DE2108926C3 - Process for the preparation of 3-acyl-4-hydroxy-buten- (2) -saurelactonen - Google Patents

Description

R ¹ -C-COOH

Il ο

(i)

HR ²

c --- c - c - = o

(II)

It is from Houben-Weyl, Methods of Organic Chemistry, 4th Edition Volume 7/1 (1954), pages 85 ff and Organic Reactions, Volume 16, pages 15 ff (John Wiley & Sons, Inc., New York 1968) known that «, ^ - unsaturated aldehydes or ketones, which am ^ -Carbon atom carry at least two hydrogen atoms, under the influence of a basic catalyst enter into an aldol reaction with aldehydes. The condensation takes place at the y-position, that of the Double bond is adjacent. With the ketones there is the additional possibility of an attack the second «carbon atom to the keto group if it bears at least two hydrogen atoms. You get in mostly unsatisfactory yields polyene-carbonyl compounds, which in turn are based on 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, polymerization or resinification also occurs as side reactions.

4-Hydroxy-buten (2) -acid lactones have so far only been cumbersome, multi-stage and uneconomical Ways made z. B. starting from 3-chloropropanediol (l, 2) and potassium cyanide or by reaction of 2,3-epoxy-butanoic acid esters with glacial acetic acid and hydrogen bromide (Houben-Weyl, methods of organisehen Chemistry, Volume VI / 2, 4th edition [! 963T, pages 658, 712 ff).

It has now been found that 3-acyl-4-hydroxybutene- (2) -acid lactones the general formula

in which R ¹ , R ² , R ³ and R ⁴ each denote a hydrogen atom or an alkyl radical having 1 to 7 carbon atoms, characterized in that an -oxo-carboxylic acid of the general formula

with an α, / J-unsaturated carbonyl compound of general formula

wherein R ¹ , R ² , R ³ and R ^{4 have} the aforementioned meaning, reacts at temperatures between 40 and 200 ° C. without using a catalyst.

40

Il

R ² -C

10

R ⁴

= C

(III)

C)

wherein R ¹ , R ^2, R- and R ⁴ each represent a hydrogen atom or an alkyl radical having 1 to 7 carbon atoms, advantageously obtained when a <x -oxo-carboxylic acid of the general formula

R ¹ -C-COOH

Il ο

(D

with a «, ^ - unsaturated carbonyl compound of general formula

JO

C ^ = C-C = O

(II)

R ⁴

wherein Ri, R2, R ^ and R ^{4 have} the aforementioned meaning, reacts at temperatures between 40 and 200 ° C without using a catalyst.

The implementation is carried out for the case of the use of crotonaldehyde and glyoxylic acid the following reaction equation is illustrated.

OHC

OHC-CH

OCH -H, O

HjC- CH HOOC

H ₃ C

With regard to the known processes, the process according to the invention surprisingly yields 3-acyl-4-hydroxy-buten (2) acid lactones («-Butenolide) in a simpler and more economical way in better yield and purity. The carbonyl group of «-Oxocarboxylic acid reacts with the« position of the carbonyl compound, which is according to the state of the art was not to be expected. 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. B. Aldolization of the Carbonyl compound, formation of polyene carbonyl compounds, Diels-Alder reactions, and one accordingly Mixtures of different end products would be obtained. The inventive method is therefore with surprisingly its beneficial results.

The starting materials can be used in stoichiometric amounts or in excess, preferably in one Ratio of 1 to 5 moles of one starting material to 1

Moles of the other starting material.

Suitable α-oxocarboxylic acids are, for. E.g .: glyoxylic acid, Pyruvic acid, isobutylglyoxylic acid.

Suitable «, ^ - unsaturated Carbcnylverbindungen are for example acrolein, crotonaldehyde, dimethylacrolein; Methyl vinyl ketone, pent-3-en-2-one, mesityl oxide.

Another surprising advantage of the process according to the invention is that it can be used of catalysts is not necessary.

The reaction is generally carried out without pressure or under pressure, advantageously under the pressure of the reaction mixture established at the reaction temperature, continuously or batchwise. Temperatures between 80 and 130 ^° C. are preferably used. If appropriate, solvents which are inert under the reaction conditions, such as water, are used; 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 is expediently used in an amount of 1 to 5% by weight, based on the Λ-oxocarboxylic acid.

In general, the reaction is carried out as follows: A mixture of the starting materials, if appropriate together with a solvent, is for 2 to 4 hours at the reaction temperature held. It is expedient to add the unsaturated carbonyl compound to the starting mixture stabilizing substance, e.g. B. hydroquinone, too. One can also choose one of the at the beginning of the reaction Add starting materials to the remainder of the mixture over a period of 15 to 45 minutes. When the boiling range of the mixture is above 100 ° C, the water of reaction can from the equilibrium are distilled off at normal pressure or in vacuo. The water can also by azeotropic distillation with an additional component, e.g. B. benzene, can be removed. at continuous operation, the starting mixture is expediently at the reaction temperature in initiated the reactor and at the same time the reaction mixture is released into a column for distillation. the end the reaction mixture is then the process product in a conventional manner, for. B. by distillation or Crystallization, separated

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

The process products which can be prepared by the process according to the invention are valuable starting materials for the production of solvents, dyes, plastics, paints, pesticides, Fragrances and cosmetics. For example, by splitting off the 3-acyl group, the in Ullmann's Encyclopedia of Industrial Chemistry, Volume 14 (1963), pages 769 ff.

In the following examples, parts mean parts by weight.

example

70 parts (1 mol) of crotonaldehyde, stabilized with 0.1% by weight of hydroquinone, are added in portions to 92 parts of glyoxylic acid hydrate (1 mol) at 80 ° C. over the course of 30 minutes, with stirring. The reaction mixture is still 1 ^! / Maintained at 100 ° C. for 2 hours and then distilled. 93 parts (74% of theory) of 4-methyl-3-formyl-4-hydroxy-buten (2) acid lactone with a boiling point of 95 to 97 ° C. are obtained Phenylhydrazone derivative of this compound melts at 183.5 to 185 ° C.

Example 2

While stirring, at 80 ° C., 70 parts of methyl vinyl ketone are added in portions to 92 parts of glyoxylic acid hydrate over the course of 45 minutes. The temperature is then maintained at 80 ° C. for 15 minutes, at 95 ° C. for 15 minutes and then increased to 110 ° C. After a further 2 hours, 89 parts (71% of theory) of 3-acetyl-4-hydroxy- butene- (2) Kp received from the -säurelacton ₃₁₂₁ ⁰ C. The phenylhydrazone of this compound melts at 193.5 to 194 ° C.

Claims (1)

Claim: Process for the preparation of 3-acyl-4-hydroxybutene- (2) -acid lactones the general formula Il R ² -C R- ¹ R ⁴ (HI)