DE2108926A1 - 3-acyl-4-hydroxy-2-butenoic acid lactone prepn - from an alpha-ketocarboxylic acid and an alpha beta unsatd carbonyl cpd - Google Patents

Abstract

3-Acyl-4-hydroxy-2-butenoic acid lactones, useful as inters. for solvents, dyes, plastics, paints, plant-protection agents, perfumes and cosmetics, are prepd. by reacting an alpha-oxo-carboxylic acid with a carbonyl cpd. having a double bond in the alpha,beta-posn. and an H-atom on the unsubstd. alpha-C atom.

Description

Process for the preparation of 3-acyl-4-hydroxy-buten (2) acid lactones The invention relates to a process for the preparation of 3-acyl-4-hydroxy-butene (2) acid lactones by reacting α-oxocarboxylic acids with β-unsaturated carbonyl compounds with a hydrogen atom on the unsaturated α-carbon atom.

It is from Houben-Weyl, Methods of Organic Chemistry, Volume 7/1, Pages 85 ff and Organic Reactions, Volume 16, Pages 15 ff (John Wiley & Sons, Inc., New York 1968) known that α, ß-unsaturated aldehydes or ketones, which am y carbon atom carry at least two hydrogen atoms, under the influence of one basic catalyst enter into an aldol reaction with aldehydes. The condensation takes place at the 7-position adjacent to the double bond. With the ketones there is also the additional possibility of an attack on the second α-carbon atom to the keto group if it bears at least two hydrogen atoms. You get in mostly unsatisfactory yields of polyene carbonyl compounds, which in turn follow the same Reaction principle can continue to react. Depending on the constitution of the starting materials one often obtains mixtures of different components that are difficult to separate, moreover polymerizations or resinification occur as side reactions.

4-IIydroxy-buten- (2) -acid lactones have so far only been used on inconvenient, produced in a multi-stage and uneconomical way, e.g. starting from 3-chloro-propanediol- (1,2) and potassium cyanide or by reacting 2,3-epoxy-butanoic acid esters with glacial acetic acid and hydrogen bromide (Houben-Weyl, loc. Cit., Volume VI / 2, pages 658, 712 ff).

It has now been found that 3-acyl-4-hydroxy-buten (2) acid lactones advantageously obtained when a-oxocarboxylic acids with carbonyl compounds in , ß-position a double bond and on the unsaturated a-carbon atom still carry a hydrogen atom.

In the case of using crotonaldehyde and glyoxylic acid, the conversion can be represented by the following formulas: With regard to the known processes, the process according to the invention surprisingly provides 3-acyl-4-hydrozy-buten-2-acid lactones (α-butenolides) in a simpler and more economical way in better yield and purity. The carbonyl group of the α-oxocarboxylic acid reacts with the α-position of the carbonyl compound, which was not to be expected from the prior art. Since both starting materials are polyfunctional, it had to be assumed that different reactions would occur side by side in the reaction mixture, e.g. aldolization of the carbonyl compound, formation of polyene-carbonyl compounds, Diels-Alder reactions, and mixtures of different end materials would be obtained accordingly. The advantageous results of the process according to the invention are therefore surprising.

As a rule, starting materials for the process are α-oxocarboxylic acids of the general formula a, ß-unge saturated carbonyl compounds of the general formula and thus end products of the general formula in question, in which R1, R2, R3 and R4 can be the same or different and each represent a hydrogen atom, an aliphatic, araliphatic, cycloaliphatic, aromatic or heterocyclic radical, in addition, R2 and R3 together with the adjacent carbon atoms or R3 and R4 together with the adjacent carbon atom denote members of a common alicyclic or heterocyclic ring.

Preferred starting materials I and II and accordingly preferred End products III are those whose formulas R1, R2, R3 and R are identical or different and each can be a hydrogen atom, an alkyl radical with 1 to 7 carbon atoms, an alkenyl radical with 2 to 7 carbon atoms, a cycloalkyl radical with 5 or 6 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms, a naphthyl or denote a phenyl radical. In addition, R2 and R3 can be used together with the adjacent carbon atoms or R3 and R4 together with the adjacent carbon atom Members of a common 5- to 8-membered ring, in addition to carbon atoms may also contain a nitrogen atom or an oxygen atom.

The radicals and rings mentioned can still be carried out under the reaction conditions inert groups and / or atoms, e.g. alkyl groups, alkoxy groups each with 1 to 4 carbon atoms, cyano groups, carbalkoxy groups, substituting the phenyl nucleus Chlorine atoms. The starting materials can be used in stoichiometric amounts or in excess, preferably in a ratio of 1 to 5 mol of the one starting material to 1 mole of the other starting material.

Suitable a-oxocarboxylic acids are e.g .: glyoxylic acid, pyruvic acid, Phenylglyoxylic acid, isobutylglyoxylic acid, cyclohexylglyoxylic acid, Naphthylglyoxylic acid, p-methoxyphenylglyoxylic acid, α-oxo-phenylpropionic acid.

Suitable, ß-unsaturated carbonyl compounds are, for example Acrolein, crotonaldehyde, dimethylacrolein, cyclohexylidene acetaldehyde, cinnamaldehyde, Furyl- (2) -acrolein, pyridyl- (2) -acrolein, cyclohexyl-acrolein, phenyl-crotonaldehyde; Methyl vinyl ketone, pent-3-en-2-one, vinylphenyl ketone, cyclohex-2-en-1-one, isophorone, 5,6-dihydro-y-pyran-4-one, mesityl oxide, benzyl vinyl methyl ketone, vinyl naphthyl ketone, Cyclohexylidene acetone.

There is a surprising advantage of the method according to the invention in that the use of catalysts is not necessary. Is preferred the reaction carried out in the absence of catalysts. If necessary, can Catalysts, suitably basic catalysts, are used0 Suitable are, for example, amine salts such as piperidine acetate; Hydroxides such as potassium, calcium, barium, Lead hydroxide; Alkali salts such as potassium, sodium carbonate, potassium cyanide, sodium acetate, sec-sodium phosphate; basic ion exchangers such as polyvinylbenzylammonium or Polyalkyleneamine resins; or corresponding mixtures.

The catalyst usually comes in an amount from 0.01 to 0.1 Moles per mole of a-oxocarboxylic acid into consideration.

The reaction is generally carried out at a temperature between 0 and 2000C, without pressure or under pressure, advantageously below that at the reaction temperature adjusting pressure of the reaction mixture, continuously or discontinuously carried out. Temperatures between, without the use of catalysts, are preferred 40 and 2000C, in particular between 80 and 1300C, and in the case of using Catalysts between 0 and 100 ° C., in particular between 20 and 50 ° C., are possible. If appropriate, solvents which are inert under the reaction conditions are used like water; aliphatic ethers such as diethyl ether; aromatic hydrocarbons such as benzene, toluene; Halogenated hydrocarbons such as trichlorethylene; Esters such as ethyl acetate; or corresponding mixtures. The solvent conveniently comes in an amount From 1 to 5 wt., based on to oxo-oxo-carboxylic acid, in questions.

Never reaction can be carried out as follows: A mixture of the husga-ng substances, optionally together with a solvent, is for 2 to 4 hours at the reaction temperature is advantageously kept one to the starting mixture the unsaturated carbonyl compound stabilizing substance, e.g. hydroquinone. One of the starting materials can also be added to the remainder of the mixture at the beginning of the reaction Add 15 to 45 minutes, If the boiling range of the mixture is above 1000C, the water of reaction can be out of equilibrium at normal pressure or in vacuo are distilled off. The water can also be used by azeotropic distillation an additional component, e.g. benzene, can be removed In operation, the starting mixture is expediently fed into the reactor at the reaction temperature initiated and at the same time the reaction mixture in a column for distillation relaxed.

The end product is then converted from the reaction mixture in the usual way, e.g. by distillation or crystallization.

An excess of starting material can either by distillation or in the case of an α-oxocarboxylic acid also by extraction with sodium bicarbonate solution removed.

The end products which can be produced by the process of the invention are valuable raw materials for the production of solvents, dyes, plastics, Paints, pesticides, fragrances and cosmetics. Regarding the Use, reference is made to the publications mentioned.

By splitting off the 3-acyl group, the in Ullmanns Encyklopadie der technical chemistry, volume 14, pages 769 ff described lactones can be obtained.

The parts given in the following examples are parts by weight.

Example 1 To 92 parts of glyoxylic acid hydrate are at 80 ° C. within of 30 minutes 70 parts of crotonaldehyde, stabilized with 0.1 wt.% Hydroquinone, under Stirring added in portions. The reaction mixture is still 1 1/2 hours at Held 1000C and then distilled. Man he @@@@ t 93 parts (74% theory) 4-methyl-3-formyl-4-hydroxy @@@@@@ n @) - sä @ relact @ n (Kp0.5 = 95 to 97 ° C., The @@@ nylhydr @ @@@@@@@@@@@@ @chmilzt at 183.5 to 1 @@@@@.

Example 2 With stirring @@@@@ n at 80 ° C to 92 parts of glyoxylic acid hydrate 70 parts of methyl vinyl ketone were added in portions within minutes. You keep that Temperature for another 15 minutes at 80 ° C, 15 minutes at 95 ° C and then increased to 110 ° C. After a further 2 hours, 89 parts (71% of theory) of 3-acetyl-4-hydroxybutene- (2) -acid lactone separated by distillation at bp3 = 121 ° C. The phenylhydrazone melts at 193.5 up to 194 ° C.

Claims (1)

Claim Process for the preparation of 3-acyl-4-hydroxy-buten (2) acid lactones, d u r c h e k e n n n z e i c h n e t that one can use α-oxo-carboxylic acids with Carbonyl compounds, which have a double bond in α, ß-position and on the unsaturated α-carbon atom still carry a hydrogen atom, converts.