芳香族カルボン酸アルカリ塩の熱交換に関する研究-2-ベンゾニトリルと炭酸カリウムの反応によるテレフタル酸の合成

概要

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The synthesis of terephthalic acid from Benzonitrile and potassium carbonate has been studied under various conditions. In addition to terephthalic acid, the reaction products identified were benzoic, isophthalic, and trimesic acids, and potassium cyanate. Significant amounts of benzoic, isophthalic, and trimesic acids were initially formed and their yields decreased with the reaction time. The yield of terephthalic acid, on the other hand, increased mainly at the expense of benzoic acid. The changes in the product composition occured during the reaction showed similar patterns to that observed in the potassium benzoate-carbonate-cyanate systems. The reversible formation of benzonitrile from potassium benzoate and cyanate is suppressed by the presence of excess potassium carbonate. Meta- and p-toluic acids were obtained from the corresponding tolunitriles under similar conditions . The reaction mechanisms may be summarized as follows : Firstly, potassium benzoate and cyanate were formed from benzonitrile and potassium carbonate by the reversible bimolecular reaction. Terephthalic acid was then produced by the competitive reactions, namely, the disproportionation of potassium benzoate and the direct carboxylation of potassium benzoate with potassium carbonate. Sodium carbonate, however, failed to react with benzonitrile at 385°C.
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