阅读说明：本技术 在磷化合物存在下将炔醇选择性氢化成烯醇 (Selective hydrogenation of alkynols to enols in the presence of phosphorus compounds ) 是由 维尔纳·邦拉蒂 乔纳森·艾伦·麦德洛克 于 2020-05-26 设计创作，主要内容包括：本发明涉及一种在添加剂(其为带有膦基团或氧化膦基团的有机磷化合物)存在下,使用氢化催化剂(其为负载在载体上的钯)通过氢气将炔醇选择性氢化为烯醇的方法；并且前提条件是在添加剂带有膦基团的情况下,添加剂带有两个或更多个膦基团。(The present invention relates to a process for the selective hydrogenation of alkynols to alkenols by hydrogen in the presence of an additive which is an organophosphorus compound carrying a phosphine group or a phosphine oxide group, using a hydrogenation catalyst which is palladium supported on a carrier; and with the proviso that in the case of an additive carrying a phosphine group, the additive carries two or more phosphine groups.)

1. A process for the selective hydrogenation of alkynols to alkenols by means of hydrogen in the presence of an additive of an organophosphorus compound bearing phosphine groups or phosphine oxide groups, using a supported palladium hydrogenation catalyst; characterized in that in the case of the additive carrying phosphine groups, the additive carries two or more phosphine groups.

2. A process according to claim 1, characterized in that the alkynol is an alkynol having a hydroxyl group attached to a carbon alpha to the carbon-carbon triple bond of the alkynol.

3. The method according to claim 1 or claim 2, characterized in that the carbon-carbon triple bond is a terminal carbon-carbon triple bond.

4. Process according to any one of the preceding claims, characterized in that the alkynol is an alkynol of formula (I)

And the enol is of formula (II)

Wherein

R¹Represents H or a methyl or ethyl group, preferably a methyl or ethyl group; and is

R²Represents a saturated or unsaturated, linear or branched or cyclic hydrocarbon radical having 1 to 46C atoms, optionally comprising at least one chemical functional group, in particular at least one hydroxyl group;

or

R¹And R²Together represent an alkylene group forming a 5-to 7-membered ring;

with the proviso that R¹Have the same meaning in the formulae (I) and (II), and R²Have the same meaning in the formulae (I) and (II).

5. Process according to any one of the preceding claims, characterized in that R¹Is methyl.

6. Process according to any one of the preceding claims, characterized in that R²Is methyl.

7. Process according to any one of the preceding claims 1 to 5, characterized in that R²Selected from the group consisting of: formula (R2-I), (R2-II), (R2-III), (R2-IV), (R2-V), (R2-VI) and (R2-VII),

wherein the dotted line represents a bond linking a substituent of formula (R2-I), (R2-II), (R2-III), (R2-IV), (R3-V), (R2-VI) or (R2-VII) to the remainder of said compound of formula (I) or formula (II);

and having a dotted line thereinRepresents, independently of one another, a carbon-carbon single bond or a carbon-carbon double bond, preferably a carbon-carbon single bond;

and wherein any wavy lines represent, independently of each other, a carbon-carbon bond which, when connected to a carbon-carbon double bond, is in the Z configuration or the E configuration;

and wherein n represents 1,2, 3, 4, 5 or 6, in particular 1 or 2 or 3, preferably 3 or 2, most preferably 2.

8. Process according to any one of the preceding claims 1 to 7, characterized in that the additive has more than one phosphine group of formula (III)

Wherein R is an alkyl group or a cycloalkyl group or an aryl group, in particular a phenyl or tolyl group, and wherein the dotted line represents the bond joining the substituent of formula (III) to the remainder of the additive.

9. The process according to any one of the preceding claims 1 to 7, characterized in that the organophosphorus compound is selected from the group consisting of: 1, 2-bis (diphenylphosphino) ethane, 1, 3-bis (diphenylphosphino) propane, 1, 4-bis (diphenylphosphino) butane, 1, 3-bis (diphenylphosphino) -2- (diphenylphosphino) methyl-2-methylpropane, 2 '-bis (diphenylphosphino) -1,1' -binaphthyl, and bis (2-diphenylphosphinoethyl) phenylphosphine, preferably selected from the group consisting of: 1, 2-bis (diphenylphosphino) ethane and 1, 3-bis (diphenylphosphino) propane.

10. The process according to any of the preceding claims, characterized in that the hydrogenation is carried out in the absence of any organic quaternary ammonium compound.

11. The process according to any of the preceding claims, characterized in that the hydrogenation is carried out in the absence of any organic solvent.

12. The process according to any one of the preceding claims, characterized in that the support is a carbon or inorganic support, in particular an oxide or carbonate, preferably silica, alumina or ceria or titanium oxide or calcium carbonate.

13. The process according to any of the preceding claims, characterized in that the hydrogenation catalyst is in the form of a colloidal suspension.

14. The process according to any of the preceding claims, characterized in that the weight ratio of the additive to the catalyst is in the range of 0.01:1 to 100:1, preferably 0.1:1 to 10:1, more preferably 0.2:1 to 3: 1.

15. A composition comprising

-Compounds of formula (I)

Wherein

R¹Represents H or a methyl or ethyl group, preferably a methyl or ethyl group; and is

R²Represents a saturated or unsaturated, linear or branched or cyclic hydrocarbon radical having 1 to 46C atoms, optionally comprising at least one chemical functional group, in particular at least one hydroxyl group;

or

R¹And R²Together represent an alkylene group forming a 5-to 7-membered ring;

-a hydrogenation catalyst, the hydrogenation catalyst being palladium supported on a carrier; and

-at least one additive being an organophosphorus compound bearing a phosphine group or a phosphine oxide group;

characterized in that in the case of the additive carrying phosphine groups, the additive carries two or more phosphine groups.

Technical Field

The invention relates to the hydrogenation of alkynols to alkenols.

Background

Alkynes can be hydrogenated to alkenes by hydrogen in the presence of a noble metal catalyst. Palladium catalysts can be used for the hydrogenation of alkynols to alkenols.

Alkynols or alkenols, respectively, are substances which are produced on an industrial scale and are of high importance, in particular for the field of vitamins and aroma chemicals. A non-exhaustive list of such important alkynols and alkenols is 2-methylbut-3-yn-2-ol, 2-methylbut-3-en-2-ol, 3, 7-dimethyloct-6-en-1-yn-3-ol, 3, 7-dimethyloct-1, 6-dien-3-ol, 3,7,11, 15-tetramethylhexadec-1-yn-3-ol and 3,7,11, 15-tetramethylhexadec-1-en-3-ol.

There are several problems in the hydrogenation of alkynols. One problem is that other chemical groups than carbon-carbon triple bonds may also be hydrogenated. To some extent, this problem can be solved by the use of protecting groups. However, this requires additional protection and deprotection steps, which are disadvantageous in view of additional time, cost and waste formation.

Another problem is that the selectivity at high conversion is not high enough. As in any chemical reaction, the goal is to convert as much of the starting material as possible into the desired product. In the present case, there is a further drive to obtain as high a conversion as possible, since alkynols (i.e. the starting materials) and enols (i.e. the products of the selective hydrogenation) are very difficult to separate. Therefore, it is very difficult to perform the reaction at a partial conversion, and then separate the unreacted starting materials and repeat the reaction.

One particularly problematic aspect in the selective hydrogenation of alkynols is over-hydrogenation. The over-hydrogenation describes the following effects: the hydrogenation of alkynols does not stop at the enol stage but continues to produce a substantial amount of alkanols, i.e. the hydrogenation reaction does not selectively hydrogenate only the carbon-carbon triple bond to a carbon-carbon double bond, but the carbon-carbon double bond is also substantially hydrogenated to a carbon-carbon single bond. The over-hydrogenated compound may be difficult to separate from the desired product.

Lindlar in US 2,681,938 discloses a process for the selective hydrogenation of alkynes to alkenes using palladium catalysts modified with lead or bismuth.

In US 3,715,404 a selective hydrogenation is disclosed using a palladium catalyst which is partially deactivated by some specific organic sulphur compounds.

Furthermore, the hydrogenation of alkynols leads to the formation of undesirable by-products, such as dimers or oligomers derived from the alkynols or enols.

Disclosure of Invention

The problem underlying the present invention was therefore to provide a process for the selective hydrogenation of alkynols to alkenols which leads to high conversions, high selectivities and low over-hydrogenations.

Surprisingly, a solution to this problem has been provided by the method according to claim 1. It has been found that the use of additives having 2 or more phosphine groups, in particular, is highly advantageous in providing this combination of desired properties.

Other aspects of the invention are the subject of other independent claims. Particularly preferred embodiments are the subject of the dependent claims.

Detailed Description

In a first aspect, the present invention relates to a process for the selective hydrogenation of alkynols to alkenols by hydrogen in the presence of an additive which is an organophosphorus compound carrying a phosphine group or a phosphine oxide group, using a hydrogenation catalyst which is palladium supported on a carrier; characterized in that in the case of an additive carrying a phosphine group, the additive carries two or more phosphine groups.

For clarity, some terms used in this document are defined as follows:

in this document, "C_x-yAn alkyl "group is an alkyl group containing x to y carbon atoms, i.e., for example, C_1-3Alkyl is an alkyl group containing 1 to 3 carbon atoms. The alkyl group may be linear or branched. For example-CH (CH)₃)-CH₂-CH₃Is regarded as C₄An alkyl group.

Any wavy line in any formula of this document represents a carbon-carbon bond which is in either the Z configuration or the E configuration when connected to a carbon-carbon double bond.

In case the same label for a symbol or group is present in several formulae, in this document the definitions of said group or symbol made in the context of one particular formula also apply to the other formulae comprising said same label.

In this document, an "alkynol" is a compound having at least one carbon-carbon triple bond and at least one hydroxyl group in its chemical formula. In other words, an alkynol is a hydroxyl-functionalized alkyne.

Similarly, an "enol" is a compound having at least one carbon-carbon double bond and at least one hydroxyl group in its chemical formula. In other words, an enol is a hydroxyl-functionalized alkene.

In this document, a "hydrocarbyl" group is a monovalent group that is formally formed by removing a hydrogen atom from a hydrocarbon.

Alkynols

In this process, alkynols are selectively hydrogenated to the corresponding enols.

Alkynols have at least one carbon-carbon triple bond and at least one hydroxyl group in their chemical formula, while the corresponding alkenols have at least one carbon-carbon double bond and at least one hydroxyl group in their chemical formula.

It is important for the present invention that the hydrogenation is selective, i.e. the reduction of a carbon-carbon triple bond to the corresponding carbon-carbon double bond. In other words, the hydroxyl groups, as well as any other chemical groups that may be present in the alkynol, are not modified by the hydrogenation reaction. In particular, the hydrogenation is also selective in the following sense: the carbon-carbon double bond of the enol is not further hydrogenated to a carbon-carbon single bond or at least not significantly further hydrogenated to a carbon-carbon single bond ("over-hydrogenated").

Furthermore, it has been observed that by the above process, in addition to the reduced formation of over-hydrogenated products, the formation of other by-products, such as dimers or oligomers derived from the starting material or product, is also significantly reduced.

In a preferred embodiment of the preferred embodiments, the alkynol is an alkynol having a hydroxyl group attached to a carbon that is alpha to the carbon-carbon triple bond of the alkynol, i.e. the alkynol is preferably an alpha-alkynol.

The alkynol preferably has the following structural elements

In the formula, wherein denotes one or more positions of the other substituent or substituents.

In an even more preferred embodiment, the alkynol is one in which the carbon-carbon triple bond is a terminal carbon-carbon triple bond.

In a very preferred embodiment, the alkynols have the following structural elements

In the formula, wherein denotes the position of the other substituent or substituents.

In a very preferred embodiment, the alkynol is an alkynol of the formula (I)

Wherein

R¹Represents H or a methyl or ethyl group, preferably a methyl or ethyl group; and is

R²Represents a saturated or unsaturated, linear or branched or cyclic hydrocarbon radical having 1 to 46C atoms, optionally comprising at least one chemical function, in particular at least one hydroxyl group;

or

R¹And R²Together represent an alkylene group forming a 5-to 7-membered ring;

with the proviso that R¹Have the same meaning in the formulae (I) and (II), and R²Have the same meaning in the formulae (I) and (II).

Preferred substituents R in formula (I)¹Is a methyl group.

Preferably, R is²Represents a saturated linear or branched or cyclic hydrocarbon radical having 1 to 46C atoms, optionally comprising at least one chemical function, in particular at least one hydroxyl group.

Further preferred is a substituent R in formula (I)²Is methylA group.

A very highly preferred alkynol of the formula (I) is 2-methylbut-3-yn-2-ol (i.e.R)¹＝R²Methyl).

In another embodiment, R¹And R²Together represent an alkylene group forming a 5-to 7-membered ring. The alkylene group may be linear or branched, and optionally comprise at least one chemical functional group, and/or be ethylenically unsaturated. Preferably, the alkylene group is not ethylenically saturated.

Preferably, the alkylene group is a pentylene group. One of the preferred alkynols for this embodiment is 1-ethynylcyclohex-1-ol.

In another preferred embodiment, the substituent is R²Selected from the group consisting of: formula (R2-I), (R2-II), (R2-III), (R2-IV), (R2-V), (R2-VI) and (R2-VII)

Wherein the dotted line represents a bond linking a substituent of formula (R2-I), (R2-II), (R2-III), (R2-IV), (R2-V), (R2-VI) or (R2-VII) to the remainder of the compound of formula (I) or formula (II);

and having a dotted line thereinRepresents, independently of each other, a carbon-carbon single bond or a carbon-carbon double bond, preferably a single carbon-carbon single bond;

and wherein any wavy lines represent, independently of each other, a carbon-carbon bond which, when connected to a carbon-carbon double bond, is in the Z configuration or the E configuration;

and wherein n represents 1,2, 3, 4, 5 or 6, in particular 1 or 2 or 3, preferably 3 or 2, most preferably 2.

The alkynol is preferably an alkynol selected from the group consisting of: 3-methyl-5- (2,6, 6-trimethylcyclohex-1-en-1-yl) pent-1-yn-3-ol, (E) -3-methyl-1- (2,6, 6-trimethylcyclohex-1-en-1-yl) pent-1-en-4-yn-3-ol, (Z) -3-methyl-1- (2,6, 6-trimethylcyclohex-1-en-1-yl) pent-1-en-4-yn-3-ol, (E/Z) -3-methyl-1- (2,6, 6-trimethylcyclohex-1-en-1-yl) pent-1-en-4-yn-3-ol -alcohol, 3-methyl-5- (2,6, 6-trimethylcyclohex-2-en-1-yl) pent-1-yn-3-ol, (E) -3-methyl-1- (2,6, 6-trimethylcyclohex-2-en-1-yl) pent-1-en-4-yn-3-ol, (Z) -3-methyl-1- (2,6, 6-trimethylcyclohex-2-en-1-yl) pent-1-en-4-yn-3-ol, 3, 7-dimethyloct-6-en-1-yn-3-ol, 3, 7-dimethyloct-1-yn-3-ol, 2-dimethyloct-1-en-3-ol, 3, 6-dimethyloct-1-en-3-ol, 2-ol, 6-dimethyloct-1-en-3-ol, E, (E) -3, 7-dimethylnon-6-en-1-yn-3-ol, (Z) -3, 7-dimethylnon-6-en-1-yn-3-ol, (E/Z) -3, 7-dimethylnon-6-en-1-yn-3-ol, 3, 7-dimethylnon-1-yn-3-ol, 3,7, 11-trimethyldodec-1-yn-3-ol, (E) -3,7, 11-trimethyldodec-6-en-1-yn-3-ol, (Z) -3,7, 11-trimethyldodec-6-en-1-yn-3-ol, and mixtures thereof, (E/Z) -3,7, 11-trimethyldodec-6-en-1-yn-3-ol, 3,7, 11-trimethyldodec-10-en-1-yn-3-ol, (E) -3,7, 11-trimethyldodec-6, 10-dien-1-yn-3-ol, (Z) -3,7, 11-trimethyldodec-6, 10-dien-1-yn-3-ol, (E/Z) -3,7, 11-trimethyldodec-6, 10-dien-1-yn-3-ol, 3,7,11, 15-tetramethylhexadec-1-yn-3-ol, (E) -3,7,11, 15-tetramethylhexadec-6-en-1-yn-3-ol, (Z) -3,7,11, 15-tetramethylhexadec-6-en-1-yn-3-ol, (E/Z) -3,7,11, 15-tetramethylhexadec-6-en-1-yn-3-ol, (E) -3,7,11, 15-tetramethylhexadec-10-en-1-yn-3-ol, (Z) -3,7,11, 15-tetramethylhexadec-10-en-1-yn-3-ol, (E/Z) -3,7,11, 15-tetramethylhexadec-10-en-1-yn-3-ol 3,7,11, 15-tetramethylhexadec-14-en-1-yn-3-ol, (6E,10E) -3,7,11, 15-tetramethylhexadec-6, 10-dien-1-yn-3-ol, (6E,10Z) -3,7,11, 15-tetramethylhexadec-6, 10-dien-1-yn-3-ol, (6Z,10E) -3,7,11, 15-tetramethylhexadec-6, 10-dien-1-yn-3-ol, (6Z,10Z) -3,7,11, 15-tetramethylhexadec-6, 10-dien-1-yn-3-ol, (E) 3,7,11, 15-tetramethylhexadeca-10, 14-dien-1-yn-3-ol, (Z) -3,7,11, 15-tetramethylhexadeca-10, 14-dien-1-yn-3-ol, (6E,10E/Z) -3,7,11, 15-tetramethylhexadeca-6, 10-dien-1-yn-3-ol, (6Z,10E/Z) -3,7,11, 15-tetramethylhexadeca-6, 10-dien-1-yn-3-ol, (6E/Z,10E) -3,7,11, 15-tetramethylhexadeca-6, 10-dien-1-yn-3-ol, (6E/Z,10Z) -3,7,11, 15-tetramethylhexadeca-6, 10-dien-1-yn-3-ol, (6E/Z,10E/Z) -3,7,11, 15-tetramethylhexadeca-6, 10-dien-1-yn-3-ol, (E) -3,7,11, 15-tetramethylhexadeca-6, 14-dien-1-yn-3-ol, (Z) -3,7,11, 15-tetramethylhexadeca-6, 14-dien-1-yn-3-ol, (E/Z) -3,7,11, 15-tetramethylhexadeca-6, 14-dien-1-yn-3-ol, (E) 3,7,11, 15-tetramethylhexadeca-10, 14-dien-1-yn-3-ol, (Z) -3,7,11, 15-tetramethylhexadeca-10, 14-dien-1-yn-3-ol, (E/Z) -3,7,11, 15-tetramethylhexadeca-10, 14-dien-1-yn-3-ol, (6E,10E) -3,7,11, 15-tetramethylhexadeca-6, 10, 14-triene-1-yn-3-ol, (6E,10Z) -3,7,11, 15-tetramethylhexadeca-6, 10, 14-triene-1-yn-3-ol, (6Z,10E) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, (6Z,10Z) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, (6E,10E/Z) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, (6E/Z,10E) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, (6Z,10E/Z) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, (6E/Z,10Z) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol, and (6E/Z,10E/Z) -3,7,11, 15-tetramethylhexadec-6, 10, 14-trien-1-yn-3-ol.

Hydrogenation catalyst

The process uses a hydrogenation catalyst which is palladium on a support.

Such hydrogenation catalysts are known primarily to those skilled in the art. Palladium is a noble metal. In the present invention, palladium is supported on the carrier, i.e., palladium is attached and/or deposited on the carrier. The carrier is a solid material.

Preferably, the support is a carbon or inorganic support. Preferred inorganic supports are oxides or carbonates. Preferred oxides are oxides of silicon, aluminum or titanium or cerium. Particularly preferred are silica, alumina and titania and ceria.

Silica can be used as fumed silica (pyrogenic silica), or precipitated or ground silica as a carrier. Preferably, the silica used as support is fumed silica or precipitated silica. The most preferred silica is substantially pure SiO₂Of (4) silicon dioxide. Changeable pipeIn other words, it is preferred that the silica support consists of more than 95 wt%, more preferably more than 98 wt%, even more preferably more than 99 wt% of SiO₂And (4) forming.

Calcium carbonate is the preferred carbonate. The preferred calcium carbonate is precipitated calcium carbonate.

The support used may be a mixed oxide.

In addition, the supported palladium catalyst may be doped with other metals, such as lead. One well-known catalyst of this type is the "Lindlar catalyst", which is palladium on calcium carbonate (with lead) doped with lead. Such lindlar catalysts are commercially available, for example, from Sigma-Aldrich, Evonik, Johnson-Matthey or Hindusan Platinum.

More preferred hydrogenation catalysts are palladium on carbon (Palladium on carbon), palladium on silica (Palladium on silica) and palladium on alumina (Palladium on alumina) and palladium on carbonate (Palladium on carbonate); even more preferred is palladium on calcium carbonate (palladium on calcium carbonate), most preferred is palladium on calcium carbonate doped with lead.

The amount of palladium in the hydrogenation catalyst is preferably in the range of 0.5 to 20 wt. -%, more preferably in the range of 2 to 5 wt. -%, most preferably in the range of about 5 wt. -%, based on the total weight of the hydrogenation catalyst.

In one embodiment, the hydrogenation catalyst is used in the form of a colloidal suspension.

Very suitable hydrogenation catalysts are disclosed in WO 2009/096783A 1 or in Peter T.Witte et al, Top Cat (2012)55:505-^TMA commercial catalyst.

In another preferred embodiment, the hydrogenation catalyst does not comprise any organic quaternary ammonium containing compounds.

Additive agent

The process is carried out in the presence of an additive which is an organophosphorus compound carrying a phosphine group or a phosphine oxide group.

In case the additive carries a phosphine oxide group, it is preferred that the additive has one or two, more preferably one phosphine oxide group.

Particularly preferred as additives, which are organophosphorus compounds with phosphine oxides, are diphenylphosphine oxides.

In case the additive carries a phosphine group, the additive has 2 or more, preferably 2 to 4, more preferably 2 to 3 phosphine groups.

In a preferred embodiment, the additive has more than one, preferably two, phosphine groups of the formula (III)

Wherein R is an alkyl group or a cycloalkyl group or an aryl group, in particular a phenyl or tolyl group, and wherein the dotted line represents the bond joining the substituent of formula (III) to the remainder of the additive.

Alkyl is preferably C_1-6An alkyl group. Cycloalkyl is preferably C_5-8A cycloalkyl group.

In a preferred embodiment, the additive is selected from the group consisting of: 1, 2-bis (diphenylphosphino) ethane, 1, 3-bis (diphenylphosphino) propane, 1, 4-bis (diphenylphosphino) butane, 1, 3-bis (diphenylphosphino) -2- (diphenylphosphino) methyl-2-methylpropane, 2 '-bis (diphenylphosphino) -1,1' -binaphthyl, and bis (2-diphenylphosphinoethyl) phenylphosphine, preferably selected from the group consisting of: 1, 2-bis (diphenylphosphino) ethane and 1, 3-bis (diphenylphosphino) propane.

The additives may be added to the alkynol as such, either as a pre-mixture or as a pre-solution before the start of the hydrogenation reaction, or during the hydrogenation process. In the case of a pre-solution or pre-mixture, the additive is dissolved or dispersed in a small amount of organic solvent or preferably the alkynol.

It is preferred that the weight ratio of additive to catalyst is in the range of from 0.01:1 to 100:1, preferably from 0.1:1 to 10:1, more preferably from 0.2:1 to 3: 1.

The amount of hydrogenation catalyst (i.e. the sum of palladium and support) is preferably in the range of 0.0001 to 10 wt. -%, more preferably in the range of 0.001 to 1 wt. -%, most preferably in the range of 0.01 to 0.1 wt. -%, based on the weight of the alkynol.

The amount of palladium is preferably from 1 to 10 wt%, preferably from 3 to 7 wt%, based on the weight of the hydrogenation catalyst.

The hydrogenation reaction is preferably carried out at a temperature in the range of 10 ℃ to 150 ℃, more preferably at a temperature in the range of 20 ℃ to 100 ℃, most preferably at a temperature in the range of 40 ℃ to 90 ℃.

The hydrogenation reaction is preferably carried out at a hydrogen pressure in the range of 1bara (absolute bar) to 25bara hydrogen, more preferably in the range of 2bara to 10bara hydrogen, even more preferably in the range of 2bara to 6bara hydrogen, even more preferably in the range of 2.5bara to 4bara hydrogen, most preferably in the range of 2.5bara to 3bara hydrogen.

The hydrogenation reaction may be carried out without a solvent or in the presence of an organic solvent. The organic solvent is preferably selected from the group consisting of: hydrocarbons, halogenated hydrocarbons, alcohols, ethers, esters, carbonates, amides, nitriles, and ketones, and mixtures thereof. More preferably C_4-10Aliphatic hydrocarbons, C_6-10Aromatic hydrocarbons, substituted by one or more C_1-4Straight chain alkyl or C_3-4Branched alkyl or halogen substituted C_6-10Aromatic hydrocarbons, C_1-4Straight-chain alcohols or C_3-4Branched alcohols, acyclic and cyclic C_4-10Ether, C_3-10Esters, C_3-10Ketones and mixtures thereof. Particularly preferred organic solvents are selected from the group consisting of: hexane, heptane, toluene, methanol, ethanol, n-propanol, 2-propanol, n-butanol, t-butanol, tetrahydrofuran, 2-methyl-tetrahydrofuran, dioxane, ethyl acetate, isopropyl acetate, ethylene carbonate, propylene carbonate, acetone, and mixtures thereof. The most preferred solvent is heptane.

Preferably, however, the hydrogenation is carried out in the absence of any organic solvent.

In a preferred embodiment, the hydrogenation is carried out in the absence of any organic quaternary ammonium compound.

In a very preferred embodiment, the hydrogenation is carried out in the absence of any organic solvent and any organic quaternary ammonium compound.

The above process selectively produces the corresponding enol. The alkenols have the same chemical structure as the alkynols, except that the carbon-carbon triple bond in the alkenols is a carbon-carbon double bond.

In other words, when preferred, the alkynols of the formula (I)

Is hydrogenated, the enol formed by selective hydrogenation being of formula (II)

With the proviso that R¹Have the same meaning in the formulae (I) and (II), and R²Have the same meaning in the formulae (I) and (II).

It has been found that the above-described process for the selective hydrogenation of alkynols to alkenols provides both very high selectivity and very low over-hydrogenation at very high conversion.

In another aspect, the present invention relates to a composition comprising

-Compounds of formula (I)

Wherein

R¹Represents H or a methyl or ethyl group, preferably a methyl or ethyl group;and is

R²Represents a saturated or unsaturated, linear or branched or cyclic hydrocarbon radical having 1 to 46C atoms, said radical optionally comprising at least one chemical function, in particular at least one hydroxyl radical;

or

R¹And R²Together represent an alkylene group forming a 5-to 7-membered ring;

-a hydrogenation catalyst, the hydrogenation catalyst being palladium supported on a carrier; and

-at least one additive which is an organophosphorus compound bearing a phosphine group or a phosphine oxide group, characterized in that in the case of an additive bearing a phosphine group, said additive bears two or more phosphine groups.

The compounds of formula (I), the hydrogenation catalysts and the additives have been disclosed and discussed in great detail above.

Said composition is also very suitable for being hydrogenated by molecular hydrogen, as previously disclosed, and produces enols of formula (II) with very high selectivity

Examples

The invention is further illustrated by the following experiments.

List of additives used in the examples:

selective hydrogenation series 1:

hydrogenation of methylbut-3-yn-2-ol to methylbut-3-en-2-ol

The hydrogenation catalyst (80mg, palladium-lead on calcium carbonate containing 5 wt% palladium) was placed in a 500ml pressure reactor. The corresponding additive in the amounts given in Table 1 and a total of 270g 2-methylbut-3-yn-2-ol were added to the reactor. The vessel was sealed and purged 3 times with nitrogen (pressurized to 6bara and released). The reactor was heated to 70 ℃ and purged 3 times with hydrogen (pressurized to 4bara and released). The reactor was pressurized to 2.5bara and the mixture was stirred. The mixture was sampled several times near the end of the reaction to determine when the conversion reached > 99.9%. Samples were analyzed by GC (area%) to determine selectivity.

TABLE 1 hydrogenation of methylbut-3-yn-2-ol.

¹Determination by GC in area%

²And (3) selectivity: amount of enol in the final reaction mixture

^*Perhydrogenation ═ perhydrogenation: methylbutan-2-ol as determined by GC in area%

Selective hydrogenation series 2:

hydrogenation of 3, 7-dimethyloct-6-en-1-yn-3-ol to 3, 7-dimethyloct-1, 6-dien-3-ol

The hydrogenation catalyst (56mg, palladium-lead on calcium carbonate containing 5 wt% palladium) was placed in a 500ml pressure reactor. The corresponding additives in the amounts given in Table 2 and a total of 250g3, 7-dimethyloct-6-en-1-yn-3-ol were added to the reactor. The vessel was sealed and purged 3 times with nitrogen (pressurized to 6bara and released). The reactor was heated to 55 ℃ and purged 3 times with hydrogen (pressurized to 4bara and released). The reactor was pressurized to 3bara and the mixture was stirred. The mixture was sampled several times near the end of the reaction to determine when the conversion reached > 99.9%. Samples were analyzed by GC (area%) to determine selectivity.

TABLE 23 hydrogenation of 7-dimethyloct-6-en-1-yn-3-ol.

¹Determination by GC in area%

²And (3) selectivity: amount of enol in the final reaction mixture

^*Perhydrogenation ═ perhydrogenation: determination of 3, 7-Dimethyloct-6-ene by GC in area%

-3-ol and 3, 7-dimethyloct-1-en-3-ol and 3, 7-dimethyloctan-3-ol

Selective hydrogenation series 3:

hydrogenation of 3,7,11, 15-tetramethylhexadec-1-yn-3-ol to 3,7,11, 15-tetramethylhexadec-1-ene- 3-alcohols

The hydrogenation catalyst (50mg, palladium-lead on calcium carbonate, 5 wt% palladium) was placed in a 500ml pressure reactor.

The corresponding additives in the amounts given in Table 3 and a total of 260g of 3,7,11, 15-tetramethylhexadec-1-yn-3-ol were added to the reactor. The vessel was sealed and purged 3 times with nitrogen (pressurized to 6bara and released). The reactor was heated to 85 ℃ and purged 3 times with hydrogen (pressurized to 4bara and released). The reactor was pressurized to 3bara and the mixture was stirred. The mixture was sampled several times near the end of the reaction to determine when the conversion reached > 99.9%. Samples were analyzed by GC (area%) to determine selectivity.

TABLE 33 hydrogenation of 7,11, 15-tetramethylhexadec-1-yn-3-ol, 3, 7-dimethyloct-6-en-1-yn-3-ol.

¹Determination by GC in area%

²And (3) selectivity: amount of enol in the final reaction mixture

^*Perhydrogenation ═ perhydrogenation: 3,7,11, 15-tetramethylhexadec-3-ol was determined by GC in area%.