反应详情

Dehydrogenation may be carried out in an inert solvent. It is advantageous however to dehydrogenate the 2,5,6-trimethyl-2-cyclohexen-1-one or 2,3,6-trimethyl-2-cyclohexen-1-one in the gas phase, for example by passing it as a gas at the dehydrogenation temperature over a palladium/silica gel catalyst. In gas-phase dehydrogenation the trimethyl-2-cyclohexen-1-one is preferably passed over the catalyst in admixture with an extraneous gas such as nitrogen, steam, carbon dioxide and particularly hydrogen; generally a ratio by volume of extraneous gas to gaseous trimethyl-2-cyclohexen-1-one of from about 1:2 to 5:1 is chosen. Temperatures of from 200° to 400° C., preferably from 250° to 350° C., are usually used in gas-phase dehydrogenation. The time that the trimethyl-2-cyclohexen-1-one is in contact with the catalyst is generally from half to fifty, preferably from two to ten seconds. The 2,3,6-trimethylphenol is obtained in a more than 95% yield in gas-phase dehydrogenation.

1. customof from 200° to 400° C.
2. custompreferably from 250° to 350° C.
3. waitis generally from half to fifty, preferably from two to ten seconds