Optically active aryloxy-alkanoic acid herbicides prepn. - by reacting optically active alkali metal 2-halo-alkanoic acids with alkali metal phenolate in aq. medium

摘要

Preparation of optically active aryloxy-alkanoic acid derivs of formula (I) Ar-O-CHR-A (I) comprises reacting on aq. or aq. organic soln. of an alkali metal salt of an optically active, 3-6C, 2-halo-alkanoic acid, Hat-CHR-COOM (II), with an aq. soln. of an alkali metal salt of a phenol, Ar-OH (III), at elevated temp. and under a pressure below that of the vapour pressure of water at the reaction temp., to form an optically active, alkali metal salt of formula Ar-O-CHR-COOM (Ia), and opt. converting this, by known methods, to form other (I) cpds. With the reservation, that the prepn. does not include the prepn. of (D) 2-phenoxy-propionic acids or their alkali salts, by reaction of an aq. alcoholic or aq. soln. of an alkali. salt of optically active 2-chloropropionic acid with an aq. soln. of an alkali salt of a (X)2 substd. phenol (where X is halo or methyl and n is 1-5). This conditions does not apply when (II) is prepd. in situ by hydrolysis of an alkyl 2-haloalkanoate with alkali metal hydroxide. (Ar is 6-10C, mono- or bi-cyclic aromatic hydrocarbyl, opt. substd. by 1-3 independently chosen halo, 1-4C alkyl gps, phenoxy (opt. substd. by 1-3, independently chosen halo, q-.