DE1068696B - Process for the preparation of /, δ-olefinically unsaturated ketones which are branched in the d-position - Google Patents

Description

It is known that unsaturated ketones, which contain the double bond in the γ, <5-position, can be produced by thermal treatment via the acetoacetic esters of / 3, γ-unsaturated alcohols.

These acetoacetic esters were obtained in the first stage of the process by transesterification of the methyl or ethyl acetoacetate with the β, γ-unsaturated alcohols or by adding them to diketene (J. Amer. Soc, Vol. 65, 1943, pp. 1992 to 1998 ).

γ, (3-unsaturated ketones can also be obtained from ethyl acetoacetate and higher unsaturated alcohols, e.g. linalool and geraniol, if these are heated for a long time at 200 to 220 ° C (Caroll, J. Chem. Soc, 1941, 507 to 511).

The lower, olefinically unsaturated alcohols, whose boiling point is below about 160 ^° C., could not previously be converted directly with acetoacetic ester to form unsaturated ketones. They had to be obtained in very poor yields using the two cumbersome methods mentioned above.

The tertiary alcohols whose boiling point is below 14O ⁰ C, failed and the method of transesterification. For example, a mixture of acetoacetic ester with 2-methylbutene- (3) -ol- (2) can be refluxed for several days without the desired reaction occurring.

It has recently become known that lower unsaturated alcohols, such as. B. allyl or crotyl alcohol, directly with acetoacetic ester into the corresponding unsaturated ketones, such as allylacetone and 3-methylhexen- (l) -oii- (5), are transferrable if they according to British patent specification 695 313 to temperatures of Heated between 300 and 600 ° C.

However, only primary and secondary β, γ-unsaturated alcohols are accessible to this reaction, since the tertiary β, γ-unsaturated alcohols are largely converted into diolefins with elimination of water under these conditions. For example, isoprene and water are formed from 2-methylbutene- (3) -ol- (2) under these conditions.

It has now been found in the liquid phase, a method for preparing branched at <5 position y, ö-olefinically-unsaturated ketones by reacting tertiary ß, y-olefinically unsaturated alcohols with alkyl esters of acetoacetic acid at from 160 to 25O ⁰ C. This method consists in that one tertiary ß under 14O ⁰ C boiling, branched, y-olefinically unsaturated alcohols in alkyl acetoacetate or a mixture of Acetessigsäureaikylester with a solvent or a mixture of the alcohol with alkyl acetoacetate in a solvent is introduced, the respective reaction medium is preheated to the reaction temperature.

Suitable alkyl esters of acetoacetic acid are, in particular, those which differ from alcohols with 1 to 5 carbons for the production

of branched in <5-position,

γ, δ-olefinically unsaturated ketones

Applicant:

Aniline & Soda Factory in Baden

Stock corporation,

Ludwigshafen / Rhine

Dr. Heinrich Pasedach. and Dr. Matthias Seefelder,

Ludwigshafen / Rhine,
have been named as inventors

derive material atoms, especially from methanol and ethanol.

It leads to the unsaturated alcohol in the liquid, heated to 170 to 180 ° C or acetoacetic ester in a solution of acetoacetic ester in an inert solvent, which is also heated to 170 to 190 ⁰ C, and distilled continuously from the low-boiling components. These are ethyl alcohol in the case of ethyl acetoacetate and the low-boiling alcohol that has not reacted. The reaction temperature should not fall below 160 ° C.

As inert solvents are, for. B. tetrahydronaphthalene, decahydronaphthalene, naphthalene, diphenyl ether suitable. A solvent is expediently used which is different from the unsaturated ketone formed can easily be separated by distillation.

One can also proceed in such a way that a high-boiling inert material heated to the temperature mentioned is used Submit solvent and introduce a mixture of acetoacetic ester and unsaturated alcohol. Also in this In case, all low-boiling components are continuously distilled off.

To achieve good yields, it is advisable to use the unsaturated alcohol in excess, e.g. B. in a molar ratio of 2: 1.

The unsaturated ketone is obtained after the reaction has ended, which is reflected in the cessation of gas evolution recognizes by fractional distillation.

This process, which can also be carried out under increased pressure, is used to create the unsaturated ketones to be prepared in a simple manner in one reaction stage with good yields.

909 648/419

Claims (1)

3 4 Another advantage is that working with one gets 272 parts of 2-methylhepten- (2) -one- (6) and the strongly irritating and unstable diketene 38 parts of unreacted acetoacetic ester. The yield is avoided. is 80 ⁰ J ₀ , based on converted acetoacetic ester. Also from another work by M. F. Carroll. (J. Chem. Soc, 1940, pp. 704 to 706) is the implementation 5 Example ά known from linalool with alkyl esters of acetoacetic acid. 1000 parts of tetrahydronaphthalene are, as in the case of The inventive nature of the present process compared to game 1 described, heated to 175 ° C and then the However, this known procedure consists in the mixture of 390 parts of acetoacetic ester and 516 parts tertiary ß, γ-olefinically unsaturated 2-methylbutene- (3) -ol- (2) boiling below 140 ° C in the course of 6 hours Alcohols, which thus leads to the reaction temperature (160 to io. When distilling off, 453 parts of ethyl alcohol are obtained 250 ° C) are normally in gaseous form, obtained in liquid and methylbutenol and in the fractionated Phase can be implemented. This is achieved by distilling 222 parts of 2-methylhepten- (2) -one- (6) and by using a higher-boiling medium, e.g. B. obtained 25 parts of acetoacetate. Acetoacetic acid alkyl ester, an inert solvent, a The yield is 63%, based on converted acetoacetic acid Mixture of the two, or the ester obtained in the process, standing unsaturated ketones and the under Example 4 140 ° C boiling branched tertiary ß, y-olefinic- ^ unsaturated alcohol optionally together with 1000 parts of diphenyl ether are heated to 170 ° C and Acetoacetic acid alkyl ester in the reaction tem- at 170 to 180 ° C a mixture of 160 parts of 3-methyl temperature heated template introduces. If you put z. B. 20 pentene (4) -ol- (3) and 115 parts of acetoacetic ester in the course Methylbutenol entered after the lead of 4 hours given by Carroll. write at reflux temperature with acetoacetic ester, a distillate of 44 parts of ethyl alcohol is obtained so no methylheptenone is obtained even after hours. Methyl pentenol and, in the case of further fractionation, more It was therefore surprising that when 60 parts of methyl pentenol and 76 parts of 3-methylocten- (3) - Methylbutenol in the acetoacetic acid-25-on- (7), heated to 170 ° C, of b.p. ₁₈ 91 to 92 ° C. ethyl ester complete conversion is achieved, although the compound is a semicarbazone of mp. Methylbutenol boils at 98 ° C, resulting in a very low 113 ° C. Residence times for the methylbutenol introduced, Example 5 give. Nevertheless, the methylbutenol is completely ^v implemented, and the resulting low-boiling Aiko- 30 80 parts of diphenyl oxide are continuously distilled off in the bubble of a hole. Distillation apparatus at 19O ⁰ C and then warmed intra-The accessible by the method ketones are half of 15 hours, the mixture of 156 parts Acetwertvolle intermediates, in particular acetic acid ethyl ester perfume and 240 parts of 2,3-Dimethylbutenstoffindustrie. (3) -ol- (2) entered. The parts given in the examples are by weight. At the same time, a mixture is formed at the top of the column share. of ethyl alcohol and 2,3-dimethylbutene- (3) -ol- (2) in the Example 1 way distilled that the pot temperature during the reaction is from 175 to 185 ⁰ C. The distillation In a stirred vessel with attached distillation column, the column is connected to a gas meter, 650 parts of ethyl acetoacetate to 17O ⁰ C- 40 After entering the mixture of 2,3-dimethyl heats and in the course of 6 hours 860 parts of 2-methyl-buten- (3) -ol- (2) and acetoacetic ester is theoretically too buten- (3) -ol- (2) set free by a carbonic acid expected at the bottom of the mixing vessel, reaching pipe introduced. The reaction mixture is fractionally distilled. At the top of the distillation column while 772 parts are obtained in Kp. _10mm 78 to 8O ⁰ C, 126 parts of 2,3-di- Obtained distillate of bp 75 to 90 ° C, which vor- 45 methylhepten ^ -one-o.
contains mainly ethyl alcohol and methylbutenol. The carbonic acid produced during the reaction is also a patent claim removed at the top of the column. When the addition is complete, the reaction mixture is used to prepare processes for the (5-position) Heated for a further 1 hour and then fractionated 50 branched, γ, δ-olefinically unsaturated ketones through distilled. Implementation of tertiary ß, y-olefinically unsaturated 380 parts of 2-methylhepten- (2) -one- (6) from alcohols with alkyl esters of acetoacetic acid are obtained Boiling point 173 to 174 ° C and 60 parts of unreacted 160 to 250 ° C in the liquid phase, which means that Acetoacetic ester and 25 parts of dehydroacetic acid. draws that one boiling below 140 ° C, branched The yield is 66 ° / ₀ , based on converted 55 tertiary ß, γ-olefinically unsaturated alcohols in acet Acetoacetic ester. acetic acid alkyl ester or in a mixture of acet Example 2 acetic acid alkyl ester with a solvent or a Mixture of the alcohol with alkyl acetoacetate in 1000 parts of tetra solvent are introduced into the vessel described, the respective hydronaphthalene heated to 175 ° C and then 390 parts of 60 reaction medium to the reaction temperature. Acetoacetic ester added all at once. In this mixture is warm.
are in the course of 3 hours 516 parts of 2-methylbutene (3) -ol- (2) introduced. During the same period, considered publications will be: 460 parts of ethyl alcohol and methylbutenol are distilled off. Journal of the chemical society (London), 1940, After a further one hour, the reaction mixture is 65 pp. 704 to 706; Heat fractionally distilled. Chem. Zentralblatt, 1941, I, p. 3209. © 909 648/419 11.59