The invention relates to a method for producing o-chloromethyl benzoic acid chlorides
of formula (I), in which R1 to R4 can be the same or different
and represent hydrogen C1-C4 alkyl, halogen or trifluoromethyl,
by reaction benzo condensed lactones of formula (II), in which R1 to
R4 have the above-mentioned meaning, with thionyl chloride. The inventive
method is characterized in that the reaction is carried out in the presence of
catalytic quantities of a Lewis acid and in the presence of catalytic quantities
of a phosphine derivative.
