Alpha-branched alkenoic acids and the use of alpha-branched alkanoic and alkenoic acids as a fragrance

Abstract

The present invention refers to alpha branched alkanoic and alkenoic acids of formula (I) ##STR00001## wherein X and R have the same meaning as given in the description. The invention further refers to perfume compositions and fragrance applications comprising them.

Claims

1. A fine perfumery comprising as odorant a compound of formula (I) or a mixture thereof, ##STR00003## wherein X is selected from methyl and ethyl; R is selected from C.sub.4-C.sub.6 alkyl and C.sub.4-C.sub.6 alkenyl, and a fine perfumery consumer product base, and wherein the fine perfumery comprises an olfactory acceptable amount up to 2 weight % of the odorant compound of formula (I) or a mixture thereof.

2. The fine perfumery according to claim 1 wherein the compound of formula (I) is selected from the group consisting of 2-methyl decanoic acid, 2-methyl undecanoic acid, 2-ethyl decanoic acid, 2-ethyl undecanoic acid, 2-methyl undec-9-enoic acid, 2-methyl undec-10-enoic acid, 2-methyl undec-8-enoic acid, 2-methyl undec-7-enoic acid and 2-methyl dodecanoic acid.

3. The fine perfumery according to claim 1 wherein the compound of formula (I) comprises 2-methyl undecanoic acid.

4. A method of improving, enhancing or modifying a consumer product base comprising adding to the consumer product base as odorant an olfactory acceptable amount of a compound of formula (I) or a mixture thereof ##STR00004## wherein X is selected from methyl and ethyl; R is selected from C.sub.4-C.sub.6 alkyl and C.sub.4-C.sub.6 alkenyl, wherein the olfactory acceptable amount comprises up to 2 weight % of a compound of formula (I) or a mixture thereof, wherein the consumer product base is a fine perfumery.

5. The method according to claim 4 wherein the compound of formula (I) is selected from the group consisting of 2-methyl decanoic acid, 2-methyl undecanoic acid, 2-ethyl decanoic acid, 2-ethyl undecanoic acid, 2-methyl undec-9-enoic acid, 2-methyl undec-10-enoic acid, 2-methyl undec-8-enoic acid, 2-methyl undec-7-enoic acid and 2-methyl dodecanoic acid.

Description

EXAMPLE 1

2-methylundecanoic acid

(1) Jones reagent (61 ml, containing 163 mmol CrO.sub.3 and 280 mmol H.sub.2SO.sub.4) was added dropwise to the cooled (−25° C.) solution of 2-methylundecanal (45.0 g, 245 mmol) in acetone (80 ml) during 20 min. The solution was stirred at −5° C. for further 15 min, then poured into a biphasic mixture of 10% aq. NaOH-solution (400 g) and toluene (400 ml) and thoroughly stirred for 15 min. The phases were separated in a separatory funnel (emulsions were broken by the addition of small amounts of EtOH and solid NaCl). The alkaline aqueous layer was transferred into an Erlenmeyer flask, mixed with toluene (ca. 100 ml), and acidified by the addition of 6 N aqueous HCl-solution (200 ml, 1.2 mol). The aqueous layer is then extracted with toluene, washed neutral with half-saturated aq. NaCl-solution and dried over MgSO.sub.4. After removal of the solvent, the crude was subjected to a short-path distillation at 0.05 mbar/111-123° C., followed by fine distillation over a Vigreux-column at 0.05 mbar/118-121° C. to yield 20.1 g (41%) of 2-methylundecanoic acid as a colourless oil.

(2) IR (thin film): 2923m, 2854m, 1703vs, 1465w, 1236w, 938w.,

(3) .sup.1H-NMR (400 MHz, CDCl.sub.3): 11.76 (br. s, 1 H); 2.44 (hex, J=7.0 Hz, 1 H); 1.71-1.63 (m, 1 H); 1.46-1.37 (m, 1 H); 1.35-1.23 (m, 14 H); 1.16 (d, J=6.8 Hz, 3 H); 0.87 (t, J=7.0 Hz, 3 H).

(4) .sup.13C-NMR (100 MHz, CDCl.sub.3): 183.7 (s), 39.4 (d), 33.5 (t), 31.9 (t), 29.6 (t), 29.5 (t), 29.5 (t), 29.3 (t), 27.1 (t), 22.7 (t), 16.8 (q), 14.1 (q).

(5) MS (EI, 70 eV): 200 (2, M.sup.+), 185 (<1), 171 (1), 157 (5), 143 (11), 129 (7), 87 (41), 74 (100).

(6) Odour description: Olibanum, Elemi, citrus

EXAMPLE 2

2-Methyldecanoic acid

(7) Following the protocol according to Example 1, 2-methyldecanoic acid was prepared starting from 2-methyldecanal. The title compound was purified by fine distillation over a Vigreux-column at 0.05 mbar/115-130° C. (colourless oil, yield 49%).

(8) IR (thin film): 2924m, 2855m, 1703vs, 1465w, 1238w, 938w.

(9) .sup.1H-NMR (400 MHz, CDCl.sub.3): 11.59 (br. s, 1 H); 2.44 (hex, J=6.9 Hz, 1 H); 1.73-1.62 (m, 1 H); 1.47-1.37 (m, 1 H); 1.36-1.22 (m, 12 H); 1.16 (d, J=6.8 Hz, 3 H); 0.87 (t, J=7.0 Hz, 3 H).

(10) .sup.13C-NMR (100 MHz, CDCl.sub.3): 183.5 (s), 39.4 (d), 33.5 (t), 31.9 (t), 29.5 (t), 29.4 (t), 29.2 (t), 27.1 (t), 22.7 (t), 16.8 (q), 14.1 (q).

(11) MS (EI, 70 eV): 186 (2, M.sup.+), 143 (9), 129 (11), 87 (39), 74 (100), 55 (20).

(12) Odour description: citrus, aldehydic, resinous, Olibanum.

EXAMPLE 3

2-Methyl dodecanoic acid

(13) Following the protocol according to Example 1, 2-methyldodecanoic acid may be prepared starting from 2-methyldodecanal.

(14) Odour description: aldehydic, resinous, raspberry.

EXAMPLE 4

Further Compounds

(15) The following compounds may be prepared following the protocol according to Example 1: 2-ethyl decanoic acid; 2-ethyl undecanoic acid; 2-methyl undec-9-enoic acid; and 2-methyl undec-10-enoic acid;

EXAMPLE 5

2-Methyl undec-9-enoic acid and 2-methyl undec-10-enoic acid

(16) a) Sulfuric acid (62%, 88.7 g, 0.56 mol, 1.1 equiv.) is added at 10° C. to diethylamine (81.4 g, 1.1 mol, 1.1 equiv.) Formaldehyde (36.5% in water, 93.3 g, 1.12 mol, 1.12 equiv.) is added to the white suspension at 15° C. At the same temperature are added dropwise over 25 min the solution of BHT (0.67 g) in aldehyde iso C11 (mixture of E-/Z-9-undecenal and 10-undecenal; 168 g, 1 mol). The mixture was further stirred during 1.5 h at room temperature, during 3.5 h at 110° C. and during 16 h at room temperature. The mixture was diluted with cyclohexane and the organic layer washed 3 times with water, once with sat. aq. NaHCO.sub.3 and twice with brine. The crude obtained after drying the organic layer with MgSO.sub.4 and removing the solvents was pre-purified by a short-path distillation at 0.06 mbar/90° C. to isolate 119 g (66%) of a colourless oil, which was fine-distilled at 0.05 mbar/71-79° C. to isolate 104 g (58%) of a mixture of 2-methylene undec-9-enal (1) and 2-methylene undec-10-enal (2) as a colourless oil.

(17) .sup.1H-NMR (400 MHz, CDCl.sub.3): 9.54 (s, 1H), 6.24 (s, 1H), 5.98 (s, 1H), 5.85-5.75 (m, 0.14H), 5.43-5.31 (m, 1.6H), 4.99-4.88 (m, 0.29H), 2.23 (t, J=7.6, 2H), 2.03-1.90 (m, 2H), 1.62-1.56 (m, 2H), 1.45-1.39 (m, 3H), 1.35-1.23 (m, 8H).

(18) MS (EI, 70 eV): (1) 180 (M.sup.+, 2), 165 (2), 151 (8), 123 (9), 109 (17), 95 (29), 81 (33), 67 (41), 55 (100).

(19) b) The mixture of 2-methylene undec-9-enal (1) and 2-methylene undec-10-enal (2) (18 g, 100 mmol) prepared above was treated with triethylsilane (12.2 g, 105 mmol, 1.05 equiv.) and tris(triphenylphosphine)chlororhodium(I) (100 mg, 0.1 mmol, 0.1 mol-%) and the resulting solution stirred at 50° C. for 1 h and at 60° C. for 2 h. The dark mixture was diluted with hexane and the solution washed 3 times with water. After drying the organic layer over MgSO.sub.4 and removal of the solvent a yellow oil was obtained (30.1 g), which was distilled at 0.06 mbar/105-133° C. to yield a colourless oil (20.8 g, 70%). This product (15 g, 50.6 mmol) was dissolved in toluene (50 ml). The solution was cooled to 5° C. and a solution of tetrabutyl ammonium fluoride (1 M in THF, 20 ml, 20 mmol, 0.4 equiv.) was added dropwise over 4 min, followed by the addition of solid potassium fluoride (5.8 g, 100 mmol, 2 equiv) and methanol (50 ml). The resulting white suspension was stirred at 0-5° C. for 3 h, then treated with sat. aq. NaHCO.sub.3 solution (80 ml) and stirred thoroughly for 15 min. The mixture was extracted with methyl t-butyl ether and the organic layer washed 3 times with brine/water 1:1. The organic layer was dried over MgSO.sub.4 and the solvent removed. The resulting colourless oil (15 g) was purified by flash column chromatography over silica gel with hexane/toluene 1:1 to yield 5.74 g (31%) of a colourless oil, which was further purified by distillation at 0.05 mbar/58-62° C. to yield 2.2 g (7%) of a colourless oil. Of this product, 1.09 g (6 mmol) were dissolved in ethanol (20 ml) and a solution of silver nitrate (2.24 g, 13.2 mmol, 2.2 equiv.) in water (10 ml) was added, followed by a 12.5% wt/wt aqueous sodium hydroxide solution (30 g, 94 mmol). During the addition, the temperature rose to 35° C. The grey emulsion was stirred intensely for 22 h at room temperature. The precipitate was removed by filtration and the filter cake was rinsed thoroughly with ethanol. The ethanol was removed from the filtrate and the residual alkaline aqueous solution was diluted with methyl t-butyl ether. The aqueous phase was separated and the organic layer was extracted with 4 N aq. NaOH. The combined alkaline aqueous layers were washed with methyl t-butyl ether, then acidified with dilute hydrochloric acid to pH 1 and extracted with methyl t-butyl ether. The organic layer was washed with brine, dried over MgSO.sub.4 and concentrated in the rotary evaporator. The residue was purified by bulb-to-bulb distillation at 0.06 mbar/140-150° C. to isolate 1.15 g (96%) of colourless oil, which consisted of a mixture of E-2-methylundec-9-enoic acid (3a, 56.3%), Z-2-methylundec-9-enoic acid (3b, 32.4%) and 2-methylundec-10-enoic acid (4, 11.3%).

(20) IR (thin film): 3500-2600 br, 2925 m, 2855 w, 1703 vs.

(21) .sup.1H-NMR (400 MHz, CDCl.sub.3): δ ppm 11.8 (br. s, 1H), 5.80 (m, 0.2H), 5.39 (m, 1.8H), 4.94 (m, 0.4H), 2.44 (td, J=13.8, 6.9 Hz, 1H), 1.99 (m, 2H), 1.64 (m, 3H), 1.36 (m, 10H), 1.16 (d, J=6.7 Hz, 3H).

(22) MS (EI, 70 eV): (3a) 198 (M.sup.+, 4), 180 (5), 165 (<1), 125 (11), 87 (32), 74 (89), 69 (65), 55 (100).

(23) (3b) 198 (M.sup.+, 4), 180 (7), 165 (<1), 125 (13), 87 (30), 74 (91), 55 (100).

(24) (4) 198 (M.sup.+, 2), 180 (5), 165 (<1), 125 (9), 87 (24), 74 (100).

(25) Odour description: incense, olibanum.

EXAMPLE 6

Further Compounds

(26) The following compounds may be prepared following the protocol according to Example 5: 2-methyl undec-8-enoic acid and 2-methyl undec-7-enoic acid.

EXAMPLE 7

Preparation of Perfume Accords

(27) Base Accord:

(28) TABLE-US-00001 Ingredients Weight parts Cashmeran 10% in Diethylphtalate 8 (6,7-dihydro-1,1,2,3,3-pentamethyl-4(5H)-indanone) Frankincense 50% in Diisopropylphtalate 8 Ethyl Vanillin 0.1% in Dipropylene glycol 1 Georgywood * 10 (1-(1,2,3,4,5,6,7,8-octahydro-1,2,8,8-tetramethyl-2- naphthalenyl)ethanone) Hedione (methyl (2-pentyl-3-oxocyclopentyl)acetate) 20 Javanol* 10% in dipropylene glycol 8 ((1-methyl-2-((1,2,2-trimethylbicyclo[3.1.0]hexan-3-yl) methyl)cyclopropyl)methanol) Phenoxanol (3-methyl-5-phenylpentan-1-ol) 16 Moxalone* 50% in triethyl citrate 9 (1a,2,3,4,5,6,7,7a-octahydro-1a,3,3,4,6,6-hexamethyl- naphth[2,3-b]oxirene) Pepperwood* (dimethylcarbamic acid 3,7-dimethylocta- 16 1,6-dien-3-yl ester) Dipropylene glycol 4 Total: 100 *Givaudan Schweiz AG, Vernier

(29) 5.1: The replacement of 4% of dipropylene glycol in the above base accord formula by 4% of 2-methyldecanoic acid at 10% in dipropylene glycol brings a fresh, sparkling, natural, citrus note and a rich natural woody piney note, characteristic of fir.

(30) 5.2: The replacement of 4% of dipropylene glycol in the above base accord formula by 2-methylundecanoic acid at 10% in dipropylene glycol imparts an intense, rich and natural olibanum note, characteristic of burning olibanum.