WO2007039245A1

WO2007039245A1 - Cleavage of alkynediols

Info

Publication number: WO2007039245A1
Application number: PCT/EP2006/009476
Authority: WO
Inventors: Werner Bonrath; Julius Jeisy; Francesco Mascarello
Original assignee: Dsm Ip Assets B.V.
Priority date: 2005-09-29
Filing date: 2006-09-29
Publication date: 2007-04-12
Also published as: CN101277918B; CN101277918A

Abstract

The present invention relates to a process for the manufacture of a mixture of ketones of the formula I and II, wherein R1, R2, R3 and R4 are independently from each other C1-30-alkyl, by reacting an alkynediol of the formula III in the presence of a catalyst at a temperature of at least 500C and/or at a pressure of at most atmospheric pressure. In preferred embodiments of the invention the ketones of the formulae I and II are identical. Preferably the catalyst is a basic catalyst, most preferably selected from the group consisting of aqueous NaOH and aqueous KOH solutions, and KF on alu minium oxide. The alkynediol is most preferably selected from the group consisting of 2,6,9,13- tetramethyl-tetradeca-2, 12-dien-7-yne-6,9-diol, 2,6, 10, 13 , 17,21 -hexamethyl-docos- 11-yne-10,13-diol, 2,6,10,14,17,21,25,29-octamethyl-triacont-15-yne-14,17-diol, 3,7,10,14-tetramethyl-hexadeca-3,13-dien-8-yne-7,10-diol, 3,6-dimethyl-oct-4-yne-3,6-diol and 2,5-dimethyl-hex-3-yne-2,5-diol. Advantegeously the process of the present invention may be used in the processes for the manufacture of dehydrolinalool or dehydroisophytol to recycle at least one of the starting materials.

Description

Cleavage of alkynediols

The present invention relates to a process for the manufacture of a mixture of ketones of the formula I and II,

wherein R¹, R², R³ and R⁴ are independently from each other Ci_-3o-alkyl, by reacting an alkynediol of the formula III

in the presence of a catalyst at a temperature of at least 50°C and/or at a pressure of at most atmospheric pressure. In preferred embodiments of the invention the ketones of the formulae I and II are identical. Preferably the catalyst is a basic catalyst, most preferably selected from the group consisting of aqueous NaOH and aqueous KOH solutions, and KF on aluminium oxide. The alkynediol is most preferably selected from the group consisting of 2,6,9,13- tetramethyl-tetradeca-2, 12-dien-7-yne-6,9-diol, 2,6, 10, 13 , 17,21 -hexamethyl-docos- 11 -yne- 10,13-diol, 2,6,10,14,17,21,25,29-octamethyl-triacont-15-yne-14,17-diol, 3,7,10,14- tetramethyl-hexadeca-3,13-dien-8-yne-7,10-diol, 3,6-dimethyl-oct-4-yne-3,6-diol and 2,5- dimethyl-hex-3-yne-2,5-diol.

Advantegeously the process of the present invention may be used in the processes for the manufacture of dehydrolinalool or dehydroisophytol to recycle at least one of the starting materials.

In the process for the manufacture of compounds such as dehydrolinalool and dehydroisophytol alkynediols of the formula m as defined below are obtained as by-products. Until now these alkynediols were mostly disregarded which meant a loss in material. The applicant now surprisingly found out that these alkynediols can be converted back into the start- ing materials thus leading to economically more attractive processes.

Thus, the present invention is directed to a process for the manufacture of a mixture of ketones of the formula I and π,

wherein R¹, R², R³ and R⁴ are independently from each other C_1-30-alkyl, prefably C_1-20- alkyl, by reacting an alkynediol of the formula IE

in the presence of a catalyst at a temperature of at least 50°C. Concerning the substituents R¹ to R⁴: "Cι_-3o-alkyl" means in the context of the present invention straight chain C_1-30-alkyl as well as branched C_3-3o-alkyl and C_5-30-cycloalkyl. It further means cycloalkyl substituted with straight chain or branched alkyl, straight chain alkyl substituted with cycloalkyl and any other possible combination leading to a carbon hydrogen unit with 1 to 30 carbon atoms. Preferably two of R¹ to R⁴ are identical. More preferably R¹ is identical with R³ or R⁴ and R² is identical with R³ or R⁴, with the proviso that R¹ and R² are different from each other. Even more preferably the alkynediol of the formula IH is selected from the group consisting of 2,6,9, 13-tetramethyl-tetradeca-2, 12- dien-7-yne-6,9-diol, 2,6,10,13,17,21-hexamethyl-docos-l l-yne-10,13-diol,

2,6, 10, 14, 17,21 ,25,29-octamethyl-triacont- 15-yne-l 4, 17-diol, 3,7, 10, 14-tetramethyl- hexadeca-3,13-dien-8-yne-7,10-diol, 3,6-dimethyl-oct-4-yne-3,6-diol and 2,5-dimethyl- hex-3-yne-2,5-diol.

In the latter case the invention is, therefore, directed to a process for the manufacture of a ketone of the formula I

R¹

I wherein R¹ and R² are independently from each other C_1-3o-alkyl, preferably C_1-2o-alkyl, by reacting an alkynediol of the formula Oa

in the presence of a catalyst at a temperature of at least 50°C.

Concernin^g the catalyst: Preferably the catalyst is a basic catalyst. More preferably the catalyst is selected from the group consisting of alkalimetal hydroxides, ammonium hydroxide, alkalimetal fluoride, primary, secondary and tertiary amines such as NR³R⁴R⁵ with R³, R⁴ and R⁵ being hydrogen or C_1-20-alkyl such as tributylamine, aryl amines such as N,N-dimethylaminopyridine and mixtures thereof. Even more preferably the catalyst is sodium hydroxide, potassium hydroxide and/or ammonium hydroxide, or any of their mixtures, especially their aqueous solutions, and potassium fluoride. The potassium fluoride is especially used on a carrier material, preferably on aluminum oxide. Such catalysts are e.g. commercially available from Fluka. Furthermore, the catalyst may also be produced in situ, potassium hydroxide e.g. may be obtained by reacting KF on aluminum oxide.

The term "aryl amines" hereby encompasses aromatic hydrocarbon moieties having from 5 to 15 carbon atoms and optionally containing at least one hetero atom such as oxygen, nitrogen and sulphur which bear at least one NR³R⁴R⁵ group with R³, R⁴ and R⁵ being hy- drogen or Ci-io-alkyl. Examples of "aryl amines" are N,N-dimethylaminopyridine, N,N- dimethylaniline, aniline and chinoline.

In preferred embodiments of the present invention the used aqueous solutions of NaOH and KOH have a concentration of from 35 to 50 weight-%, preferably of from 40 to 48 weight-%, more preferably of from 41 to 45 weight-%.

Furthermore, solid NaOH and KOH could also be used.

Reaction conditions

Preferably the alkynediol of the formula HU]Ra is reacted at a temperature of at most 200°C, more preferably of at most 15O⁰C. Even more preferably the alkynediol of the formula iπ/πia is reacted at a temperature of from 50 to 200⁰C, especially at a temperature of from 60 to 150⁰C. If aqueous solutions of NaOH and/or KOH are used as catalyst it is es- pecially preferred to carry out the reaction at a temperature in the range of from 80 to 100⁰C.

Preferably the reaction is carried out at a pressure in the range of from 50 mbar to atmospheric pressure.

The molar ratio of the catalyst to the alkynediol of the general formula m/HIa may vary from 1 : 10 to 1 : 30, preferably from 1 : 15 to 1 : 25.

hi preferred embodiments of the present invention at least one of the thus obtained ketones of the formula I and II is further purified afterwards. In further preferred embodiments of the present invention the formation of the ketone of the formula I and/or the ketone of the formula II and its/their purification is performed simultaneously, i.e. that the process is carried out as so-called "reactive distillation".

The purification is preferably performed by distillation or rectification.

As already mentioned above the process of the present invention is advantageously per- formed as a step in the process for the manufacture of an α-alkynol of the formula IV, thus leading to the recycling of at least one of the starting materials.

The invention is, therefore, also directed to a process for the manufacture of an α-alkynol of the formula IV,

^R H ^IV

wherein R¹ and R² are independently from each other C_1-3o-alkyl, preferably Ci_-2o-alkyl, comprising the following steps: a) reacting of a ketone of the formula I with alkyne in the presence of a catalyst

R¹

I

to an α-alkynol of the formula IV, whereby an alkynediol of the formula ma is obtained as by-product,

b) separating the α-alkynol of the formula IV from the alkynediol of the formula πia or vice versa, e.g. via distillation and/or extraction, c) subjecting the separated alkynediol of the formula πia to a process as described above to re-obtain a ketone of the formula I and alkyne, d) (optionally) further purifying the ketone of the formula I obtained in step c), e) (optionally) further purifying the alkyne obtained in step c), f) (optionally) recycling the ketone of the formula I obtained in step c) or d) back into step a), and g) (optionally) recycling the alkyne obtained in step c) or e) back into step a).

The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose. Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23), whose content is incorporated by reference.

In preferred embodiments of the present invention the α-alkynol is selected from the group consisting of dehydrolinalool, ethyldehydrolinalool, 3,7,1 l-trimethyl-dodecyne-3-ol, and dehydroisophytol; especially preferred are dehydrolinalool and dehydroisophytol. Thus, the present invention makes their manufacture economically and commercially more attractive.

In an especially preferred embodiment of such a process the α-alkynol is dehydrolinalool.

Thus, the present invention also encompasses a process for the manufacture of dehydrolinalool, comprising the following steps: a) reacting of 6-methyl-5-hepten-2-one with ethyne to dehydrolinalool (3,7-dimethyl-6- octen-l-yne-3-ol), whereby 2,6,9, 13-tetramethyltetradeca-2,12-dien-7-yne-6,9-diol is ob- tained as by-product, b) separating dehydrolinalool from 2,6,9, 13-tetramethyltetradeca-2,12-dien-7-yne-6,9-diol or vice versa, e.g. via distillation or extraction, c) subjecting the separated 2,6,9,13-tetramethyltetradeca-2,12-dien-7-yne-6,9-diol to a process as described above to re-obtain 6-methyl-5-hepten-2-one and ethyne, d) (optionally) further purifying 6-methyl-5-hepten-2-one obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the 6-methyl-5-hepten-2-one obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15 and example 1) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23 and the example), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

In a further preferred embodiment of such a process the α-alkynol is dehydroisophytol.

Thus, the present invention also encompasses a process for the manufacture of dehydroisophytol, comprising the following steps: a) reacting of 6,10,14-trimethyl-2-pentadecanone with ethyne to dehydroisophytol in the presence of a catalyst, whereby 3,7, 11 , 15-tetramethyl- 1 -hexadecyne-3-ol is obtained as byproduct, b) separating dehydroisophytol from 3,7,11,15-tetramethyl- 1 -hexadecyne-3-ol or vice versa, e.g. via distillation or extraction (preferably via extraction, especially with aqueous sulphuric acid), c) subjecting the separated alkynediol of the formula ma to a process as described above to re-obtain 6,10,14-trimethyl-2-pentadecanone and ethyne, d) (optionally) further purifying 6,10,14-trimethyl-2-pentadecanone obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the 6,10,14-trimethyl-2-pentadecanone obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15 and example 3) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

In a further embodiment of the present invention the α-alkynol is ethyl dehydrolinalool (3 ,7-dimethyl-6-nonen- 1 -yn-3 -ol).

Thus, the present invention also encompasses a process for the manufacture of ethyl dehy- drolinalool, comprising the following steps: a) reacting of ethylheptenone (6-methyl-5-octen-2-one) with ethyne to ethyldehydrolinalool in the presence of a catalyst, whereby 3,7,10,14-tetramethyl-hexadeca-3,13-dien-8-yne- 7,10-diol is obtained as by-product, b) separating ethyldehydrolinalool from SJjlOjH-tetramethyl-hexadeca-SjlS-dien-δ-yne- 7,10-diol or vice versa, e.g. via distillation or extraction, c) subjecting the separated 3,7,10,14-tetramethyl-hexadeca-3,13-dien-8-yne-7,10-diol to a process as described above to re-obtain ethylheptenone and ethyne, d) (optionally) further purifying ethylheptenone obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the ethylheptenone obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15 and example 4) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

In another embodiment of the present invention the α-alkynol is 3,7,11 -trimethyl- dodecyne-3-ol.

Thus, the present invention also encompasses a process for the manufacture of 3,7,11- trimethyl-dodecyne-3-ol, comprising the following steps: a) reacting of 6,10-dimethylundecan-2-one with ethyne to 3,7,1 l-trimethyl-dodecyne-3-ol in the presence of a catalyst, whereby 2,6,10,13,17,21-hexamethyl-docos-l l-yne-10,13- diol is obtained as by-product, b) separating 3,7,1 l-trimethyl-dodecyne-3-ol from 2,6, 10,13,17,21-hexamethyl-docos-l l- yne-10,13-diol or vice versa, e.g. via distillation or extraction, c) subjecting the separated 2,6,10,13, 17,21-hexamethyl-docos-l l-yne-10,13-diol to a process as described above to re-obtain 6,10-dimethylundecan-2-one (hexahydropseudoionone) and ethyne, d) (optionally) further purifying 6,10-dimethylundecan-2-one obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the 6,10-dimethylundecan-2-one obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15 and example 2) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

In a another embodiment of the present invention the α-alkynol is 3-methyl-but-l-yne-3-ol.

Thus, the present invention also encompasses a process for the manufacture of 3-methyl- but- 1 -yne-3-ol, comprising the following steps: a) reacting of acetone with ethyne to 3 -methyl-but-1 -yne-3-ol in the presence of a catalyst, whereby 2,5-dimethyl-hex-3-yne-2,5-diol is obtained as by-product, b) separating 3 -methyl-but-1 -yne-3-ol from 2,5-dimethyl-hex-3-yne-2,5-diol or vice versa, e.g. via distillation or extraction, c) subjecting the separated 2,5-dimethyl-hex-3-yne-2,5-diol to a process as described above to re-obtain acetone and ethyne, d) (optionally) further purifying acetone obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the acetone obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15) and WO 2003/029175 (see especially page 1 , line 26 to page 5, line 23), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

In a another embodiment of the present invention the α-alkynol is 3-methyl-pent-l-yn-3-ol.

Thus, the present invention also encompasses a process for the manufacture of 3-methyl- pent-l-yn-3-ol, comprising the following steps: a) reacting of ethyl methyl ketone with ethyne to 3-methyl-pent-l-yn-3-ol in the presence of a catalyst, whereby 3,6-dimethyl-oct-4-yn-3,6-diol is obtained as by-product, b) separating 3 -methyl-pent- l-yn-3-ol from 3,6-dimethyl-oct-4-yn-3,6-diol or vice versa, e.g. via distillation or extraction, c) subjecting the separated 3,6-dimethyl-oct-4-yn-3,6-diol to a process as described above to re-obtain methyl ethyl ketone and ethyne, d) (optionally) further purifying methyl ethyl ketone obtained in step c), e) (optionally) further purifying the ethyne obtained in step c), f) (optionally) recycling the methyl ethyl ketone obtained in step c) or d) back into step a), and g) (optionally) recycling the ethyne obtained in step c) or e) back into step a).

Steps a) and b) may be carried out according to any process known to the person skilled in the art, especially according to WO 2004/018400 (see especially page 2, line 13 to page 5, line 15 and example 5) and WO 2003/029175 (see especially page 1, line 26 to page 5, line 23), whose content is incorporated by reference. The purification steps d) and e) may e.g. be carried out via distillation or rectification or any other method suitable for this purpose.

These α-alkynols (dehydrolinalool, ethyldehydrolinalool, 3,7,1 l-trimethyl-dodecyne-3-ol, dehydroisophytol) are important intermediates for other compounds. Dehydrolinalool is e.g. an important precursor for dehydrolinalyl acetate, linalool, linalyl acetate, pseudoio- none, vitamin A, citral, vitamin E and vitamin Kl. 3,7,1 l-Trimethyl-dodecyne-3-ol is e.g. an important precursor for isophytol, vitamin E and carotenoids. Dehydroisophytol is e.g. an important precursor for isophytol and vitamin E (see Barbara Elvers, Stephen Hawkins, Ullmann's Encyclopedia of industrial chemistry, volume A 27, VCH Verlagsgesellschaft mbH, Weinheim (Germany) 1996, chapter "vitamins" (page 443 -613), especially page 459-466 and page 484-488).

The present invention is also directed to a process for the manufacture of dehydrolinalyl acetate, whereby dehydrolinalool obtained by a process as described above is reacted with acetic acid, its anhydride and/or halide as known by the person skilled in the art.

The present invention is also directed to a process for the manufacture of linalool, whereby dehydrolinalool obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst) as known by the person skilled in the art.

The present invention is also directed to a process for the manufacture of linalyl acetate, whereby dehydrolinalool obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst) as known by the person skilled in the art, and the thus obtained linalool is further reacted with acetic acid, its anhydride and/or halide as known by the person skilled in the art.

The present invention is also directed to a process for the manufacture of citral (3,7- dimethyl-2,6-octadienal), whereby dehydrolinalool obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst) as known by the person skilled in the art, and the thus obtained linalool is further rearranged to citral as also known by the person skilled in the art. It is also possible to directly manufacture citral starting from dehydrolinalool by catalyzed rearrangement (see especially US 6,198,006 and EP-A 947 492).

The present invention is also directed to a process for the manufacture of pseudoionone, whereby dehydrolinalool obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst) as known by the person skilled in the art, and the thus obtained linalool is further rearranged to citral and then reacted with acetone to pseudoionone. These steps are well known by the person skilled in the art. Alternatively pseudoionone may be obtained by reacting dehydrolinalool as obtained by a process according to the present invention with diketene or isopropenyl methyl ether (see Barbara Elvers, Stephen Hawkins, Ullmann's Encyclopedia of industrial chemistry, vol- ume A 27, VCH Verlagsgesellschaft mbH, Weinheim (Germany) 1996, chapter "vitamins", page 459, bottom of left column and top of right column and references cited therein).

The present invention is also directed to a process for the manufacture of vitamin A, whereby dehydrolinalool obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst), the thus obtained linalool is further rearranged to citral and then reacted with acetone to pseudoionone, which is rearranged to β-ionone. These steps are well known by the person skilled in the art as well as the further reactions of β-ionone to vitamin A (esters) (see Barbara Elvers, Stephen Haw- kins, Ullmann's Encyclopedia of industrial chemistry, volume A 27, VCH Verlagsgesellschaft mbH, Weinheim (Germany) 1996, chapter "vitamins", page 459-466).

The present invention is also directed to a process for the manufacture of isophytol, whereby dehydroisophytol obtained by a process as described above is reacted with hydro- gen in the presence of a catalyst (e.g. a Lindlar catalyst) as known by the person skilled in the art.

The present invention is also directed to a process for the manufacture of vitamin E (α- tocopherol), whereby dehydroisophytol obtained by a process as described above is reacted with hydrogen in the presence of a catalyst (e.g. a Lindlar catalyst) to isophytol. Isophytol is then further condensed with trimethylhydroquinone (derivatives) to vitamin E. These steps are well known by the person skilled in the art and e.g. disclosed in EP-A 782 993, WO 98/21197, US 7,105,686, WO 2005/054 223, WO 2005/121115, US 6,066,745, EP-A 949 255, US 6,452,023, EP-A 970 953, EP-A 1 000 940, EP-A 1 134 218, EP-A 1 180 517, EP 1 227 089, WO 03/037883, WO 2004/046127 and WO 2005/005407, as well as in Barbara Elvers, Stephen Hawkins, Ullmann's Encyclopedia of industrial chemistry, volume A 27, VCH Verlagsgesellschaft mbH, Weinheim (Germany) 1996, chapter "vitamins", page 484-488 and references cited therein. The thus obtained vitamin E may be further reacted to vitamin E esters such as vitamin E acetate (as known by the person skilled in the art (see e.g. WO 2005/103 026, EP-A 1 172 363, WO 2004/046126, WO 2004/063182, WO 2004/096790 and WO 2004/096 791) and partly also disclosed in the documents cited above) and be further formulated. Thus, the present invention is also directed to a process for the manufacture of vitamin E acetate, propionate, pivalate, succinate, nicotinate, palmitate or benzoate comprising the step of reacting the vitamin E as obtained by the reaction of isophytol and trimethylquinone as described above with an acylating agent selected from the group consisting of acetic acid, propionic acid, pivalic acid, succinic acid, nicotinic acid, palmitic acid or benzoic acid, their anhydrides or halides, respectively.

Thus, the present invention is also directed to a process for the manufacture of formulations of α-tocopherol or its alkanoates. The α-tocopherol or its alkanoate can be formulated by any method known to the person skilled in the art, e.g. as those disclosed in US 6,162,474, US 2001/0009679, US 6,180,130, US 6,426,078, US 6,030,645, US 6,150,086, US 6,146,825, US 6,001,554, US 5,938,990, US 6,530,684, US 6,536,940, US 2004/0053372, US 5,668,183, US 5,891,907, US 5,350,773, US 6,020,003, US 6,329,423, WO 96/32949, US 5,234,695, WO 00/27362, EP 0 664 116, US 2002/0127303, US 5,478,569, US 5,925,381, US 6,651,898, US 6,358,301, US 6,444,227, WO 96/01103 and WO 98/15195.

The invention is illustrated further by the following Examples.

Examples

Example 1

220.38 g (0.791 mol) of 2,6,9, 13-tetramethyl-tetradeca-2,12-dien-7-yne-6,9-diol were stirred and heated to 100°C. 3.3 ml of 42.4 weight-% aqueous KOH (0.035 mol) were added. After 2 h the reaction mixture was cooled to room temperature. 55.1 g of the crude product (total amount: 199.83 g) were further purified by distillation at 85°C and 50 mbar. Methylheptenone was obtained in a yield of 83% and a purity of 95.5%.

Example 2

196.32 g (0.641 mol) of 3,7,10,14-tetramethyl-hexadeca-3,13-dien-8-yne-7,10-diol were stirred and heated to 100°C. 3.0 ml of 42.4 weight-% aqueous KOH (0.032 mol) were added. After 2 h the reaction mixture was cooled to room temperature. 50.11 g of the crude product (total amount: 177.01 g) were further purified by distillation at 85°C and 100 mbar. Ethylheptenone was obtained in a yield of 86% and a purity of 98.0%.

Example 3 192.9 g (0.456 mol) of 2,6,10,13,17,21-hexamethyl-docos-l l-yne-10,13-diol were stirred and heated to 100°C. 3.0 ml of 42.4 weight-% aqueous KOH (0.032 mol) were added. After 2 h the reaction mixture was cooled to room temperature. 49.79 g of the crude product (total amount: 180.45 g) were further purified by distillation at 150°C and 50 mbar. Hexa- hydropseudoionone was obtained in a yield of 77% and a purity of 97.7%.

Example 4

194.0 g (0.345 mol) of 2,6,10,14,17,21,25,29-octamethyl-triacont-15-yne-14,17-diol were stirred and heated to 100°C. 3.0 ml of 42.4 weight-% aqueous KOH (0.032 mol) were added. After 2 h the reaction mixture was cooled to room temperature. 50.0 g of the crude product (total amount: 184.49 g) were further purified by distillation at 150°C and 5 mbar. 6,10,14-trimethyl-2-pentadecanone was obtained in a yield of 64% and a purity of 92.0%. Example 5

9.81 g (69.99 mmol) of 2,5-dimethyl-hex-3-yne-2,5-diol (a lightly caramel collared powder) were heated up to 100° C (heating-cooling jacket temperature 120°C). The 2,5- dimethyl-hex-3-yne-2,5-diol melt at 50⁰C. Under stirring (1250 rpm) 600 μl of KOH (41% (g/g)) (6.1 mmol) were added. The formed acetone was directly distilled off with a short way apparatus. After 2 h reaction time the 2,5-dimethyl-hex-3-yne-2,5-diol was totally converted to acetone and ethyne, which were distilled off.

7.72 g of acetone were isolated as a colorless liquid with a purity of 92.4% (analyzed by gas chromatography). The yield of acetone was 89%.

Example 6

9.81 g (69.99 mmol) of 2,5-dimethyl-hex-3-yne-2,5-diol (a lightly caramel collared pow- der) were heated up to 100° C (heating-cooling jacket temperature 120°C). The 2,5- dimethyl-hex-3-yne-2,5-diol melt at 50°C. Under stirring (1250 rpm) 1.0 g of KF/A1₂O₃ (ex Fluka, No 60244) were added. The formed acetone was directly distilled off with a short way apparatus. After 2 h reaction time the 2,5-dimethyl-hex-3-yne-2,5-diol was totally converted to acetone and ethyne, which were distilled off.

8.0 g of acetone were isolated as a colorless liquid with a purity of 91% (analyzed by gas chromatography). The yield of acetone was 90%.

Claims

Claims 1. Process for the manufacture of a mixture of ketones of the formula I and π,

wherein R > 1 , τ R>2 , τ Rj3 a „n„d j τ R>4 are independently from each other Ci-₃₀-alkyl, by reacting an alkynediol of the formula IE

in the presence of a catalyst at a temperature of at least 5O⁰C.

2. The process according to claim 1, wherein two of R¹ to R⁴ are identical.

3. The process according to claim 1 and/or 2, wherein R¹ is identical with R³ or R⁴ and R² is identical with R³ or R⁴, with the proviso that R¹ and R² are different from each other.

4. The process according to any of the preceding claims, wherein the catalyst is a basic catalyst.

5. The process according to claim 4, wherein the catalyst is an alkalimetal hydroxide, an alkalimetal fluoride, a primary, secondary or tertiary amine or an aryl amine.

6. The process according to claim 4, wherein the basic catalyst is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, and po- tassium fluoride, optionally on a carrier.

7. The process according to claim 6, wherein the sodium and/or potassium hydroxide is used in form of its aqueous solution.

8. The process according to claim 5, wherein the alkalimetal fluoride is potassium fluoride, especially potassium fluoride on a carrier material, preferably on aluminum oxide.

9. The process as in any of the preceding claims, wherein the alkynediol is reacted at a temperature of at most 200°C, preferably of at most 150⁰C.

10. The process as in any of the preceding claims, wherein the alkynediol is reacted at a temperature of from 50 to 200⁰C, especially at a temperature of from 60 to 150⁰C.

11. The process as in any of the preceding claims, wherein the molar ratio of the catalyst to the alkynediol is from 1 : 10 to 1 : 30, preferably from 1 : 15 to 1 : 25.

12. The process as is any of the preceding claims, wherein the alkynediol is selected from the group consisting of 2,6,9, 13-tetramethyl-tetradeca-2,12-dien-7-yne-6,9-diol,

2,6,10,13,17,21-hexamethyl-docos-ll-yne-10,13-diol, 2,6,10,14,17,21,25,29- octamethyl-triacont- 15-yne- 14, 17-diol, 3 ,7, 10, 14-tetramethyl-hexadeca-3, 13 -dien-8- yne-7,10-diol, 3,6-dimethyl-oct-4-yne-3,6-diol and 2,5-dimethyl-hex-3-yne-2,5-diol.

13. The process as in any of the preceding claims wherein at least one of the thus obtained ketones of the formulae I and II is further purified afterwards.

14. The process as in any of claims 1 to 12, wherein the formation of the ketones of the formulae I and II and their purification is performed simultaneously.

15. The process as in claim 13 or 14, whereby the purification is performed by distillation.

16. Process for the manufacture of an α-alkynol of the formula IV,

wherein R¹ and R² are independently from each other C_1-3o-alkyl, comprising the following steps: a) reacting of a ketone of the formula I with alkyne

to an α-alkynol of the formula IV, whereby an alkynediol of the formula Ilia is obtained as by-product,

b) separating the α-alkynol of the formula IV from the alkynediol of the formula DIa or vice versa, c) subjecting the separated alkynediol of the formula ma to a process as claimed in any of claims 1 to 15 to re-obtain a ketone of the formula I and alkyne, d) (optionally) further purifying the ketone of the formula I obtained in step c), e) (optionally) further purifying the alkyne obtained in step c), f) (optionally) recycling the ketone of the formula I obtained in step c) or d) back into step a), g) (optionally) recycling the alkyne obtained in step c) or e) back into step a).

17. The process as claimed in claim 16, wherein the α-alkynol is dehydrolinalool.

18. The process as claimed in claim 16, wherein the α-alkynol is dehydroisophytol.

19. A process for the manufacture of dehydrolinalyl acetate comprising the step of reacting the dehydrolinalool as obtained by a process according to claim 17 with acetic acid, its anhydride and/or halide.

20. A process for the manufacture of linalool comprising the step of reacting the dehy- drolinalool as obtained by a process according to claim 17 with hydrogen in the presence of a catalyst.

21. A process for the manufacture of linalyl acetate comprising the step of reacting the linalool as obtained by a process according to claim 20 with acetic acid, its anhydride and/or halide.

22. A process for the manufacture of citral comprising the step of rearranging the linalool as obtained by a process according to claim 20.

23. A process for the manufacture of citral comprising the step of rearranging the dehy- drolinalool as obtained by a process according to claim 17 in the presence of a catalyst.

24. A process for the manufacture of pseudoionone comprising the step of reacting the citral as obtained by a process according to claim 22 or 23 with acetone.

25. A process for the manufacture of pseudoionone comprising the step of reacting the dehydrolinalool as obtained by a process according to claim 17 with diketene or iso- propenyl methyl ether.

26. A process for the manufacture of β-ionone comprising the step of rearranging the pseudoionone as obtained by a process according to claim 24 or 25.

27. A process for the manufacture of vitamin A (esters) using the β-ionone as obtained by a process according to claim 26 as starting material.

28. A process for the manufacture of isophytol comprising the step of reacting the dehy- droisophytol as obtained by a process according to claim 18 with hydrogen in the pres- ence of a catalyst.

29. A process for the manufacture of vitamin E comprising the step of reacting the isophytol as obtained by a process according to claim 28 with trimethylhydroquinone.

30. A process for the manufacture of vitamin E acetate, propionate, pivalate, succinate, nicotinate, palmitate or benzoate comprising the step of reacting the vitamin E as obtained by a process according to claim 29 with an acylating agent selected from the group consisting of acetic acid, propionic acid, pivalic acid, succinic acid, nicotinic acid, palmitic acid or benzoic acid, their anhydrides or halides, respectively.

31. A process for the manufacture of formulations of vitamin E (esters) using the vitamin E or vitamin E ester as obtained by a process according to claim 29 or 30 as starting material.

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