AU2010100311A6 - A process for the synthesis of polyhalogenated perhaloalkylaniline compounds - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT A PROCESS FOR THE SYNTHESIS OF POLYHALOGENATED PERHALOALKYLANILINE COMPOUNDS The following statement is a full description of this invention, including the best method of performing it known to me.

TITLE A PROCESS FOR THE SYNTHESIS OF POLYHALOGENATED PERHALOALKYLANILINE COMPOUNDS FIELD OF THE INVENTION The present invention relates to a process for the synthesis of polyhalogenated perhaloalkylaniline compounds, particularly useful as intermediates for the synthesis of agrochemicals. Particularly, the present invention envisages a process for the manufacture of 2,6-dichloro-4-trifluoromethyl aniline. BACKGROUND AND THE PRIOR ART Trifluoromethylaniline derivatives and more particularly 4-trifluoromethyl aniline derivatives are valuable intermediates used for the synthesis of agrochemicals. Halogenation, and in particular chlorination of benzotrifluoride needs to be very selective in order to obtain desired polyhalogenated derivatives like p chlorobenzotrifluoride or 3,4-dichlorobenzotrifluoride. It is not only difficult but also time consuming. The synthesis of aniline derivatives are generally performed by the hydrogenation of aromatic nitro compounds. This technique has some 1 limitations restricting its usefulness. For example, hydrogenation is not appropriate in the presence of other substituents on the benzene ring, which are sensitive to hydrogenolysis, thus leading to side reactions and byproducts. Moreover, p-nitrobenzotrifluoride is very difficult to prepare since nitration of benzotrifluoride yields significant quantities of meta isomer. J.Org.Chem.44,4731(1970) discloses the preparation of p-amino bezotrifluoride by ammonolysis of 4-chlorobenzotrifluoride in the presence of copper (I) chloride and potassium fluoride. However, the reaction conditions are drastic, the conversions are low and the yields are very less for an industrial process. U. S. Patent No.3,484,487 granted to James S. Dix discloses the use of copper chloride and polar organic solvents such as N-methylpyrrolidone, dimethylacetamide and hexamethylphosphoramide for the amination of aryl halides. These solvents are not suitable for the amination of p chlorobenzotrifluoride since transamination occurs to a significant extent to form unwanted N,N'-dimethylaminobenzotrifluoride. Tetrahedron Letters, 1975,143 (T.Cohen and J.G.Tirpak) describes Ullman coupling and ammonolysis of activated aryl halides catalyzed by copper compounds. However no alkali metal or ammonium halide is used for ammonolysis. Ammonolysis of aryl iodides and bromides is described which are known to aminate more readily than aryl chlorides. 2 U.S.Patent no 2,194,925 and 2,194,926 discloses reaction of nitro-halo benzotrifluoride with gaseous ammonia in a solvent medium and in the presence of a copper salt to produce nitro-amino-benzotrifluorides. p-Aminobenzotrifluoride is also made by reacting trichloromethylphenyl isocyanate first with anhydrous hydrofluoric acid and then with water to obtain trifluoromethylaniline hydrochloride from which the free aniline is released by a base. Polyhalogenated trifluoromethylaniline derivatives are also made by ammonolysis of polyhalogenated benzotrifluoride in the presence of alkaline halides at a temperature ranging between 150'C to 350'C. WO 2000/35851 discloses the synthesis of 2,6-dichloro-4-trifluromethyl aniline, starting from 3,4,5-trichlorobenzotrifluoride in the presence of alkaline fluorides like lithium fluoride and anhydrous ammonia under pressure in N methylpyrrolidone at 250'C to give 97% conversion and 87% selectivity. The main drawback of the process is the synthesis of 3,4,5 trichlorobenzotrifluoride in high yield and purity. Chlorination of p chlorobenzotrifluoride gives mixture of 3,4,5-trichlorobenzotrifluoride in 72% GLC conversions, 3,4-dichlorobenzotrifluoride and tetrachloro benzotrifluoride. The process to get pure 3,4,5-trichlorobenzotrifluoride from this mixture by fractionation followed by crystallization is very tedious and industrially unviable. Moreover, in-spite of using very pure intermediates, substantial amount of an undesired isomer (3-amino-4,5 dichlorobenzotrifluoride) is obtained. 3 Another approach to generate 3,4,5-trichlrorobenzotrifluoride with high purity is to perform dinitration of p-chlorobenzotrifluoride with mixed acids containing oleum, which is very selective & then subjecting 3,5-dinitro-4 chlorobenzotrifluoride to denitrochlorination at 200-220'C in the presence of a catalyst. Even though the process produces 3,4,5 trichlorobenzotrifluoride in high yield & high purity, the process has various drawbacks, it generates large quantity of spent acid as a waste. Also dinitration reactions are very exothermic in nature & hence hazardous from an industrial point of view. Further denitrochlorination is done at a temperature greater than 200'C and nitrosyl chloride is obtained as a byproduct. U.S. Patent no.5,401,882 discloses synthesis of deactivated anilines by reacting 3,4-dichloro-benzotrifluoride with dimethylformamide in the presence of an alkali metal hydroxide at a temperature ranging between 150 and 250'C. Reaction of 3,4-dichlorobenzotrifluoride with dimethyl formamide in the presence of an alkali metal hydroxide at 180 to 210'C gave 4-trifluoromethyl-2-chloro-N,N'-dimethylaniline in 93% conversion with 93% selectivity. This is reacted with sulfuryl chloride under UV light to yield an isomer mixture of 2,6-dichloro-4-trifluoromethyl-N.N'-dimethyl aniline and 2,3-dichloro-5-trifluoromethyl-N,N'-dimethyl aniline. The isomer mixture is then treated with an excess of 50% aqueous alkali to yield of 2,6-dichloro-4-trifluoromethylaniline. The patent also discloses dealkylation of the above isomer mixture by passing chlorine at 10'C and illuminating by means of a UV light to give 92% conversion and 64% yield of 2,6-dichloro-4-trifluoromethylaniline. Dealkylation is also accomplished by illumination with UV light in carbon tetrachloride and then treating with 4 50% sodium hydroxide in water. The patent also discloses dealkylation of 2,6-dichloro-4-trifluoromethyl-N,N'-dimethylaniline by heating the content with 4-6 m/m of pyridine hydrochloride at 180-190'C with 76 m% yield of 2,6-dichloro-4-trifluoromethylaniline. A solution of 2,6-dichloro-4 trifluoromethyl-N,N'-dimethylaniline when treated with 47% aqueous hydrobromic acid as dealkylating agent gave 89% conversion and 55% yield of 2,6-dichloro-4-trifluoromethylaniline as disclosed. There is therefore felt a need for preparing polychlorinated perhaloalkyl aniline compounds, typically 2,6-dichloro-4-trifluoromethylaniline from easily available raw materials in a simple and economical manner at an industrial level, with high yield and purity. OBJECTS OF THE INVENTION It is an object of the present invention is to develop a process for the manufacture of 2,6-dihalo-4-trifluoromethylaniline using commercially available raw materials. Yet, another object of the present invention is to develop a process for the manufacture of 2,6-dihalo-4-trifluoromethylaniline with high yield and purity. 5 SUMMARY OF THE INVENTION: In accordance with the present invention there is provided a process for preparing polyhalogenated perhaloalkylaniline compounds comprising the following steps: a) reacting, in a polar solvent, a compound of formula (I) R2

R

3 Formula (I) wherein: R, and R, contain elements of halogen group respectively; and

R

3 is a perhaloalkyl, with an alkylamine, at a temperature of about 140'C to about 240'C and a pressure of about 10 to about 30 kg/cm 2 to form substituted perhaloalkyl-N alkylaniline; b) reacting the substituted perhaloalkyl-N-alkylaniline of step a) with a halogenating agent to form polyhalogenated perhaloalkyl-N-alkylaniline; and c) dealkylating polyhalogenated perhaloalkyl-N-alkylaniline to form polyhalogenated perhaloalkylaniline. In the preferred embodiment of the present invention R, and R 2 are chlorine. In the preferred embodiment of the present invention R 3 is trifluoromethyl. 6 In the preferred embodiment of the present invention the polyhalogenated perhaloalkylaniline is 2,6-dichloro-4-trifluoromethylaniline. Typically, the halogenating agent is at least one selected from a group consisting of chlorine, sulfuryl chloride, thionyl chloride and phosphorus pentachloride (PCl 5 ). Typically, the polar solvent is selected from a group consisting of N methylpyrrolidone, Diphenylsulfone, N,N-dimethylimidazolidinone and dimethyl sulfone. The preferred solvent is N-methyl pyrrolidone. Typically, the reaction of step (a) is carried out at a temperature of about 140'C to about 180'C. Typically, the reaction of step (a) is conducted at a pressure in the range of about 15 to about 25 kg/cm2. Typically, the alkylamine is monomethylamine. In the preferred embodiment of the present invention, dealkylation of the polyhalogenated perhaloalkyl-N-alkylaniline is carried out in the presence of mineral acids. 7 Typically, the mineral acid is selected from a group consisting of hydrochloric acid and hydrobromic acid. Typically the mineral acid is anhydrous hydrobromic acid. In the preferred embodiment of the present invention dealkylation of the polyhalogenated perhaloalkyl-N-alkylaniline is carried out with about 30% to 50% anhydrous hydrobromic acid in acetic acid. In accordance with another aspect of the present invention the dealkylation of the polyhalogenated perhaloalkyl-N-alkylaniline is carried out with dry hydrochloric acid gas in the presence of catalytic quantity of pyridine salt. Typically, the pyridine salt is selected from a group consisting of pyridine hydrochloride and pyridine hydrobromide. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, polyhalogenated perhaloalkylaniline compounds is prepared by a) reacting in a polar solvent a compound of the formula (I) with alkylamine, at a temperature of about 140'C to about 240'C and a pressure of about 10 to about 30 kg/cm 2 to form a substituted perhaloalkyl-N-alkylaniline and 8 b) reacting substituted perhaloalkyl-N-alkylaniline with a halogenating agent to form polyhalogenated perhaloalkyl-N alkylaniline followed by c) dealkylating polyhalogenated perhaloalkyl-N-alkylaniline to form polyhalogenated perhaloalkylaniline. R, R2 R3 Formula (I) wherein: R 1 and R2 contain elements of halogen group respectively; and

R

3 is a perhaloalkyl. In a preferred embodiment of the present invention R 1 and R 2 are chlorine and R 3 is trifluoromethyl. The compound of formula I is typically 3,4 dichlorobenzotrifluoride. According to a preferred embodiment of the present invention polyhalogenated perhaloalkylaniline is 2,6-dichloro-4-trifluoromethyl aniline. A process for the preparation of 2,6-dichloro-4-trifluoromethylaniline compound from 3,4-Dichloro benzotrifluoride is depicted in the reaction scheme below. 9

CF

3

CF

3

CF

3

CF

3

CH

3 N H 2 chlorination dealkylation 1 -1 1 1 CI CI CI CI 11C C1 H 3 C'NH H 3 C/NH NH 2 2,6-Dichloro-4-trifluoromethylaniline 3,4-dichlorobenzotrifluoride is aminated with monomethylamine in the presence of a solvent at an elevated temperature to give 2-chloro-4 trifluoromethyl-N-methylaniline which is further chlorinated to yield 2,6 dichloro-4-trifluoromethyl-N-methylaniline. The resultant 2,6-dichloro-4 trifluoromethyl-N-methylaniline is dealkylated to give the desired compound 2,6-dichloro-4-trifluoromethyl aniline. In a preferred embodiment of the present invention, 3,4 dichlorobenzotrifluoride is manufactured in high purity and yield by chlorination of commercially available p-chlorobenzotrifluoride in the presence of a Lewis acid catalyst. Amination of 3,4-dichlorobenzotrifluoride with monomethylamine in the presence of a solvent at elevated temperature gives 2-chloro-4-trifluoromethyl-N-methylaniline. Use of anhydrous monoalkylamine, preferably monomethylamine is preferred as aminating agent both from the reactivity point of view as well as to reduce the load of dealkylation. Monoalkylamine is used in excess of 4m/m to 6m/m on 3,4 dichlorobenzotrifluoride. The reaction is conducted at temperature ranging between 140 to 240'C, more preferably between 140 tol8 0 'C. The reaction is conducted under pressure at 10 to 30 kg/cm 2 , more preferably at 15 to 25 kg/cm 2 . 10 In a preferred embodiment of the present invention, the solvent employed in the present process can be any solvent or a mixture of solvents, which do not decompose under the reaction condition and is inert with respect to the reactants. Preferably, the solvent used is a polar solvent .The polar solvent is selected from a group consisting of N-methylpyrrolidone, Diphenyl sulfone, N,N-dimethylimidazolidinone and dimethylsulfone. N-methylpyrrolidone (NMP) is a solvent of choice as it does not interact with the reactants. In preferred embodiment of the present invention, the halogenation of substituted perhaloalkyl-N-alkylaniline is carried out using halogenating agents like chlorine, sulfuryl chloride, thionyl chloride and phosphorus pentachloride (PCl 5 ) at a temperature ranging between 0 0 C to 100 0 C, preferably at 0 0 C to 70'C. Among various halogens, the preferred halogen is chlorine unless a specific halogen is desired. The amount of halogenating agent used is limited to 10 to 50% excess, relative to the stoichiometric amount, preferably about 10 to 20% of the stoichiometric excess. Preferably, halogenation occurs in chlorinated hydrocarbon solvents with boiling point below 100 0 C or under reduced pressure to drive the reaction. The preferred solvents used for halogenations are dichloromethane, dichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene and carbon tetrachloride. In one aspect of the present invention the dealkylation of polyhalogenated perhaloalkyl-N-alkylaniline is carried out with dry hydrochloric acid in the presence of catalytic amount of pyridine salt, most preferably, pyridine hydrochloride salt. The catalytic quantity of pyridine hydrochloride salt is used between 0.1 to 0.5 m/m. Preferably, 2-10 moles, more preferably 2-5 11 m/m of dry hydrochloric acid gas is passed over a period of time to drive the dealkylation to completion. In accordance with another aspect of the present invention, the dealkylation of polyhalogenated perhaloalkyl-N-alkylaniline is carried out using 30 to 50% anhydrous hydrobromic acid in acetic acid. The amount of hydrobromic acid used in the reaction is in the range of 1.5 to 2.5 m/m of the alkyl group present, more preferably 1.7 to 2 m/m. The reaction is carried out at a temperature range of 50 to 150'C, more preferably at 80 to 100 0 C. The purity of the product is determined by gas chromatography. The invention is illustrated with respect to the following examples which do not limit the scope of the invention in any way. In the examples m/m means one gram mole of product obtained from 1 gram mole of substrate input. Example-1 860 g of 3,4-dichloro-benzotrifluoride was mixed with 2000 ml of N-methyl pyrrolidone (moisture content < 0.1%) in a pressure reactor, 620 g (5 m/m) of anhydrous monomethyl amine was then fed to reactor from a pressure pot at ambient temperature. The reaction mixture was heated to 160'C liquid temperature for a period of 2 hours to attain a reactor pressure of 23-24 kg/cm 2 at 160'C and further maintained at this temperature for 7 hours. Reaction mixture was then cooled to 80-90'C and stirred for 1 hour. Excess methylamine was slowly vented off and scrubbed in cold water. Gas 12 chromatography of the reaction mass sample showed 99% conversion of 3,4 dichloro benzotrifluoride and GLC ratio of 2-chloro-4-trifluoromethyl-N methyl aniline to 2-chloro-5-trifluoromethyl-N-methyl aniline was 91:9%. After treatment of the reaction medium, 2-chloro-4-trifluoromethyl-N methyl aniline was obtained in 90% yield by fractionation under reduced pressure. Example-2 430 g of 3,4-dichloro-benzotrifluoride (GC 99.9%) was added to 800 ml of N-methylpyrrolidone in a pressure reactor, 248 g (4 m/m) of anhydrous monomethyl amine was fed to the reactor from a pressure pot at room temperature. The reaction mixture was heated to 140'C to attain the reactor pressure of 16 kg/cm 2 and further maintained at this temperature for 10 hours. After treatment of the reaction medium, gas chromatography of the reaction mixture showed 94% conversion of 3,4-dichloro-benzotrifluoride and isomer ratio of 2-chloro-4-trifluoromethyl-N-methyl aniline: 2-chloro-5 trifluoromethyl-N-methyl aniline as 94:6. After treatment of the reaction medium, 2-chloro-4-trifluromethyl-N-methyl aniline was obtained with a purity of more than 980% and with 910% yield. Example-3 1389 g (GC purity 98.3%) 2-Chloro-4-trifluoromethyl-N-methylaniline was mixed with 1000 ml of chlorobenzene & heated to 55-60'C. 924 g (1.05 m/m) of sulfuryl chloride was added slowly and the reaction was maintained at this temperature till gas chromatography of the reaction mixture showed extinction of 2-chloro-4-trifluoromethyl-N-methyl aniline. Reaction mixture 13 was worked up , chlorobenzene was recovered by vacuum distillation to get 1629 g of concentrated mixture with GLC composition showing 10.16% chlorobenzene, 73.47% 2,6-dichloro-4-trifluoromethyl-N-methylaniline and 15.47% 2,6-dichloro-4-trifluoromethylaniline, the combined yield was 91.5 m%. Example-4 290g of a mixture containing 74.4% 2,6-dichloro-4-trifluoromethyl-N methylaniline(0.884 mole), 11.3% 2,6-dichloro-4-trifluoromethylaniline (0.143 mole) was mixed with 8.15 g pyridine (0.103 m). Pyridine was converted to pyridine hydrochloride by passing dry HCl in the reaction mixture at 30-50'C liquid temperature. Reaction mixture was further heated to 180 to 185'C and dry HCl gas was passed below the surface of the mixture at the rate of 0.38 m/hour over a period of 8 hour maintaining the reaction mixture temperature at 180 and 185'C. Reaction progress was monitored by GLC. Reaction mixture was worked up by alkali treatment and extraction with chlorobenzene. After distillation 184.3 g (78 %) of 2,6 dichloro-4-trifluoromethylaniline was obtained. Example-5 362 g of a mixture containing 73.47% 2,6-dichloro-4-trifluoromethyl-N methylaniline (1.09 mole), 15.47% 2,6-dichloro-4-trifluoromethylaniline (0.243 mole) and 10.1% chlorobenzene was taken in a glass reactor and 720 g of anhydrous hydrobromic acid (as 33% solution in acetic acid) was added to the reaction mixture at an ambient temperature. Reaction mixture was gradually heated to 90 to 95'C liquid temperature and further maintained at this temperature for 9 hours till gas evolution subsided. Reaction progress 14 was monitored by gas chromatography. Acetic acid and excess HBr wa distilled under reduced pressure. After treatment of the reaction medium, 286.82 g of distilled cut was obtained with GLC composition showing 91.05% 2,6-dichloro-4-trifluoromethylaniline, 1.97% 2,6-dichloro-4 trifluoromethyl-N-methylaniline with 6.1% constituents with high retention signals. Organic layer on treatment with alkali and distillation gave 2,6 dichloro-4-trifluoromethylaniline in 85% yield. Example 6 161.3 g of 3,4-dichlorobenzotrifluoride (99.8 %, 0.75 mole) is charged along with 375 ml of N,N-dimethylimidazolidone in a stainless steel reactor. 139.5 g (4.5 m) of N-methylamine was passed from a pressure pot & the resultant mixture was heated to 160'C / 23 kg/cm2. The mixture was further maintained at 160'C for further 6 hrs. After treatment of the reaction mixture, GLC of the reaction mixture showed 99.5% conversion of 3,4 dichlorobenzotrifluoride with isomer ratio of 2-chloro- 4-trifluromethyl-N methylaniline:2-chloro-5-trifluoromethyl-N-methylaniline as 91:9% .After solvent recovery 2-chloro-4-trifluoromethy-N-methylaniline is obtained in 86.5 % yield. Example 7 860 g of 3,4-dichlorobenzotrifluoride (99.8 %, 4 mole) was charged along with 2000 ml of N-methylpyrrolidone in a stainless steel reactor. 620 g (20 m) of N-methylamine was passed from a pressure pot & the resultant mixture was heated to 160'C and pressure 23.5 kg/cm2. The mixture was further maintained at 160'C for 7 hr, the pressure dropped to 16.5 kg/cm2 at the end of 7 hr. After treatment of the reaction mixture, GLC of the reaction 15 mixture showed 100 % conversion of 3,4-dichlorobenzotrifluoride with isomer ratio of 2-chloro-4-trifluromethyl-N-methylaniline:2-chloro-5 trifluoromethyl-N-methylaniline as 93:7% After solvent recovery 2-chloro 4-trifluoromethy-N-methylaniline was obtained in 89 % yield. Example 8 1075 g of 3,4-dichlorobenzotrifluoride (99.8 %, 5 mole) was charged along with 2000 ml of N-methylpyrrolidone in a stainless steel reactor. 465 g (15 m) of N-methylamine was passed from a pressure pot & the resultant mixture was heated to 160'C and pressure 18 kg/cm2. The mixture was further maintained at 160'C for further 6 hr. After treatment of the reaction mixture, GLC of the reaction mixture showed 100 % conversion of 3,4 dichlorobenzotrifluoride with isomer ratio of 2-chloro-4-trifluromethyl-N methylaniline:2-chloro-5-trifluoromethyl-N-methylaniline as 91:9 % . After solvent recovery, 2-chloro-4-trifluoromethy-N-methylaniline was obtained in 87 % yield. Example 9 106 g (0.50 m, 99 %) of 2-chloro-4-trifluoromethyl-N-methylaniline was added to 250 ml dichloroethane in a mechanically agitated reactor & 71 g (0.52m) sulfuryl chloride was added at 55-60 'C over 1 hr & the resultant mixture was stirred at 55-60 'C for 4 hrs & then at 70-75 'C for 2 hrs till gas chromatography of the reaction mixture sample showed greater than 99 % GC conversion. The reaction mixture was worked up by adding water & treating with alkali. Organic layer after drying was concentrated under reduced pressure to remove EDC to get 117 g concentrate containing 98.6 % 2,6-dichloro-4-trifluromethyl-N-methylaniline. Yield was 94.3 %. 16 The numerical values of various parameters given in the specification are but approximations and slightly higher or slightly lower values of these parameters fall within the ambit and the scope of the invention. While considerable emphasis has been placed herein on the specific steps of the preferred process, it will be highly appreciated that many steps can be made and that many changes can be made in the preferred steps without departing from the principles of the invention. These and other changes in the preferred steps of the invention will be apparent to those skilled in the art from the disclosures herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. 17

Claims (5)

1. A process for the synthesis of polyhalogenated perhaloalkylaniline 5 compounds comprising the following steps: a) reacting, in a polar solvent, selected from a group consisting of N methylpyrrolidone, diphenylsulfone, N,N-dimethylimidazolidinone and dimethylsulfone, preferably N-methyl pyrrolidone, a compound of the formula (I) R2 R 3 [0 Formula (I) wherein: R, and R 2 contain elements of halogen group respectively; and R 3 is a perhaloalkyl. 5 with alkylamine, preferably monomethyl amine , at a temperature of about 140'C to about 240'C, preferably about 140'C to about 180'C , and a pressure of about 10 kg/cm 2 to about 30 kg/cm 2 , preferably about 15 kg/cm 2 to about 25 kg/cm 2 to form a substituted perhaloalkyl-N-alkylaniline; b) reacting substituted perhaloalkyl-N-alkylaniline with a halogenating agent, 20 the said halogenating agent being atleast one selected from a group consisting of chlorine, sulfuryl chloride, thionyl chloride and phosphorus pentachloride (PCl 5 ), to form a polyhalogenated perhaloalkyl-N-alkylaniline; and c) dealkylating polyhalogenated perhaloalkyl-N-alkylaniline with a mineral acid selected from a group consisting of hydrochloric acid and hydrobromic acid, to 5 form polyhalogenated perhaloalkylaniline. 18

2. A process for the synthesis of polyhalogenated perhaloalkylaniline compounds according claim 1 wherein, R 1 , R 2 are chlorine and R 3 is trifluoromethyl. 5

3. A process for the synthesis of polyhalogenated perhaloalkylaniline compounds according claim 1 wherein, in step (c) dealkylation of the polyhalogenated p-trifluoromethyl-N-methylaniline is carried out using hydrobromic acid, preferably 30% to 50% anhydrous hydrobromic acid in acetic acid. 0

4. A process for the synthesis of polyhalogenated perhaloalkylaniline according to claim 1 wherein, in step (c) the dealkylation of the polyhalogenated p trifluoromethyl-N-methylaniline is carried out using hydrochloric acid ,preferably dry hydrochloric acid gas in the presence of catalytic quantity of 5 pyridine salt, preferably pyridine hydrochloride or pyridine hydrobromide.

5. A process for the synthesis of polyhalogenated perhaloalkylaniline according to any one of the preceding claims wherein the polyhalogenated perhaloalkylaniline is 2,6-dichloro-4-trifluoromethyl aniline. 20 Applicant: KEKI HORMUSJI GHARDA by 25 Jogias Patent and Trade Mark Attorneys 02 April 2010 19