DE1021355B - Process for the preparation of doubly unsaturated ketones - Google Patents

Description

The invention relates to a process for the preparation of diunsaturated ketones as follows Formula used as intermediates in the synthesis of other polyene compounds and of drying oils can be used.

The process according to the invention for the preparation of doubly unsaturated ketones of the formula

RR ¹ C = CH-CH = CR ² COCH ₃ ,

where R and R ^{1 are} either saturated or olefinically unsaturated aliphatic hydrocarbon radicals or together with the adjacent tertiary carbon atom form a cycloaliphatic ring and R ^{2 is} a low molecular weight alkyl group or a hydrogen atom, is characterized in that a tertiary acetylenecarbinylacetoacetic ester of the formula

RR ¹ C (CeEeCH) OCOCHR ² COCh ₃ ,

wherein R, R ¹ and R ^{2 have} the above meaning, subjected to pyrolysis in the presence of an acidic catalyst.

According to the invention, for. B. the following compounds are produced, S-Cyclohexyliden-penten-S-one ^, 3-Ethyl-6-methylheptadien-3,5-on-2 and 6-methyloctadien-3,5-on-2, which have not yet been described have been.

The reaction of the method according to the invention can be represented by the following equation:

Method of manufacture
of doubly unsaturated ketones

Applicant:

The Distillers Company Limited,
Edinburgh (Great Britain)

Representative: Dr. W. Schalk and Dipl.-Ing. P. Wirth,

Patent attorneys,
Frankfurt / M., Große Eschenheimer Str. 39

Claimed priority:
Great Britain April 15, 1952

Richard Norman Lacey, Salt End, Hedon, Hull,

Yorkshire (UK),
has been named as the inventor

RR ¹ C (CSeCH) O-CO-CHR ² . COCH ₃ ->
-> RR ¹ C = CH - CH = CR ² -CO-CH ₃ + CO ₂

Those preferably used for the preparation of doubly unsaturated ketones according to the invention Acetoacetic esters are those in which the carbon atom is in the α-position to the acetyl group of the acetoacetic ester residue is not substituted, but acetoacetic esters, which are in the α-position by lower alkyl radicals are substituted, also use. Such acetoacetic esters substituted in the α-position can be found in In a manner not claimed here, they can easily be represented by unsubstituted in the α-position to the carbonyl group Acetoacetic ester with an alkyl halide in the presence of an alkali alcoholate according to the following equation

RR ¹ C (C = CH) - O • COCH ₂ - CO - CH ₃ + R ² X -> - > RR ¹ C (C = CH) - O • CO • CHR ² • CO • CH ₃ + HX

converts, where X is a halogen atom.

The substituents R and R ^{1 of} the carbinylacetoacetic esters which are used for the present invention can be any aliphatic saturated or olefinically unsaturated hydrocarbon radicals which contain 1 to 20 carbon atoms or together with the adjacent tertiary carbon atom form a cycloaliphatic ring. Preferred esters are those in which R and R ^{1 are} lower alkyl groups such as methyl, ethyl, propyl, butyl or amyl groups. The esters that can be used are, for example, the acetoacetic esters of the following compounds: ethynyldimethylcarbinol, ethylethynylmethylcarbinol, ethynylmethyl-n-propylcarbinol, n-butylethinylmethylcarbinol, isobutylethinylmethylcarbinol, tert-butylethinylmethylcarbinol, tert.-butylethinylmethylcarbinol, tert-butyldiisopropylmethylcarbinol, ethynyl-diisopropylmethylcarbinol, ethynyl-di-isopropanol, 1- Ethynylcyclohexanl-ol, l-ethynyl ^ -methylcyclohexan-l-ol, l-ethynyl-3-me-

thylcyclohexan-1-ol and 1-ethynyl-4-methylcyclohexanl-ol.

The heat cleavage of the tertiary acetylenecarbinylacetoacetic esters can preferably take place at temperatures above 100.degree between 150 and 250 °, can be carried out in the liquid phase. Suitable catalysts are, for example strong mineral acids such as sulfuric acid and phosphoric acid, organic sulfonic acids such as p-toluenesulfonic acid, and ferric chloride. The heat splitting can be effected in the liquid phase, expediently by the acetoacetic ester is mixed with the catalyst and the temperature is maintained until the gas is released stops. The released gases consist mostly of carbon dioxide, which results from the regrouping derives from the acetoacetic ester, which is

709 846/483

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tion conditions takes place. Other gaseous products neutralize the catalyst with solid acetic acid substances derived from secondary reactions. Pie heat dissipation can. trium: distilled and gave 6.7 parts by weight of 6-methylic in the vapor phase by adding heptadien-3,5-one-2 with boiling point 85 to 94 ° / 12 mm the vapor of the acetoacetic ester over an acidic mercury. Repeated distillation yielded the pure active catalyst, ζ., Β. one of the above-mentioned 5 ketones with a boiling point of 87 to 89 ° / 12 mm Hg, refraction catalysts, -which of an inert carrier material .coefficient n ™ = 1.5265. The ketone showed an absorbent adsorbed, conducts. Suitable temperatures are intermediate bands in the ultraviolet region (λ = 2890 A, see “about 250 and about 500 °, more expediently ε = 29500), which is characteristically above about 300 ° for the diene system. The acetoacetic ester is required. It an oxime was produced which did not necessarily have the melting point from the heat splitting isolated at 114 ° to 115 ° the starting material for the process has a properties: boiling point 164 to 165 °, refractive basic catalyst has been used, a coefficient »f = 1.4162; 2,4-Dinitrophenylhydrazone add excess of an acidic catalyst, melting point 74 to 75 °; Semicarbazone melting point after the reaction "between diketene and the 15 152 to 153 °.

Carbinol has been completed, and the resulting- Similar yields of the same dienone are due to

de subject the mixture to heat splitting directly. If the p-toluenesulfonic acid has been replaced by sulfuric acid, an acidic catalyst has been used for the starting phosphoric acid, benzenesulfonic acid or naphthalene material, further 2-sulfonic acid can be added.
Catalyst be unnecessary, and the reaction product ^{20 -R - -Io}

from the first stage can be without further treatment of the example ~

Be subjected to heat splitting. Optionally, 50 parts by weight of the acetone described in Example 1

the heat cleavage of the acetoacetic ester in the presence of the acetic acid ester were one in the course of 70 minutes corresponding carbinols can be made by inserting a heat splitting tube with an internal diameter of 2 cm z. B. less than the stoichiometric amount of diketene led 25, which over 17 cm of its length with pumice the first procedural stage applies. grains of 6.25 mm was filled. Was on the pumice stone

The doubly unsaturated ketones produced by heat splitting - all in all phosphoric acid with a weight of 5 parts - can be removed from the heat splitting part. The catalyst was heated to 340 ° and the product obtained was kept at this temperature. There were neutralized 4830 parts by volume of product and then under reduced 30 of a gas containing ₀ to 96 ° consisted / from carbon dioxide, distilled entDruck. The acetoacetic ester used as starting materials, 11.2 parts by weight of 6-methylheptadien-3,5-one-2 and the production of which is not under patent protection here, equal to 4 parts by weight of unchanged ester and 7 parts, are expedient by converting the weight of the corresponding carbinol.
Carbinols depicted with diketene. The implementation will be 35 ...
at a moderately elevated temperature, advantageously below Example 3

100 °, e.g. B. at 50 to 75 ° causes. The implementation takes 15 parts by weight of the acetoacetic ester of 1-ethynylcyclo-

with the release of heat and must therefore be carried out under sufficient hexan-1-ols (made from 1-ethynylcyclohexan-l-ol with cooling. Appropriately, diketene is added in the presence of triethylamine), the diketene was slowly added to the carbinol with one another 40 0.4 parts by weight of p-toluenesulphonic acid heated at 180 to 200 ° for 70 minutes to maintain the required temperature. During this time they were tern. Indifferent solvents can be present to dilute 1430 parts by volume of gas with a content of 67% CO ₂ . Such solvents are e.g. B. benzene. Neutralization and distillation gave 3.3 Ge-toluene, chloroform and ether. parts of the dienone from boiling point 130 to 137 ° /

The catalysts for the production of acetoacetic esters 45 12 mm mercury. The analysis agreed with the emsind expediently basic nature, for example such a piric formula C ₁₁ H ₁₆ O.
Salts, which, when dissolved in water, have an alkaline The product consisted of a mixture of isomers,

Have reaction, or most conveniently tertiary which differ from each other through the position of the double amines. Acidic catalysts, such as sulfur binding, are differentiated from a mixture acid, phosphoric acid and p-toluenesulfonic acid, 50 of 5-cyclohexylidenepenten-3-one-2,5- (l-cyclohexenyl) can also be used be used. penten-4-one-2 and 5- (l-cyclohexenyl) penten-3-one-l. That

The tertiary Acetylencarbinylacetessigester can 2,4 Dinitrophenylhydrazone melted with decomposition by distillation under reduced pressure or at 194 ° and the semicarbazone, also with decomposition, Vacuum isolated. Is an acidic catalyst at 204 °.

sator has been applied ", then this is before the distillation

neutralize lation. . - ""

The following examples, in which the parts by weight 18.2 parts by weight of the acetoacetic ester of 3-methyl-

are in the same proportion to the spatial parts as pentin-l-ols-3 (made from the corresponding car-gram to cubic centimeters, are supposed to be practical to explain the binol with diketene in the presence of triethylamine) Carrying out the process according to the invention with 0.05 part by weight of p-toluenesulfonic acid 70 Mifahrens to serve. grooves heated in a bath to 180 to 200 °, with

Example 1 rend this time 2190 parts by volume of gas with a content

of 96% CO ₂ were given off. The liquid product

17 parts by weight of ethynyldimethylcarbinylacetoacetate was neutralized with solid acetic acid sodium, (prepared from ethynyldimethylcarbinol and diketene in 65 then distilled and yielded 0.95 parts by weight of 3-methyl in the presence of triethylamine) were with 0.05 parts by weight of pentyn-1-ol-3 and 6 , 88 parts by weight of 6-methyloctadiene p-toluenesulfonic acid heated in an oil bath to 170 to 3.5-one-2 (49.8%) than a 180 ° boiling at 93 to 98714 mm. During a period of 2 ¹ Z ₂ hours Oil. Refractive index »| ⁹ = 1.5212. The 2,4-dinitro were evolved from 2100 parts by volume of gas containing phenylhydrazone crystallized from aqueous acetic acid in 93% CO ₂ . The product was after re-70 needles with a melting point of 183 to 185 °.

Example 5

11.8 parts by weight of the α-ethyl acetate of 3-methylbutyn-1-ols-3 (prepared by alkylating the starting ester with ethyl iodide and tert. Potassium butoxide) were heated with 0.05 parts by weight of p-toluenesulfonic acid at 200 to 220 ° for 3 hours, whereby 1010 parts of gas with a content of 93% CO _{2 were} developed. Upon fractionation of the resulting product, 4.8 parts by weight of a substance was obtained which boiled at 96 to 102 ° at a pressure of 10 mm of mercury and, as can be seen from the analysis with ultraviolet light, at about 40 to 50 ° / ₀ consisted of 3-ethyl-6-methylheptadien-3,5-one-2, the remainder consisted of unchanged ester with a similar boiling point. The identity of the dienone was verified by hydrogenation to 3-ethyl-6-methylheptan-2-one and by comparing the semicarbazone, which melted at 86 to 87 °, with an authentic sample of the saturated ketone.

Claims (3)

Patent claims: 1. Process for the preparation of diunsaturated ketones of the formula RR ¹ C = CH-CH = CR ² COCH ₃ , wherein R and R ^{1 are} either saturated or olefinically unsaturated aliphatic hydrocarbon radicals or together with the adjacent tertiary carbon atom form a cycloaliphatic ring and R ^{2 is} a low molecular weight alkyl group or a hydrogen atom, characterized in that a tertiary acetylenecarbinylacetoacetic ester of the formula RR ¹ C (C = CH) ■ OCOCHR ² COCh ₃ , wherein R, R ¹ and R ^{2 have} the above meaning, subjected to pyrolysis in the presence of an acidic catalyst. 2. The method according to claim 1, characterized in that a catalyst acting as acidic strong mineral acid or an organic sulfonic acid, optionally applied to an inert carrier, is used. 3. The method according to claim 1 and 2, characterized in that that the pyrolysis in the liquid phase at 150 to 250 ° or in the vapor phase above 250 °, preferably at 300 to 500 °, is carried out. Considered publications:
German Patent Nos. 706 322, 717 652;
Karrer, textbook of the organ. Chemie, 11th edition, 1950, p. 304. © 709 846/483 12.57