Process for the preparation of 3,7-dimethylnonan-1-ol

Abstract

The present invention is related to a novel and improved process for the preparation of 3,7-dimethylnonan-1-ol.

Claims

1. A two-step process for the production of a compound of formula (I): ##STR00009## wherein the process consists of: (i) subjecting in a first step a compound of formula (II): ##STR00010## to a rearrangement reaction to obtain a compound of formula (III); ##STR00011## and thereafter (ii) subjecting in a second step the compound of formula (III) to hydrogenation in the presence of a nickel/chromium catalyst with Fe/Cr promoter to obtain the compound of formula (I) with a conversion of greater than 99%.

2. The two-step process according to claim 1, which comprises using in step (i) a catalyst of formula (IV): ##STR00012## wherein R.sup.1, R.sup.2 and R.sup.3 are independently from each other a linear or branched C.sub.1-C.sub.10-alkyl moiety or Si(R.sup.4).sub.3, and wherein each R.sup.4 is independently from each other a linear or branched C.sub.1-C.sub.10-alkyl moiety or substituted or unsubstituted phenyl.

3. The two-step process according to claim 1, which comprises using in step (i) a catalyst of formula (IV′): ##STR00013##

4. The two-step process according to claim 1, wherein the reaction of step (i) is carried out in at least one hydrocarbon solvent.

5. The two-step process according to claim 1, wherein the reaction of step (i) is carried out at a temperature of 50° C. to 200° C.

6. The two-step process according to claim 1, wherein the reaction of step (i) is carried out at normal pressure.

7. The two-step process according to claim 1, wherein step (ii) is carried out using pure H.sub.2-gas or a gas mixture which comprises H.sub.2.

8. The two-step process according to claim 1, wherein the hydrogenation of step (ii) is carried out at a pressure of 1.5-40 bar.

9. The two-step process according to claim 1, wherein the catalyst of step (ii) is a sponge nickel/chromium catalyst with Fe/Cr promoter.

10. The two-step process according to claim 1, wherein step (ii) is carried out in the absence of solvents.

11. The two-step process according to claim 1, wherein step (ii) is carried out in a solvent or a solvent mixture.

12. The two-step process according to claim 11, wherein the solvent is at least one selected from the group consisting of linear, branched or cyclic aliphatic hydrocarbons having 5-10 carbon atoms; aromatic hydrocarbons having 5-10 carbon atoms; esters; ethers; and alcohols.

13. The two-step process according to claim 12, wherein the solvent is at least one selected from the group consisting tetrahydrofuran (THF), n-hexane, n-heptane, 2-propanol, toluene and ethyl acetate.

14. The two-step process according to claim 8, wherein the hydrogenation of step (ii) is carried out at a pressure of 2-30 bar.

Description

EXAMPLES

Example 1—Preparation of 3,7-dimethylnona-2,6-dienal

(1) Ethyl-dehydrolinalool (3,7-dimethylnon-6-en-1-yn-3-ol, 27.4 g), stearic acid (465 mg), triphenylsilanol (5.87 g), tris-(triphenylsiloxy)-vanadiumoxide (2.95 g) and paraffin oil (163 g) were placed in a 350 ml four-necked flask. With the oil bath (Temperature 145° C.), the mixture was heated up under a slight argon overflow. An internal temperature of ˜138° C. was reached and the reaction mixture was stirred for a total of five hours. The reaction mixture was cooled down to a TI of ˜70° C. and distillation equipment was installed on the reaction flask. The product including unconverted ethyl-dehydrolinalool was distilled at a head temperature of up to 59° C. at 0.05-0.08 mbar. After approximately 1 h, the distillation was completed. The product was analyzed by GC with internal standard. (hexadecane)

(2) A clear slightly yellow oil (28.1 g) was isolated.

(3) GC analysis showed 0.96 w % unconverted ethyl-dehydrolinalool and 88.9 w % of four ethyl-citral isomers. Conversion: 99.0%, yield 92.2%.

Example 2a—Preparation of 3,7-dimethylnonan-1-ol

(4) The nickel catalyst (Johnson Matthey A4000, 250 mg) was added to a 100 ml reactor fitted with a gas entrainment stirrer. The catalyst was washed with 3× anhydrous ethanol and 2× heptane. 3,7-Dimethylnona-2,6-dienal (5.0 g) and the heptane (40 g) were added and the autoclave was sealed. The reactor was purged 5 times with nitrogen and 5 times with hydrogen. The reactor was heated to 80° C. and then pressurized to 20 bar with hydrogen. The reaction mixture was stirred for 20 hours. At the end of the reaction the reactor was cooled to room temperature, the pressure released and purged once with nitrogen. The reaction mixture was filtered and analysed by GC for conversion and selectivity. Yield: 5.0 g of a colourless oil conversion>99%, product 98.5%.

(5) 1H NMR: 3.77-3.61 (2H, m), 1.70-1.48 (2H, m), 1.47-1.00, 11H, m) and 0.94-0.81 (9h, m)

(6) Mass spectrum: 154 (M-H.sub.2O), 139, 125, 97, 83, 70, 55, 41, 29

(7) IR (cm.sup.−1): 3324 (br), 2957, 2925, 2872, 1461, 1377

Example 2b—Preparation of 3,7-dimethylnonan-1-ol

(8) In a similar way to example 2a, 3,7-dimethylnona-2,6-dienal (5.0 g), ethyl acetate (40 g) and the nickel catalyst (Johnson Matthey A4000, 250 mg) were reacted at 80° C., 20 bar hydrogen for 20 hours. Yield: 5.00 g of a colourless oil, conversion>99%, product 98.9%.

Example 3—Preparation of 3,7-dimethylnonan-1-ol, solvent-free

(9) The nickel catalyst (1 g) was added to a 100 ml reactor fitted with a gas entrainment stirrer. The catalyst was washed with anhydrous ethanol and ethyl acetate. E-citral (3,7-dimethylnona-2,6-dienal, 40 g) was added and the reactor was sealed. The reactor was purged 5 times with nitrogen and 5 times with hydrogen. The reactor was heated to 80° C. and then pressurized to 20 bar with hydrogen. The reaction mixture was stirred for 30 hours. At the end of the reaction the reactor was cooled to room temperature, the pressure released and purged once with nitrogen. The reaction mixture was filtered and analysed by GC for conversion and selectivity. Yield: 39.29 g of a colourless oil, conversion>99%, product 98.6%.