble K ₂ S0 ₄ precipitate which requires filtering before an accurate colorimetry reading can be taken on the measurable species. This filtration requirement makes usage of the described process in an on-line system impracticable. The amount of solids produced would necessitate frequent, regular filter changes, either necessitating manual operator action, or the implementation of automated filter changing device which is expensive and difficult to engineer, and may be unreliable. The use of NaOH was found to surprisingly produce significantly less precipitate at similar concentrations of KOH as described in U.S. Patent App. Pub. No. 2006/0105465. It was further found that by controlling the water content in the final mixture via the third solution, the salt precipitates can be completely solubilized forming a clear colored solution. Thus, the inventors discovered that the need for filtration is obviated through the use of a sodium based basic reagent and concentration adjustment.

[0036] The separation of the second and third reagents until use surprisingly solved an additional disadvantage with the method described in U.S. Patent App. Pub. No. 2006/0105465 identified by the present inventors. It was discovered that KOH slowly catalyzed oxidation of the alcohol solvent of the basic solution to produce a carbonyl compound such as acetaldehyde. This carbonyl growth caused uncontrollable variation in carbonyl measurement of the sample if the basic solution was not changed regularly and frequently. For example, it was found that trace carbonyl compounds created by reagent instability contributed up to more than 100 times more than carbonyl compounds within the measured sample. By separating the strong base in a second reagent and the ethanol solvent in a third reagent, this instability is avoided and the reagents may be stored and used in an online analyzer without frequent manual reagent exchange.

[0037] Experimental

[0038] Tests were performed comparing the inventive method of carbonyl content analysis to an analysis method disclosed in US Patent App. Pub. No. 2006/0105465 (the "Comparative Method").

[0039] Eight (8) samples were prepared from Oxo alcohol products of differing grade and carbonyl content. The composition of the eight samples are set forth in Table 1. Examples 1-8 and Comparative Examples 1-8 were performed using the corresponding Sample. To illustrate, Example 1 and Comparative Example 1 were conducted using the same Cs isooctyl alcohol sample - Sample 1.

Table 1

[0040] For each Example 1-8, 10 ml of the corresponding Sample (from Table 1) was combined with 4 ml of DNPH solution in a mixing vessel to form a reaction mixture. The DNPH solution constituted 2.6 wt% DNPH, 24.3 wt% sulfuric acid, 21.1% water, and 52.0 wt% water. The reaction mixture was mixed for 1 minute. After mixing, 2.0 ml of 1.8M NaOH solution and 6 ml of ethanol solution were combined with 0.125 ml of reaction mixture in a cuvette to form a final mixture. The ethanol solution constituted 70% denatured ethanol and 30% water. The final mixture was mixed for 3 minutes and allowed to rest before undergoing UV spectroscopy analysis with examination of absorbance at 590 nm. The results were correlated to carbonyl number (CN) using a calibration sample of 1-octanone in 0.0 CN 1-octanol. The results of the CN analysis for Examples 1-8 are set forth in Table 2.

[0041] For each Comparative Example 1-8, 1.0 ml of the corresponding Sample (from Table 1) was combined with 1 ml of DNPH solution to form a reaction mixture. The DNPH solution is the same as used in Examples 1-8. The resulting reaction mixture was mixed for 1 minute. After mixing, 5.0 ml of a KOH/ethanol solution was combined with 0.1 ml of the reaction mixture to form a final mixture. The KOH/ethanol constituted 0.356M KOH in aqueous alcohol solution of 55% denatured ethanol and 45% water. The final mixture was mixed for 1 minute and filtered through a 0.5 μιη filter before undergoing colorimetry analysis. The results were correlated to carbonyl number (CN) using a calibration sample of 1-octanone in 0.0 CN 1-octanol. The results of the CN analysis for Comparative Examples 1- 8 are set forth in Table 2.

Table 2

[0042] The Example results show that the analysis method has good sensitivity, and good reproducibility. Additionally, each Example took from 5-10 minutes to ascertain results. Thus, this analysis method could be performed up to 12 times per hour, whereas it has been found that the Comparative Method can only be performed 1-3 times per hour.

[0043] The present invention provides for an improved analytical method for quantitative determination of carbonyl number. Although the method is not limited to the Oxo Process, as applied to the Oxo Process, it provides for an improved product by way of, inter alia, a more uniform product quality, whether sodium borohydride or catalytic hydrogenation is used to remove residual carbonyl-containing moieties.

[0044] The present invention also allows for real time measurement of carbonyl number allowing for accurate, real time control over a hydro finishing process. As stated in copending US patent application No. 62/040,827, such control over the hydro finishing process makes it possible to produce a low carbonyl number Oxo alcohol product and avoiding overtreatment, which may create dangerous hydrogen levels in a finished product or require additional hydrogen-removal processes.

[0045] Trade names used herein are indicated by a™ symbol or ® symbol, indicating that the names may be protected by certain trademark rights, e.g., they may be registered trademarks in various jurisdictions.

[0046] All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

[0047] When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.

[0048] The invention has been described above with reference to numerous embodiments and specific examples. Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims.