Process for the preparation of hydroquinones

摘要

The invention relates to a process for the preparation of a hydroquinone compound of formula (I);
wherein R2, R3, R5 and R6 have the meaning according to claim 1, with the steps of formylating a substituted phenol and oxidizing the resulting substituted 4-hydroxy-benzaldehyde under acidic conditions to the corresponding hydroquinone of formula (I). Another object of the invention concerns the intermediate 2,3,5-trimethyl-4-hydroxy-benzaldehyde for synthesis of 2,3,5-trimethyl-hydroquinone (TMHQ) and (dl)α-tocopherol.

主权项

1. A process for the preparation of 2,3,5-trimethylbenzene-1,4-diol, comprising the steps of:
(a) heating to reflux temperature 2,3,6-trimethyl-phenol with 0.3 to 0.4 equivalents of hexamethylenetetramine in an organic acid, followed by adding a hydrolysis medium, which is an aqueous acid, and heating the resulting mixture to yield 2,3,5-trimethyl-4-hydroxy-benzaldehyde, and (b) reacting 2,3,5-trimethyl-4-hydroxy-benzaldehyde with an oxidizing agent in a solvent under acidic conditions to yield 2,3,5-trimethylbenzene-1,4-diol.