| 摘要 |
1,181,369. Purifying dimethyl terephthalate. MITSUBISHI CHEMICAL INDUSTRIES Ltd. 21 Aug., 1967 [26 Aug., 1966], No. 38389/67. Heading C2C. A process for the purification of a crude dimethyl terephthalate, a product of the esterification with methanol of a crude terephthalic acid obtained by the partial oxidation of pxylene, comprises contacting the crude dimethyl terephthalate with molecular oxygen at a temperature in the range 140-280‹ C. and in the presence of a cobalt-comprising material and a bromine-comprising material both of which are soluble in the crude dimethyl terephthalate. The purified dimethyl terephthalate is recovered by distillation. The active life of the cobalt- and bromine-containing materials may be extended by including in the reaction mixture manganese or manganese compounds. Many cobalt, manganese and bromine comprising materials are listed. The examples describe the esterification of crude terephthalic acid with methanol and subsequent purification by oxidation. |
