| 摘要 |
PURPOSE:To easily obtain the titled compound having high purity in a short time in high yield, suppressing the production of by-product, by sulfonating a polystyrene, removing the solvent and neutralizing the sulfonated product using a specific method under specific condition. CONSTITUTION:A polystyrene having an average molecular weight of 200-50,000 is sulfonated in a halogenated hydrocarbon solvent (e.g. ethyl chloride) and the solvent is removed from the reaction mixture. The polystyrenesulfonic acid free from the solvent is neutralized with an aqueous dispersion containing an alkaline earth metal oxide under a condition to satisfy the formulas A<=6 and 4<=B/A<=10 wherein A is pH of the solution of the polystyrenesulfonic acid salt after neutralization and B is time (min) necessary for neutralization. After neutralizing the residual polystyrenesulfonic acid in the neutralized solution with an alkali metal hydroxide, the alkaline earth metal sulfate is separated from the aqueous solution to obtain the objective compound.
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