| abstract |
The present invention is directed to a process for the manufacture of 2,3,5-trimethyl-hydro- p -benzoquinone comprising the following steps: a) hydrogenating 2,6-dimethyl- p -benzoquinone with hydrogen in the presence of a hydrogenation catalyst in an organic solvent to obtain 2,6-dimethyl-hydro- p -benzoquinone; b) reacting 2,6-dimethyl-hydro- p -benzoquinone with a secondary amine and formal-dehyde in an organic solvent to obtain 2,6-dimethyl-3-(N,N-disubstituted aminomethyl)-hydro- p -benzoquinone; c) reacting 2,6-dimethyl-3-(N,N-disubstituted aminomethyl)-hydro- p -benzoquinone with hydrogen in the presence of a hydrogenolysis catalyst in an organic solvent to obtain 2,3,5-trimethylhydro- p -benzoquinone; wherein the organic solvent in all steps a), b) and c) is independently selected from the group consisting of methyl tert. -butyl ether, ethyl tert . -butyl ether, methyl tert . -amyl ether, methoxycyclopentane and any mixtures thereof. Preferably the organic solvent used in all steps a), b) and c) is the same. |