Process for the preparation of alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydroxybenzoic acid

US4276431A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Peter Schnegg · Odenthal, DE
• Walter Rapp · New Iberia, US
• Bernhard Vosteen · Cologne, DE

Key dates

• Filing date: Sep 20, 1979
• Grant date: Jun 30, 1981
• Expiry date: Sep 20, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C69/84
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Alkali metal salts of hydroxybenzoates are claimed which are substantially anhydrous and free from hydrobenzoic acid and have the formula ##STR1## in which R.sup.1 denotes alkyl, alkenyl, cycloalkyl or aralkyl, PA0 R.sup.2 and R.sup.3 are identical or different and represent hydrogen, halogen, hydroxyl, amino, alkylamino, alkyl, alkoxy, aralkyl or aryl and PA0 Me denotes an alkali metal. Furthermore a process for the preparation of the said alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydrobenzoic acid, characterized in that a solution or suspension of a hydroxybenzoate of the formula ##STR2## in which R.sup.1, R.sup.2 and R.sup.3 have the abovementioned meaning, is neutralized with an alkali metal hydroxide at -10.degree. to +50.degree. C. until the degree of neutralization is 0.95 to 1.05, a degree of neutralization of 1.00 denoting the end point of the neutralization of the phenolic OH group by the alkali metal hydroxide, and the resulting solution or suspension of the alkali metal salt of the hydroxybenzoate is passed to a mild drying operation which does not damage the product and is in itself known, after a time such that the content…