METHOD FOR PREPARING PHTHALIC ESTER BY USING LOWER ALCOHOL

摘要

PURPOSE: Provided is a method for preparing a phthalic ester having improved economic efficiency and quality, by reducing the reaction time and decreasing an amount of the used reaction material. CONSTITUTION: The method for preparing phthalic acid dimethyl or diethyl ester by reacting methanol or ethanol with phthalic anhydride, is characterized by comprising the steps of (i) at the beginning of material infusion, charging phthalic anhydride and 2-3 equivalent of alcohol in the presence of dialkyl sulfate catalyst of formula II(wherein R1 and R2, which are the same or different, represent a linear or branched, C1-C4 aliphatic alkyl group) to perform an esterification with reflux, and (ii) elevating the reaction material to 150-180 deg.C at atmospheric pressure, and then continuously infusing the lower alcohol in liquid state at the above temperature and pressure, and finally removing a formed water from the reaction product together with alcohol.