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US3971830A
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US
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Process for the semihydrogenation of citral to citronellal
Assignee: Syensqo USA LLC
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Filing: 1975-03-24
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Granted: 1976-07-27
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Expires: 1995-03-24
Abstract
Abstract A process is provided for the semihydrogenation of the olefinic group in conjugated position to a carbonyl group in citral, a dienic aldehyde. The dienic aldehyde is hydrogenated with hydrogen in the presence of a palladium catalyst, a lower aliphatic alcohol, and an aqueous alkaline solution. The process is of particular application to the semihydrogenation of citral to citronellal.
Inventors
- 👤 Peter S. Gradeff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:41
CPC Classifications
C; C07; C07C; C07C45/00; C07C45/61; C07C45/62
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
222 words
In the process for the selective hydrogenation of the olefinic group in a conjugated position to the carbonyl group in dienic aldehydes having the formula: ##SPC3## wherein R 1 , R 2 , R 3 , R 4 , and R 6 are selected from the group consisting of hydrogen and lower alkyl groups having from one to about five carbon atoms and R 5 is a lower alkyl group having from one to about five carbon atoms, which comprises hydrogenating the dienic aldehyde in the presence of a palladium metal catalyst, alkali, and water, the improvement which comprises carrying out the hydrogenation at a temperature within the range from about 5° to about 200°C, and at a pressure within the range from atmospheric pressure to about 500 psi, in the presence of a palladium metal catalyst in an amount within the range from about 0.001 g to about 1 g of palladium metal per 100 g of dienic aldehyde with a lower alkanol having from one to about five carbon atoms in a liquid aqueous alkaline reaction medium, the alkali being in an amount within the range from about 0.05 to about 5% by weight of the dienic aldehyde, and the alkanol being in an amount within the range from about 10 to about 200% by weight of the dienic aldehyde.
Claim 2
Dependent Claim
222 words
In the process for the selective hydrogenation of the olefinic group in a conjugated position to the carbonyl group in dienic aldehydes having the formula: ##SPC3## wherein R 1 , R 2 , R 3 , R 4 , and R 6 are selected from the group consisting of hydrogen and lower alkyl groups having from one to about five carbon atoms and R 5 is a lower alkyl group having from one to about five carbon atoms, which comprises hydrogenating the dienic aldehyde in the presence of a palladium metal catalyst, alkali, and water, the improvement which comprises carrying out the hydrogenation at a temperature within the range from about 5° to about 200°C, and at a pressure within the range from atmospheric pressure to about 500 psi, in the presence of a palladium metal catalyst in an amount within the range from about 0.001 g to about 1 g of palladium metal per 100 g of dienic aldehyde with a lower alkanol having from one to about five carbon atoms in a liquid aqueous alkaline reaction medium, the alkali being in an amount within the range from about 0.05 to about 5% by weight of the dienic aldehyde, and the alkanol being in an amount within the range from about 10 to about 200% by weight of the dienic aldehyde.
Claim 3
Dependent Claim
17 words
The process of claim 1 in which the aldehyde is citral, 3,7-dimethyl-2,6-octadiene-al, which is converted to citronellal.
Claim 4
Dependent Claim
24 words
The process of claim 1 in which the aldehyde is selected from the group consisting of: 3-ethyl-7-methyl-2,6-octadiene-al 3-isobutyl-7-methyl-2,6-octadiene-al 3-amyl-7-methyl-2,6-octadiene-al 2,3,4,5,7-pentamethyl-2,6-octadiene-al 3,5,7-trimethyl-2,6-octadiene-al 3,4,4,5,5,7-hexamethyl-2,6-octadiene-al 2,4,7-trimethyl-3-isopropyl-2,6-octadiene-al 2,3,7-trimethyl-2,6-octadiene-al
Claim 5
Dependent Claim
28 words
The process of claim 1 in which the alcohol is a water-soluble alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, 2-butanol, tert-butanol, and isobutanol.
Claim 6
Dependent Claim
26 words
The process of claim 1 in which the amount of alcohol is at least about 10 up to about 100% by weight of the dienic aldehyde.
Claim 7
Dependent Claim
26 words
The process of claim 1 in which the amount of alkali is at least about 0.1 up to about 5% by weight of the dienic aldehyde.
Claim 8
Dependent Claim
24 words
The process of claim 6 in which the alkali is selected from the group consisting of alkali metal and the alkaline earth metal hydroxides.
Claim 9
Dependent Claim
13 words
The process of claim 6 in which the alkali is an organic amine.
Claim 10
Dependent Claim
31 words
The process of claim 1 in which the alkaline alcoholic reaction medium comprises water in an amount within the range from about 0.1 to about 200% by weight of the alcohol.
Claim 11
Dependent Claim
15 words
The process of claim 1 in which the palladium is supported on an inert carrier.
Claim 12
Dependent Claim
31 words
The process of claim 1 in which the amount of palladium is within the range from about 0.005 g to about 0.1 g palladium metal per 100 g of dienic aldehyde.
Claim 13
Dependent Claim
24 words
The process of claim 1 in which the hydrogen is at a pressure within the range from atmospheric pressure up to about 30 psi.
Claim 14
Dependent Claim
51 words
The process of claim 1 in which the reaction mixture is then agitated under a hydrogen atmosphere until absorption of hydrogen ceases, and the hydrogenation of the olefinic group in a conjugated position to the carbonyl group has been substantially completed, the catalyst is removed, and the semihydrogenated reaction product recovered.
Claim 15
Dependent Claim
24 words
The process of claim 1 in which the reaction is carried out at a temperature within the range from about 5° and about 100°C.
References Cited (Backward Citations)
US1210681A
Cited
US3280192A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-27 | 1980-01-26 | 1980-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-27 | 1984-01-26 | 1984-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-27 | 1988-01-26 | 1988-07-27 | $7700.00 | Window Closed / Lapsed |