CH616138A5 - Process for the preparation of ketones containing a secondary or tertiary aliphatic carbon atom in at least one of the positions alpha to the carbonyl group - Google Patents

Abstract

The ketones of formula (I) are prepared by reaction of an alkyl halide of formula (II) with an enoxysilane of formula (III) in the presence, as catalyst, of a metal from groups 1b, 2b, 3b, 4a, 4b, 5a, 5b, 6b, 7b and 8 of the periodic classification of the elements. In the formulae, Ro is an aliphatic or cycloaliphatic hydrocarbon radical, R1, R2, R3 and R are hydrocarbon radicals, it being possible for one of the radicals R2 and R3 to form, with the other of them, or with R1, a divalent hydrocarbon radical, it additionally being possible for R2 and R3 to be hydrogen. The hydrocarbon radicals can be substituted. n is equal to 1, 2 or 3. This process applies especially to the preparation of 2-methyl-2-hepten-6-one by reaction of a [(propen-2-yl)oxy]triorganosilane with isoprene hydrochloride. <IMAGE> <IMAGE> <IMAGE>

Description

The present invention relates to a process for the preparation of ketones comprising a secondary or tertiary aliphatic carbon atom in at least one of the positions a of the carbonyl group.

The ketones comprising at least one secondary or tertiary carbon atom in position a with respect to the carbonyl group can be obtained in particular by alkylation of ketones having an active hydrogen atom in position a, by means of an alkyl halide. Generally, this reaction involves the intermediate formation of the enolate anion by the action of a strong base with the enolisable ketone, then the reaction of the anion with the chosen alkyl halide; these two steps can in certain cases be carried out simultaneously. As bases capable of causing the formation of enolate, alkali alcoholates and in particular tertiary alkaline alcoholates (sodium, potassium tbutylate) have been used; alkaline amides (sodium, potassium amide, lithium dimethyl amide); the alkaline derivatives of triphenylmethane (triphenylmethyl sodium for example); alkali hydrides or alkaline bases such as soda or potash. Whatever the base used, it has been found that the alkylation reaction is accompanied by various side reactions giving rise to complex mixtures of various products. For example, there may exist alongside the monoalkylated ketone, compounds resulting from a di- or polyalkylation of the ketone, into a and / or a 'of the carbonyl group; this polyalkylation can occur even when there is no excess of alkaline base in the reaction medium, due to reactions of exchange of the alkali metal which occur between the starting enolate and the alkylated ketone produced (cf. PA Tar-della, Tetrahédron Letters 1969 1117-1120); it is particularly difficult to control the progress of this polyalkylation. One way of achieving this consists in the slow addition of the alkaline enolate in an excess of alkyl halide, however such a method does not offer industrial interest. Ultimately there is no technique for controlling the secondary polyalkylation reactions during the preparation of alkylated ketones. Furthermore, the processes implementing the reaction of an alkaline enolate with an alkyl halide or of an enolisable ketone with an alkyl halide in the presence of an alkaline base (especially sodium hydroxide and potash) frequently give rise to to ketolization reactions leading to the formation of heavy products.

The subject of the present invention is precisely a process for the preparation of alkylated ketones which makes it possible to avoid the drawbacks linked to the implementation of the processes using the reaction of an alkyl halide with an alkaline enolate, whether the latter is formed extemporaneously or in the alkylation medium.

Subsequently, the term “secondary or tertiary aliphatic carbon” will denote any carbon atom belonging to an aliphatic or cycloaliphatic hydrocarbon residue, saturated or not, optionally substituted by one or more functional groups inert with respect to the reactants used under the conditions of the reaction. By "alkylation" means the attachment to a carbon atom of an aliphatic or cycloaliphatic residue saturated or not, optionally substituted by one or more functional groups or aromatic radicals. The term "lower alkyl" denotes an alkyl radical containing from 1 to 4 carbon atoms.

More specifically, the present invention relates to a process for the preparation of ketones comprising at least one aliphatic carbon atom secondary or tertiary in a of the carbonyl group of general formula:

O R2

II X

RÏ-C-C (I)

| \ R3 Ro

5

10

15

20

25

30

35

40

45

50

55

60

65

616138

4

in which:

. Ro is an aliphatic or cycloaliphatic hydrocarbon radical saturated or not optionally substituted by one or more inert functional groups, comprising from 1 to 30 carbon atoms, 5

. Ri is a hydrocarbon radical containing from 1 to 30 carbon atoms, optionally substituted as specified below,

. R2 and R3 represent hydrogen or hydrocarbon radicals having from 1 to 30 carbon atoms, one of the radicals R2 and R3 being able to form with Ri a divalent hydrocarbon radical having from 3 to 13 carbon atoms, or R2 and R3 together form a divalent hydrocarbon radical having 4 to 14 carbon atoms, R2 and R3 being optionally substituted as specified below, characterized in that an aliphatic halide of general formula is reacted:

Ro-X

(II)

in which Ro has the meaning already given and X represents a chlorine, bromine or iodine atom, with an enoxysilane of general formula:

Ri

I

JC

(R) 4-n-Si-

C R2

</% /

R3

III

in which:

. Ri, R2 and R3 have the meanings indicated above,

. n is an integer from 1 to 3,

. R represents a hydrocarbon radical having from 1 to 20 carbon atoms, or, when n is equal to 1 or 2, at most one of the radicals R symbolizes a radical of general formula:

25

30

35

IV 45

in which:

. Ri, R2, R3 and n have the meaning given above, so. R4 is a hydrocarbon radical having from 1 to 20 carbon atoms, identical or different from R,

. A represents a valence bond, an oxygen atom, a divalent hydrocarbon radical having from 1 to 10 carbon atoms, in the presence of a catalyst consisting of a metal or an ss derived from a metal of groups lb, 2b, 3b , 4a, 4b, 5a, 5b, 6b, 7b and 8 of the Periodic Table of the Elements (Handbook of Chemistry and Physics 45th Edition p. 2).

In formulas I to IV the various symbols more specifically represent:

. Ro a linear or branched alkyl radical preferably having from 1 to 25 carbon atoms optionally substituted by a cycloalkyl or cycloalkenyl radical having from 5 to 6 cyclic carbon atoms; an arylalkyl radical having from 1 to 10 carbon atoms in the alkyl part; a cycloalkyl radical having 5 to 10 cyclic carbon atoms, optionally substituted with 1 to 3 lower alkyl radicals; a linear or branched alkenyl radical preferably having 1

60

65

containing 25 carbon atoms and possibly comprising one or more ethylenic carbon-carbon double bonds, conjugated or not, optionally substituted by a cycloalkyl radical or; cycloalkenyl having 5 to 6 cyclic carbon atoms; an alkinyl radical comprising 1 or more triple carbon-carbon bonds and having from 2 to 10 carbon atoms; an arylalkenyl radical containing from 2 to 10 carbon atoms in the alkenyl residue; a cycloalkenyl radical containing from 5 to 10 cyclic carbon atoms, optionally substituted by 1 to

3 lower alkyl radicals. Ro may be substituted by any functional group inert with respect to enoxysilane under the conditions of the reaction. As particular examples of these functional groups, mention may be made of the NO2 - groups; lower alkoxy; alkoxycarbonyl; nitrile.

. Ri, R2, R3, identical or different, alkyl radicals, linear or branched, cycloalkyls or arylalkyls such as those defined for Ro; aryl radicals comprising from 1 to 3 benzene rings forming, where appropriate, an ortho or ortho and pericondensed system, optionally substituted by 1 to 3 lower alkyl radicals; linear or branched alkenyl, cycloalkenyl or arylalkenyl radicals as defined for Ro with the restriction that the radicals R2 and R3 do not contain an ethylenic double bond conjugated with the enolic double bond of the enoxysilane of formula III; Ri can also form with R2 and R3 an alkylene or alkenylene radical (in this case the double bond not being conjugated with the enolic double bond) comprising from 3 to 4 carbon atoms and of which two successive carbon atoms can be part of an aliphatic or benzene hydrocarbon cycle, or of a system of 2 to 4 aliphatic and / or benzene hydrocarbon cycles.

When Ri, R2 and R3 are substituted, it can be by any functional group inert with respect to the aliphatic halides used under the reaction conditions such as the nitro, lower alkoxy, alkoxycarbonyl or nitrile groups.

. R, linear or branched alkyl radicals having from 1 to 20 carbon atoms; cycloalkyl radicals having 5 to 6 carbon atoms; phenyl radicals optionally substituted with 1 to 3 lower alkyl radicals; phenylalkyl radicals having from 1 to 4 carbon atoms in their alkyl part.

When n is less than 3 the various radicals R carried by a silicon atom can be identical or different.

. R4, alkyl, cycloalkyl, phenyl and phenylalkyl radicals such as those defined for R, R4 can then be identical or different from R.

. A, a linear or branched alkylene radical having from 1 to 10 carbon atoms; an alkenylene radical having from 1 to 10 carbon atoms; a cycloalkylene radical having 5 to 6 carbon atoms; a phenylene radical.

As specific examples, the various symbols of formulas I to IV represent:

Ro, an alkyl radical such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, decyl, pentadecyl; an alkylaryl radical such as benzyl, ß-phönylethyl; a cycloalkyl radical such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, 2,6,6-trimethyl cyclohexyl; a radicyl allyl, 2-methyl allyl, butene-2 yl, methyl-2-butene-2-yl, methyl-

4 pentene-3 yl, hexene-3 yl, hexadiene-3,5-yl, 2,4-dimethyl-3 pentene-3 yl, dimethyl-3,4 pentene-3 yl, 2,4-dimethyl-2,4-pentadiene-2,4 yl , dimethyl-3,7 nonatetraene-2,4,6,8 yl, [trimethyl-2 ', 6', 6 'cyclohexene-1' yle] -9 dimethyl-3,7 nonaté-traène-2,4,6 , 8 yl, dimethyl-3,7 octadiene-2,6 yl, trimethyl-3,7,11 dodecatriene-2,6,10 yl, [trimethyl-2 ', 6', 6 'cyclohexene-1' yl] - 2 ethyl; a phenyl-3 propene-2 yl radical; a cycloalkenyl radical such as the cyclohexene-2 yl radical, the trimethyl-2,6,6 cyclohexene-2 yl radical.

Ri, alkyl, cycloalkyl, arylalkyl radicals such as

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15

those cited as an example for Ro; aryl radicals such as phenyl, biphenyl, anthracenyl, naphthyl, tolyl, xylyl radicals; alkenyl radicals such as vinyl, allyl, methallyl, butene-2 yl, 2-methyl butene-2 yl, butene-1 yl, butadiene-1,3 yl, 2-methyl butadiene-1,3 yl, methyl- 3 butadiene-1,3 yl, 4-methyl-pentene-3 yl, hexene-3 yl, hexadiene-3,5 yl, 5-methyl-hexadiene-3,5 yl, 2,4-dimethyl-3-pentene-3 yl, dimethyl- 3,4-pentene-3 yl, 2,4-dimethyl-2,4-pentadiene-2,4 yl, 3,7-dimethyl nonatetraene-2,4,6,8 yl, [trimethyl-2 ', 6', 6 'cyclohexene-1 'yl] -9-dimethyl-3,7 nonatetraene-2,4,6,8 yl, dimethyl-3,7 octadiene-2,6 yl, trimethyl-3,7,11 dodecatriene-2,6,10 yl, [ trimethyl-2 ', 6', 6'cyclohexene-yl] -2 ethyl; a phenyl-2 vinyl radical, phenyl-3 propene-2 yl; a cycloalkenyl radical such as the cyclohexene-1 yl radical, cyclohexene-2 yl, trimethyl-2,6,6 cyclohexene-1 yl, trimethyl-2,6,6 cyclohexene-2 yl.

R2 and R3 alkyl, cycloalkyl, arylalkyl radicals such as those cited as examples for Ro; aryl radicals such as phenyl, biphenyl, anthracenyl, naphthyl, tolyl, xylyl radicals; alkenyl radicals such as allyl radicals; methallyl; 3-methyl-2-butene-yl; 3-methyl-2-pentene-yl; butene-3 yl; 3-methyl-3-butene-yl; pentadiene-2,4 yl; hexene-2 yl; 3-methyl-2-hexene yl; 2,3-dimethyl butene-2 yl; cyclopentene-1 ylmethyl; dimethyl-3,4 ', pentene-2 yl; [cyclohexene-1 'yl] -2 ethyl; 2,4-dimethyl-3-pentene-yl; 2,4-dimethyl-2,4-pentadiene-yl; dimethyl-3,7 nonatetraene-2,4,6,8 yl; dimethyl-3,7 octadiene-2,6 yl; trimethyl-3,7,11 dodecatriene-2,6,10 yl; [2-trimethyl, 6 ', 6' cyclohexene-1 'yl] -2 ethyl; cycloalkenyl radicals such as cyclohexene-2 yl; dimethyl-6,6 cyclohexene-2 yl; trimethyl-2,6,6 cyclohexene-2 yl.

As examples of alkylene or alkenylene radicals that R 1 can form with R 2 or R 3, mention may be made of the trime-thylene, tetramethylene radicals; butene-2 ylene-1,4; 2-methyl tetra-methylene or radicals of the formula: 35

20

ch2 - CH. - CH - CH2

\ Ac:

.CHg "

45

R and R4, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, octyl, pentadecyl decyl radicals; cyclohexyl, cyclopentyl radicals; phenyl, tolyl, xylyl radicals; benzyl, ß-plreny ^ thyle radicals.

A, a methylene, ethylene, trimethylene, isopropyly-dene, propenylene, 1,4-cyclohexylene, p-phenylene radical.

Among the various meanings indicated above, the symbols appearing in formulas I to IV preferably have the following:

Ro represents an alkyl radical having from 1 to 4 carbon atoms, linear or branched; a linear or branched alkenyl radical having from 2 to 25 carbon atoms and comprising 1 or more ethylenic double bonds, conjugated or not, optionally substituted by a cyclohexyl or cyclohexenyl radical which may be substituted by 1 to 3 methyl radicals; a cyclohexyl or cyclohexenyl 65 radical optionally comprising from 1 to 3 methyl groups.

Ri, is an alkyl radical having from 1 to 6 carbon atoms,

R2 and R3, which are identical or different, represent hydrogen atoms or alkyl radicals containing from 1 to 4 carbon atoms,

R represents an alkyl radical having from 1 to 4 carbon atoms, a phenyl radical, a benzyl radical, X represents a chlorine or bromine atom.

Among the meanings already indicated, Ro more preferably still represents a radical of general formula:

R "

R '

/ \ / CH

CH C

R ",

(V)

in which:

x is an integer ranging from 1 to 5 and preferably from 1 to 3,

R ', R ", R'" and R "" identical or different represent hydrogen atoms or methyl or ethyl groups,

Y represents a hydrogen atom; a methyl or ethyl radical; a cyclohexyl or cyclohexenyl radical optionally substituted with 1 to 3 methyl radicals.

As examples of aliphatic halides of formula (II) which can be used in the process of the invention, mention may be made of:

alkyl halides such as chloride and methyl bromide; ethyl; n-propyl; isopropyl; n-butyl; t-butyl; n-pentyl; n-hexyl,

alkenyl halides such as: allyl chloride; allyl bromide; methallyl chloride; 1-chloro-butene-3; chloro-1 butene-2; chloro-1 methyl-3 butene-3; 1-bromo-3-methylene-2-butene; 1-chloro-2-methylene-2-butene; 1-chloro-2,3-dimethyl-butene-2; 1-chloro-dimethyl-3,7 octene-7; bromo-1 dimethyl-3,7 octene-6; 1-chloro-tetramethyl-5,5,7,7 octene-2; geranyl chloride; geranyl bromide; farnesyl chloride; 1-chloro-tetramethyl-3,7,11,15 hexadecatetraene-2,6,10,14,

cycloalkyl or cycloalkenyl halides such as cyclohexyl chloride; 1-chloro-2-methyl cyclohe-xane; chloro-1, trimethyl-2,6,6 cyclohexane; 1-chloro-cyclohexene-2; 1-chloro-cyclohexene-3; chloro-1, trimethyl-2,6,6 cyclohexene-2.

alkynil halides such as propargyl chloride and bromide.

arylalkyl halides such as benzyl or 2-phenylethyl chloride and bromide.

Alkyl halides of general formula:

55

60

Y—

R "

R '

/ cx / "

CH C

R ",

R "

-X

(VI)

in which X, Y, R ', R ", R'", R "" and x have the meanings given above, constitute a preferred class of reagents suitable for implementing the method according to the invention.

Among the enoxysilanes of formula (III) there may be mentioned by way of nonlimiting example:

616138

6

- 2-trimethylsilyloxy propene

- 2-triethylxilyloxy-butene-1

- 2-methyldiethylxilyloxy-2-butene

-n-propyldimethylsilyloxy-2-methyl-3-butene-1

- trimethylsilyloxy-2-1,3-butadiene

- 2-phenyldimethylsilyloxy-3-methyl-2-butene

- 3-methyl-trimethylsilyloxy-2, butadiene-1,3

- 2-trimethylsilyloxy-pentene-1

- 2-trimethylsilyloxy-pentene-2

- 3-trimethylsilyloxy-pentene-2

- trimethylsilyloxy-3 methyl-2 pentene-2

- 2-trimethylsilyloxy-4-methyl-pentene-2

- 1,4-trimethylsilyloxy-1,4-pentadiene

- trimethylsilyloxy-3-pentadiene-1,3

- 2-trimethylsilyloxy-4-methyl-1,4-hexadiene

- 2-trimethylsilyloxy-3,4-dimethyl-1,4-hexadiene

- trimethylsilyloxy-2 heptene-2

- trimethylsilyloxy-3 heptene-2

- trimethylsilyloxy-3 heptene-3

- trimethylsilyloxy-2 heptene-1

- 2-trimethylsilyloxy-4-methyl heptene-1

- 2-trimethylsilyloxy-4-methyl-heptene-2

- trimethylsilyloxy-2-methyl-5-heptadiene-1,5

- trimethylsilyloxy-2-methyl-5-heptadiene-2,5

- 2,5-trimethylsilyloxy-2,5-hexadiene

- 1,4-trimethylsilyloxy-1,4-hexadiene

- trimethylsilyloxy-2-hexadiene-1,5

- trimethylsilyloxy-4 dimethyl-2,6 heptene-3

- trimethylsilyloxy-2 octene-1

- trimethylsilyloxy-2 octene-2

- trimethylsilyloxy-5-methyl-2-octadiene-1,5

- trimethylsilyloxy-5-methyl-2-octadiene-1,4

- trimethylsilyloxy-1 cyclohexyl-1 ethylene

-trimethylsilyloxy-l [cyclohexene-2 'yl] -l ethylene

- trimethylsilyloxy-1 [trimethyl-2 ', 6', 6 'cyclohexene-2' yl] -l ethylene

- trimethylsilyloxy-1 phenyl-1 ethylene

- 1-trimethylsilyloxy-1-phenylpropylene

- trimethylsilyloxy-1 cyclopentene - trimethylsilyloxy-1 cyclohexene

- trimethylsilyloxy-1 methyl-2 cyclohexene

- bis [2-propene-yloxy] dimethylsilane

- tris [2-propene-yloxy] methylsilane

15

20

The enoxysilanes of formula (III) which are used to carry out the process of the invention are known products which are easily prepared, for example by reaction of a mono-, di- or trihalogenoorganosilane of general formula:

(R) 4-n - Si - (X) n in which R and n have the meaning already given and X represents a chlorine or bromine atom, with an enolisable ketone, that is to say ketones comprising at least one hydrogen atom at position a and / or a 'with respect to the carbonyl group. The reaction of halooorganosilanes with enolizable ketones can be carried out in the presence of zinc chloride and a hydracid acceptor according to the process described in Belgian patent 670,769.

When the enolisable ketone has different organic residues on either side of the carbonyl group and at least one hydrogen atom on the carbon atoms in a and a 'of this same group, a mixture of isomeric enoxysilanes is obtained which can be separated before reaction with the alkyl halide or used as a mixture; in this case, a mixture of alkyl ketones at a and alkyl ketones at a 'is obtained.

The enoxysilane resulting from the reaction of the insoluble ketone with the haloorganosilane can be isolated before reaction with the alkyl halide or can be used in the raw state without prior isolation. In the latter case, it suffices to add to the reaction mass resulting from the preparation of enoxysilane, the appropriate quantity of alkyl halide and optionally a catalyst.

The process of the invention is ultimately presented as a means of alkylating ketones comprising at least one hydrogen atom on the and / or the carbon atoms located at a and / or a 'with respect to the carbonyl group, which successively implements the reaction of an enolisable ketone with a halooorganosilane, then the reaction of the enoxysilane formed with an alkyl halide with formation of the alkylated ketone corresponding to the starting ketone and of the initial halooorganosilane which can be used again 40 for the enoxysilane preparation step. Without the invention being in any way limited to a particular mechanism, such a process can be represented diagrammatically in the following manner:

30

Ri

O

/

CH

R2 + (X) n - Si (R) 4-n -> (R) 4-n - Si -

R3

Ri

Ri

O

+

.R2

R3

+ n HX

C ^, R2 + '(X) n - Si (R) 4-n' O C

- n Ro - X

R3

Ro

Such a process is of great industrial interest because it makes it possible to prepare a practically infinite number of ketones; moreover the prior preparation of enoxysilane avoids the secondary polyalkylation reactions inherent in direct alkylation processes in the presence of alkaline bases, in particular alkali hydroxides, as well as the reactions of ketones with themselves or with the products of the alkylation that occur during the reaction of the starting ketone with

65

alkyl halide in a strongly basic medium and lead to the formation of heavy products.

Among the metals which can be used as catalysts in the process of the invention, non-limiting examples include: Zr, Ti, Mo, W, Mn, Fe, Ru, Pd, Os, Co, Cu, Ni, Zn, Cd, Sn, Pb, Sb, Re, Au as well as the lanthanides and actinides and in particular uranium.

7

616138

Although the course of the reaction necessitates the presence of a metal, the form in which it is present is not critical and it can therefore be in the form of free metal or in the form of any derivative, of varying degree of oxidation; it has in fact been observed that the reaction takes place even when the metal is in the free state; when a metal derivative is used, the remainder linked to the metal does not play a particular role in the course of the reaction. Consequently, any organic or mineral salt or any complex of metals or their derivatives can be used with electronic doublet donors. By way of nonlimiting examples of metallic derivatives of the aforementioned metals, mineral salts such as halides, oxyhalogenides, sulfates, nitrates, carbonates, heteropolyacid salts such as phosphomolybdates, phospho-tungstates, vanadates; the salts of carboxylic acids such as acetates, propionates, formates, butyrates, hexa-noates, heptanoates, octoates stearates, napthenates, benzoa-tes; salts of sulfonic acids; chelates derived from p-dicarbonylated compounds such as ß-diketones. As specific examples of metallic derivatives can be cited tin chloride, tin acetate, ferric chloride, ferric acetyl acetonate, cobalt bromide, nickel chloride, palladium chloride, chloride of ruthenium, cupric chloride, cuprous chloride, titanium tetrachloride, zirconium tetrachloride, uranium trichloride, uranyl acetylacetonate, rhenium chloride, zirconyl acetylacetonate, acetylacetonate of vanadyl, molybdyl acetylacetonate, zinc chloride, zinc acetate, zinc bromide.

When the metal is used in the free state it can be used alone or deposited on the supports usually used in catalysis such as carbon black, alumina, silica, aluminosilicates, pierreponce, barium carbonates or calcium.

The amount of catalyst expressed as the number of gram atoms of metal or of metal ions per mole of alkyl halide can vary within wide limits. Generally an amount of catalyst corresponding to an amount of metal of between 0.00001 and 0.4 gram atom or metal ion per mole of alkyl halide is very suitable; in practice these quantities are between 0.0001 and 0.2. We could go beyond the limits indicated above but without this having any particular advantage.

The temperature at which the reaction is carried out depends on the reagents used. Generally a temperature between -50 and + 200 ° C, and preferably between -20 and 150 ° C is suitable. It is possible to operate at normal pressure or at pressure lower or higher than atmospheric pressure, for example under the autogenous pressure of the reactants under the chosen temperature conditions. A simple test allows in each case to choose the appropriate temperature.

The condensation of the alkyl halide with the enoxysilane can be carried out indifferently within an organic solvent inert with respect to the reagents used, or in the absence of any solvent. In the first case, aliphatic (hexane, heptane), cycloaliphatic (cyclohexane), aromatic (benzene) hydrocarbons can be used; ethers (ethyl oxide; tetrahydrofuran; diglyme); halogenated derivatives (chloroform, carbon tetrachloride); nitriles (acetonitrile, propionitrile, benzonitrile); to tertiary carbo-xamides (dimethylformamide, dimethylacetamide, n-methyl-pyrrolidone).

The quantities of enoxysilane and aliphatic halide used to conduct the reaction may be close to the stoichiometry, that is to say close to 1 mole of alkyl halide per enoxy group present in the enoxysilane , or can deviate widely by using either an excess of one or the other of the reagents. Thus, an amount of alkyl halide of 5 moles per enoxy group used in the reaction could be used, but in general it does not exceed 2 moles of alkyl halide per enoxy group. It is preferably carried out with an excess of enoxysilane relative to the alkyl halide, this excess having no critical upper limit, the enoxy compound possibly even serving as a solvent when it is liquid under the conditions of reaction. When it is not desired to use enoxysilane as solvent, the quantity used can be such that the number of moles of alkyl halide per enoxy group is at least 0.1. In short, the respective amounts of alkyl halide and of enoxysilane can be such that the ratio [number of moles of halide] / [number of enoxy groups] is between 5 and 0.1 and, preferably between 2 and 0.1.

As already indicated, the process according to the invention makes it possible to prepare a very large number of ketones. It is of particular interest for the preparation of ethylenic ketones and in particular of ketones comprising in their structure isoprenic units. These ketones are of great industrial interest because they are used in the field of perfumes; others are sought-after intermediaries in organic synthesis. This is the case for 2-methyl heptene-2 one-6, which is one of the links in the synthesis of vitamin A. More particularly, the process according to the invention lends itself well to the synthesis of mono- or polyisoprenic ketones of general formula:

30

35

O R2 Ri-C-C-R3

R '

I

CH

R '"C

VS

i

R "

CH-

I

R ""

(VII)

-Y x in which Ri, R2, R3, R ', R ", R'", R "", Y and x have the meanings already given.

Among the ketones corresponding to this formula include in particular:

- 2-methyl-heptene-2 one-6

- geranyl acetone 45 - f arnesylacetone

- trimethyl-3,6,10 undecadiene-5,9 one-2

- dimethyl-4,7 octene-6 one-3

- methyl-8 nonene-7 one-4

- dimethyl-2,7 octene-6 one-3 so - dimethyl-2,8 nonene-7 one-4

- 3-isopropyl-6-methyl-heptene-5 one-2

- [methyl-3 butene-2 yl] -2 cyclohexanone

- dimethyl-2,8 nonadiene-2,7 one-4

- propyl-4 methyl-7 octene-6 one-3

55 - isopropylidene-3 methyl-6 heptene-5 one-2

- n-pentyl-3 methyl-6 heptene-5 one-2

- dimethyl-2.10 undecadiene-2.9 one-6

- [methyl-3 butene-2 yl] -5 methyl-2 heptene-2 one-6

- trimethyl-2,5,5 heptene-2 one-6 60 - dimethyl-6,9 decene-8 one-5

- 2,8-dimethyl-5-isopropyl-nonene-7 one-4

- 2-methyl-decadiene-2.9 one-6

- allyl-5 methyl-2 heptene-2 one-6

In practice, the reagents can be loaded in any order. At the end of the reaction, the unprocessed products and those resulting from the reaction are separated by the usual routes, for example by extraction using solvents, and / or by distillation. Halooorganosilane formed

616138

8

can be reused either in the raw state or after purification for the preparation of enoxysilane. The process can be easily carried out continuously.

The following examples illustrate the invention and show how it can be practiced. 5

Example 1

In a 250 cm3 glass flask comprising three tubes, equipped with an ascending refrigerant, a stirring system, a pouring bulb and an argon inlet, the following is charged:

- 75 cm3 of acetonitrile

- 170 mg of zinc chloride

- 97.5 g of 2-trimethylsilyloxy propene (TMSP)

The agitation is started then the contents of the flask are refluxed (72 ° C); 13.75 g of 3-methyl-1-chloro-2-butene are then added over 8 min. One hour is maintained under these conditions and then the light products are distilled at atmospheric pressure. In this way, a fraction composed of trimethylchlorosilane, acetonitrile and TMSP is collected between 60.5 and 75 ° C. The residue is then distilled under 15 mm of mercury; 14.4 g of a fraction distilled between 65 and 80 ° C. are obtained, containing 81.4% 2-methyl-heptene-2 one-6 measured by gas-liquid chromatography. The yield relative to the charged methyl chlorobutene amounts to 70.6%.

Example 2

The procedure is as in Example 1 but by varying the TMSP / methylchlorobutene molar ratio. This ratio which was 5.7 in Example 1 is reduced to 0.85. The yield of methylheptenone relative to the charged methylchlorobutene is 68%.

Example 3

In the apparatus used in Example 1, we load:

- acetonitrile: 15 cm3

- ZnCk: 34 mg -TMSP: 19.5 g

The contents of the flask are brought to 45-48 ° C. then 2.75 g of methyl chlorobutene are added over 3 minutes. Maintained 6 h 30 under these conditions and then treated the reaction mass as in Example 1. 2.90 g of a fraction are collected in which 74% of methylheptenone is assayed.

The yield relative to methyl chlorobutene is 65.6%.

Examples 4 to 7

The procedure is as in Example 1, replacing the acetonitrile with different solvents. The other conditions and the results are shown in the following table:

20

Ex

ZnCl2

T °

Duration

TMSP

CDI (1)

Solvent

Rdten

in mg

° C

moles moles

Nature Volume cm3

MHen% (2)

4

34

91

15 mins

0.15

0.0263

HEPTANE 15

43

5

170

86

30 mins

0.796

0.1315

PROPIO- 75 NITRILE

65

6

34

92-

-95

30 mins

0.15

0.0263

BENZO- 15 NITRILE

62.5

7

136

92-

-94

4:30 a.m.

0.15

0.0263

DIMETH- 15

YLFOR-

MAMID

25.2

(1) CDI designates 1-chloro-3-butene-2-methyl or isoprene 45-hydrochloride

(2) MH denotes methylheptenone

Examples 8 to 10 By operating as in Example 3, a series of experiments was carried out, the results of which are given in the following table, by varying the nature of the catalyst.

Ex

Nature Catalyst

Weight in mg

Temperature in ° C

Duration

Yield in MH%

8

CuCl

75

74

3:30 a.m.

40.7

9

Acetate

55

72

1 h 30

62.5

zinc

dihydrate

10

SnCU

65

53

1 h 30

44.8 (1)

(1) this test was carried out in 15 cm3 of methylene chloride

65

Example 11

The experiment of Example 1 is repeated, but loading 510 mg of zinc chloride and maintaining the reaction mass for 15 min at 75 ° C., after which the light products are distilled at normal pressure. 165 g of a distilling fraction is collected in this way between 70.8 and 75 ° C. in which the chlorotrimethylsilane is metered chemically (hydrolysis and determination of the hydrochloric acid released). It is found that this fraction contains 91% of chlorotrimethylsilane which should have theoretically formed from the charged CDI. The entire TMSP in excess relative to the CDI, ie 6.25 × 10 −1 mole, is also assayed in this fraction.

The distillation residue is then rectified under a pressure of 15 mm of mercury; we get two fractions:

- a fraction of 0.25 g in which 50.3% of methylheptenone is assayed by gas / liquid chromatography.

- a fraction of 13.7 g distilling between 45 and 70 ° C and containing 85.5% of methylheptenone.

The yield compared to the loaded CDI amounts to 71.5%.

Example 12

In the device described in Example 1, we load:

-acetonitrile: 25 Cm3 - ZnCh: 56.6 mg -TMSP: 32.6 g

60

9

616138

The contents of the flask are brought to reflux (72 ° C.) and then 4.58 g of CDI are added over 4 minutes with stirring. Maintained for 1 hour under these conditions and then the light products are eliminated: acetonitrile; chlorotrimethylsilane; TMSP in excess, by distillation under reduced pressure; 57.6 g of a fraction Fi are obtained, distilling between 68 and 83 ° C under 760 mm of mercury and then 4.75 g of a fraction distilling between 90 and 100 ° C under 120 mm of mercury and in which is 74% methylheptenone. The yield compared to the loaded CDI amounts to 64%. io

We repeat the experiment by loading in the same device:

- the fraction Fi

- ZnCh 56.6 mg

-TMSP 5.43 g xs then 4.58 g of CDI under the same conditions as above. Heating is continued for 1 hour 30 minutes then the reaction mass is treated as before. A fraction of light products of 60.8 g (F2) is collected, then 5.40 g of a fraction in which 65.4% of methylheptenone is assayed (yield / charged CDI: 64%).

The previous experiment is repeated a second time by adding to the fraction F2 the light, 56.6 mg of ZnCk and 5.43 g of TMSP then 4.58 g of CDI. 2s

Distillation of the reaction mass gives a fraction F3 of light weighing 63.5 g and a fraction of 5.6 g containing 63.3% of methylheptenone (yield / loaded CDI: 65.4%).

This example shows that raw acetonitrile and TMSP can be recycled without loss of yield. 30

Example 13 In the apparatus described in Example 1, we load:

- acetonitrile: 56 cm3 35 -ZnCh:

- acetone:

- triethylamine:

56.2 mg 52.1 g

15.15 g

The contents of the flask are brought to reflux (63 ° C.) and then 16.3 g of chlorotrimethylsilane are added with stirring over 7 min. It is maintained for 1 hour 30 minutes at 63 ° C. and then cooled to 20 ° C. 20.4 g of ZnCh are then added. It is brought to reflux again and then added over 3 min 2.75 g of CDI and maintained for 30 min under these conditions. The reaction mass is treated as in Example 1. A fraction of light products of 95.7 g is collected (Eb76o = 59-81 ° C) then a fraction of 6.6 g (Eb95 =

85-115 ° C) containing 27.5% methylheptenone (Yield / CDI loaded with 54.6%). so

Example 14

In a 100 cm3 glass flask equipped as in Example 1, we load:

ss

Example 15

In a 50 cm3 glass flask, equipped as in Example 1, we load:

-acetonitrile: 15 cm3

- tris (isopropenyloxy) methylsilane: 16.05 g

- zinc chloride: 11.3 mg

The load is brought to reflux (82 ° C) and then added within 3 min 2.75 g of CDI. It is maintained for 15 min under these conditions and then quickly distilled under a pressure of 30 mm of mercury. 13.15 g of a distilling fraction are collected between 35 and 70 ° C. in which 13.9% of methylheptenone is assayed (yield: 55% relative to the loaded CDI).

By operating as in Example 1, the catalytic activity of the following metals or metal derivatives was still tested qualitatively: powdered iron, ferric chloride, ferric acetylacetonate, stannous chloride (SnCk), stannous acetate, cobalt bromide (CoBr2, 2 H2O); NiCk, PdCk, RuCk, CuCk, TiCk, ZrCk, UCk, uranyl acetylacetonate, ReCb; all have been shown to be good catalysts for methylheptenone formation.

Example 16

In a 50 cm3 glass flask equipped as in Example 1, we load:

- 17 g of trimethylsilyloxy-1 cyclohexene -15 cm3 of acetonitrile

- 1.85 g of isoprene hydrochloride at 92%

then 300 mg of zinc chloride - the contents of the flask are brought to reflux (82 ° C.) with stirring and maintained for 1 hour 30 minutes under these conditions.

After cooling, most of the light products are distilled. This gives 17 g of a distillate passing between 65 and 83 ° C under 760 mm of mercury and 20 g of residue which is subjected to distillation under reduced pressure; we collect 2 fractions:

a) 11 g of a distilling product between 70 and 95 ° C under 40 mm of mercury consisting almost entirely of the starting enoxysilane.

b) 3.2 g of a product distilling between 95 and 125 ° C under 40 mm of mercury and in which 67% by weight of ketone by formula have been determined by nuclear magnetic resonance:

The conversion rate of isoprene hydrochloride is 100% and the yield of ketone relative to the latter of 79.5%.

- acetonitrile: 30 cm3

- bis (isopropenyloxy) dimethylsilane: 12.9 g

- ZnCk: 34 mg

It is refluxed and then added with stirring 2.75 g of CDI over 30 minutes. Maintaining 1 h 15 at 82 ° C and then distilling the contents of the flask under reduced pressure (20 mm of mercury). 9 g of a distillation fraction between 40 and 75 ° C. are obtained in which 22.4% of methylheptenone is assayed (yield: 61% relative to the loaded CDI). In addition, 30.5 g of light products are recovered from the dry ice / acetone traps.

Example 17 In the apparatus used in Example 16, load:

60

- 23 g of trimethylsilyloxypropene at 96% by weight

- 15 cm3 of acetonitrile

- 3.18 g of benzyl chloride - 170 mg of zinc chloride

65

then the contents of the flask are brought to reflux (75 ° C.) with stirring for 18 hours. The reaction mass is then

616138

- 59% unprocessed benzyl chloride

- 17.8% 3-phenyl butanone, a yield of 68%

compared to transformed benzyl chloride.

treated as in Example 16. 3.9 g of a fraction distilling between 50 and 110 ° C. is collected under 15 mm of mercury and in which the following are assayed by gas-liquid chromatography:

B

Claims (19)

616138 2. Method according to claim 1 characterized in that Ro represents: a linear or branched alkyl radical comprising from 1 to 25 carbon atoms, optionally substituted by a cycloalkyl or cycloalkenyl radical having from 5 to 6 cyclic carbon atoms; an arylalkyl radical having from 1 to 10 carbon atoms in the alkyl residue; a cycloalkyl radical having 5 to 10 cyclic carbon atoms optionally substituted by 1 to 3 lower alkyl radicals; a linear or branched alkenyl radical preferably having from 2 to 25 carbon atoms and possibly comprising one or more carbon-carbon double bonds, conjugated or not, optionally substituted by a cycloalkyl or cycloalkenyl radical having from 5 to 6 carbon atoms; an alkinyl radical comprising 1 or more carbon-carbon triple bonds and having from 2 to 10 carbon atoms; an arylalkenyl radical having from 2 to 10 carbon atoms in the alkenyl residue; a cycloalkenyl radical having 5 to 10 cyclic carbon atoms, optionally substituted by 1 to 3 lower alkyl radicals. 2 CLAIMS 1. Process for the preparation of ketones comprising a secondary or tertiary aliphatic carbon atom in at least one of the positions a of the carbonyl group, of general formula: O R2 He / Ri-C-C i \ Ro R3 (I) characterized in that a halide of general formula is reacted: Ro-X (II) with an enoxysilane of general formula: (R) 4-n-Si. Ri I .VS. o- V R2 R3 (III) 3 616138 are hydrogen atoms or alkyl radicals having 1 to 4 carbon atoms. 3. Method according to claim 2, characterized in that Ro represents an alkyl radical having from 1 to 4 carbon atoms, linear or branched; a cyclohexyl or cyclohexenyl radical optionally comprising from 1 to 3 methyl groups. 4. Method according to claim 2, characterized in that Ro represents an alkenyl radical corresponding to the general formula: c o R3 - If - A - ! (R4) 3-n (IV) or: . Ri, R2, R3 and n have the meaning already given, . R4 is a hydrocarbon radical having from 1 to 20 carbon atoms, identical or different from R, R, " .VS. Y - CH I R "" Y R " R 'CH- (V) in which: . x is an integer ranging from 1 to 5, 45. R ', R ". R'" and R "", which are identical or different, represent hydrogen atoms or methyl or ethyl groups, . Y represents a hydrogen atom; a methyl or ethyl radical; a cyclohexyl or cyclohexenyl radical optionally substituted with 1 to 3 methyl radicals. 50 5. Method according to claim 4, characterized in that Ro is a 3-methyl-2-butene-yl radical; geranyl; farmésyle. 6. Method according to one of claims 1 to 5, characterized in that the radicals Ri, R2 and R3 represent linear or branched alkyl radicals; cycloalkyls; arylalkyls; 55 aryls comprising from 1 to 3 benzene rings forming, where appropriate, an ortho- or ortho- and pericondensed system, optionally substituted by 1 to 3 lower alkyl radicals; linear or branched alkenyl, cycloalkenyl or arylalkenyl radicals, R2 and R3 having no double bond 60 conjugated with the enolic double bond of enoxysilane; Ri forms, with R2 or R3, an alkylene or alkenylene radical comprising from 3 to 4 carbon atoms and of which two successive carbon atoms may form part of an aliphatic or benzene hydrocarbon ring or of a system of 2 to 4 65 aliphatic rings and / or benzene. 7. Method according to claim 6, characterized in that Ri is a linear or branched alkyl radical having from 1 to 6 carbon atoms, R2 and R3 identical or different represent 8. Method according to one of claims 1 to 7, characterized in that Ri represents methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyles, hexyl radicals and R.2 and R3 represent atoms of hydrogen or one of the radicals previously mentioned for Ri. 9. Method according to one of claims 1 to 8, characterized in that in formula (III) R represents linear or branched alkyl radicals having from 1 to 20 carbon atoms; cycloalkyl radicals having 5 to 6 carbon atoms; phenyl radicals optionally substituted with 1 to 3 lower alkyl radicals; phenylalkyl radicals containing from 1 to 4 carbon atoms in the alkyl residue. 10. Method according to claim 9, characterized in that R is an alkyl radical having from 1 to 4 carbon atoms, a phenyl radical, a benzyl radical. 10 11. Method according to one of claims 1 to 8, characterized in that in formula (IV) R4 represents an alkyl radical having from 1 to 4 carbon atoms, a phenyl radical, a benzyl radicyl and A is an alkylene radical having from 1 to 10 carbon atoms; a cycloalkylene radical having 5 to 6 carbon atoms; a phenylene radical. 12. Method according to one of claims 1 to 11, characterized in that a metal or a metal derivative taken from the group formed by: Zr, Ti, Mo, W, Nm, Fe is used as catalysts , Ru, Pd, Os, Co, Cu, Ni, Zn, Cd, Sn, Pb, Sb, Re, Au, U. 13. Method according to one of claims 1 to 12, characterized in that one uses as derivatives of metals, salts of mineral or organic acids or metal complexes with donors of electronic doublets. 14. Method according to one of claims 1 to 13, characterized in that a metal halide, an oxyhalide, a sulfate, a nitrate, a phosphate, a carbonate, a carboxylic acid salt, is used as the metal derivative. , a salt of organosulfonic acids, a chelate derived from ß-dicarbonyl compounds. 15. Method according to one of claims l to 14, characterized in that the quantity of catalyst expressed in gram atom of metal or in metal ions per mole of alkyl halide-nide can vary between lxlO "5 and 0 , 4 at.g. or ion per mole of halide of formula (II). 15 20 25 in the presence of a catalyst consisting of a metal or a derivative of a metal from groups lb, 2b, 3b, 4a, 4b, 5a, 5b, 6b, 7b and 8 of the periodic table of the elements, in which formulas: - Ro is an aliphatic or cycloali-phatic hydrocarbon radical, saturated or not, optionally substituted by one or more inert functional groups, comprising from 1 to 30 carbon atoms, Ri is a hydrocarbon radical containing from 1 to 30 carbon atoms, optionally substituted by a functional group inert with respect to the aliphatic halides used under the reaction conditions, - R2 and R3 represent hydrogen; hydrocarbon radicals having from 1 to 30 carbon atoms, or one of the radicals R2 and R3 forms with Ri a divalent hydrocarbon radical having from 3 to 13 carbon atoms, or R2 and R3 together form a divalent hydrocarbon radical having from 4 with 14 carbon atoms, R2 and R3 which can be substituted in all cases by an inert functional group with respect to the aliphatic halides used, - X represents a chlorine, bromine or iodine atom, - n is an integer from 1 to 3 - R represents a hydrocarbon radical having from 1 to 20 carbon atoms, or, when n is equal to 1 or 2, at most one of the radicals R symbolizes a radical of general formula: Ri . A represents a valence bond, an oxygen atom, a divalent hydrocarbon radical having from 1 to 10 carbon atoms. 16. Method according to one of claims 1 to 15, characterized in that the reaction temperature is between -50 and + 200 ° C and the pressure higher or lower or equal to atmospheric pressure. 17. Method according to one of claims 1 to 16, characterized in that the respective amounts of enoxysilanes and alkyl halide are such that the number of moles of alkyl halide per enoxy residue present in the enoxysilane is at most 5 and preferably at most 2. 18. Method according to one of claims 1 to 17, characterized in that the respective amounts of enoxysilane and of alkyl halide are such that the number of moles of alkyl halide is between 2 and 0, 1 per enoxy residue present in enoxysilane. 19. Method according to one of claims 1 to 18, characterized in that the 2-methyl-heptene-2 one-6 is prepared by reaction of 1-chloro-3-methyl-2-butene with 2-trimethylsilyl-oxy propene, bis (isopropenyloxy) dimethylsilane, tris (isopropenyloxy) methylsilane.