The preparation method is to react 3-phenoxybenzaldehyde with potassium cyanide (or sodium cyanide) in a solvent under neutral conditions to obtain (±)α-cyano-3-phenoxybenzyl alcohol.
It is also possible to react the adduct obtained by the reaction of m-phenoxybenzaldehyde with sodium cyanite with potassium cyanide to prepare α-cyano-3-phenoxybenzyl alcohol, which has a higher yield.
α-cyano-3-phenoxybenzyl alcohol is generally unstable and easy to decompose during storage. For this reason, when α-cyano-3-phenoxybenzyl alcohol is required for the preparation of pyrethroids, it is now in use. Using the acyl chloride-ether aldehyde method, that is, chrysanthemum chloride, m-phenoxybenzaldehyde, and sodium cyanide are reacted in a solvent in the presence of a phase transfer catalyst to prepare pyrethro, during the reaction process, 3-phenoxybenzaldehyde reacts with sodium cyanide to generate cyanohydrin, and immediately reacts with chrysanthemum chloride to generate pyrethroids. The reaction is very rapid and the yield is very high. Now most industries use this method to produce pyrethroids.