METHOD FOR MEASURING ACID VALUE OF ESTER

PURPOSE:To easily measure the acid value of ester by dissolving a sample in an org. solvent, adding an inorg. electrolyte thereto and measuring the hydrogen ion concn. of the soln. CONSTITUTION:A mixture composed of p-xylene and p-methyl toluylate is air-oxidized in the presence of a catalyst and is then esterified by methanol to obtain the ester mixture composed essentially of the p-methyl toluylate and methyl phthalate. Such ester mixture is fed at about 5ml per minute, the methanol as a solvent at about 9.3ml per minute, and a potassium chloride/methanol soln. as the inorg. electrolyte at about 0.3l per minute to a storage tank having a stirrer by which the uniform soln. is prepd. The soln. is thereafter fed to a hydrogen ion concn. meter by which the hydrogen ion concn. in the soln. is measured. Since there is a correlative relation between the hydrogen ion concn. and the acid value of the ester mixture which is the sample, the acid value of the ester mixture is obtd.