GB627709A - Process for the preparation of chlorinated ª‡-aryloxy fatty acids - Google Patents

Abstract

Alpha-(dichloroaryloxy)-aliphatic carboxylic acids or their esters, amides or like functional derivatives, especially dichlorinated phenoxy, cresoxy or napthoxy acetic and propionic acids, are produced by a direct two-stage chlorination of the aryloxy acids non-chlorinated in the nucleus, or their said derivatives, in a first stage with a substantially equimolecular amount of gaseous chlorine for the formation of the monochloro compound, and in a second stage by direct chlorination at a temperature higher than that used in the first chlorination with a second amount of gaseous chlorine substantially equal to that used in the first stage. In examples: (1) phenoxy acetic acid is dissolved in glacinal acetic acid, a trace of iodine added and the solution cooled. Gaseous chlorine is then introduced until an equimolecular proportion has been absorbed and the solution is then warmed to 60-80 DEG C. and an equal amount of gaseous chlorine introduced. On cooling 2, 4-dichlorophenoxy acetic acid crystallises; (2) a -(2,4-dichlorophenoxy)-propionic acid is obtained from a -phenoxy propionic acid as in (1), the second stage chlorination being effected at 50 DEG C.; (3) 2-naphthoxy acetic acid suspended in glacial acetic acid with the addition of a trace of metallic iron is chlorinated as in (1), the first stage being effected at 40 DEG C. and the second stage at 60 DEG C., the product is probably the 1,4-dichloro compound. Other starting materials specified are phenoxy acetic acid ethyl ester, phenoxy acetamide, a -phenoxy propionic acid ethyl ester, a -phenoxy-n-butyric acid, 1-naphthoxy acetic acid. Specification 607,113 is referred to. The Specification as open to inspection under Sect. 91 is not restricted to the two-stage chlorination process and states that the chlorination may be effected by direct chlorination with gaseous chlorine, using the amount of chlorine which is to be introduced into the acid molecule. Additional examples are also given in which phenoxy acetic acid, phenoxy acetic acid ethyl ester, a -phenoxy propionic acid, ethyl-a -phenoxy propionate, 1-naphthoxy acetic acid and a -phenoxy n-butyric acid are dissolved in glacial acetic acid and treated with gaseous chlorine in the presence of a trace of iodine to yield 4-chlorophenoxy acetic acid, 2,4 - dichlorophenoxy acetic acid, 4 - chlorophenoxy acetic acid ethyl ester, ethyl-a -(4-chlorophenoxy) - propionate, 2,4 - dichloro - 1-naphthoxy acetic acid, and a -(2,4-dichlorophenoxy)-n-butyric acid respectively, while phenoxy acetamide and 1-(and 2-)-naphthoxy acetic acid are chlorinated in glacial acetic acid in the presence of a trace of iron to form 4 - chlorophenoxy acetamide, 2,4 - dichlorophenoxy acetamide, 4 - chloro - 1 - naphthoxy acetic acid, and 1-chloro-2-naphthoxy acetic acid respectively. This subject-matter does not appear in the Specification as accepted.