DE2103686B2 - Process for the preparation of α-hydroxy-γ-lactones - Google Patents

Description

The condensation of aldehydes with olefins under the action of Lewis acids or in strongly acidic Medium is known as the "Prins reaction". For example from the work of D. Savostianoff in Comptes Rendus Volume 263, pages 605-607 (1966), this reaction results when used of «-Ketocarbonsäuren part of the aldehyde for Bi'dung of a-Hydroxy-y-lactones, which as well as the «-substituted butenolides derived therefrom in natural product chemistry or pharmaceuticals Chemistry matter.

f) However, the reaction does not proceed without formation of by-products. Especially when using isobutylene or similar, easily with water accumulation Olefins which can be converted into alcohols are obtained instead of the α-hydroxy-γ-lactone Ether, as Savostianoff has shown using the example of the reaction of isobutylene with glyoxylic acid, the tert-butyl ether of 2-hydroxy-4-methyI -) '- valerolactone is obtained.

If a halogen-substituted styrene is used as the olefinically unsaturated compound, the result is By-product the appropriately substituted aroylpropionic acid or a phenyl-13-dioxanderi va t.

In addition, Λ-oxocarboxylic acids tend to z. B. especially glyoxylic acid in the presence of strong acids to split off CO ₂ (decarboxylation).

The object of the invention was to keep the reaction between glyoxalic acid and olefins as free from byproducts as possible, to lead clearly and with high yield in the direction of the «-hydroxy-y-lactone formation.

It has been found that a -hydroxy-γ-lactone by reacting glyoxylic acid with an olefin from the group of derivatives of ethylene with terminal or central double bond in which the carbon atoms carrying the double bond are simple or are twice substituted, where the substituents can be identical or different and are alkyl radicals with I to 10, or aryl radicals with 6 to 12 or aralkyl radicals represent having 7 to 13 carbon atoms, in the presence of an acidic catalyst advantageously and obtained in high yields by the fact that the reaction at a temperature between 50 and 240 "C performs and only the glyoxylic acid itself as acidic catalyst can act.

It is surprising that the reaction proceeds without a further acidic catalyst, and that the

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concerned «-Hydroxy-y-lactone in good yields is obtained.

It is a particular advantage of the process according to the invention that the reaction products are neutralized either is not necessary or the excess acid can be easily removed by normal cleaning or cleaning. Separation process can be removed. That The reaction mixture is considerably less corrosive than when a strong acid such as e.g. B. at known procedure is the case. The decarboxylation of glyoxylic acid is avoided.

As olefins suitable derivatives of ethylene with terminal or central double bond are for Example propene, 1-butene, isobutylene, styrene, ethylidenecyclohexane, Hexene, cyclooctene, 5,6-dihydro-2-pyran or 2 ^ -dihydrofuran.

The inventive reaction of 'rtefin with glyoxylic acid is carried out in the specified temperature range of 50 to 240 ° C; At temperatures of about 80 to 240 ^° C., but especially at temperatures of 120 to 180 ° C., the reaction also proceeds in an advantageous manner with regard to the rate. The conditions naturally depend on the reactivity of the olefin. In general, it can be said that that olefins with terminal doubly substituted double bonds, ie vinylidene groups, are mostly more reactive than corresponding olefins with central double bonds.The best reaction temperature in the given range also depends on the stability of the starting and end products.

The glyoxylic acid reacts at a temperature of about 120 to 140 ^° C. The reaction can then be carried out without pressure without difficulty if the boiling point of the starting materials is above the reaction temperature. If the boiling point of a starting material is below the selected reaction temperature in the relevant range, the reaction is expediently carried out in an autoclave

But you can also gradually add the lower-boiling portion to the higher-boiling portion, so that the Partial pressure is not greater than the equilibrium pressure at the reaction temperature. In the autoclave you usually work at the pressure that sets itself due to the selected temperature, which can be, for example, 1 to 20, but also up to 250 atmospheres.

The reaction can be carried out with an excess of about 1 to 10 moles of a reactant will. In general, an excess of the olefin in question is preferred. However, if that olefin used is thermally less stable, is it may be more advantageous to use an excess of glyoxylic acid.

The reaction can be continuous and discontinuous according to the usual principles that the A person skilled in the art is familiar with. The continuous mode of operation can be advantageous, for example, when the excess component or the reaction product easily becomes in a continuous distillation can be separated from the reactants. The further work-up can then as usual by fractionated Distillation or crystallization can be carried out.

example 1

473 g of glyoxylic acid hydrate are dissolved in 160 ml of glycol dimethyl ether 3 hours at 135 ° C. and an autogenous pressure of 11 atmospheres together with 580 g of isobutylene

The reaction mixture is then fractionally distilled, 515 g of 4,4'-dimethyl - «- hydroxy-j> -butyrolactone (b.p. 15 = 135 "C), that's 78% Yield based on glyoxylic acid is obtained

Example 2

With good stirring, are added within 30 minutes to 1000 g of hydrated glyoxylic acid at 130 ⁰ C 6000g Λ-methylstyrene. The mixture is stirred for a further 4 hours at the same temperature. The lower-boiling components are distilled off and the residue is recrystallized from a mixture of benzene and cyclohexane (in a weight ratio of 1: 1). 1310 g of 4-methyl-4-phenyl - «- hydroxy-y-butyrolactone (64% yield, based on glyoxylic acid) with a boiling point of 93.5 to 95 ° C. was obtained.

Example 3

100 g of hydrated glyoxylic acid are added to 260 g of styrene at 120 to 130 ^° C. over a period of 1/2 hour with thorough stirring. The low-boiling components are distilled off and the temperature is kept between 125 and 130 ° C. for 3 hours. The excess on

ίο styrene is distilled off and the residue from the recrystallized the aforementioned benzene-cyclohexane mixture. 128 g of 4-phenyl - «- hydroxy-y-butyrolactone are obtained (F. 123 to 126 "C), corresponding to a yield of 72% based on glyoxylic acid.

Claims (1)

Claim: Process for the production of a-hydroxy-y-lactons d irch reaction of glyoxylic acid with an olefin from the group of the descendants of ethylene with a terminal or central double bond, in which the carbon atoms carrying the double bond are singly or doubly substituted, the Substituents can be identical or different and represent alkyl radicals with 1 to 10 or aryl radicals with 6 to 12 or aralkyl radicals with 7 to 13 carbon atoms, in the presence of an acidic catalyst, characterized in that the reaction is carried out at a temperature between 50 and 240 ^° C and only lets the glyoxylic acid itself act as an acidic catalyst.