| 摘要 |
PURPOSE:To produce phenolphthaleins in high yields, by reacting phthalic anhydride with a phenol in the presence of a sulfonic acid type cation exchange resin having a low degree of crosslinking as a catalyst under specified conditions. CONSTITUTION:In a process for producing phenolphthaleins comprising reacting phthalic anhydride with a phenol in the presence of a sulfonic acid type cation exchange resin, a reactor in which resin substantially forms a suspended bed as in a stirring tank is used and a cation exchange resin having a low degree of crosslinking of 5% or below is used in a quantity of 0.3 or above by equivalent ratio based on that of phthalic anhydride. In this way, phenolphthaleins can be produced in high yields. The reaction temp. is 115 deg.C or above, but below the decomposition temp. of the cation exchange resin. When the temp. is lower than that as specified above, the reaction rate is too slow and about 120 deg.C is preferred.
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