A method of reducing the production of by-product o-acetoacetanilide method -n-

The present invention discloses a method of o-methyl -N- acetoacetanilides reduced byproduct production, alcohol was added in the reaction vessel, with stirring, at 0 ~ 30 ℃ added dropwise diketene and o-toluidine, the reaction temperature is 10 ~ 50 ℃, after the completion of dropwise addition, the reaction was incubated for 1 to 5 hours after cooling down to below 10 ℃ filtering and drying, to obtain o-methyl -N- cetoactanilide finished; addition of an acidic catalyst in alcoholic filtrate obtained was filtered, o-toluidine: mass ratio of acid catalyst is from 1: 0.0001 to 0.01, a distillation temperature of 80 ~ 100 ℃, alcohol distillate was obtained and applied to the next batch as alcohol reacted, recycled. In the method using alcohol as a solvent, to optimize product polymorph, product placement to prevent agglomeration process, to improve the appearance and performance of the product, while increasing the yield of the product, reduces the consumption of o-toluidine and diketene.