DE2521470A1 - PROCESS FOR THE MANUFACTURING OF VINYLESTER EPOXIDES - Google Patents

Description

"Process for the production of vinyl ester epoxides"

The invention "relates to an economically beneficial one Process for the preparation of epoxides of vinyl esters of the general formula:

CH

OCOR

wherein R is an alkyl, arylalkyl, aryl or cycloalkyl radical is; these compounds are used to produce glycolaldehyde by hydrolysis and this in turn is an intermediate for the synthesis of solvents, plastics, d, £ -serine, etc.

As for the preparation of d, £ -sine made with the help If the Strecker reaction and its variants takes place, the reaction can advantageously be carried out directly on that according to the invention

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252H70

produced vinyl ester epoxide are carried out because the hydrolysis to glycolaldehyde takes place in situ due to the alkaline conditions of the reaction itself.

It is known that vinyl acetate epoxide can be obtained by epoxidation of vinyl acetate can be produced with the help of perbenzoic acid (B.S. Gorton and J.A. Reeder, J.Org.Chem., 27, 2920 1962).

However, the process is uneconomical because the cost of the perbenzoic acid is relatively high and one only low yields (25%) achieved.

In contrast, in the present process, the epoxidation of the starting compound proceeds with high yield with the aid of peracetic acid (provided that it is free of undesirable additions such as water, hydrogen peroxide, alcohols and strong acids), which results in significantly lower production costs . can be produced on an industrial scale by oxidizing a solution of acetaldehyde in an inert solvent with molecular oxygen. This reaction proceeds according to the following scheme:

GH ₀ = CH-O-COR + CH ₂ COOOH - * CH ₀ - CH - 0 COR + CH-, COOH

3 2 3

^X 0 ^/

and is carried out at temperatures between -20 ⁰ C and +50 ⁰ C, preferably at about O.

In order to obtain good yields in the epoxidation with acetic acid, care must be taken in the presence of a strong one Working excess vinyl ester in order to avoid that the epoxy vinyl ester thus formed in the course of the reaction reacts with the acetic acid.

5098 4 7/1196

_ 3 -

The large excess of vinyl ester makes it possible to work in such a dilute system that the epoxides react is suppressed with the acetic acid, without the epoxidation itself is slowed down at the same time, since the diluent is the basis of this reaction.

in presence The reaction is preferably carried out by / by traces a common radical scavenger such as 4, V-thiodi- (6-t-butyl-3-methylphenol); 2,6-di-t-butyl-4-methylphenol; Dilauryl 3 »3'-thiodipropionate or distearyl 3,3'-thiodipropionate.

In this way, the reaction proceeds quantitatively and gives the pure product, depending on the type of purification and isolation in a yield of at least 65% ₅ which can still be substantially increased by work-up of the filtrates, etc. in a known manner.

The method is explained in more detail using an example that is not restrictive.

Be i s ρ i e 1

For the preparation of vinyl acetate epoxide from vinyl acetate with the aid of peracetic acid, 56 ml (52 g, 0.605 mol) are added vinyl acetate cooled to 0 ° 0 with traces of a radical scavenger (e.g. of 2,6-di-tert-butyl-4-methylphenol) and add 7 ml of a 5i3 molar solution (corresponding to 37 mmol) of peracetic acid in acetic acid.

The peracetic acid solution was prepared according to the method of Y. Ogata and Y. Sawaki in Tetrahedron, 23, 3327 (1967) by alkaline perhydrolysis of acetic anhydride in water (in the absence of methanol) in the presence

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name of Mg SO ^. 7 HpO and subsequent acidification m t HoSO ^ ,, being the peracid together with the acetic acid extracted several times with CHpCIp and finally the solvent is driven off under atmospheric pressure in a 1 m Vigreux column; in this way one gets a concentrated one Solution of the peracid in acetic acid that is free from undesirable impurities.

The above mixture was allowed to stand in a closed vessel at 0 ° for 7 days. At this stage a gas chromatography shows Test using a standard curve of the reaction mixture a substantial yield of vinyl acetate peroxide, calculated on the peracid used. Then 9-25 g of sodium bicarbonate were added to the reaction mixture and the suspension was vigorously stirred for 3 hours at room temperature, protected from atmospheric moisture. This will remove almost all of the acetic acid without losing epoxy.

The suspension was then filtered and the filter residue was washed out with a little methylene chloride. To remove the vinyl acetate and methylene chloride, the combined filtrates were fractionally distilled at about 20 mmHg and 15 ° G. The piston was there with a Liebig Büekflufikülilea? equipped, which was filled with Raschig rings and in which water at 10 ° C circulated; the template was cooled with liquid air. In this way a partial reflux was obtained, which ensures proper fractionation. At the end of the distillation, 3> 93 6 epoxide of 81 % purity remained, which corresponded to 84% of the theoretical yield; the remainder had passed over together with the vinyl acetate, the methylene chloride and traces of acetic acid and the impurities consisted of vinyl acetate and acetic acid in a ratio of about 3 ^ 1 and traces of monoacetoxyaeetaldehyde.

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252U70

For further purification, the reflux condenser is removed, and the remaining residue in the flask is evaporated at about 50 mm Hg in a water bath at 20 ⁰ C. By interrupting this operation when the residue in the flask is 95% thick vinyl acetate epoxide (the remainder being acetic acid and traces of vinyl acetate), the product is obtained in an amount of 2.58 g, which corresponds to a 65% yield (calculated on the peracetic acid used) corresponds to pure vinyl acetate epoxide.

PATENT CLAIMS:

509847/1196

Claims (1)

PATENT CLAIMS Process for the preparation of vinyl ester epoxides, characterized in that vinyl esters the general formula: CH - OCOR wherein R is an alkyl, arylalkyl, aryl or cycloalkyl radical is reacted with peracetic acid. (2) Process according to claim 1, characterized in that the reaction is carried out in the presence of excess vinyl ester. (3) The method of claim 1 or 2, characterized geke η η is characterized in that, preferably at about 0 °, the reaction is performed at a temperature between -20 and + 5O ⁰ C. (4) Process according to Claim 1, 2 or 3j, characterized in that the reaction is carried out in the presence a common radical scavenger such as 4,4'-thiodi (6-t-butyl-3-methylphenol); 2,6-di-t-butyl-4-methylphenol; Dilauryl 3> 3'-thiodipropionate or distearyl 3,3'-thiodipropionate performs. 86XXIV 509847/1136