A SYSTEM AND PROCESS OF PREPARATION OF MONO-NITRO BENZO TRIFLUORIDE (NBTF)

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

The present application claims priority from the Indian patent application, having application number 202221028001, filled on 16 ^th May 2022, incorporated herein by a reference.

TECHNICAL FIELD

The present subject matter described herein, in general, relates to a system and process to produce Mono-Nitro benzo trifluoride (NBTF). In particular, the invention relates to an improved, continuous process and system for production of 3 -nitro benzo trifluoride, 2-nitro benzo trifluoride, and 4-nitro benzo trifluoride.

BACKGROUND

The process of nitrating benzo trifluoride is old and well known and has been commercially practiced for many years to yield mono-nitro compounds or generally nitro mass. The produced nitro mass is used, in turn, in the production of corresponding amino compounds. Conventionally, the manufacture of nitro mass comprises the batchwise, stepwise or continuous addition of nitric acid to the mixture of sulfuric acid and benzo trifluoride or addition of nitrating mixture to the benzo trifluoride.

Since the acid phase and the organic phase are not miscible, the reaction rate and the reaction efficiency between the phases are largely limited by mass transfer; that is, by the ability to expose large interfacial areas of each of the phases to each other. As the interfacial areas are increased, the reaction rate between the phases is enhanced. In conventional nitro mass production facilities, these interfacial areas are normally created by reacting the two phases in one or more agitated vessels where high shear forces are applied to the liquids. In the Chemical Engineering Handbook (Perry), 6th Edition, several methods are proposed to achieve intimate mixing or contact between liquids including, for example, in-line motionless mixers, mechanical agitation, gas agitation, jet mixers, injectors, orifice mixers and nozzle mixers. Another problem, which generally arises in the mono-nitration of benzo trifluoride, is a high-level formation of Hydrofluoric acid (HF) or liquid hydrogen fluoride. As known in the art, the highly corrosive nature of (HF) reduces service life of the reaction units involved.

In the case of batch process, the problem of formation of high quantity (HF) is generally observed. Also, the batch type reaction for the production of NBTF leads to a large and extended time period to increase the yield and for maximum conversion of starting materials. Also, to carry out batch type reaction reactors utilizing larger space area are required.

None of the aforesaid methods for achieving large interfacial areas of contact between immiscible liquid phases is completely satisfactory nor has any method, other than mechanical agitation, been used commercially to any degree in the manufacture of mono-nitro compound. These methods either suffer from longer-time duration, maintenance costs and high-power requirements, and thereby high capital, as in the case of agitated vessels, or they are difficult to control in terms of optimum reaction efficiency as in the case of impinging streams or jets.

Therefore, there is a long-felt need to devise a production system and process enabling high-yield, corrosion-free, rapid, compact, cheaper, and economically feasible production NBTF by mononitration. Also, there is a long felt need of implementing reusable recovery spent acid in the process to achieve environmental effectiveness and cost efficiency.

OBJECTS OF THE INVENTION

It is an object of the present disclosure to provide a compact system for large-scale production of mono nitro benzo trifluorides, in a rapid mode, achieving higher productivity in a smaller set-up.

It is an object of present disclosure to provide a process for the reliable and high yield manufacture of mono nitro benzo trifluorides which obviates or mitigates the known deficiencies of the prior art processes.

It is an object of present disclosure to provide a safe and environmentally friendly manufacturing process of mono nitro benzo trifluorides.

It is an object of the present invention to provide a continuous process to produce mono nitro benzo tri fluorides.

SUMMARY

This summary is provided to introduce concepts related to a system and preparation method of mono nitro-benzo trifluorides (NBTF). This summary is not intended to identify essential features of the claimed subject matter, nor it is intended for use in determining or limiting the scope of the disclosed subject matter.

In one embodiment, a system for continuous production of mono nitro-benzo trifluorides (NBTF) is disclosed herein. The system may comprise a first reactor configured for mono-nitration of benzo trifluoride by 90-98% reaction conversion of reactants comprising BTF, H2SO4, and nitric acid. The system may further comprise a second reactor configured for mono-nitration of benzo trifluoride with the remaining 2-10% reaction conversion of the reactants. The system may further comprise a third reactor enabled for separation of spent acid and organic layer comprising nitrobenzo trifluoride by the water addition to maintain the desired strength of spent acid. In one embodiment, the reaction generates 84-85% strength spent acid in the nitro-mass which is diluted while layer separation of spent acid to 72% for the recycle and reuse other member of same family of benzo trifluorides.

The system may further comprise a washing unit for washing of organic layer and separation of 4- nitro benzo trifluorides (4-NBTF), 2-nitro benzo trifluorides (2 -NBTF), and 3 -nitro benzo trifluorides (3 -NBTF) in a specific % ratio.

In an embodiment, the first reactor may comprise a modified agitator, a plurality of turbine blades, a vortex breaker device (which is configured for proper and uniform mixing of the reactants), one or more internal baffles, an internal cooling brine coil, a cooling jacket, an overflow outlet comprising a cleat enabled for transferring the reaction mass of the first reactor to the second reactor.

In another embodiment, a process for continuous synthesis of mono-nitro-benzo trifluoride (NBTF) is disclosed. The process may comprise a step of addition of predetermined molar ratio of benzo trifluoride (BTF) and 98% sulfuric acid (H2SO4) in a first reactor. The process may further comprise a step of addition (403) of a predetermined molar ratio of nitrating agent such as strong nitric acid (HN03) after cooling the first reactor (105) within a temperature range of 5-10°C. The process may further comprise a step of determining a level of reaction mixture in the first reactor reaching up to an overflow level, enabling simultaneous addition of 98% sulfuric acid (H2SO4), strong nitric acid (HNO3), and benzo trifluoride (BTF) in the first reactor. The process may further comprise a step of maintaining the above reaction for about 45-90 minutes for a predetermined flow rate to obtain a nitro-mass comprising a mixture of mono-nitro benzo trifluorides (NBTFs). The inlet and outlet flow rate from the second reactor is optimized for residence time of 45 mins to 2 hrs. The process may further comprise a step of passing the said nitro-mass obtained in the second reactor to a third reactor for layer separation into aqueous and organic layers. Further, the process may comprise a step of passing the said organic layer separated in the third reactor to a washing and distillation unit to obtain pure 3- Nitro benzo trifluoride (3-NBTF), 2- Nitro benzo trifluoride (2-NBTF), and 4- Nitro benzo trifluoride (4-NBTF) in a specific % ratio.

LIST OF ABBREVIATIONS

BTF- Benzo-trifluoride

NBTF- mono nitro Benzo-trifluoride

4-NBTF- 4- nitro Benzo-trifluoride

2-NBTF- 2- nitro Benzo-trifluoride

3-NBTF- 3- nitro Benzo-trifluoride

Mixed acid- mixture of nitric acid and sulfuric acid used in nitration

BRIEF DESCRIPTION OF FIGURES

The detailed description is described with reference to the accompanying Figures. In the Figures, the left-most digit(s) of a reference number identifies the Figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 depicts a system (100) for continuous production of mono nitro-benzo trifluorides (NBTF), in accordance with an embodiment of the present subject matter.

Figure 2 depicts a first reactor (105) enabled for mono-nitration of benzo trifluoride by 90-98% reaction conversion of reactants, in accordance with an embodiment of the present subject matter.

Figure 3 depicts a second reactor (106) configured for mono-nitration of benzo trifluoride with the remaining 2-10% reaction conversion of reactants.

Figure 4 depicts a process (400) for continuous synthesis of mono-nitro-benzo trifluoride (NBTF), in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items.

It must also be noted that, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary methods are described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.

Various modifications to the embodiment may be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art may readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein. The detailed description of the invention will be described hereinafter referring to accompanied drawings.

In one embodiment of the present disclosure, Referring to Figure 1 and 4 a system (100) and process (400) for preparation of mono nitro-benzo trifluoride (NBTF) are disclosed. In one embodiment, the system (100) comprises a plurality of a continuous stirred tank reactors. The said continuous stirred tank reactors of the system (100) may be connected in, but not limited by, series mode, cascade mode, or step-down mode.

In one embodiment, referring to Figures 1 and 2, the system (100) for continuous production of mono nitro-benzo trifluorides (NBTF) is disclosed herein. The system may comprise a first reactor (105) configured for mono-nitration of benzo trifluoride by 90-98% reaction conversion of reactants. The system (100) may further comprise a second reactor (106) configured for mononitration of benzo trifluoride with the remaining 2-10% reaction conversion of reactants.

In another embodiment, the system (100) may further comprise a third reactor (107) enabled for the water treatment of said nitro-mass to separate aqueous layer comprising spent acid and organic layer comprising nitro-benzo trifluoride. The system may further comprise a washing (108) for washing of organic layer and separation of 4-nitro benzo trifluorides (4-NBTF), 2-nitro benzo trifluorides (2-NBTF), and 3-nitro benzo trifluorides (3-NBTF) in a specific % ratio. In a related embodiment, the washing unit (108) may further transfer the 4-nitro benzo trifluorides (4-NBTF), 2-nitro benzo trifluorides (2-NBTF), and 3-nitro benzo trifluorides (3-NBTF) to distillation unit (not shown in figure).

An effluent obtained from the washing unit (108) may further be processed for acidic/alkaline effluent aqueous layer separation. The effluent is then transferred to effluent treatment plant (not shown).

In one embodiment, the system (100) may be enabled for feeding of benzo trifluoride (BTF) from a BTF feed tank (101). In one embodiment, benzo trifluorides employed may be acquired from any convenient source. In one embodiment, benzo trifluorides may be obtained from the reaction of benzene with other chloro- and Fluro- components.

In one embodiment, the system (100) may be enabled for feeding nitrating agent from a nitrating agent feed tank (104). In an embodiment, the nitrating agent feed tank (104) is enabled for feeding strong nitric acid (72%) and 98% sulfuric acid to the first reactor (105).

In one embodiment, the nitrating acid employed in the process of the invention is selected from strong 72% nitric acid and 98% nitric acid. In which the 72% /98% nitric acid is 1.0 to 1.10, preferably 1.05 to 1.15 times the theoretical amount of nitric acid required to nitrate all of the benzo tri fluoride present to mono nitro benzo trifluoride. It has been discovered that when the amount of nitric acid used for this continuous process is more than 1.15 times of theoretical value, the content of by-product spent acid having more nitric acid increases sharply, and when the amount of nitric acid is less than 1.00 times this theoretical value, the amount of unreacted benzo trifluoride increases.

In one embodiment, the system (100) may be enabled for feeding sulfuric acid (H2SO4) from a FFSCfifeed tank (102). The FFSCfifeed tank (102) is enabled for feeding of 98% FFSCfito the first reactor (105).

In one embodiment, the sulfuric acid and nitric acid concentration may be selected such that the reaction could be carried out at a lower temperature without having a super-atmospheric pressure. Contents of sulfuric acid and spent acid added in the reaction of the first reactor (105) are 22-24.0 % nitric acid (72%), and 74-77% sulfuric acid (98%).

In an alternate embodiment, the spent acid having 22.0-24.0 % nitric acid (72%), and 74-77% sulfuric acid (98%) may also be incorporated in the first reactor (105). Further, the ratio of nitric acid and sulfuric acid may be selected such that the nitric acid is preferably low and is substantially fully dissociated to nitronium ion, and commingling the benzo trifluoride with the nitronium ion solution so as to provide a fine emulsion, whereby the reaction can be carried out at a low temperature and at atmospheric pressure to lower the residence time within the first reactor (105) to provide NBTF product having no or low levels of impurities.

146.11 191.11

Referring to Figure 2, in one embodiment, the first reactor (105) may comprise a modified agitator (204) having one or more turbine blades (205), a vortex breaker device (208) configured for proper and uniform mixing of the reactants. As the present disclosure of NBTF preparation is achieved by mass transfer governed reaction, well-designed stirrer blades (205) are introduced in the first reactor (105) for high shear agitation. Referring to figure 2a, is a top view of the first reactor (105) which depicts positioning of one or more baffles (206) with respect to the agitator (204).

Furthermore, to avoid the vortexing, the one or more baffles (206) are provided in the first reactor (105). The width and thickness of baffles are adjusted in such a way that it breaks the vortexing generated due to agitation to ensure thorough mixing. In one embodiment, the residence time is kept between 60-90 minutes to achieve conversion between 90-98%. In one embodiment, the first reactor (105) may further comprise an overflow outlet (209) having a cleat (210) enabled for controlled transferring of the reaction mass without siphoning of the reaction mass from the first reactor (105) to the second reactor (106).

In one embodiment, the second reactor (106) may be enabled for receiving and collecting the overflow of the reaction mass from the first reactor (106). The rest of the 2-10% reaction may take place in the second reactor (106) with a residence time of 45 to 60 mins. In one embodiment, the second reactor (106) may be configured for agitation of the reaction mass kept at high shear to achieve upto 100% conversion of the reaction mass within a predefined period of time achieving reduction in time of reaction.

In one embodiment, the second reactor (106) may comprise an inlet (301) to receive and collect the overflow of the reaction mass from the first reactor (105). The second reactor (106) may further comprise a simple stirrer unit (302) having one or more blades (303) selected from any of propeller blades, turbine blades, or paddle blades. The second reactor (106) may further comprise a controlled cooling mechanism having a jacketed brine cooling (304) and a single internal cooling coil (305). The second reactor (106) may further comprise a plurality of baffles (306) at the internal edge of the reactor. In an embodiment, an outlet (307) from the bottom of the second reactor (106) is configured for transfer of a nitro mass to a third reactor (separator) (107).

In an embodiment, an outlet (307) from the bottom of the second reactor (106) is configured for transfer of a nitro mass to a third reactor (separator) (107).

In one embodiment, the first reactor (105) and the second reactor (106) may comprise scrubber vent(s) (not shown in figure) to scrub out acid fumes for the reactors.

In one embodiment, the reactors involved in preparation of NBTF may be continuous stirred tank reactors. In another embodiment, the respective raw materials with required flow rates are fed by means of a metering pump. As the reaction is highly exothermic, it is controlled by enabling circulation of lower temperature brine of water and methanol in the cooling brine jacket (207), (304) and the internal cooling coil (211), and (305).

In one embodiment, the first reactor (105) may comprise a double internal cooling coil (211) along with the cooling brine jacket (207) and the second reactor (106) may comprise a single internal cooling coil (305) along with the cooling brine jacket (304).

It should be noted herein that, in the conventional method, the temperature of the reaction was not optimized and often led to freezing of the reaction mass in the first reactor because of too low supply of utility temperature (-10°C) which further led to chocking of the overflow line. Therefore, to overcome this issue, in the present invention, temperature of the first and second reactor was maintained between 1-12°C and preferably 4 to 9°C by adjusting using combination of jacketed and internal circulation cooling brine at a predefined temperature and pressure conditions.

In one embodiment, as shown in Figure 1, the system (100) may comprise a BTF and H2SO4 mixing chamber (103). The mixing chamber (103) is configured for addition of pre-mix of BTF and H ₂ SO ₄ to the first reactor (105). In one embodiment, BTF and H2SO4 from the BTF feed tank (101) and H2SO4 feed tank (102), respectively, are added to the first reactor (105) before addition of nitric acid from the feed tank (104).

In one embodiment, as shown in figure 2, the first reactor (105) may comprise one or more reactant inlets such as 72% (or 98%) nitric acid inlet (201), nitro benzo trifluoride inlet (202), and 98% sulfuric acid inlet (203). All the reactants are fed into the first reactor using respective reactant inlets (201), (202) and (203). In one embodiment, the rate of flow of each of the raw material of benzo trifluoride, nitric acid and sulfuric acid components is controlled by adjusting the operating rates of metering pumps so that the reactants are delivered into the reaction chamber of the first reactor (105) in stoichiometric ratio of benzo tri-fluoride and the reaction temperature is maintained below 5°-7°C. The 90-98% conversion of the main reactant is being carried out in the first reactor (105).

In another embodiment, a process (400) for continuous synthesis of mono-nitro-benzo trifluoride (NBTF) is disclosed. It may be understood that invention is in terms of the introduction of a reaction stream of mixed sulfuric acid with benzo trifluoride containing about 25-28% sulfuric acid, and from 13-16 % nitric acid.

The process (400) may comprise a plurality of steps. The process (400) may comprise a step of addition (401) of predetermined molar ratio of benzo trifluoride (BTF) and 98% sulfuric acid (H2SO4) in the first reactor (105). The process (400) may comprise a step of addition (402) of a predetermined molar ratio of nitrating agent such as strong nitric acid (HN03) after cooling the first reactor (105) within a temperature range of 5-10°C. The temperature of range of 5-10°C is maintained by the combination of jacketed and internal circulation brine cooling. The strong nitric acid (HNO3), wherein the nitric acid is having a concentration between 72%-98%.

The process (400) may comprise a step of determining (403) a level of reaction mixture in the first reactor (105) reaching up to an overflow level of about 85% of the first reactor, enabling simultaneous addition of 98% sulfuric acid (H2SO4), 72% nitric acid (HNO3)/ 98% nitric acid, and benzo trifluoride (BTF) in the first reactor. In one embodiment, at step (403) benzo trifluoride, 98% sulfuric acid and 72% nitric acid/98% nitric acid are fed continuously into the first reactor (105) through corresponding feed tanks (101, 102, 103, 104).

In one embodiment, wherein at step (403) benzo trifluoride, 98% sulfuric acid and 98% nitric acid are fed continuously into the first reactor (105) through corresponding feed tanks (101, 102, 103, 104), wherein a molar ratio of BTF: 98% H2SO4: 98% HN03 is 1 : 1.01 : 1.02 to 1 : 1.1 : 1.05.

In one embodiment, wherein at step (403) benzo trifluoride, 98% sulfuric acid and 72% nitric acid are fed continuously into the first reactor (105) through corresponding feed tanks (101, 102, 103, 104), wherein a molar ratio of BTF: 98% H2SO4: 72% HN03 is 1 :2.08: 1.02 to 1 :2.08: 1.05.

In one embodiment, a state of complete emulsification throughout the mixture is created in the first reactor (105) by an agitating system as disclosed herein. In one embodiment, at step of determining (403) a level of reaction mixture in the first reactor (105) reaching up to an overflow level enables a short residence time (60-80 minutes) to the reaction mixture to obtain a nitro-mass comprising a mixture of mono-nitro benzo trifluorides (NBTFs). The 90-98% conversion of the main reactant is being carried out in the first reactor (105).

In one embodiment, the process (400) may comprise a further step of maintaining (404) the above reaction for about 45-90 minutes for a predetermined flow rate and continuously discharging the reaction mixture into a second reactor where rest 2-10% reaction is going to complete. In one embodiment, the process (400) wherein an inlet and outlet flow rate from second reactor (106) is optimized (405) for residence time of 45 mins to 2 hrs.

In an alternative embodiment, the process of the invention may be reversed, that is, benzo trifluoride may be delivered into a stream or body of mixed acid. It will also be understood that the process will be applicable to other nitration or other chemical reactions which are mass transfer limited.

The process (400) may comprise a step of passing (406) the said nitro mass obtained in the second reactor (106) to a third reactor (107) (hereinafter may be alternatively referred to as “separating reactor”) for layer separation of spent acid and organic layer. At this step the organic layer comprising the nitro mass with spent acid is transferred to a separating reactor (107) which is configured to dilute the mixture of organic products 3- nitro benzo trifluoride, 2- nitro benzo trifluoride and 4- nitro benzo trifluorides and separate from spent acid by means of water addition to such extent to keep the spent acid concentration from 84-85% to about 72%- 75% for recycle and reuse in nitration reaction for production other member of same family of benzo trifluorides.

The mixture of organic products comprising nitro mass then separated from the spent acid layer. The collected nitro mass is further subjected for reaction workup and finally fed to fractionating columns to receive the pure compound 1 and compound 2,3 i.e., 3- nitro benzo trifluoride and 2- nitro benzo tri fluoride, 4- nitro benzo tri fluoride.

At step (406), the spent mixed acid separated from the organic layer comprising the mixture of organic products comprising nitro mass may be recycled and reused. In this improved process, the reaction is carried out under atmospheric pressure, and the spent acid contains 1.0-1.5 % nitric acid, 72.0-75.0 % sulphuric acid.

The process (400) may comprise a step of passing (407) the said organic layer separated in the third reactor to washing and distillation unit to obtain pure 3- Nitro benzo trifluoride (3-NBTF), 2- Nitro benzo trifluoride (2-NBTF), and 4- Nitro benzo trifluoride (4-NBTF) in a specific % ratio. In fact, separation of mono nitro benzo trifluorides is possible by performing the distillation process. The isomers like 3- nitro benzo trifluoride, 2- nitro benzo trifluorides and 4- nitro benzo trifluorides separated to each fraction is done in distillation column by means of adding some additives to reduce the distillation hazards. In one embodiment, a maximum overall yield of desired 3-Nitro BTF product was obtained up to 89-91%, 2-Nitro BTF product up to 7-8%, and 4- Nitro BTF product up to 2-2.5%.

The instant invention is further described by the following examples:

Experimental Details:

Example 1: Production of mono nitro-benzo trifluorides (NBTF) in single reactor batch mode

In this example, a predetermined amount of benzo tri-fluoride from BTF feed tank is charged in reactor and predetermined amount of 98% H2SO4 is charged in reactor. After that continuous addition of 72% nitric acid/98% nitric acid is charged keeping the temperature of the reaction between 4-7 degree centigrade. The agitator RPM speed was maintained between 350-450. The residence time in the first reactor was maintained as 45 min to 75 min to achieve maximum conversion of the BTF reactant. The observations of batch type reaction are represented below in Table 1.

Table 1

Referring to Table 1, for an overall residence time of 75 minutes the yield of 3-Nitro BTF was obtained in a range of 89-89.9% and about 0.8% nitric acid remained present in the spent. Further, in case of a single reactor many reaction and safety related issues were observed such as: freezing of reaction mass, formation of high level of HF content and inconsistent conversion. Therefore, the reaction mode was changed to continuous mode, the advantages and technical effects of which are explained in the following examples.

Example 2a: Production of mono nitro-benzo trifluorides (NBTF) in continuous mode by using 72% nitric acid In this example, a predetermined amount of BTF from BTF feed tank at a flow rate of 35-45 kg/hr is mixed with a predetermined amount of 98% H2SO4 at a flow rate of 72.8- 94 kg/hr. The mixture is added to a 100 Lit. first continuous stirred tank reactor comprising at least two baffles, vortex breaker at the bottom and an agitator having 3 turbine blades and a modified overflow line comprising opening/closing cleat component. The agitator RPM speed was maintained at 550-600. After a predefined time period a predefined amount of 72% nitric acid at a flow rate of 22.3- 30 kg/hr is fed to the first reactor, wherein a molar ratio of BTF: 98% H2SO4: 72% HN03 is 1 :2.08: 1.02 to 1 :2.08: 1.10. Upon reaching an overflow limit set in the first reactor, a simultaneous addition of all three reactants in initiated. The reaction mass is transferred to second reactor to maintain the overflow limit, siphoning of the reaction mass and maximum conversion of the reaction mass. After a certain level is reached in a second reactor, the bottom valve of the second reactor, and the circulation line valve is opened. The agitator RPM speed was maintained between 100-150. The residence time in the first reactor was maintained as 60-90 minutes and residence time in a 250 Ltr second reactor was maintained as 300-320 minutes. The temperature of the first reactor was maintained at 5-7 degrees by jacketed and internal circulation of chilled brine. After a predetermined period of 300-320 minutes, the transferring valve was opened, and the nitro-mass was transferred from the second reactor to the separator reactor for dilution and separation process. While transferring to separator the sample from overflow line was analyzed for % BTF ~ 0.1- 0.8%, 3-NBTF~88.5-89.5% in nitro-mass and %HN03~ 1.0-1.4% in Spent acid. A predefined amount of water was added in a separator for dilution and stirring was carried out for 30 mins. The aqueous layer comprising spent acid % H2SO4 ~ 72-73%, %HN03 ~ 0.8- 1.2% and an organic layer comprising nitro mass having NBTF 88.5-89.5% was observed. In the next stage, stirring was stopped and settled mass after 30 mins was separated and the organic sample was analyzed to observe % BTF ~ 0.01-0.02%, 3-NBTF ~ 89.5-89.9% in nitro-mass. In this example, the overall conversion of reactants in a continuous reactor mode was achieved about 92% in the first reactor and rest up to 8% conversion was carried out in the second reactor. The nitro mass was further transferred for distillation.

The nitro-mass yield obtained from first and second reactor is disclosed in Table 2a as below:

Table 2a

Referring to Table 2b, for an overall residence time of 60-90 minutes and 300-320 minutes in the second reactor, the yield of 3-Nitro BTF was obtained in a range of 89-89.9% and about 1-1.5% nitric acid remained present in the spent. Further, in case of dual reactor mode formation HF content is reduced to 5-10 ppm. Further, safety related problems such as flow fluctuation, freezing of reaction mass and chocking of overflow line, inconsistent flow, syphoning in overflow line and sudden flow were eliminated. Further, maximum conversion of the reactants was observed.

Example 2b: Production of mono nitro-benzo trifluorides (NBTF) in continuous mode by using 98% nitric acid

In this example, a predetermined amount of BTF from BTF feed tank at a flow rate of 60 kg/hr is mixed with a predetermined amount of 98% H2SO4 at a flow rate of 66 kg/hr. The mixture is added to a 100 Ltr first continuous stirred tank reactor comprising at least two baffles, vortex breaker at the bottom and an agitator having 3 turbine blades and a modified overflow line. After a predefined time period a predefined amount of 98% nitric acid at a flow rate 18.5-20 kg/hr, is fed to the first reactor, wherein a molar ratio of BTF: 98% H2SO4: 98% HN03 is 1 : 1.10: 1.02 to 1 : 1.10: 1.05. The agitator RPM speed was maintained between 550-650. The residence time in the first reactor was maintained as 60-90 minutes and residence time in a 250 Ltr second reactor was maintained as 240 minutes. The temperature of the first reactor was maintained at 5-7 degrees by jacketed and internal circulation of chilled brine. In this example, the overall conversion of reactants in a continuous reactor mode was achieved about 98% in the first reactor and rest up to 2 % conversion was carried out in the second reactor. The nitro-mass yield obtained from first and second reactor is disclosed in Table 2b as below:

Table 2b

Referring to Table 2b, for an overall reduced residence time of 60-90 minutes and 240 minutes in the second reactor to achieve maximum conversion and the yield of 3 -Nitro BTF was obtained in a range of 89.06-90% and about 0.8-2% nitric acid remained present in the spent. Further, in case of dual reactor mode formation HF content is reduced to 5-10 ppm. Further, safety related problems such as flow fluctuation, freezing of reaction mass and chocking of overflow line, inconsistent flow, syphoning in overflow line and sudden flow were eliminated. Further, maximum conversion of the reactants was observed.

In accordance with embodiment of the present disclosure, the system (100) and process (100) of continuous production of mono nitro-benzo trifluorides (NBTF) described above have following advantages including but not limited to:

• Significant reduction in the reaction cycle time.

• Improvement in the overall production scale using a compact space.

• Significant reduction in formation of corrosive side products (HF) quantity Consistent conversion up to 99.6%.

The embodiments, examples and alternatives of the preceding paragraphs or the description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A person of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For limiting the scope of the invention, a subsequent Complete Specification be filed to determine the true scope and content of the disclosure.