Patent GB-446532-A (GB)
Title: Manufacture of aminotrifluoromethyl-aryl-sulphonic acids
IPC: C07C309/45
Filed: 1934-11-02
Abstract: Amino-trifluoromethyl-aryl sulphonic acids are prepared by treating amino-trifluoromethylaryl compounds with chlorsulphonic acid.  The reaction may be effected with an excess of chlorsulphonic acid at atmospheric or raised temperature, or with equimolecular proportions of the reagents in an inert organic solvent at a raised temperature; halogenated hydrocarbons (several specified) and nitrobenzene are suitable solvents.  Examples are given in which the following sulphonic acids are prepared from the corresponding unsulphonated compounds and chlorsulphonic acid: 1-amino-3-trifluoromethylbenzene-4-sulphonic acid; 1-amino-4-trifluoromethylbenzene - 2 - sulphonic acid; 1-amino-2-trifluoromethylbenzene-4-sulphonic acid; 1-amino-2-chloro-5-trifluoromethylbenzene - 4 - sulphonic acid; 1 - amino - 2 : 4-dichloro - 5 - trifluoromethylbenzene-6-sulphonic acid; 1-amino-2 : 5-dichloro-3-trifluoromethylbenzene-4-sulphonic acid; 1-amino-2-bromo-5-trifluoromethylbenzene-4-sulphonic acid; 1-amino - 4 - chloro - 2 - trifluoromethylbenzene - 6-sulphonic acid; 1-amino-4-chloro-3-trifluoromethylbenzene-6-sulphonic acid; 1-amino-2-methoxy-5-trifluoromethylbenzene-4-sulphonic acid; 1 - amino - 4 - methoxy - 5 - trifluoromethylbenzene-2-sulphonic acid; 1-amino-2-ethoxy-5-trifluoromethylbenzene - 4 - sulphonic acid; 1-amino - 4 - phenoxy - 5 - trifluoromethylbenzene-2-sulphonic acid; 1 - amino - 2 - benzyloxy - 5 - trifluoromethylbenzene - 4 - sulphonic acid; 1-amino - 2 : 4 - dimethoxy - 5 - trifluoromethylbenzene-6-sulphonic acid; 1-amino-2-nitro-4-trifluoromethylbenzene - 6 - sulphonic acid; 1 amino - 2 - nitro - 5 - trifluoromethylbenzene - 4 - sulphonic acid; 1 - amino - 4 - nitro - 5 - trifluoromethylbenzene - 2 - sulphonic acid; 1-amino - 3 : 5 - bis - trifluoromethylbenzene - 4 - sulphonic acid; 1-amino-2 : 5-bis-trifluoromethylbenzene-4-sulphonic acid; 1-amino-2-chloro-3 : 5 - bis - trifluoromethylbenzene - 4 - sulphonic acid; 1 - amino - 5 - trifluoromethylbenzene - 2 - ethylsulphone-4-sulphonic acid; 1-amino-3-trifluoromethylbenzene - 4 - methylsulphone - 6 - sulphonic acid; 1-amino-2-trifluoromethylbenzene - 4 - phenylsulphone - 6 - sulphonic acid; and 1 - amino - 5 - trifluoromethylbenzene - 2-benzylsulphone-4-sulphonic acid.  Amino-trifluoromethyl-aryl compounds.  Particulars of the preparation of various starting materials, used in making the products specified above, are given as follows:  1-Amino-2- and -4-nitro-5-trifluoromethylbenzenes are prepared from 1-acetylamino-3-trifluoromethylbenzene, which is nitrated to yield a mixture of 1-acetylamino-2- and -4-nitro-5-trifluoromethylbenzenes; the acetyl group is saponified and the nitroamine mixture is separated into its components by steam distillation.  1-Amino-2- and -4-trifluoromethylbenzenes are prepared from 1-amino-2- and -4-nitro-5-trifluoromethylbenzenes by deamination followed by reduction.  1 - Amino - 2 : 4 - dichloro - 5 - benzotrifluoride is prepared from 2 : 4-dichlorobenzotrichloride by heating with antimony trifluoride to form 2 : 4-dichlorobenzotrifluoride, which is then nitrated and reduced (cf. Specification 361,097).  1 - Amino - 2 : 5 - dichloro - 3 - benzotrifluoride is prepared similarly from 2 : 5-dichlorobenzotrichloride.  1-Amino-2-bromo-5-benzotrifluoride is prepared similarly from 4-bromobenzotrichloride. 1-Amino-4-chloro-2-benzotrifluoride is obtainable similarly from 3-chlorobenzotrichloride.  1-Amino-4-chloro-3-benzotrifluoride is obtainable similarly from 2-chlorobenzotrichloride. 1-Amino-4-methoxy-5-benzotrifluoride is prepared by converting 4-chloro-5-benzotrichloride, by the reactions indicated in Specification 361,097, into 1-nitro-4-chloro-5-benzotrifluoride, in which the chlorine atom is then replaced by the methoxy group and the nitro group is reduced.  1 - Amino - 2 - ethoxy - 5 - benzotrifluoride, 1-amino-4-phenoxy-5-benzotrifluoride, 1-amino-2-benzyloxy-5-benzotrifluoride and 1-amino-2 : 4-dimethoxy - 5 - benzotrifluoride are obtained similarly from the corresponding nitrochlorobenzotrifluorides.  1-Amino-3 : 5-bis-trifluoromethylbenzene is prepared by treating 1 : 3-bis-trichloromethylbenzene with anhydrous hydrogen fluoride, and subjecting the product to nitration and reduction (cf. French Specification 745,293).  1 - Amino - 2 : 5 - bis - trifluoromethylbenzene and 1-amino-2-chloro-3 : 5-bis-trifluoromethylbenzene are similarly obtainable.  1 - Amino - 5 - trifluoromethylbenzene - 2 - ethylsulphone is prepared by condensing 1-nitro-2-chloro-5-benzotrifluoride with the sodium salt of ethanesulphinic acid, and reducing the nitro group in the product. 1-Amino- 3 -trifluoromethylbenzene - 4 - methylsulphone, 1-amino-2-trifluoromethylbenzene-4-phenylsulphone, and 1-amino-5-trifluoromethylbenzene-2-benzylsulphone are obtainable similarly from the corresponding nitrochlorobenzotrifluorides. Specification 440,207 also is referred to.