WO2000014046A1 - METHOD FOR PRODUCING η,δ-UNSATURATED KETONES BY CARROLL-REACTION - Google Patents

Abstract

The invention relates to a method for producing gamma , delta -unsaturated ketones of general formula (I) by reacting an acetoacetic alkyl ester with an allyl alcohol or a propargyl alcohol of general formula (II) in which R<1> can represent H or a saturated or unsaturated, branched hydrocarbon radical which is optionally substituted by methoxy groups and which has 1 to 33 C-atoms, and the dashed line can represent another bond between the C-atoms carrying the same. The reaction is carried out at temperatures ranging from 150 to 220 DEG C in an optionally modified Carroll reaction, in the presence of an aluminum catalyst, and by distilling off the alkanol formed during the reaction. The inventive method is characterized in that an acetoacetic ester of general formula (III) is used as an acetoacetic alkyl ester in which R<2> represents an alkyl group with 1 to 4 C-atoms.

Description

Process for the production of γ, δ-unsaturated ketones by Carroll reaction

description

The invention relates to an improved process for the production of γ, δ-unsaturated ketones, in particular methylheptenone, geranyl acetone and farnesylacetone or their dihydro derivatives or geranylgeranylacetone by a Carroll reaction in the presence of aluminum catalysts.

A Carroll reaction is the chain extension of an allyl or propargyl alcohol with acetoacetate or diketene to form γ, δ-unsaturated ketones. For example, it can proceed according to the following reaction scheme:

Acetoacetylation

Claisen decarboxy

Rearrangement

In the key step, the new acetoacetic ester of the unsaturated alcohol, which is primarily formed from the allyl or propargyl alcohol and the acetoacetic acid ester or diketene, is rearranged in a Claisen rearrangement to give β-keto acid, which then spontaneously decarboxylates. Initial studies on Carroll reactions are in J. Am. Chem. Soc. 65 (1943) 1992-1998.

Since the beginning of the 1950s, this reaction has been used in a variety of ways in the production of terpenes. For example, the terpenes required as essential precursors for vitamin A and vitamin E are 2-methyl-2-hepten-6-one, 6, 10-dimethyl-5, 9-undecadien-2-one (geranylacetone) and 6, 10 , 14-Trimethyl-5, 9, 13-pentadecatrien-2-one (farnesylacetone), produced on an industrial scale by the Carroll reaction.

For example, from GB 695 313 Carroll reactions in the gas phase at 300 to 600 ° C. using allyl or crocylacetoacetate are known. No. 2,628,250 discloses the preparation of 2-methyl-2-hepten-6-one from 2-methyl-3-buten-2-ol and diketene.

The production of tetrahydrofarnesylacetone from tetrahydronerolidol and diketene is known from US Pat. No. 2,660,608.

According to the process of US Pat. No. 2,795,617, aluminum alcoholates, in particular the aluminum isopropylate of the formula AI (0-CH (CH ₃ ) ₂ ) ₃ , were used as catalysts for Carroll reactions in amounts of 0.8 to 2.5 mol% on the alcohol used as the starting material.

According to the method of GB 886 353, aluminum complexes with acetylacetone or acetoacetic esters, such as aluminum tri (acetylacetonate), aluminum tri (methyl acetoacetate) or aluminum tri (ethyl acetoacetate), were used as catalysts for Carroll reactions.

In the previously known Carroll reactions of an acetoacetic acid ester with a tertiary vinyl carbinol or propargyl alcohol, the methyl ester or the ethyl ester was generally used as the alkyl acetoacetic acid ester. The low-boiling primary alcohol (methanol or ethanol) split off during the acetoacetylation of the unsaturated alcohol was distilled off during the reaction together with the carbon dioxide formed in the decarboxylation.

The yields achieved in the Carroll reaction with methyl acetoacetate or ethyl ester are not yet completely satisfactory for use on an industrial scale. This is due on the one hand to the relatively long reaction times required and on the other hand to the fact that, under the reaction conditions, the unsaturated ketones formed are hydrogenated to a small extent to alcohols which are difficult to remove, as a result of which the yields are impaired.

It was therefore the object of the invention to shorten the reaction times for the production of γ, δ-unsaturated ketones by reacting allyl or propargyl alcohols with acetoacetic esters in an aluminum-catalyzed Carroll reaction, and thus to improve the possibility of continuous process control. It was also the object of the invention to improve the yields even further.

It has now surprisingly been found that when using acetoacetic acid esters of tertiary alcohols, such as tert. -Butanol, ter. -Pentyl alcohol (2-methyl-butan-2-ol) or dimethylpropylcar- binol (2-methyl-pentan-2-ol) instead of methyl acetoacetate (AME) or ethyl acetoacetate, the Carroll reactions to γ, δ-unsaturated ketones proceed faster and with higher yields, ie with the formation of fewer by-products. 5 These improvements are particularly important when using a higher and therefore more valuable unsaturated alcohol as the starting compound. This applies, for example, to the use of 3, 7-dimethyl-l, 6-octadien-3-ol (linalool), 3,7,11-trimethyl-1, 6, 10-dodecatrien-3-ol (nerolidol) , 3,7,10-tri-10-methyl-1, 6-dodecadien-3-ol (dihydrolinalool) and especially for E, E-9, 7, 11, 15-tetramethyl-1, 6, 10, 14-hexatetraene -3-ol (E, E-geranyllinalool).

It was already known from EP 376 859 B1 that one can also achieve good yields in the acetoacetylation of nucleophiles such as alkanols, alkylamines or alkylthiols with acetoacetic acid esters or their derivatives if esters of tertiary alcohols, such as acetoacetic acid esters, can be obtained tert. -Butanol or tert. -Amyl alcohol is used, but this is not about Carroll reactions, but about the func ionalization by acetoacetylation of low-molecular or polymeric nucleophiles, which are ultimately used as coatings to improve the dyeing technique.

The invention relates to a process for the preparation of γ, δ-unsaturated ketones of the general formula I

30 by reacting an allyl alcohol or a propargyl alcohol of the general formula II

in which R ^{1 represents} H or a saturated or unsaturated branched hydrocarbon radical with 1 to 33 C atoms, optionally substituted by methoxy groups, and the dotted line can represent a further bond between the C atoms carrying it,

with an acetoacetic acid alkyl ester at temperatures of 150 to 45 220 ° C in an optionally modified Carroll reaction in the presence of an aluminum catalyst and distilling off the alkanol which is formed, which is characterized in that an acetoacetic acid ester of the general formula III as the acetoacetic acid alkyl ester

in which R ^{2 represents} an alkyl group having 1 to 4 carbon atoms.

Surprisingly, with the aid of the process according to the invention, the higher γ, δ-unsaturated ketones can be obtained in yields of 92 to 96% of theory in a simple manner and in continuous process control, which is particularly desirable for processes on an industrial scale, even if none Excess or only a slight excess of one of the reaction components is used. Furthermore, it is a great advantage that the space-time yields of the previously known methods can be increased by the method according to the invention.

The process according to the invention is of particular importance for the reaction of alcohols of the general formula (II) in which R ^{1 is} for a group of the general formula IV

in which n stands for an integer from 1 to 5 and x and y either stand for H, or x stands for methoxy and y stands for H or x and y together for an additional bond between the C and X bearing y Atoms are, such as 3, 7-dimethyl-1,6-octadien-3-ol (linalool),

3, 7-dimethyl-1-octen-3-ol, 3,7, 11-trimethyl-1, 6, 10-dodecatrien-3-ol (nerolidol), 3, 7, 11-trimethyl-1-dodecene -3-ol,

3, 7, 11-trimethyl-l, 6-dodecadien-3-ol (dihydronerolidol) and

3, 7, 11, 15-tetramethyl-l, 6, 10, 14- (E, E) hexadecatetraen-3-ol (E, E-

Geranyllinalool).

The use of acetoacetic acid tert. -butyl ester or ter. - Amyl ester has the advantage of faster conversion and the avoidance of by-products. The quantities used Reactants are advantageously chosen so that a molar ratio of alcohol of formula II to acetoacetic acid alkyl ester of formula III is between 0.8 and 1.2, preferably from 0.95 to 1.10.

Suitable organic aluminum compounds for the process according to the invention are essentially compounds of the general formula V.

in der R⁴ verzweigte oder unverzweigte Alkyl- oder Alkoxygruppen mit 1 bis 4 C-Atomen, vorzugsweise Methyl- oder Ethylgruppen be- deutet, R⁵ und R⁵ verzweigte oder unverzweigte Alkyl- oder Alkoxygruppen mit 1 bis 5 C-Atomen, vorzugsweise eine Methyl- oder eine 2-Butyl-gruppe bedeuten, R⁷ für eine verzweigte oder unverzweigte Alkylgruppe mit 1 bis 4 C-Atomen steht und m sowie n eine ganze Zahl von 0 bis 3 bedeuten können, wobei n+m ≤ 3 ist, sowie Aluminiumtriaryloxylate in Betracht. Besonders bevorzugt werden flüssige Aiuminiumverbindungen, insbesondere Aluminiumverbindungen, bei denen R⁵ ein Methylrest, R⁶ ein Butylrest und die Summe aus n+m - 3 und das Verhältnis n/m > 0,3 ist.

in which R ^{4 is} branched or unbranched alkyl or alkoxy groups with 1 to 4 C atoms, preferably methyl or ethyl groups, R ⁵ and R ^{5 is} branched or unbranched alkyl or alkoxy groups with 1 to 5 C atoms, preferably one Are methyl or a 2-butyl group, R ^{7 is} a branched or unbranched alkyl group having 1 to 4 carbon atoms and m and n can be an integer from 0 to 3, where n + m 3 3, and Aluminum triaryloxylates into consideration. Liquid aluminum compounds, in particular aluminum compounds, in which R ^{5 is} a methyl radical, R ^{6 is} a butyl radical and the sum of n + m −3 and the ratio n / m> 0.3 are particularly preferred.

The first-mentioned catalysts are therefore lower aluminum trialcoholates, such as aluminum trimethylate, triethylate, triisopropoxide, tri-sec. -butylate and compounds which are formed in the reaction of the aluminum trialcoholates mentioned with stoichiometric amounts of acetylacetonate, alkyl acetoacetate or alkyl malonate with elimination of alcohol and transesterification. Examples include aluminum triacetoacetate, aluminum triacetylacetonate, aluminum monoacetoacetate diethylate, aluminum monoacetoacetate diisopropylate, aluminum diacetoacetate monoisopropylate.

The aluminum trialcoholates, in particular the aluminum triisopropylate and the aluminum trisec, are preferably used. -butylate. Mixed aluminum triacetoacetates, which are obtained by reacting aluminum sec. -butylate or aluminum triisopropylate with methyl acetoacetate with elimination of 2-butanol or iso-propanol and transesterification of the methoxy groups with the released 2-butanol or iso-propanol, the degree of transesterification should be over 30%.

We call aluminum triaryloxylates the aluminum salts of aromatic hydroxy compounds such as aluminum triphenolate, aluminum tricresolates, aluminum trixylene enolates, aluminum tri- naphtholates, the aryl radicals of which can also be substituted by lower alkyl or alkyloxy groups, ie alkyl or alkyloxy groups having 1 to 4 carbon atoms, hydroxyl groups or phenyl. Of these, the relatively easily accessible aluminum triphenolate is used with particular advantage.

It is advantageous to use liquid catalysts or solutions of solid catalysts and to feed them into the reaction vessel in liquid form. For example, aluminum trialcoholates dissolved in alkyl acetoacetate or a mixture of alkyl acetoacetate and an alcohol of the general formula II can be used.

The amount of the aluminum compound is generally such that its concentration in the reaction mixture does not fall below 0.05% by weight Al and does not exceed 6% by weight Al at the start of the reaction. Based on the alkyl acetoacetate to be reacted, 0.5 to 5 mol% of the aluminum compound are generally required. For the preferably used aluminum triisopropylate and the above-described mixed aluminum sec. Butylate and methyl acetoacetate produced aluminum triacetoacetate are e.g. Amounts of about 1 to 3 mol% based on the alkyl acetoacetate to be reacted are used.

When using allyl alcohols of the formula II with a boiling point below 120 ° C., such as 2-methyl-3-buten-2-ol, it is particularly advantageous if the Carroll reaction is carried out in a cyclic carbonate of the general formula VI or a γ-lactone of the general formula VII

in denen die Reste R¹, R² und R³ für H, Methyl oder Ethyl, vor- zugsweise für H oder Methyl stehen und R⁴ für H, Methyl, Ethyl, Isopropyl, Phenyl oder Methoxymethyl, vorzugsweise für H oder Methyl, steht, als Lösungsmittel durchführt.

in which the radicals R ¹ , R ² and R ^{3 are} H, methyl or ethyl, preferably H or methyl and R ^{4 is} H, methyl, ethyl, isopropyl, phenyl or methoxymethyl, preferably H or methyl , as a solvent.

Cyclic 5-ring carbonates of the general formula VI are, in addition to the customary alkylene carbonates, such as ethylene carbonate, 1, 2-propylene carbonate, isobutylene carbonate and 1, 2-butylene carbonate, ie carbonates of the general formula VI, in which R ¹ to R ⁴ are H or methyl, or R ¹ to R ^{3 is} H or methyl and R ^{4 is} ethyl, also those in which R ¹ to R ^{3 can} additionally be ethyl and R ^{4 is} H, methyl, ethyl, Isopropyl, phenyl or methoxymethyl. 5

The cyclic carbonates used can also be produced very inexpensively on an industrial scale by reacting the corresponding alkylene oxides with CO ₂ . They generally have such high boiling points that temperatures of 10 170 ° C can be easily reached under normal pressure.

Particularly suitable 5-ring lactones of the general formula VII are v-butyrolactone and 3-methyl-γ-butyrolactone, in particular γ-butyrolactone. 15

The γ-butyrolactones of the general formula VII used according to the invention can also be prepared on an industrial scale by dehydrogenation of the corresponding butanediols.

20 The alkanol formed in the reaction surprisingly attacks the cyclic carbonates or lactones under the reaction conditions so little that, for example, when using propylene carbonate, the solvent can be reused for up to 10 reaction cycles without any purification

25 (cf. comparative example 1b). The cyclic carbonate or lactone separated after the isolation of the γ, δ-unsaturated ketone can be fed into new reaction cycles without addition of the catalyst. Residues of unreacted acetoacetate remain in the solvent and are not lost.

30

The 5-ring carbonates and 5-ring lactones are generally used in amounts of 50 to 1000% by weight, preferably 100 to 500% by weight, based on the γ, δ-unsaturated ketone formed.

35 When using alcohols of the formula II which have a boiling point above 140 ° C., the Carroll reaction can advantageously also be carried out without the addition of substantial amounts of a solvent. This has advantages when working up the reaction mixture.

40

The process according to the invention can be carried out batchwise and continuously. In order to carry out the process according to the invention continuously, the procedure is advantageously such that the starting compounds and the catalyst are combined with a

45 heat bath provided reaction vessel with attached condensation device for the alcohol released and for the discharge of Pumped carbon dioxide and pumps the reaction product with the help of an overflow.

With the aid of the process according to the invention, the coveted γ, δ-unsaturated ketones of the general formula I can be obtained in a simple manner with surprisingly high yields. The tertiary alcohols released from the acetoacetic acid ester can be recovered almost completely.

Examples

Example la

Carroll reaction of 2-methyl-3-buten-2-ol with acetoacetic acid ester. -butyl ester in propylene carbonate at 180 ° C

A mixture of a mixture of 50 ml (45 g) 1, 2-propylene carbonate and 2.8 g of a separately (according to GB 886 353) aluminum tri-methylacetoacetate catalyst was made at 170 ° C within 2 hours 25.7 g of a 92% 2-methyl-3-butene-2-ol and 39.8 g of acetoacetic acid tert. -butyl ester added dropwise. During the dropping, CO ₂ and low boilers developed lively, which were continuously distilled off (bp = 80-85 ° C.). After the dropping had ended, the mixture was stirred for a further 10 minutes (min) until the evolution of gas had ended and then cooled. A feed of 2.5 g and 30.9 g of a main fraction consisting of 96-98% 2-methyl-2-hepten-6-one was then distilled off at about 100 mbar. The yield (with the amount remaining in the distillation bottoms) was 92% of theory.

Example lb (comparative example)

Reaction of 2-methyl-3-buten-2-ol with methyl acetoacetate in 1,2-propylene carbonate

a) To a mixture of 45 g of 1, 2-propylene carbonate and 2.8 g of a separately (according to GB 886 353) manufactured aluminum trimethylacetoacetate catalyst was a mixture within 2 hours (h) with stirring at 180 ° C. pumped from 29.03 g (0.25 mol) of methyl acetoacetate (AME; purity 98%) and 23.68 g (0.275 mol) of 2-methyl-3-buten-2-ol (MBE; purity 94%). During this time, CO ₂ outgassed and 8 g of low boilers were distilled off, about 2/3 of which consisted of methanol and about 1/3 of unreacted 2-methyl-3-buten-2-ol. The mixture was then stirred at 180 ° C. for a further 30 minutes (min), then cooled and extracted from the reaction mixture at a reduced pressure of 100 mbar distilled off the desired 2-methyl-2-hepten-6-one.

b) The distillation residue obtained here was again mixed with the amounts of AME and MBE indicated above at 180 ° C. in the course of 2 h, the reaction mixture was stirred at 180 ° C. for 30 min, then cooled and the 2-methyl-2-heptene obtained therefrom 6-distilled off.

c) Process b) was repeated 8 times. The mean yield of 2-methyl-2-hepten-6-one over all 10 batches was 88% of theory, based on the converted MBE (gas chromatographic determination with an internal standard).

Example 2a

Carroll reaction of 3, 7-dimethyl-l, 6-octadien-3-ol (linalool) with acetoacetic acid tert. -butyl ester to 6, 10-dimethyl-5, -undecadien-2-one

5.6 g of aluminum tri-methylacetoacetate (made from aluminum triisopropylate analogous to GB 886353) were initially charged, the mixture was heated to 180 ° C. and a homogeneous mixture of 115.7 g of linalool and 128 g of acetic acetic acid was pumped at this temperature in 2 hours. tert. -butyl ester in the reaction vessel. This spontaneously formed CO ₂ and tert-butanol, which was condensed. 51 g of tert were isolated. -Bucanol. After the end of the feed, the mixture was stirred for a further 20 min at an internal temperature of 180-190 ° C. and then allowed to cool. The reaction discharge was distilled under a pressure reduced to 0.1 mbar. A total of 139.7 g of 6, 10-dimethyl-5, 9-undecadien-2-one (geranylacetone) was obtained in two fractions, which corresponds to a yield of 96% of theory.

Example 2b (comparative example)

Carroll reaction of linalool with methyl acetoacetate

5.6 g of the aluminum catalyst described there were introduced as in Example 2a) and a mixture of 115.4 g of linalool and 94 g of methyl acetoacetate was pumped in at an internal temperature of 180 ° C. This spontaneously formed C0 ₂ and methanol, which was condensed. As in Example 2a), the reaction mixture was stirred for a further 20 min until the CO ₂ evolution had ceased and then cooled. It was distilled under reduced pressure and 133 g of geranyl acetone were obtained. The yield was 91.5% of theory. As a side pro Products had formed 1.6 g of 6, 10-dimethyl-5, 9-undecadien-2-ol, which were not detectable in Example 2a).

Example 3a

Carroll reaction of 3,7,11,15-tetramethyl-1, 6, 10, 14 (E, E) hexadecatetraen-3-ol (E, E-geranyllinalool) with tert-butyl acetoacetate to give 6, 10, 14, 18-tetramethyl-5, 9, 13, 17-nonadecatetraen-2-one (geranylgeranylacetone)

10

2.5 g aluminum tri-tert. -butylacetoacetate were tert at 40 ° C in 42.1 g of acetoacetic acid. -butyl ester dissolved and 72.5 g of E, E-geranyllinalool added to this at 20 ° C. This mixture obtained was pumped uniformly into a lying heated reaction vessel 15 with an overflow and a distillation bridge attached. The feed rate was adjusted so that the average residence time was 10 minutes. The internal temperature was 190-200 ° C. 15 g of tert distilled during the reaction. -Butanol.

20 After the end of the feed, the reaction product was distilled. 75.9 g of geranylgeranylacetone with a purity of 98.8% were obtained. This corresponds to a yield of 92% of theory.

Example 3b (Comparative Example) 25

Carroll reaction of E, E-geranyllinalool with methyl acetoacetate to geranylgeranylacetone

2.2 g of aluminum tri-methylacetoacetate were dissolved in 37.6 g of 30 methyl acetoacetate at 60 ° C. and the solution was mixed with 87 g

E, E-geranyllinalool. This solution was pumped evenly into the horizontal reactor vessel described in Example 3a). The pumping rate was matched to the available reaction volume so that there was an average residence time of 10 ± 0.5 min. At 190-200 ° C 35 internal temperature, the mixture reacted continuously to geranylgeranylacetone. After the feed had ended, the contents of the reactor were heated for a further 10 minutes and then added to the cooled reaction discharge. It was distilled at 0.3 mbar and 84.2 g of geranylgeranylacetone with a purity of 40 97.1% were obtained in the main fraction. This corresponds to a yield of 85% of theory.

45 Example 4a

Carroll reaction of nerolidol with acetoacetic acid (2 ^λ- methyl-but-2 ^λ -yl) ester

5.6 g of aluminum tri-methylacetoacetate were placed in the same reaction vessel as described in Example 4a and the mixture was heated to 190.degree. A mixture of 166 g of nerolidol and 139 g of an iso-pentyl acetoacetic acid prepared in a manner known per se (purity> 98%) was added dropwise uniformly within 2 h. The reaction temperature was kept at 190-200 ° C. by heating. After the end of the feed, the mixture was stirred for a further 15 minutes and then cooled. 212 g of raw material were obtained, which were distilled at 0.1 mbar. Two fractions gave 178.7 g of farnesyl acetone. This corresponds to a yield of 91% of theory.

Example 4b (comparative example)

Reaction of nerolidol with methyl acetoacetate:

5.6 g of aluminum tri-methylacetoacetate were placed in a 500 ml reaction vessel with metering device, blade stirrer and a 10 cm column with a reflux condenser and distillation bridge. It was heated to 180-190 ° C. A homogeneous mixture of 166.5 g (0.75 mol) of nerolidol and 94 g (0.81 mol) of methyl acetoacetate was pumped in uniformly within 2 h. The reaction temperature was kept at 180-190 ° C by external heating. The methanol formed was condensed. After the end of the feed, the mixture was stirred for a further 15 minutes and then cooled.

208 g of raw material were obtained, which was distilled under greatly reduced pressure. A total of 167 g of farnesylacetone were isolated in two fractions. This corresponds to a yield of 85% of theory.

Example 5

Carroll reaction of nerolidol with acetoacetic acid (2 ^x -methyl-2'-pentyl) ester (acetoacetic acid-iso-hexyl ester):

2.8 g of aluminum tri-methylacetoacetate were placed in the reaction vessel described in Example 4a. At a reaction temperature of 190-200 ° C., a mixture of 83 g of nerolidol and 75 g of an acetoacetic acid ~ iso-hexyl ester (purity> 98%) prepared from isohexanol and diketene was pumped in within 1 h. After the end of the feed, the reaction mixture was a further 10 min stirred at 200 ° C and cooled after the evolution of gas has ended. 108 g of raw material were obtained, which were distilled under greatly reduced pressure. In this way, 88 g of pure farnesylacetone were isolated. This corresponds to a yield of 90% of theory.

Example 6

a) Implementation of E, E-geranyllinalool according to the invention with acetoacetic acid-tert. -butyl ester

In a magnetically stirred reaction vessel consisting of a 100 ml three-necked flask heated to 190 to 200 ° C. with an overflow in the middle (corresponding to a usable volume of the flask of 45 ml), 263 ml were added at a rate of 5.6 ml / min a reaction solution consisting of 145 g (0.5 mol) E, E-geranyllinalool, 5 g aluminum tri-ter. -butylacetoacetate and 83 g (0.525 mol) acetoacetic acid-tert. -butyl ester pumped. 185 g of crude product and 30.5 g of low boilers were obtained. In the raw product, 13% was unreacted

E, E-Geranyllinalool and 79% of the desired Geranylgeranylaceton contain.

b) reaction of E, E, -Geranyllinalool with methyl acetoacetate (comparative example)

In the above, heated to 190 to 200 ° C

Reaction tubes were at a rate of

5.0 ml / min 234 ml of a reaction solution consisting of 145 g (0.5 mol) of E, E-geranyllinalool, 5 g of aluminum tri-tert-butylacetoacetate and 61 g (0.525 mol) of methyl acetoacetate were pumped.

199.9 g of crude product and 5.7 g of low boilers were obtained. The crude product contained 53% unreacted E, E-geranyllinalool and only 34% of the desired geranylgeranylacetone.

A comparison of Example 6a with Comparative Example 6b clearly shows that the reaction with the acetoacetic acid tert. - Butyl ester runs much faster (3 to 10 times faster) than that with the methyl acetoacetate previously used for Carroll reactions.

Claims

claims 1. Process for the preparation of γ, δ-unsaturated ketones of the general formula I

by reacting an allyl alcohol or a propargyl alcohol of the general formula II

in which R ^{1 represents} H or a saturated or unsaturated branched hydrocarbon radical with 1 to 33 C atoms, optionally substituted by methoxy groups, and the dotted line can represent a further bond between the C atoms carrying it, with an alkyl acetoacetic acid at temperatures from 150 to 220 ° C in an optionally modified Carroll reaction in the presence of an aluminum catalyst and distilling off the alkanol which forms, characterized in that an acetoacetic acid ester of the general formula III is used as the alkyl acetoacetate

in which R ^{2 represents} an alkyl group having 1 to 4 carbon atoms. 2. The method according to claim 1, characterized in that the Carroll reaction with an acetoacetic acid ester of the general formula III, 0 // CH ₃ - CO ^■ CH ₂ C CH ₃ \; ιn: -CR ^2nd CH ₃ in the R ^{2 represents} a methyl group. Process according to Claim 1, characterized in that the alcohol used as the allyl alcohol of the general formula II is one in which R ^{1 is} for a group of the general formula IV CH-

y in which n stands for an integer from 1 to 5 and x and y either both stand for H, or x stands for methoxy and y stands for H, or x and y together form an additional bond between the C and X bearing y -Atoms mean. 4. The method according to claim 1, characterized in that 2-methyl-3-buten-2-ol, linalool, 6, 7-dihydro-linalool, Nerolidol, 10, 11-dihydro-nerolidol or geranyllinalool used as allyl alcohol of the general formula II. 5. The method according to claim 3, characterized in that when using 2-methyl-3-buten-2-ol as allyl alcohol of the general formula II, the Carroll reaction in a cyclic carbonate of the general formula VI or a γ-lactone general formula VII

in which the radicals R ³ , R ⁴ and R ^{5 are} H, methyl or ethyl, and R ^{6 is} H, methyl, ethyl, isopropyl, phenyl or methoxymethyl, as a solvent. 6. The method according to claim 4, characterized in that when using 2-methyl-3-buten-2-ol as allyl alcohol of the general formula II, the Carroll reaction in a cyclic carbonate of the general formula VI or a γ-lactone general formula VII

in which the radicals R ³ , R ⁴ <R ⁵ and R ^{6 represent} H or methyl. A method according to claim 1, characterized in that when using alcohols of the general formula II with a boiling point higher than 140 ° C, the Carroll reaction is carried out without the addition of substantial amounts of a solvent.