Xu Ya
2002
Citations
0
Influential Citations
0
Citations
Journal
Fine chemicals
Abstract
Dimethoxybenzoic acid was synthesized by three step reaction.Firstly,2,6 dihydroxybenzoic acid was prepared by the reaction of resorcinol,anhydrous potassium carbonate and carbon dioxide in mole ratio 1 0∶0 5∶1 5 with DMF as solvent at 135-137 ℃ under 1 3 MPa for 16 5 h.Then,under alkaline condition,2,6 dihydroxybenzoic acid and dimethyl sulfate in mole ratio 1∶3 reacted to give methyl 2,6 dimethoxybenzoate.Finally,2,6 dimethoxybenzoic acid was obtained through alkaline hydrolysis of methyl 2,6 dimethoxybenzoate and acidification.In the first step, the reaction temperature was lower than that given in the literature (150-180 ℃),thus reducing the formation of by product.The aftertreatment for recovering resorcinol included zinc dust reduction and decolorization and ether extraction,thus increasing the use ratio of resorcinol and the product yield.The yield of 2,6 dihydroxybenzoic acid was 52% in this step.The latter two steps were carried out continuously.Alkylation was done by dropping w (NaOH)=30% aqueous solution at 30-45 ℃,then hydrolysis was done by adding w (NaOH)=40% aqueous solution at elevated temperature. Total yield of the two steps was 92 6%. The overall yield of 2,6 dimethoxybenzoic acid was 47 8%. Mass fraction of the product is 99 1% as determined by chemical method.