Diphenyl carbonate → Oxalic acid, diphenyl ester

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Reaction Steps

400 parts of an aqueous solution of sodium hydrogencarbonate having a pH of 10 were added to 200 parts of diphenyl carbonate, obtained through the decarbonylation reaction of diphenyl oxalate using triphenyl phosphine oxide and oxalyl chloride as catalysts, and the mixture was heated to 90° C. and stirred for 1 hour. This washing step was repeated twice. To the obtained heavy solution (diphenyl carbonate layer) was further added 400 parts of distilled water, and the resulting mixture was heated to 90° C. and stirred for 1 hour. The resulting heavy solution was purified by distillation in the same manner as in Example 3 at an yield of 90% to obtain diphenyl carbonate containing 1.1 ppm of hydrolyzable chlorine. An ester interchange reaction between this diphenyl carbonate and bisphenol A was carried out in the same manner as in Example 1 except that a disodium salt of bisphenol A was used in place of sodium hydroxide as an ester interchange catalyst in an amount of 2.0×10−6 mole, in terms of sodium, based on bisphenol A, to synthesize polycarbonate. A pellet of this polycarbonate was used for the measurement of its physical properties. The conditions and results are shown in Tables III-A and III-B below.

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