To produce a synthetic pyrethroid having uses as insecticides, etc., in a short time according to simple operations by carrying out the azeotropic esterification of a specific carboxylic acid with tetrafluorobenzyl alcohol.
The azeotropic esterification of a carboxylic acid of formula I (R1 and R2 are each methyl, difluoromethyl, trifluoromethyl or chlorine) with 2,3,5,6-tetrafluorobenzyl alcohol is carried out to provide a synthetic pyrethroid of formula II. A suitable solvent such as toluene is preferably used when performing the azeotropic esterification. The reaction is preferably conducted especially under atmospheric pressure and the latter alcohol is preferably used in an amount of 1mol based on 1-1.5mol carboxylic acid. A mixture of (+)-trans- permethrin with toluene and sulfuric acid is heated until refluxing is caused and the 2,3,5,6-tetrafluorobenzyl alcohol mixed in the toluene is then added thereto by especially using the method to carry out the azeotropic esterification. The resultant reactional mixture is subsequently cooled to ambient temperature to remove excessive amounts of the acid and solvent. Thereby, the objective compound of formula II is obtained.
MIHIYAERU ESAA
MARUTEIN RITSUTOMAN
HANSUUPEETAA ZEENEMU
