CS232394B1 - Process for preparing 1-phenyl-1,3-propanediol - Google Patents

Abstract

The invention relates to the preparation of 1-phenyl1,3-propanediol by transesterification of 1-phenyl-1,3-propanediol diacetate with methanol. Potassium carbonate is used as a transesterification catalyst in an amount of 1 gram to 50 grams per kilogram of starting 1-phenyl-1,3-propanediol diacetate. The field of application is in perfumery, where it serves as an intermediate for the extraction of aromatic acetals and has repellent effects.

Description

The invention relates to a process for the preparation of 1- (4-phenyl) -1,3-propanediol.

Direct hydrolysis of 4-phenyl-1,3-dioxane to 1-phenyl-1,3-propanediol is not possible. Dioxane is stable in an alkaline medium, in an acidic medium due to the very easy dehydration of the diol, and subsequent polymerization leads to hydrolysis to maximum polymeric products. For these reasons, the two-stage process has so far been carried out, whereby in the first step the reaction of dioxane with acetic anhydride gives 1-phenyl-1,3-propanediol diacetate which in the second step reacts with methanol to give 1-phenyl-1,3-propanediol and methyl acetate. So far, this reaction has been catalyzed only by sodium metal, which in the reaction mixture has been converted to sodium methoxide, as described in Hesling A. Hec. trav. chim. Pays-Bas 78, 474 (1979). The reaction had a good yield but carried all the disadvantages of a not very aqueous catalyst. Šorygina v Ž. obšč. chim. 26, 1460 (1956) used a 16% solution of sodium hydroxide in ethanol for transesterification, but the yields of Dyly were only 58-65%.

These drawbacks are reliably overcome by the process of the present invention, which is prepared by 1-phenyl-1,3-propanediol by transestenfixing 1-phenyl-1,3-propanediol diacetate with methanol, using potassium carbonate in an amount of 1 gram to 50% grams per kilogram of starting 1-phenyl-1,3-propanediol diacetate. A mixture of 1-phenyl-1,3-propanediol diacetate with methanol and potassium carbonate is heated to boiling while gradually distilling off the methyl acetate formed. After completion of the reaction, unreacted excess methanol is distilled off and then 1-renyl-1,3-propanediol is distilled under vacuum.

1-Penyl-1,3-propanediol diacetate is obtained by acidolysis of 4-phenyl-1,5-dioxane with acetic anhydride, catalyzed by, for example, chloride

- 2 232 394 ferric according to MS. 4-Phenyl-1,3-dioxane is readily obtained. The prins reaction of formaldehyde with styrene is described in a number of works, for example in Org. Syntheses 33, 72 (1953), Beets M.G.J. in Rec. trav. chim. Pays-Bas 70, 20 (1951), Isaguljans V.J., Rachmankulov D.L. and Safarov M.G. prikl. chim. 43,

2703 (1970) and elsewhere.

The process for preparing 1-phenyl-1,3-propanediol according to the invention achieves high yields of the product obtained in an amount of at least 85%.

The process for preparing 1-phenyl-1,3-propanediol according to the invention is obvious from another of the following examples of a specific embodiment.

Example 1

A mixture of 236.3 g (1 mol) of 1-phenyl-1,3-propanediol diacetate, 320 g (10 ml) of methanol and 4.1 g (0.03 mol) of potassium carbonate was heated under reflux for 4 hours. The reaction cell was equipped with a distillation column packed with stainless steel coils (5x5 mm) having an efficiency of about 8 TP. The resulting methyl acetate / bv was distilled off during the reaction. 57.3 ° C. After completion of the reaction, excess methanol / bv was distilled off. 64 ° C) and 1-phenyl-1,3-propanediol was distilled under vacuum. 163 DEG C. (0.258 kPa) which was obtained in a yield of 88.7% of theor.

Example 2

It was carried out in an analogous manner to Example 1 except that half the amount of methanol was used, the amount of potassium carbonate was 3 g. The reaction was terminated after 3 hours. The reaction rate was higher due to the higher temperature (85 ° C) in the distillation flask (versus the previous procedure, where it was about 70 ° C). This was because in this experiment most of the methanol was in the distillation column. The yield of 1-phenyl-1,3-propanediol was 91%.

1-Phenyl-1,3-propanediol is one of the relatively poorly available substances. Its use could be very wide. It has repellent effects, which excel especially in combination with diethyltoluamide, where it shows 5 232 394 a synergistic effect. It is also a suitable substance for the preparation of talc with various aldehydes, many of which have scented aromatic properties.

Claims (1)

SUBJECT OF THE INVENTION 232 394 A process for the preparation of 1-phenyl-1,3-propanediol by transesterification of 1-phenyl-1,3-propanediol diacetate with methanol, characterized in that potassium carbonate is used as a transesterification catalyst in an amount of 1 to 50 grams per kilogram of starting 1-phenyl-1. Of 5-propanediol diacetate.