Process for preparing monomethylated or dimethylated phenols

US5723694A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Artur Botta · Krefeld, DE
• Hans-Josef Buysch · Krefeld, DE

Key dates

• Filing date: Nov 22, 1996
• Grant date: Mar 3, 1998
• Expiry date: Nov 22, 2016

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C37/50
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Phenols monomethylated or dimethylated in the ortho or para position to the OH group and having the formula ##STR1## can be prepared by reaction of tert-alkyl-substituted phenols of the formula ##STR2## in which at least one free ortho or para position to the OH group is present, in three reaction steps a), b) and c). In a), (II) is reacted with formaldehyde or its polymers and a carboxylic acid of the formula EQU R.sup.3 --COOH, (III) which gives a mixture of substituted phenols of the formulae ##STR3## In b) the mixture of (IV)/(V) is hydrogenated using catalytically activated hydrogen to give the substituted phenols of the formula ##STR4## which, if m=0, are reacted in c) in the presence of an acid cleavage catalyst with elimination of tert-alkenes to give the methylated phenols of the formula (I). Before or during the hydrogenation, the phenols of the formulae (IV) and (V) can be reacted with the aid of an alcohol of the formula EQU R.sup.4 --OH (VII) to give a mixture of the etherified substituted phenols of the formulae ##STR5## which can then, in the manner indicated, be hydrogenated and freed of the tert-alkyl groups.