US Patent 688359
Improvements in or relating to Method for the Preparation of Aryl Substituted Primary Alcohols
This invention relates to a novel method for the prep of aryl substituted primary alcohols, and pertains more particularly to the preparation of such alcohols by the hydrogenolysis of 4-aryl-1,3-dioxanes.
Ar is an aryl radical, and R is hydrogen or hydrocarbon and may be the same or different. The 4-aryl-1,3-dioxanes are prepared by reacting formaldehyde with stryrene or substituted styrenes according to the method described by Shortridge, JACS, Vol. 70, p873 (1948). By the hydrogenolysis of the 4-aryl-1,3-dioxanes there are obtained in extremely high yields and purity, aryl substituted alcohols. The hydrogenolysis proceedes as depicted below:
Among the 4-aryl-1,3-dioxanes which may be used to give aryl substituted alcohols are included 4-phenyl, tolyl, naphthyl, etc. The preferred dioxanes are those in which each R is hydrogen or a saturated hydrocarbon radical containing from 1-6C. The hydrogenation is carried out below 200*C.
Example 1: 3-phenylpropanol
A mixture of 104 pts styrene, 333 pts 37% aq. Formaldehyde, 28.6pts of 96% sulfuric acid is refluxed and stirred for 16 hours. The org. layer is washed successively with dilute sodium carbonate, sodium bisulfite and water. The product is dried by azeotropic distillation with 88 pts benzene and vacuum distilled. 90% 4-phenyl-1,3-dioxane that has BP: 95*C/2mm; Nd25 = 1.5288 and d25 = 1.101
656pts the dioxane above and 132pts of palletized copper chromite are charged into a stainless steel rocking autoclave. After purging the bomb with hydrogen at 4100 psi the temperature is brought to 175*C for 8 hours. Then the mix is cooled, washed out with methanol, filtered and distilled. 529pts of 3-phenylpropanol (96%)
