Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1985-03-04
1987-02-10
Trousof, Natalie
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
562412, 562413, 562414, C07C 5109
Patent
active
046423770
ABSTRACT:
A process for the production of terephthalic acid from p-xylene and methanol by way of the dimethyl terephthalate obtained by oxidation, in the liquid phase with atmospheric oxygen in the presence of dissolved heavy metal compounds as the catalyst, of a mixture of p-xylene and a fraction containing predominantly methyl p-toluate, which fraction is recycled into the oxidation, to obtain an oxidation product containing primarily p-toluic acid and monomethyl terephthalate at a temperature of 140.degree.-170.degree. C. and under a pressure of 4-8 bar; by esterification of the oxidation product in a reactor with liquid and subsequently vaporized methanol brought to an elevated pressure, at a temperature of 220.degree.-280.degree. C. and under a pressure of 20-25 bar to obtain a raw ester containing primarily methyl p-toluate and dimethyl terephthalate; by withdrawing the raw ester fraction and a methanol-containing vapor fraction from the esterification reactor; by distillatory separation of the raw ester into a methyl p-toluate fraction and a fraction rich in terephthalic aldehyde methyl ester, which fractions are recycled into the oxidation, a raw dimethyl terephthalate fraction, and a residual fraction; and by hydrolysis of the raw dimethyl terephthalate fraction with water, obtaining the thus-formed terephthalic acid and separation of a methanol-water mixture. In this process, the methanol-containing vapor fraction and the methanol-water mixture are separated by rectification under elevated pressure and elevated temperature into a methanol-rich head fraction and an aqueous sump phase, the methanol formed at the head of the rectification stage is withdrawn in vapor phase under elevated pressure, and esterification of the oxidation product is conducted with the methanol-containing vapor brought by compression to esterification pressure and esterification temperature.
REFERENCES:
patent: 2653165 (1953-09-01), Levine
patent: 4302595 (1981-11-01), Schoengen et al.
Modic Rudolf
Porschen Jorg
Schoengen Anton
Wirges Ralf
Clarke Vera C.
Dynamit Nobel Aktiengesellschaft
Trousof Natalie
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