PROCESS FOR THE PREPARATION OF 1-(2,6,6-TRIMETHYLCYCLOHEXYL)-ALKAN-3-OLS

Abstract

The present invention relates to a process for the preparation of 1-(2,6,6-trimethylcyclohexylyalkan-3-ols, in particular 1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol. The invention further relates to 5-alkoxy-1-(2,6,6-trimethylcyclohexenyl)-1-alken-3-ones and the use of these as a fragrance or as flavor, to a fragrance containing composition and/or a fragranced product containing 5-alkoxy-1-(2,6,6-trimethylcyclohexenyl)-1-alken-3-ones and to a method for imparting or modifying a scent or a flavor to a composition by including said alkoxyalkenones into such composition.

Claims

1. A process for preparing a compound of formula (I), ##STR00004## where R.sup.1 is selected from C.sub.1-C.sub.4-alkyl, the process comprising: i) reacting a composition containing α-ionone, β-ionone or γ-ionone or mixtures thereof with an aldehyde R.sup.1—(C═O)H in the presence of a base and an alcohol R.sup.2—OH to yield a reaction product mixture comprising at least one compound of formula (I.a), where ##STR00005## R.sup.2 is C.sub.1-C.sub.6-alkyl, and the broken lines represent a single double bond that can be arranged in one of the three positions drawn, ii) treating the reaction product obtained in step i) with an acid to yield a ketone of formula (I.b) ##STR00006## and iii) hydrogenating the ketone I.b with hydrogen in the presence of a hydrogenation catalyst.

2. The process of claim 1, where the base used in step i) is selected from metal hydroxides.

3. The process of claim 1, where R.sup.1 is methyl.

4. The process of claim 1, where the alcohol R.sup.2—OH is selected from methanol, ethanol or isopropanol.

5. The process of claim 1, where the reacting step i) is performed at a temperature in a range of from −10 to 50° C.

6. The process of claim 1, where the reaction product mixture of the step i) is directly applied in step ii).

7. The process of claim 1, where the hydrogenation catalyst comprises at least one metal selected from the group consisting of nickel, rhodium and palladium.

8. The process of claim 1, further comprising distilling a reaction mixture obtained in the step iii).

9. The process of claim 1, where the steps i) and ii) or the step iii), or all steps i) to iii), are performed in a continuous manner.

10. A compound of formula (I.a), ##STR00007## where R.sup.1 is C.sub.1-C.sub.4-alkyl, R.sup.2 is C.sub.1-C.sub.6-alkyl and the broken lines represent a single double bond that can be arranged in one of the three positions drawn.

11. The compound according to claim 10, where R.sup.1 is methyl and R.sup.2 is C.sub.1-C.sub.3-alkyl.

12. The compound 5-methoxy-1-(2,6,6-trimethylhexen-1-yl)hex-1-en-3-one.

13. (canceled)

14. A fragrance or a flavor composition comprising a) at least one compound (I.a), as defined in claim 10, b) optionally at least one aroma chemical different from the compounds (I.a), and c) optionally at least one carrier, with the proviso that the composition comprises at least one of the components b) or c).

15. A product comprising at least one compound (I.a), as defined in claim 10, the product selected from the group consisting of laundry detergents, fabric detergents, cosmetic preparations, fragranced hygiene articles, foods, food supplements, fragrance dispensers, perfumes, pharmaceutical preparations and crop protection compositions.

16. A method of imparting or modifying a scent or a flavor to a composition, which method comprises incorporating at least one compound of the formula (I.a), as defined in claim 10, into a composition in such an amount that imparts or modifies the scent or flavor of the composition.

Description

EXAMPLES

I) Gas Chromatographic Analysis:

[0146] GC-System and Separation Method:

[0147] GC-system: Agilent 6890N

[0148] GC-Column: HP-5 (30 m (Length), 0.32 mm (ID), 0.20 μm (FD))

[0149] Temperature program: 60° C. to 250° C. in 6° C./min, 20 minutes at 250° C., injector temperature 250° C., detector temperature 280° C.

II) Production Examples

Example II.1

Reaction of Beta-Ionone With Acetaldehyde

[0150] To a mixture of 30.0 g beta-ionone (0.26 mol) and 17.4 g (22 mL) acetaldehyde (0,39 mol) a solution of 15 g KOH (0.26 mol) in 100 mL methanol was added, while keeping the temperature between 5 to 10° C. The reaction mixture was then stirred for 4 hours at 15° C. until 65% conversion of beta-ionone was achieved. The reaction solution was analyzed by GC showing the presence of 40% methoxy compound and 20% aldol product along with 35% unreacted beta-ionone. The reaction mixture was neutralized with diluted acid and extracted with ethyl acetate. The organic layer was dried and the solvent was distilled off to obtain 58 g of a crude reaction mixture. The crude reaction product was purified by column chromatography, whereupon 17 g unreacted beta-ionone was recovered and 14 g 5-hydroxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one (aldol product) and 16 g 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one (methoxy compound) was obtained. Both products were obtained in >95% purity (GC, area-% of the FID detector signal).

Example II.2

Elimination of Water in 5-,hydroxyl-(2,6,6-trimethylaclohexen-1-yl)hex-1-en-3one:

[0151] To the solution of 1 g of the hydroxy compound (aldol product) in TBME 0.3 mL of sulfuric acid were added and stirred for 4 hours. TLC showed complete conversion of starting material. The reaction mixture was washed with bicarbonate solution, crude yield=1 g. The crude was purified by flash chromatography to obtain 0.4 g desired product.

Elimination of Methanol in 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one;

[0152] A Mixture of 0.5 g of the methoxy compound in toluene and a catalytic quantity of para-toluenesulphonic acid (pTSA) (12 mg) were refluxed for 20 min. TLC showed the disappearance of the starting material. The reaction mixture was cooled to RT and washed with a saturated bicarbonate solution. On evaporation of solvent got 1 g crude product. Column chromatography gave 0.15 pure product.

III) Analytical Characterization

III.1) Analytical Characterization of 5-hydroxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one

[0153] The identity of 5-hydroxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one was determined using high resolution GC-MS and .sup.1H-.sup.13C-1D/2D-NMR.

[0154] .sup.1H-NMR-Analysis (300 MHz, CDCl.sub.3):

[0155] Delta=7.35 (d, 1H), 6,2 (d, 1H), 3.85 (m, 1H), 3.3 (s, 3H), 2.95 (dd, 1H), 2.7 (dd, 1H), 2.15 (m, 2H), 1.75 (s, 3H), 1.6 (m, 2H), 1.5 (m, 2H), 1.2 (d, 3H), 1.05 (s, 6H).

[0156] .sup.13C-NMR-Analysis (300 MHz, CDCl.sub.3):

[0157] Delt =198.89, 142.76, 136.32, 136.01, 130.92, 73.72, 56.31, 47.25, 39.72, 34.04, 33.57, 28.79, 28.74, 21.76, 19.55, 18.38.

III.2) Analytical Characterization of 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one

[0158] The identity of 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one was determined using high resolution GC-MS and .sup.1H-.sup.13C-1D/2D-NMR.

[0159] .sup.1H-NMR-Analysis (300 MHz, CDCl.sub.3):

[0160] Delta=7.35 (d, 1H), 6.2 (d, 1H), 3.3 (m, 1H), 2.0-2.9 (m, 12H), 2.1 (dd, 1H), 1.8 (s, 3H), 1.66 (m, 2H), 1.5 (m, 21-1), 1.2 (d, 3H), 1.05 (s, 6H).

[0161] .sup.13C-NMR-Analysis (300 MHz, CDCl.sub.3):

[0162] Delta=201.08, 143.28, 137.26, 135.90, 130.1, 64.12, 47.91, 39.73, 34.04, 33.66, 28.79, 28.76, 22.40, 21.76, 18.76.

IV) Scent Strip Tests

[0163] To evaluate the quality and intensity of the odor of 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one, scent strip tests were performed.

[0164] For this purpose strips of absorbent paper were dipped into solution containing 1 to 10 wt.-% 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one in ethanol. After evaporation of the solvent (about 30 sec.) the scent impression was olfactorically evaluated by a trained perfumer.

[0165] Scent Strip Test Results:

[0166] Odor Impression:

[0167] Intensity: 4, dry plum: 4, damascones: 3, sweet: 4, fruity: 3, tobacco: 2.

[0168] Volatility:

[0169] long lasting on blotter (>48h)

[0170] As can be deduced from the scent strip test results, 5-methoxy-1-(2,6,6-trimethylcyclohexen-1-yl)hex-1-en-3-one is a olfactively valuable compound.