| 摘要 |
Diaryl esters of aromatic dicarboxylic acids, the aryloxycarbonyl groups of which are not in adjacent positions in the aromatic nucleus, are prepared by heating the acid, or an alkyl ester thereof containing up to 6 carbon atoms in the alkyl group(s), with at least an equivalent quantity of a monohydric phenol and of an anhydride of an aliphatic acid containing 2-4 carbon atoms in the presence of a transesterification catalyst. In the first stage of the reaction, the phenol and the acid anhydride react to form an ester of the phenol with the corresponding acid, and in a modification of the process the phenol and the acid anhydride may be wholly or partly replaced by the said ester. In the second stage of the reaction, the phenolic ester is transesterified with the aromatic dicarboxylic acid or its alkyl ester at a temperature above 140 DEG C. Specified transesterification catalysts are compounds of antimony, aluminium, tin or titanium, e.g. antimony oxide or esters of titanic acid, or metallic magnesium or aluminium. In the Examples: (1) terephthalic acid, phenol and acetic anhydride, in the presence of butyl titanate, yield diphenyl terephthalate, (2) dimethyl terephthalate or terephthalic acid, m-cresol and acetic anhydride, in the presence of butyl titanate, yield di-m-cresyl terephthalate, and (3) isophthalic acid, m-cresol and acetic anhydride, in the presence of magnesium or dibutyl tin laurate, yield di-m-cresyl isophthalate. Other acids which may be esterified are 5-chloroisophthalic acid, dichloroterephthalic acid and methylterephthalic acid. Other phenols which may be used are other cresols, xylenols, butylphenols, octylphenols, benzylphenols and b -naphthol. Specification 1,009,485 is referred to. |
