2-Chloro-3,4,5-tri;fluoro-benzoic acid and 5-chloro isomer - obtd. by reaction of 2,3,4-tri:fluoro-chloro-benzene with mono: or di:chloro-acetyl chloride, followed by reaction with sodium hypochlorite

摘要

2-Chloro-3,4,5-trifluorobenzoic acid (I) is claimed, together with the isomeric ketones 2,2'-dichloro- 3,4,5-trifluoroacetophenone, 2,2',2'-trichloro- 3,4,5-trifluoroacetophenone, 5,2'-dichloro- 2,3,4-trifluoro acetophenone and 5,2',2'-trichloro- 2,3,4-trifluoroacetophenone. Also claimed is a process for the prodn. of (I) and 5-chloro- 2,3,4-benzoic acid (II), by (a) reaction of 2,3,4-trifluoro chlorobenzene (III) with mono- or di-chloroacetyl chloride (IV) at 40-150 deg.C in the presence of acetylation catalysts and opt. in inert solvent to give the corresp. isomeric monochloroacetyl or dichloroacetyl cpds., followed (opt. after isolation of the intermediate ketones) by (b) reaction with aq. NaOCl soln. at -5 to +40 deg.C. Pref. stage (a) is carried out at 50-100 (pref. 80-90) deg.C, and stage (b) is carried out at 0-10 deg.C, the catalyst is a Lewis acid, pref. AlCl3, AlBr3, AlBr3, SbCl5, FeCl3, FeCl2, TiCl4, BF3, SnCl4, BiCl3, ZnCl2 or HgCl2, or a Bronsted acid, pref. HF, H2SO4, polyphosphoric acid, p-toluenesulphonic acid, CF3SO3H, CF3CHFCF2SO3H or 2,2,3,4,4,4-hexafluoro propanesulphonic acid; reaction is carried out in CH2Cl2, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1,2- or 1,3-dichloropropane, 1,2-, 1,3- or 1,4-dichlorobutane, DMSO, sulpholane, PhNO2 or CS2; amt. of (IV) is 100-500 mol.% w.r.t. (III); (I) is worked up by acidification of the mixt. to pH below 2, followed by filtration of the ppte. or extn. with organic solvent; stage (b) is carried out with aq. NaOCl soln. contg. 110-180g active Cl/kg soln.; process can be carried out at atmos. pressure or at reduced or elevated pressure. USE/ADVANTAGE - (I) is a new cpd., useful esp. as a starting material for the prodn. of antibacterial quinolone carboxylic acid derivs.. The process enables the prodn. of (I) and (II) in good yield and high purity. The intermediate ketones (listed above) are also useful for the prodn. of biologically active materials and liq. crystal cpds..