CS198081B1 - Method of preparing primary alcohols substituted with phenyl - Google Patents

Description

The present invention relates to a process for the preparation of phenyl-substituted primary alcohols by hydrogenolysis of 4-phenyl-1,3-dioxanes. Phenyl-substituted primary alcohols find use primarily in perfumery as such or as intermediates for the preparation of esters, aldehydes, acids and other chemical compounds also useful in perfumery, the pharmaceutical industry, as plasticizers for plastics and the like.

Suitable starting materials for the preparation of phenyl-substituted primary alcohols are 4-phenyl-1,3-dioxanes readily available by the Prins reaction of formaldehyde with phenylolefins such as styrene, Λ-methyletyrene and other substituted styrenes.

The resulting phenyl substituted 1,3-dioxane of general formula

Ph where R is methyl or hydrogen and Ph phenyl can then be resolved by treatment with sodium in an alcohol, as reported by M. O. J. Beets in Rec. trav. chim. ²⁰ (1951) · The disadvantages of this procedure for industrial application are evident. A more suitable procedure is hydrogenolysis

198 081

198081 fenyleubetituovaných 1,3-dioxane using catalysts based on Cu0 PA-Cr ₂ 0P that is described WS Emerson RL Heider, RJ Jr Longleyem Shafer and TC in <7th Am. Chem. Soc. 22, 5314 (1950) and is also the subject of British patent δ. 688 359, also a catalyst based on copper oxide-chromium trioxide-barium chromate proved to work well, as reported by MS. author's certificate No. 189 945,

Hydrogenolysis is carried out using 5 to 25 wt. catalyst at the weight of the phenyl-substituted 1,3-dioxap at a temperature of about 200 ° C and a hydrogen pressure above 9.8 MPa. The reaction time is 8 to 12 hours, yield 70 to 95%. The necessity to use high pressures and temperatures, a long reaction time, even with high catalyst loads, and not always a selective course of the reaction (lower product yields) are considerable disadvantages of this process.

The above mentioned disadvantages are substantially removed by the process »preparation řenyls bstituoy ^ ^ of straight alcohols of formula R-CH (Ph) -CH ₂ 0H--eHg according to this invention whose principle consists in that a catalyst is used containing míínstý oxide, carbon % of manganese dioxide and manganese dioxide, the amount of manganese dioxide being 1 to 10 wt. of the total weight of catalyst and cuprous and chromium oxides are in a weight ratio of 1: 1.

The process is highly selective and the catalyst used has a long service life, so its consumption is minimal.

Formaldehyde formed in the reaction is reduced in the reaction mixture to methanol, which is virtually the only by-product.

The invention is illustrated by the following examples.

Example 1

In a 150 ml stainless steel autoclave was added 50 g of 4-phenyl-1,3-dioxane and 5 g of a CuO-OrgO 4 -MnOg-based catalyst (5 wt% MnOg). The autoclave was pressurized with hydrogen, heated to 100 ° C, and then stirred. During the reaction, the temperature was maintained between 100 and 170 ° C and the hydrogen pressure was between 4 and 50 psi. After 6 hours the reaction was complete, the yield of 3-phenyl-1-propsol (b.p. 237 ° C) was 100% of theory at total conversion.

Example 2

The experiment was carried out analogously to Example 1 except that the temperature was between 100 and 250 ° C and the pressure was between 5 and 8 MPa. after 1 hour 100% conversion was achieved, with a yield of 3-phenyl-1-propanol of tyl 95.4% ·

198 Ol

Example 3

The experiment was carried out analogously to Example 1 except that the hydrogenolysis was carried out at a temperature of 200 ° C and a pressure of 6.86 MPa. After 90 minutes 100% conversion was achieved with a yield of 3-phenyl-1-propanol of 99% ·

Example 4

The experiment was carried out analogously to Example 3 except that the catalyst obtained by filtration from the reaction mixture of Example 3 was used. The reaction with the catalyst used was carried out under the same conditions as the fresh catalyst in Example 3.

Example 5

The experiment was carried out analogously to Example 4 except that the catalyst obtained by filtering from the reaction mixture of Example 4 was used. The reaction with the catalyst used was carried out under the same conditions as for the fresh catalyst. No decrease in activity or selectivity was observed with the further three-time catalyst use.

Example 6

Under similar conditions to Example 1, 4-methyl-4-phenyl-1,3-dioxane was subjected to hydrogenolysis. Hydrogenolysis was performed at a temperature of 160 ° C and a pressure of 5 to 16.67 MPa. After 10 hours 100% conversion was achieved, the yield of 3-phenyl-1-butanol (bp 96 ° C / 0.26 kPa) was 96.8%.

Example 7

Under similar conditions to Example 1, 4-phenyl-1,3-dioxane was subjected to hydrogenolysis. The catalyst contained 10 wt. MnOg, 45% CuO and 45% CrgOy Hydrogenolysis at 50 ° C at 50 psi gave 3-phenyl-1-propanol in 80% yield after 20 hours.

Claims (1)

A process for the preparation of phenyl-substituted primary alcohols of the formula R-CH (Ph) -CHg-CHg-OH by hydrogenolysis of 4-phenyl-1,3-dioxanes of the formula 198 081 wherein in the formulas Ph is phenyl and R is methyl or hydrogen, in the presence of a copper oxide and chromium trioxide catalyst, characterized in that a catalyst comprising copper oxide, chromium trioxide and manganese dioxide is used, the amount of manganese dioxide % is 1 to 10 wt. the total weight of catalyst and copper and chromium oxides are in a weight ratio of 1: 1.