The present invention relates to the manufacturing of gamma, delta-unsaturated ketones.
Gamma, delta-unsaturated ketones of the formula (I) are an important class of industrial chemicals and are central products in the synthesis of vitamins and aroma ingredients. particularly important. One of the possible synthetic routes uses tertiary vinyl carbinols as starting products.
G. Saucy et al. disclose in Helv. Chim. Acta 1967, 50, 2091-2095 and Helv. Chim. Acta 1967, 50, 2095-2100 that phosphoric acid or sulfuric acid or p-toluene sulfonic acid can be used as catalyst for the reaction between tertiary vinyl carbinols and isopropenyl ethers.
C. Wang et al. disclose in Green Chemistry 2009, 11, 6, 843-847 a Saucy-Marbet reaction of tertiary propargyl alcohols and unsaturated ethers in the presence of ammonium ionic liquids. This reaction leads to allene ketones which are not gamma-, delta-unsaturated ketones.
However, the use of strong acid in is disadvantageous as these chemicals are hazardous in the handling and use special protection methods and require specific and corrosion-resistant materials for the equipment used in the manufacturing process DE 196 49 564 discloses that diverse organophosphorous compounds as catalysts.
WO 2010/046199 A2 discloses inorganic ammonium (NH4+) salts as potential catalysts. However, inorganic ammonium salts have typically a disadvantageous solubility and it been shown that the inorganic ammonium salts show lower yields and selectivities particularly when used at concentrations of less than 1 mol-%.
Therefore, the problem to be solved by the present invention is to offer a process with a high yield and selectivity using a catalyst having a suitable solubility under the absence of strong acids and corrosive conditions.
Surprisingly, it has been found that a process according to the claim 1 and the reaction mixture according to claim 17 are able to solve this problem. It has been found that organic tertiary and quaternary ammonium salts are particularly well suited as catalyst for said reaction. It has been found that particularly well suited organic tertiary and quaternary ammonium salts catalysts the ones which have anions which comprise a phosphor atom been bound to at least one oxygen atom.
Further aspects of the invention are subject of further independent claims. Particularly preferred embodiments are subject of dependent claims.
In a first aspect the present invention relates to a process for the manufacture of gamma, delta-unsaturated ketones of the formula (I)
For sake of clarity, some terms used in the present document are defined as follows:
In the present document, a “Cx-y-alkyl” group is an alkyl group comprising x to y carbon atoms, i.e., for example, a C1-3-alkyl group is an alkyl group comprising 1 to 3 carbon atoms. The alkyl group can be linear or branched. For example —CH(CH3)-CH2-CH3 is considered as a C4-alkyl group.
In case identical labels for symbols or groups are present in several formulae, in the present document, the definition of said group or symbol made in the context of one specific formula applies also to other formulae which comprises the same said label.
The term “independently from each other” in this document means, in the context of substituents, moieties, or groups, that identically designated substituents, moieties, or groups can occur simultaneously with a different meaning in the same molecule.
The term “organic” in the term “organic tertiary or quaternary ammonium salt” in this document relates to the ammonium cation. Therefore, “organic tertiary or quaternary ammonium salt” in the present document means any salt which comprises an organic tertiary or quaternary ammonium entity. In contrast to this any ammonium salt which comprises NH4+ is regarded as inorganic ammonium salt. Hence, e.g. tetrabutylammonium chloride or triethylammonium bromide or tetrabutylammonium acetate are regarded as organic tertiary or quaternary ammonium salts, whereas e.g. ammonium sulphate ((NH4)2SO4) or ammonium acetate (CH3COONH4) are not regarded as organic tertiary or quaternary ammonium salts.
In the present document, any dotted line in formulae represents the bond by which a substituent is bound to the rest of a molecule.
In the present document, any wavy line represents independently from each other a carbon-carbon bond which when linked to the carbon-carbon double bond is either in the Z or in the E-configuration.
Compound of the formula (II) is reacted either with a compound of the formula (IIIa) or of the formula (IIIb) in the presence of a catalyst (=“Cat”) being an organic tertiary or quaternary ammonium salt.
The compounds of the formula (II) are substances known to the person skilled in the art.
R1 represents a methyl or ethyl group, preferably a methyl group.
R2 represents a saturated or unsaturated linear or branched or cyclic hydrocarbyl group with 1 to 46 C atoms, preferably a methyl group.
In a preferred embodiment, R2 represents a group which is selected from the group consisting of the formula (R2-I), (R2-II), (R2-III) and (R2-IV)
The dotted line represents the bond by which the substituent of the formula (R2-1), (R2-II), (R2-III) or (R2-IV) is bound to the rest of the compound of the formula (I) or formula (II). Any double bond having dotted line represents independently from each other either a single carbon-carbon bond or a double carbon-carbon bond. Any wavy line represents independently from each other a carbon-carbon bond which when linked to the carbon-carbon double bond is either in the Z or in the E-configuration.
In the above formulae n represents 1, 2, 3 or 4, particularly 1 or 2.
In one of the preferred embodiments, R2 represents either a group of the formula (R2-I) or of the formula (R2-II).
In another preferred embodiment, R2 represents either a group of the formula (R2-III) or of the formula (R2-IV).
It is particular preferred that the compound of the formula (II) is selected from the group consisting of 2-methyl-3-buten-2-ol (“MBE”), 3-methyl-4-penten-3-ol (“EBE”), 3,7-dimethyl-1,6-octadien-3-ol (=linalool, “LL”), 3,7-dimethyl-1-octen-3-ol (“DMOE”) and 3,7,11-trimethyl-1,6-dodecadien-3-ol (nerolidol, “NL”), particularly (6E)-3,7,11-trimethyl-1,6-dodecadien-3-ol (=E-nerolidol, “E-NL”).
It is even more preferred that the compound of the formula (II) is 2-methyl-3-buten-2-ol (“MBE”) or 3,7-dimethyl-1,6-octadien-3-ol (=linalool, “LL”).
The compounds of the formula (IIIa) are substances known to the person skilled in the art.
In formula (IIIa) R3 represents a methyl or an ethyl group and R4 represents H or methyl or an ethyl group and R5 represents R5 represents a linear or branched C1-10-alkyl group, particularly a methyl or an ethyl group.
Preferably, the group R3 represents a methyl group.
Preferably, the group R4 represents H.
Preferably, the group R5 represents a methyl group.
The compound of the formula (IIIa) is most preferably either isopropenyl methyl ether (“IPM”) or isopropenyl ethyl ether (“IPE”), particularly isopropenyl methyl ether (“IPM”).
Due to the synthesis of compound of the formula (IIIa), very often also mixtures of compounds of the formula (IIIa) are used for the reaction with compound of the formula (II). For example, for butenyl methyl ether, often a mixture of 2-methoxybut-1-ene and (E)-2-methoxybut-2-ene and (Z)-2-methoxybut-2-ene being prepared from methanol and methyl ethyl ketone, is used.
The compounds of the formula (IIIb) are substances known to the person skilled in the art.
In formula (IIIb) R3 represents a methyl or an ethyl group and R4 represents H or methyl or an ethyl group.
R5′ and R5″ represent in one embodiment each either a linear or branched C1-10-alkyl group, particularly a methyl or an ethyl group. In another embodiment, R5′ and R5″ form together a linear or branched C1-10-alkylene group, particularly an ethylene or propylene group.
Preferably, the group R3 represents a methyl group.
Preferably, the group R4 represents H.
In one preferred embodiment, R5′═R5″ and particularly R5′═R5′=methyl or ethyl, more preferably R5′═R5′═CH3.
In another preferred embodiment, R5′ and R5″ form together an ethylene (CH2CH2) or propylene (CH2CH2CH2 or CH(CH3)CH2) group.
The compound of the formula (IIIb) is most preferably either 2,2-dimethoxypropane or 2,2-diethoxypropane or 2,2-dimethyl-1,3-dioxolane or 2,2,4-tri-methyl-1,3-dioxolane or 2,2-dimethyl-1,3-dioxane.
The compound of the formula (IIIb) is most preferably either 2,2-dimethoxypropane or 2,2-diethoxypropane, particularly 2,2-dimethoxypropane.
The use of the compound of formula (IIIa) is preferred over the compound of the formula (IIIb).
The reaction of a compound of the formula (II) with a compound of the formula (IIIa) or (IIIb) is performed in the presence of an organic tertiary or quaternary ammonium salt as catalyst.
In one of the preferred embodiments, the catalyst is an organic tertiary ammonium salt and has a cation of the formula (IV)
It is preferred that R20, R21 and/or R22 represent linear C1-18-alkyl groups.
It is more preferred that R20, R21 and/or R22 represent either a methyl or an ethyl group.
It is further preferred that R20═R21═R22.
It is particularly preferred that R20═R21═R22═methyl or ethyl.
In one of the other preferred embodiments, the catalyst is an organic tertiary ammonium salt and has a cation of the formula (V)
It is preferred that R30═R31═R32═R33, preferably R30═R31═R32═R33═H.
It is further preferred that one of the groups of R30, R31, R32, R33 and R34 is a methyl group.
It is also preferred that R34 represents a methyl group or H, preferably H.
Most preferred as tertiary ammonium compound of the formula (V) is pyridinium or α-picolinium or β-picolinium or γ-picolinium, preferably pyridinium.
In one of the other preferred embodiments, the catalyst is an organic quaternary ammonium salt and has a cation of the formula (VI)
It is preferred that R20 R21, R22 and/or R23 represent linear C1-18-alkyl groups.
It is more preferred that R20, R21 and/or R22 represent either a methyl or an ethyl group.
It is further preferred that R20═R21═R22═R23.
It is particularly preferred that R20═R21═R22═R23═ethyl or butyl, preferably butyl.
The organic tertiary or quaternary ammonium salts can be easily formed from their respective tertiary amine by protonation respectively by alkylation.
It has been found that the catalysts organic tertiary or quaternary ammonium salts show particularly high yields and selectivities in the desired product of the formula (I) when the anion of the organic tertiary or quaternary ammonium salt comprises a phosphor atom which is bound to at least one oxygen atom, preferably selected from the group consisting of PO43−, HPO42−, H2PO4−, P2O73−, HP2O72− and H3P2O7−.
It has been found that the reaction is preferably performed when the molar ratio of the compound of the formula (II) to the compound of the formula (IIIa) or (IIIb) is ranging from 1:15 to 1:1.
In case of using the compound of the formula (IIIa), said ratio is more preferred in the range from 1:5 to 1:2, more preferably ranging from 1:3.5 to 1:2, most preferably ranging from 1:3 to 1:2, particularly ranging from 1:2.5 to 1:2.
In case of use of the compound of the formula (IIIb) said ratio is more preferred in the range from 1:10 to 1:2, more preferably ranging from 1:8 to 1:3, most preferably ranging from 1:8 to 1:5.
Furthermore, it is preferred that the amount of the organic tertiary or quaternary ammonium salt is ranging from 0.01-0.3 mol-%, preferably ranging from 0.02-0.1 mol-%, more preferably ranging from 0.02-0.07 mol-%, based on the amount of the compound of the formula (II).
It has been, surprisingly, found that even when organic tertiary or quaternary ammonium salt catalysts are used below 1 mol-%, particularly below 0.7 mol-%, the ratio of the compound of the formula (II) to the compound of the formula (IIIa) or (IIIb) still can be used between 1:3 to 1:2, particularly 1:2.5 to 1:2 which significant lowering of selectivity and/or yield in the compound of the formula (I).
The reaction is preferably carried out at a temperature ranging from 100 to 170° C., more preferably at a temperature ranging from 110 to 160° C., most preferably at a temperature ranging from 120 to 150° C.
The reaction is preferably carried out at a pressure ranging from 5 to 15 bar, more preferably at a pressure ranging from 8 to 12 bar.
The reaction can be carried out without solvent or in the presence of an organic solvent. Preferably the reaction is carried out without solvent.
Even if the reaction is carried out in the absence of an organic solvent, the starting materials, the compounds of the formula (II) and (IIIa) or (IIIb), as well as said an organic tertiary or quaternary ammonium salt may still be provided in an organic solvent. Thus, there may be an amount of organic solvent up to 10 weight-%, preferably an amount of organic solvent up to 5 weight-%, more preferably an amount of organic solvent up to 3 weight-%, based on the total weight of the reaction mixture.
If the reaction is carried out in an organic solvent, polar aprotic organic solvents such as aliphatic ketones as e.g. acetone are preferred.
It has been found that the above reaction provides the compound of the formula (I) in high conversion, yield and selectivity.
It has been found that particularly the compound of the formula (I) being selected from the group consisting of 6-methyl-5-hepten-2-one, 6-methyl-5-octen-2-one, 6,10-dimethyl-5,9-undecadien-2-one, 6,10-dimethyl-5-undecen-2-one, 6,10,14-trimethylpentadeca-5,9-dien-2-one, 6,10,14-trimethylpentadeca-5,13-dien-2-one and 6,10,14-trimethyl-5,9,13-pentadeca-trien-2-one, preferably 6-methyl-5-hepten-2-one or 6,10-dimethyl-5,9-undecadien-2-one can be preferably produced.
The reaction mixture itself, with or without an organic solvent, is also an object of the present invention.
Thus, the present invention relates in a further aspect to a reaction mixture comprising a compound of the formula (II),
The compound of the formula (II) and of the formula (IIIa) or (IIIb) as well as the catalyst being an organic tertiary or quaternary ammonium salt have been discussed to a great extend already above.
The present invention is further illustrated by the following non-limiting experiments.
2-methyl-3-buten-2-ol (“MBE”) was mixed with 2.1 equivalents of isopropenyl methyl ether (“IPM”) in the presence of the respective catalyst, and stirred at a temperature of 150° C. during reaction time as given in table 1. The respective product, i.e. 6-methyl-5-hepten-2-one, was obtained in the yield and selectivity as indicated in table 1 (see
1(Et3NH) = triethylammonium; (pyH) = pyridinium; (Bu4N) = tetrabutylammonium
2tert. = tertiary ammonium salt; quat. = quaternary ammonium salt
3amount of catalyst relative to 2-methyl-3-buten-2-ol
3,7-dimethylocta-1,6-dien-3-ol (“LL”) was mixed with the number of equivalents given in table 2 of isopropenyl methyl ether (“IPM”) in the presence of respective catalyst in the amount as given in table 2, and stirred at a temperature of 150° during 16 hours. The respective product, i.e. 6,10-dimethyl undeca-5,9-dien-2-one, was obtained in the yield and selectivity as indicated in table 2 (see
1(pyH) = pyridinium; (Et3NH) = triethylammonium
2tert. = tertiary ammonium salt; quat. = quaternary ammonium salt; inorg. = inorganic ammonium salt
3amount of IPM relative to 3,7-dimethyl-1,6-octadien-3-ol
4amount of catalyst relative to 3,7-dimethyl-1,6-octadien-3-ol
Number | Date | Country | Kind |
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21155687.3 | Feb 2021 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2022/052850 | 2/7/2022 | WO |