Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1982-05-17
1983-07-12
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
562429, C07C 6504
Patent
active
043932347
ABSTRACT:
3-Hydroxybenzoic acid is obtained by reaction with an alkali metal hydroxide at a temperature of 220.degree. to 450.degree. C. and under a pressure of 1 to 120 bars, from a technical 3-sulphobenzoic acid mixture which contains sulphuric acid and/or sulphur trioxide and which contains at least 75% by weight of 3-sulphobenzoic acid, relative to the total organic constituents present, and not more than 35% by weight of sulphuric acid and/or SO.sub.3, relative to the total mass. For this purpose, this technical 3-sulphobenzoic acid mixture, if desired after dilution with an equal volume of water, is mixed with sufficient 50 to 100% strength by weight alkali metal hydroxide wherein the remaining 50 to 0% by weight consists essentially of water, for 2.5 to 8 mols of alkali metal hydroxide to be present per mol of 3-sulphobenzoic acid, after neutralization of the sulphuric acid and all the sulpho and carboxyl groups. In general, 10 to 45% by weight of water are present in the batch. The reaction mixture is acidified with a mineral acid to a pH value of less than 4, if appropriate after dilution with water, and the 3-hydroxybenzoic acid is isolated at temperatures within the range from -5.degree. C. to +40.degree. C.
REFERENCES:
Lieb. Ann. Chem. 280, 6, (1894).
J. Chem. Soc., 1950, 2,108.
Blank Heinz U.
Gabel Eike
Goldschmitt Ernst
Mentzel Werner
Bayer Aktiengesellschaft
Killos Paul J.
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