As disclosed in British Pat. Nos. 1,539,733 (Sheldon et al.) and 2,055,799 (Thiault et al.), it is known that 3-phenoxybenzaldehydes are useful as pesticide intermediates and that they can be prepared from 3-bromobenzaldehyde acetals. Sheldon et al., who react their acetals with phenols or alkali metal phenolates in the presence of a copper catalyst, require an aprotic organic solvent for their reaction. Tiault et al. avoid the need for the aprotic solvent by reacting their acetal with an excess of phenol in the presence of a copper catalyst and potassium carbonate at a temperature of 170.degree.-210.degree. C.
Although the process of Thiault et al. is advantageous in that it avoids several problems associated with the use of the solvents of Sheldon et al., it also has its disadvantages. The elevated temperatures required for the reaction lead to degradation of the acetal, and the potassium carbonate appears to poison the catalyst. Thus, the obtainable yield of product is comparatively low.