DE2508778A1 - PROCESS FOR PREPARING OXO COMPOUNDS - Google Patents

Description

It is known that tertiary or secondary acetylene carbinols can be catalytically converted into the corresponding small alpha, small beta-unsaturated aldehydes or ketones if vanadium-containing silicon compounds are used as catalysts. In this way, high yields and high conversions are achieved, and the vanadium-containing silicon compounds mentioned retain their full activity over many approaches.

It has now been found that compounds of the formula

III

in which Ph denotes a phenyl radical which is substituted by one or more electron-attracting groups, R denotes a hydrocarbon radical KW from the series lower alkyl, cycloalkyl, phenyl or phenyl-lower alkyl, or denotes a -Si (Ph ') [deep] 3 group, in which Ph 'denotes a phenyl radical which can be substituted by one or more electron-attracting groups, or represents a -Si (KW) [deep] 3 group, the radicals mentioned being optionally substituted by lower alkyl, m the number 1 , 2 or 3 and n denote the number 0, 1 or 2, where the sum of m and n = 3,

are particularly suitable for the above-mentioned catalytic isomerization of tertiary and secondary acetylene carbinols, because the isomerization in the presence of these new catalysts can already be carried out in a temperature range between about room temperature and about 150 ° C. in a useful time, which is the case with thermolabile starting materials and end connections can be critical.

For example, 3,7-dihydroxy-3,7-dimethyl-octa-1-yne and 2,5-dihydroxy-2,5-dimethyl-hex-3-yne, compounds which already largely disintegrate above 120 ° C., can be used and therefore it was not possible to isomerization with the known catalysts, which hitherto mainly worked in the range of this temperature, now more with the aid of the new catalysts in a temperature range between approximately room temperature and approximately 100 ° C. with a good temperature range

Isomerize the yield to the corresponding 7-hydroxy-3,7-dimethyl-oct-2-en-1-al or 2-hydroxy-2,5-dimethyl-hex-4-en-3-one.

The present invention is based on this finding and relates to a process for the preparation of oxo compounds of the general formula

I.

in which R [deep] 1 denotes hydrogen or lower alkyl, R [deep] 2 denotes an alkyl or alkenyl radical which can be linked to a cycloalkyl, cycloalkenyl or phenyl radical, or a cycloalkyl, cycloalkenyl or phenyl radical represents, R [deep] 1 and R [deep] 2 can be joined together to form a cycloalkyl or cycloalkenyl radical, and R [deep] 3 is hydrogen or an alkyl or alkenyl radical which is associated with a cycloalkyl, cycloalkenyl or phenyl radical radical can be linked, or represents a cycloalkyl, cycloalkenyl or phenyl radical; where said alkyl, alkenyl, cycloalkyl, cycloalkenyl and phenyl radicals are optionally substituted by lower alkyl, lower alkoxy, hydroxy, lower alkanoyl, aroyl, lower alkanoyloxy or aroyloxy and said alkyl, alkenyl, cycloalkyl and cycloalkenyl radicals can additionally be substituted by oxo or ketalized oxo.

The process is characterized in that one uses an alcohol of the general formula

II

in which R [deep] 1, R [deep] 2 and R [deep] 3 have the meaning given above,

with the aid of a catalyst of the general formula

III

in which Ph denotes a phenyl radical which is substituted by one or more electron-attracting groups, R denotes a hydrocarbon radical KW from the series lower alkyl, cycloalkyl, phenyl or phenyl-lower alkyl, or denotes a -Si (Ph ') [deep] 3 group, in which Ph 'denotes a phenyl radical which can be substituted by one or more electron attractive groups, or represents a -Si (KW) [deep] 3 group; where the radicals mentioned are optionally substituted by lower alkyl, m denotes the number 1, 2 or 3 and n denotes the number 0, 1 or 2, the sum of m and n = 3,

isomerized.

The invention also relates to the new catalyst of the general formula III per se as a new compound.

The lower alkyl radical R [deep] 1 includes both unbranched and branched hydrocarbons with 1-6 carbon atoms, e.g. methyl, ethyl, propyl, isopropyl and others.

The saturated or unsaturated, branched or unbranched, optionally substituted alkyl radicals R [deep] 2 and R [deep] 3 can contain up to 30 carbon atoms.

Examples of R [deep] 2 include: of the lower members, preferably methyl, of the higher members with primarily isoprene or isoprene-like structure

4-methyl-pent-3-enyl radical,

4,8-dimethyl-nona-3,7-dienyl radical,

4,8,12-trimethyl-tridecyl radical

4-Hydroxy-4-methyl-pentyl radical and the

4-methoxy-4-methylpentyl residue.

Examples of the radical R [deep] 3 are the propyl radical from the lower members and the from the higher members

2,6-dimethyl-hepta-1,3,5-trienyl radical.

The optionally substituted cycloalkyl component of the radical R [deep] 2 defined in more detail above can contain up to 20 carbon atoms. Examples of those with saturated or unsaturated, branched or unbranched alkyl radicals R [deep] 2, preferably with alkyl radicals having an isoprene or isoprene-like structure, are cycloalkyl radicals

2- (2,6,6-trimethyl-cyclohex-1-en-1-yl) vinyl radical,

2- (4-oxo-2,6,6-trimethyl-cyclohex-1-en-1-yl) vinyl radical,

2- (4-ethylenedioxy-2,6,6-trimethyl-cyclohex-1-en-1-yl) vinyl residue,

6- (2,6,6-trimethyl-cyclohex-1-en-1-yl) -4-methyl-hexa-1,3,5-trienyl radical,

6- (4-Oxo-2,6,6-trimethyl-cyclohex-1-en-1-yl) -4-methyl-hexa-1,3,5-trienyl radical, as well as the

6- (4-ethylenedioxy-2,6,6-trimethyl-cyclohex-1-en-1-yl) -4-methyl-hexa-1,3,5-trienyl radical.

Examples of the starting compounds of the general formula II described in more detail above, in which R [deep] 1 and R [deep] 2 are combined to form an optionally substituted, saturated or unsaturated cycloalkyl radical, can be listed:

1-ethynyl-cyclohexanol,

4-ethynyl-4-hydroxy-1-oxo-3,5,5-trimethyl-cyclohex-2-ene

or that

4-Ethynyl-4-hydroxy-1-ethylenedioxy-3,5,5-trimethyl-cyclohex-2-ene.

Possible substituents of the above-mentioned alkyl, alkenyl, cycloalkyl, cycloalkenyl and phenyl radicals are: lower alkyl radicals with 1-6 carbon atoms such as methyl, ethyl, propyl, isopropyl and others; lower alkoxy radicals with 1-6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy and others; lower alkanoyl radicals with 1-6 carbon atoms such as formyl, acetyl, propionyl, butyryl and others; Aroyl radicals, especially benzoyl; lower alkanoyloxy radicals having 1-6 carbon atoms such as acetyloxy, propioxyloxy, butyryloxy and others; Aroyloxy, especially benzoyloxy.

An oxo group can be ketalized by lower alkanols or glycols, e.g. by methanol or ethylene glycol.

The radical denoted by KW in formula III preferably represents lower alkyl with up to 7 carbon atoms, e.g. methyl, ethyl, isopropyl or n-butyl, as well as phenyl and lower alkyl-substituted phenyl such as tolyl or xylyl, and also phenyl-lower alkyl such as benzyl or phenethyl.

Of the compounds covered by formula I, four groups of compounds in particular, which can be represented by the following general formulas, are important:

IA

in which R '[deep] 1 and R' [deep] 2 are combined to form a cycloalkyl or cycloalkenyl radical which can be substituted by lower alkyl, lower alkoxy, hydroxy or by optionally ketalised oxo;

IB

in which R ″ [deep] 2 represents a cycloalkyl, cycloalkenyl or phenyl radical which can be substituted by lower alkyl, lower alkoxy, hydroxy or [except for phenyl] by optionally ketalised oxo;

IC

in which R '[deep] 3 denotes hydrogen or lower alkyl and a = 1, b = 1 and c = 1, or a = 0, b = 1 and c = 1, or a = 0, b = 0 and c = 1, or a = 0, b = 0 and c = 0 denote the members a, b, c, are optionally substituted by hydroxy or lower alkoxy and the dotted bonds represent an optionally present carbon-carbon bond;

and

ID

in which d = 0 or 1 means.

The starting compounds of the formula II required for the preparation of the compounds of the general formula IA, IB, IC and ID can be represented by the following general formulas:

IIA

in which R '[deep] 1 and R' [deep] 2 have the above meaning;

IIB

in which R "[deep] 2 has the above meaning;

IIC

in which R '[deep] 3 denotes hydrogen or lower alkyl and the symbols a, b and c and the dotted bonds have the meaning given above;

IID

in which d has the meaning given above.

The new process has proven to be particularly favorable and advantageous in the preparation of the following compounds.

- Cyclohexylidene acetaldehyde

- (4,4-Ethylenedioxy-2,6,6-trimethyl-cyclohex-2-en-1-ylidene) acetaldehyde

- cinnamaldehyde

- 2-methyl-hept-2-en-4-en

- senecicaldehyde,

- Citral

- 7-hydroxycitral

- 7-methoxycitral

- Farnesal

- Phytal

- small beta-C [deep] 15-aldehyde

- Vitamin A aldehyde

The phenyl groups denoted Ph in the catalyst of the formula III according to the invention are obligatory, the phenyl groups denoted Ph 'are optionally substituted by one or more electron-attracting groups.

Electron-attracting groups include, in particular, those in the "Textbook for Organic Chemistry" by Fieser and Fieser Ed. 1954 on page 651, namely:

-NO [deep] 2

-CN

-COCH [deep] 3

-CHO

-COOC [low] 2H [low] 5

-Cl

-Br

-J

and -COOH

and also -F

-CF [deep] 3

and -C [deep] 6H [deep] 5

Understood.

The following can be mentioned as examples of the catalysts according to the invention:

-Tris- [tri- (p-fluorophenyl) -siloxy] -vanadium oxide

-Tris- [tri- (p-chlorophenyl) -siloxy] -vanadium oxide

-Tris- [tri- (p-bromophenyl) -siloxy] -vanadium oxide

-Tris- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] -vanadium oxide

-Tris- [tri- (small alpha, small alpha, small alpha-trifluoro-p-tolyl) -siloxy] -vanadium oxide

-Tris- [bis- (3-nitro-4-bromophenyl) - (4-bromophenyl) -siloxy-vanadium oxide,

- (Tri-p-fluorophenyl) -siloxy-bis (triphenyl-siloxy) -vanadium oxide

-Tris- [tri- (4-biphenylyl) -siloxy] -vanadium oxide.

-Bis- [tri- (p-fluorophenyl) -siloxy] -triphenyl-siloxy-vanadium oxide,

-Bis- [tri- (p-bromophenyl) -siloxy] -cyclohexyloxy-vanadium oxide.

The catalysts of the general formula III are new compounds. They are accessible by methods known per se, e.g.

by reacting vanadium pentoxide with a silanol of the formula Ph [deep] 3SiOH [in which Ph is a phenyl radical which is substituted by one or more electrode-attracting groups] with azeotropic removal of the water released during the reaction with the aid of an entrainer such as benzene;

by reacting vanadium oxytrichloride with a silanol of the formula Ph [deep] 2SiOH [in which Ph represents a phenyl radical which is substituted by one or more electron-attracting groups] in the presence of a base such as pyridine or ammonia;

- By reacting a vanadium acid ester of the formula [R '] [deep] 3-V = 0 [where R' denotes a lower alkoxy group] with a silanol of the formula Ph [deep] 3SiOH [where Ph is a phenyl radical which is replaced by an or several electron-attracting groups is substituted] optionally in the presence of catalytic amounts of an alkyl or phenyl alkali metal silanolate, for example a trialkyl alkali metal silanolate;

- by reacting a siloxyvanadium oxide of the formula [(R ") [deep] 3SiO] [deep] 3-V = 0 [where R" denotes a lower alkyl group] with a silanol of the formula Ph [deep] 3SiOH [where Ph represents a phenyl radical which is substituted by one or more electron-attracting groups], optionally in the presence of catalytic amounts of an alkali silanolate e.g. of a tri- (lower alkyl) alkali silanolate.

- by reacting vanadium oxytrichloride with an alkali metal silanolate of the formula Ph [deep] 3SiOMe (I) [in which Ph represents a phenyl radical which is substituted by one or more electron-attracting groups and Me denotes an alkali metal] in an inert solvent such as diethyl ether;

- by converting silver ortho vanadate of the formula

Ag [deep] 3VO [deep] 4 with a silyl halide of the formula Ph [deep] 3-SiHal [where Ph represents a phenyl radical substituted by one or more electron attractive groups, and Hal denotes a halogen atom] in a solvent such as for example benzene or methylene chloride;

- by double reaction of an ester of vanadic acid of the formula [R '] [deep] 3-V = 0 [where R' denotes a lower alkoxy group] with a silyl ester of the formula Ph [deep] 3-Si-O-COR "[where Ph represents a phenyl radical which is substituted by one or more electron-attracting groups, and R "denotes a lower alkyl group], for example of tripropyl orthovanadate with triphenylsilylacetate with the escape of propyl acetate, expediently in a solvent such as n-heptane, in which the ester formed is a the reaction mixture forms separable azeotrope.

The inventive catalytic isomerization of acetylene carbinols to small alpha, small beta-unsaturated oxo compounds is expediently carried out in such a way that the corresponding carbionol is added after about 0.1 to about 5 mol% [preferably about 1.5 to about 2 mol% ] Catalyst [based on the substrate], if possible in an inert solvent, heated for a long time. The reaction can be carried out in the presence or in the absence of air.

Suitable solvents are e.g. aliphatic hydrocarbons such as heptane, cyclohexane, cyclododecane, decalin,

Paraffin and paraffin oils; aromatic hydrocarbons such as benzene, nitrobenzene; Toluene or xylene; halogenated hydrocarbons such as chlorobenzene; Ethers such as anisole or dioxane or amines such as N-methylaniline. In addition, polymeric silicon-containing solvents such as silicone oils with aliphatic or aromatic residues, e.g. methyl-phenyl-polysiloxanes.

The reaction temperature to be maintained can be within the range approximately between room temperature and about 150.degree. It is expedient to work in a range between about 40 and 110 ° C.

If necessary, the isomerization can also be carried out under pressure, pressures of up to about 50 ata can be used.

The response time can also fluctuate widely. It is generally about 2 to 20 hours.

The catalyst used retains practically its full activity during the isomerization. It can therefore continue to be used to carry out several isomerization batches before it has to be replaced.

The reaction product is separated from the unreacted proportions of the carbinol used in the usual way, e.g. by rectification. The unconverted carbinol components can be used again in the next batch. In this procedure, conversions of 70 to 80% and, depending on the starting material used, yields of more than 90% are generally achieved.

example 1

Production of tris- [tri- (p-fluorophenyl) -siloxy] -vanadium oxide.

1 g of tri- (p-fluorophenyl) -silanol in 30 ml of abs. Benzene dissolved. 0.255 ml of pyridine and 0.173 g of vanadium oxytrichloride are added to the solution with the exclusion of moisture. The mixture is first stirred for 8 hours at room temperature and then heated to boiling for 2 hours under reflux conditions. The pyridinium hydrochloride which precipitates after cooling to 10 ° C. is filtered off.

The filtrate is evaporated under reduced pressure. The remaining tris- [tri- (p-fluorophenyl) -siloxy] -vanadium oxide melts after recrystallization from n-heptane at 147 ° C.

The following can be produced in an analogous manner:

from vanadium oxytrichloride

and tri- (p-chlorophenyl) silanol [m.p. 127-128 ° C]

the tris- [tri- (p-chlorophenyl) -siloxy] -vanadium oxide

Mp: 181 ° C;

from vanadium oxytrichloride

and tri- (p-bromophenyl) silanol [m.p. 120-121 ° C]

the tris- [tri- (p-bromophenyl) -siloxy] -vanadium oxide mp: 175 ° C;

from vanadium oxytrichloride

and tri-4-biphenylyl-silanol [m.p. 199-200 ° C]

the tris [tri- (4-biphenylyl) siloxy] vanadium oxide.

Example 2

Manufacture of tris- [tri- (small alpha, small alpha, small alpha-trifluor-m-tolyl) -siloxy] -vanadium oxide.

0.5 g of tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -silanol [mp. 72-73 ° C] are in 30 ml of abs. Benzene dissolved. 0.115 g of tris (trimethylsiloxy) vanadium oxide are added to the solution. The mixture is heated to boiling under reflux conditions for 1 hour.

From the reaction mixture, first 20 ml of benzene together with the trimethylsilanol formed are distilled off at normal pressure and then, after adding 20 ml of toluene, another 20 ml of benzene-toluene mixture are distilled off at normal pressure. The toluene solution is evaporated at 50 ° C. under reduced pressure. One obtains tri- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] -vanadium oxide [Molpeak = 1504].

The following can be produced in an analogous manner:

from tris (trimethylsiloxy) vanadium oxide

and Tris- (small alpha, small alpha, small alpha-trifluoro-p-tolyl) -silanol

the tris- [tri- (small alpha, small alpha, small alpha-trifluoro-p-tolyl) -siloxy] -

vanadium oxide [mol peak = 1504];

from tris (trimethylsiloxy) vanadium oxide,

and tri- (p-fluorophenyl) silanol

and triphenylsilanol in a molar ratio of 1: 1: 2

the (tri-p-fluorophenyl) -siloxy-bis (triphenylsiloxy) -vanadium oxide melting point 203 ° C;

from tris (trimethylsiloxy) vanadium oxide,

and tri- (p-fluorophenyl) silanol

and triphenylsilanol in a molar ratio of 1: 2: 1

bis- [tri- (p-fluorophenyl) -siloxy] -triphenylsiloxy-vanadium oxide, [Molpeak = 1000]; from tris (trimethylsiloxy) vanadium oxide,

and tri- (p-bromophenyl) silanol

and cyclohexanol in a molar ratio of 1: 2: 1

bis- [tri- (p-bromophenyl) -siloxy] -cyclohexyloxyvanadium oxide. [Mol peak = 1184

bz. to [high] 79Br];

from tris (trimethylsiloxy) vanadium oxide

and bis (3-nitro-4-bromophenyl) - (4-bromophenyl) -silanol

the tris- [bis- (3-nitro-4-bromophenyl) - (4-bromophenyl) -siloxy] -vanadium oxide

[Molpeak = 1873 or to [high] 79Br].

The bis- (3-nitro-4-bromophenyl) - (4-bromophenyl) -silanol used as the starting compound can be prepared, for example, as follows:

1 g of tri- (p-bromophenyl) silanol are dissolved in 10 ml of sulfolane. 0.98 g of nitronium tetrafluoroborate [NO [deep] 2BF [deep] 4] in 25 ml of sulfolane are added dropwise to the solution at 10 ° C. with exclusion of moisture. The reaction mixture is stirred for 1 hour at room temperature, then introduced into a sodium hydrogen carbonate solution and extracted with ether. The ether extract is washed with a saturated aqueous sodium sulfate solution, dried over sodium sulfate and evaporated at room temperature under reduced pressure. The remaining bis- (3-nitro-4-bromophenyl) -4-bromophenyl-silanol melts at 211 ° C. after recrystallization from nitrobenzene / petroleum ether.

The following examples 3-12 exemplify the process according to the invention:

Example 3

A mixture of 0.835 g of 3-hydroxy-3,7-dimethyl-octa-6-en-1-yn [dehydrolinalool], 8.85 ml of high-boiling paraffin oil (boiling point 120 ° / 0.1 Torr) and 0.105 g of tris [ tri- (p-fluorophenyl) -siloxy] -vanadium oxide is stirred with exclusion of moisture for 8 hours at 95 ° C. The citral formed is separated from the unconverted dehydrolinalool by rectification. The conversion of dehydrolinalool used is 0.69 g, corresponding to 83%. The yield of citral based on converted dehydrolinalool is 0.56 g, corresponding to 81%.

In an analogous way, the following can be isomerized:

- 3,7-Dihydroxy-3,7-dimethyl-oct-1-in in the presence of tris- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] -vanadium oxide

in the course of 6 hours at 95 ° C

to 7-hydroxy-3,7-dimethyl-oct-2-en-1-al, [7-hydroxy-citral],

Conversion of 3,7-dihydroxy-3,7-dimethyl-oct-1-yne - 84% yield of 7-hydroxycitral based on the converted acetylene carbinol = 86%;

- 2,5-Dihydroxy-2,5-dimethyl-hex-3-in in the presence of tris- [tri- (small alpha, small alpha, small alpha-trifluoro-p-tolyl) -siloxy] -vanadium oxide

over 7 hours at 105 ° C

to 2-hydroxy-2,5-dimethyl-hex-4-en-3-one

Conversion of 2,5-dihydroxy-2,5-dimethyl-hex-3-yne = 84%

Yield of 2-hydroxy-2,5-dimethyl-hex-4-en-3-one based on the converted acetylene carbinol = 87.5%.

Example 4

In the isomerization of dehydrolinalool to citral described in Example 3, the following results were achieved with the catalysts listed below under the conditions given in Example 3:

- Catalyst: tris [tri- (p-chlorophenyl) siloxy] vanadium oxide

Conversion of: dehydrolinalool = 78%

Yield of: citral = 86%

- Catalyst: tris [tri- (p-bromophenyl) siloxy] vanadium oxide

Conversion of: dehydrolinalool = 81%

Yield of: citral = 88%

- Catalyst: tris [tri- (4-biphenylyl) siloxy] vanadium oxide

Conversion of: dehydrolinalool = 73%

Yield of: citral = 79%

- Catalyst: (Tri-p-fluorophenyl) -siloxy-bis- (triphenyl-siloxy) -

vanadium oxide

Conversion of: dehydrolinalool = 62%

Yield of: citral = 71%

- Catalyst: bis [tri- (p-fluorophenyl) -siloxy] -tri-phenylsiloxy-

vanadium oxide

Conversion of: dehydrolinalool = 68%

Yield of: citral = 74%

- Catalyst: bis [tri- (p-bromophenyl) -siloxy] -cyclohexyl-vanadium oxide

Conversion of: dehydrolinalool = 66%

Yield of: citral = 79%

- Catalyst: Tris- [bis- (3-nitro-4-bromophenyl) - (4-bromophenyl) -siloxy] -

vanadium oxide

Conversion of: dehydrolinalool = 59%

Yield of: citral = 71%.

Example 5

8.4 g of 3-hydroxy-3-methyl-but-1-yne, 1 g of tris- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] vanadium oxide, and 50 ml high-boiling paraffin oil (D [low] 20 [high] 4 = 0.885) is stirred for 15 hours at 90 ° C. with exclusion of moisture. The conversion of acetylene carbinol used is 6.3 g, corresponding to 75%. The yield of 3-methyl-but-2-en-1-al is 5.2 g, corresponding to 82.5%.

Example 6

22 g 3-hydroxy-3,7,11-trimethyl-dodeca-6,10-diene-1-yne, 0.7 g Tris- [tri-small alpha, small alpha, small alpha-trifluoro-p-tolyl) -siloxy] -vanadium oxide and 200 ml of silicone oil are heated to 105 ° C for 5 hours with exclusion of moisture. The conversion of the acetylene carbinol used is 15.9 g, corresponding to 72%. The yield of 3,7,11-trimethyl-dodeca-2,6,10-trien-1-al is 13.0 g, corresponding to 82%.

Example 7

29.4 g 3-hydroxy-3,7,11,15-tetramethyl-hexadec-1-yne, 0.75 g tris- [tri- (small alpha, small alpha, small alpha-trifluoromolyl) -siloxy] vanadium oxide and 500 ml high-boiling paraffin oil are heated to 100 ° C for 6 hours with exclusion of moisture. The conversion of the acetylene carbinol used is 14.4 g, corresponding to 49%. The yield of 3,7,11,15-tetramethylhexadec-2-en-1-al is 11.1 g, corresponding to 77.2%.

18.4 g 3-hydroxy-7-methoxy-3,7-dimethyl-oct-1-yne (7-methoxy-dehydrolinalool), 0.7 g Tris- [tri- (small alpha, small alpha, small alpha trifluoro-p-tolyl) -siloxy] -vanadium oxide and 150 ml of high-boiling paraffin oil are stirred with exclusion of moisture at 95 ° C. for 8 hours. The conversion of the acetylene carbinol used is 12.1 g, corresponding to 65.7%. The yield of 7-methoxy-3,7-dimethyl-oct-2-en-1-al is 10.2 g, corresponding to 84.3%.

Example 9

12.4 g of 1-ethynyl-1-cyclohexanol, 2 g of tris [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] -vanadium oxide and 100 ml of high-boiling paraffin oil are left with the exclusion of moisture for 5 hours heated to 105 ° C. The conversion of the acetylene carbinol used is 9.5 g, corresponding to 76.6%.

The following two isomerization products were isolated in this reaction.

-Cyclohexylidene acetaldehyde (I)

-Cyclohex-1-en-1-yl-acetaldehyde (II)

The total yield of I and II, based on converted starting material, is 7.9 g, corresponding to 83.0%, the molar ratio of the two aldehydes I and II formed being 38.4: 61.6 to one another.

Example 10

13.2 g 3-hydroxy-3-phenyl-prop-1-yne, 2 g tris- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] -vanadium oxide and 100 ml silicone oil are heated to 110 ° C for 4 hours with exclusion of moisture. The conversion of the acetylane used carbinols is 10.9 g, corresponding to 82.6%. The yield of cinnamaldehyde is 10.5 g, corresponding to 96%.

Example 11

12.6 2-hydroxy-2-methyl-hept-3-yne, 0.7 g tris- [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] vanadium oxide and 150 ml high-boiling paraffin oil are heated for 6 hours at 100 ° C. with the exclusion of moisture. The conversion of the acetylene carbinol used is 11.0 g, corresponding to 87.2%. The yield of 2-methyl-hept-2-en-4-one is 10.55 g, corresponding to 96.0%.

Example 12

10 g of 4-ethynyl-4-hydroxy-1,1-ethylenidoxy-3,5,5-trimethyl-cyclohex-2-ene, 0.15 g of hydroquinone, 0.02 ml of tris- [tri- (small alpha, small Alpha, small alpha-trifluoro-p-tolyl) -siloxy] -vanadium oxide and 100 ml dry toluene are heated to the boil for 9 hours at 110 ° C with exclusion of moisture. The solvent is then distilled off at 40 ° C. under reduced pressure. The remaining isomer mixture of cis / trans (4,4-ethylenedioxy-2,6,6-trimethyl-cyclohex-2-en-1-ylidene) -acetaldehyde boils after rectification in a high vacuum at 110-125 ° C / 0.1 Torr . The conversion of the acetylene carbinol used is 7.5 g, corresponding to 75%. The aldehyde is obtained in a yield of 6.95 g, corresponding to 92.5%.

The 4-ethynyl-4-hydroxy-1,1-ethylenedioxy-3,5,5-trimethyl-cyclohex-2-ene used as the starting compound can be prepared, for example, as follows:

800 ml of liquid ammonia are placed in a 2 l three-necked flask equipped with a mechanical stirrer, dropping funnel and Claisen attachment with dry ice cooling. 10 g of lithium are introduced within 30 minutes with stirring. The mixture is stirred for 60 minutes. Then acetylene is passed into the deep blue solution until the solution is almost colorless. The dry ice condenser is removed and replaced with a tube filled with potassium hydroxide. The ammonia is evaporated and replaced in the same mass by diethyl ether. The suspension of lithium acetylide obtained is treated at room temperature within 30 minutes with a solution of 20 g of 1,1-ethylenedioxy-3,5,5-trimethyl-cyclohex-2-en-4-one in 100 ml of diethyl ether. The reaction mixture is stirred for 18 hours, then carefully poured onto a mixture of ice and 400 ml of a 25% strength ammonium chloride solution. The ether phase is separated off, washed with water, dried over sodium sulfate, filtered and evaporated under reduced pressure. The remaining crystalline 4-ethynyl-4-hydroxy-1,1-ethylenedioxy-3,5,5-trimethyl-cyclohex-2-ene melts at 85-86 ° C. after recrystallization from ethyl acetate / petroleum ether.

Claims (28)

1. Process for the preparation of oxo compounds of the general formula I. in which R [deep] 1 denotes hydrogen or lower alkyl, R [deep] 2 denotes an alkyl or alkenyl radical which can be linked to a cycloalkyl, cycloalkenyl or phenyl radical, or a cycloalkyl, cycloalkenyl or phenyl radical represents, R [deep] 1 and R [deep] 2 can be joined together to form a cycloalkyl or cycloalkenyl radical, and R [deep] 3 is hydrogen or an alkyl or alkenyl radical which is associated with a cycloalkyl, Cycloalkenyl or phenyl radical can be linked, or represents a cycloalkyl, cycloalkenyl or phenyl radical; where said alkyl, alkenyl, cycloalkyl, cycloalkenyl and phenyl radicals are optionally substituted by lower alkyl, lower alkoxy, hydroxy, lower alkanoyl, aroyl, lower alkanoyloxy or aroyloxy and said alkyl, alkenyl, cycloalkyl and cycloalkenyl radicals can additionally be substituted by oxo or ketalized oxo, characterized in that one uses an alcohol of the general formula II in which R [deep] 1, R [deep] 2 and R [deep] 3 have the meaning given above, with the aid of a catalyst of the general formula III in which Ph denotes a phenyl radical which is substituted by one or more electron-attracting groups, R denotes a hydrocarbon KW from the series lower alkyl, cycloalkyl, phenyl or phenyl-lower alkyl, or denotes a -Si- (Ph ') [deep] 3 group, in which Ph 'denotes a phenyl radical which can be substituted by one or more electron-attracting groups, or represents a -Si [KW] [deep] 3 group, the radicals mentioned being optionally substituted by lower alkyl, m the number 1, 2 or 3 and n denote the number 0, 1 or 2, where the sum of m and n = 3, isomerized. 2. The method according to claim 1, characterized in that the catalyst used is a compound of the general formula IIIA in which Ph has the meaning given above. 3. The method according to claim 2, characterized in that the catalyst used is tris [tri- (small alpha, small alpha, small alpha-trifluoro-m-tolyl) -siloxy] vanadium oxide. 4. The method according to claim 2, characterized in that the catalyst used is tris [tri- (small alpha, small alpha, small alpha-trifluoro-p-tolyl) -siloxy] vanadium oxide. 5. The method according to any one of claims 1-4, characterized in that the isomerization is carried out in a solvent. 6. The method according to claim 5, characterized in that the isomerization is carried out in a hydrocarbon. 7. The method according to claim 6, characterized in that the isomerization is carried out in a paraffin oil. 8. The method according to claim 5, characterized in that the isomerization is carried out in a silicone oil. 9. The method according to claim 8, characterized in that the isomerization is carried out in methyl-phenyl-polysiloxane. 10. The method according to any one of claims 1-9, characterized in that the isomerization is carried out in a temperature range between 40-110 ° C. 11. The method according to any one of claims 1 to 10, characterized in that a compound of the general formula IIA in which R '[deep] 1 and R' [deep] 2 are combined to form a cycloalkyl or cycloalkenyl radical which can be substituted by lower alkyl, lower alkoxy, hydroxy or by optionally ketalised oxo, used as the starting compound. 12. The method according to claim 11, characterized in that 1-ethynyl-cyclohexanol is used as the starting compound. 13. The method according to claim 11, characterized in that 4-ethynyl-4-hydroxy-1,1-ethylenedioxy-3,5,5-trimethyl-cyclohex-2-ene is used as the starting compound. 14. The method according to any one of claims 1 to 10, characterized in that a compound of the general formula IIB in which R "[deep] 2 represents a cycloalkyl, cycloalkenyl or phenyl radical which can be substituted by lower alkyl, lower alkoxy, hydroxy or [except for phenyl] by optionally ketalized oxo, as the starting compound. 15. The method according to claim 14, characterized in that 3-hydroxy-3-phenyl-prop-1-yne is used as the starting material. 16. The method according to any one of claims 1 to 10, characterized in that one optionally substituted by hydroxyl, lower alkoxy or halogen compound of the general formula IIC in which R '[deep] 3 denotes hydrogen or lower alkyl and a = 1, b = 1 and c = 1, or a = 0, b = 1 and c = 1, or a = 0, b = 0 and c = 1, or a = 0, b = 0 and c = 0, the members a, b, c, optionally substituted by hydroxy or lower alkoxy, and the dotted bonds represent an optionally present carbon-carbon bond, used as the starting compound . 17. The method according to claim 16, characterized in that 2-hydroxy-2-methyl-hept-3-yne is used as the starting material. 18. The method according to claim 16, characterized in that 3-hydroxy-3-methyl-but-1-yne is used as the starting material. 19. The method according to claim 16, characterized in that 3-hydroxy-3,7-dimethyl-octa-6-en-1-yne is used as the starting material. 20. The method according to claim 16, characterized in that 3,7-dihydroxy-3,7-dimethyl-oct-1-yne is used as the starting material. 21. The method according to claim 16, characterized in that 3-hydroxy-7-methoxy-3,7-dimethyl-oct-1-yne is used as the starting compound. 22. The method according to claim 16, characterized in that 3-hydroxy-3,7,11-trimethyl-dodeca-6,10, dien-1-yne is used as the starting material. 23. The method according to claim 16, characterized in that 3-hydroxy-3,7,11,15-tetramethyl-hexadec-1-yne is used as the starting material. 24. The method according to any one of claims 1 to 10, characterized in that a compound of the general formula is used as the starting material IID in which d = 0 or 1, begins. 25. The method according to claim 24, characterized in that 5- (2,6,6-trimethyl-cyclohex-1-en-1-yl) -3-hydroxy-3-methyl-penta-4-en-1- in used as a starting material. 26. The method according to claim 24, characterized in that 9- (2,6,6-trimethyl-cyclohex-1-en-1-yl) -3-hydroxy-3,7-dimethyl-4,6,8- trien-1-yne is used as the starting material. 27. The method according to claim 24, characterized in that 9- (4-oxo-2,6,6-trimethyl-cyclohex-1-en-1-yl) -3-hydroxy-3,7-dimethyl-4, 6,8-trien-1-yne is used as the starting material. 28. The method according to claim 24, characterized in that 9- (4 ', 4-ethylenedioxy-2,6,6-trimethyl-cyclohex-1-en-1-yl) -3-hydroxy-3,7-dimethyl -4,6,8-triene-1-yne is used as the starting material.