WO1993003001A1 - Trimethylhexanal derivatives, their preparation and their use - Google Patents

Abstract

The invention concerns trimethylhexanal derivatives of general formula (I), in which R?1 and R?2, independently of each other, are an alkyl group with 1 to 3 C-atoms and R?3 is an alkyl, acyl or alkoxycarbonyl group with 1 to 3 C-atoms. These compounds possess scent characteristics with complex sandalwood and green notes and high diffusion power and can be mixed in widely varying proportions with each other and with other odiferous substances to give new scent compositions, generally containing 1 to 70 % by wt. relative to the total composition. These compositions can be used to scent cosmetic preparations and industrial products, as well as in alcohol-based fragrances.

Description

 "Trimethylhexanal Derivatives, Their Production and Use"

The invention relates to new trimethylhexanal derivatives, a process for their preparation and their use as fragrances.

Many natural odoriferous substances are available in a completely inadequate amount, measured according to need. For example, 5,000 kg of rose petals are required to obtain 1 kg of rose oil; the consequences are a very limited world annual production and a high price. It is therefore clear that the fragrance industry has a constant need for new fragrances with interesting fragrance notes in order to supplement the range of naturally available fragrances and to make the necessary adaptations to changing fashionable tastes, as well as the constantly increasing need for odor improvers for everyday products To cover needs such as cosmetics and cleaning agents.

In addition, there is generally a constant need for synthetic fragrances which can be produced cheaply and with a constant quality and which have desired olfactory properties, i.e. have pleasant, near-natural and qualitatively novel odor profiles of sufficient intensity and are able to advantageously influence the fragrance of cosmetic and consumer goods. It was therefore sought to find compounds which should have characteristic new odor profiles with high adhesive strength, odor intensity and radiance.

It has now been found that the compounds of the general formula (I) meet this requirement excellently in all respects and can be used advantageously as fragrances with differently nuanced odor notes with good adhesive strength. The subject of the invention are therefore trimethylhexanal derivatives of the general formula (I),

CH ₃

I

I I

CH3 0R3

wherein the radicals R ¹ and R ² independently of one another are an alkyl group having 1 to 3 C atoms and R ^{3 is} an alkyl, acyl or alkoxycarbonyl group having 1 to 3 C atoms.

Particular preference is given to those compounds of the general formula (I) according to the invention in which the radicals R 1 and R ² independently of one another represent an alkyl group having 1 to 2 carbon atoms. Those compounds in which R ^{3 is} an alkoxycarbonyl radical are very particularly preferred.

Another object of the invention is a process for the preparation of trimethylhexanal derivatives of the general formula (I), wherein Rl, R ² and R3 have the meaning given above, by dehydrating, base-catalyzed aldol condensation of 3,5,5-trimethylhexanal with the with the corresponding short-chain aliphatic ketones, their reduction e.g. with complex hydrides or according to the method of Meerwein-Ponndorf with aluminum alcoholates to the corresponding alcohols and finally their derivatization to the corresponding esters (Ia), carbonates (Ib) or allyl ethers (Ic).

The new compounds (I) are prepared by conventional synthetic methods of organic chemistry. Commercially available 3,5,5-trimethylhexanal serves as the starting material and can be reacted in the presence of conventional catalysts with corresponding short-chain ketones, for example 2-butanone or 3-pentanone, in a mixed aldol condensation, with intermediate aldol condensation products being used Elimination of water directly gives the corresponding α, β-unsaturated aldol condensation products (ZI). The reaction is expediently carried out with a Excess of the more reactive and volatile component. Examples of suitable catalysts are sodium hydroxide, sodium ethanolate, sodium amide, potassium tert-butoxide or heterogeneous catalysts such as potassium fluoride on aluminum oxide.

I.

CH ₃

The carbonyl function of the aldol condensation products (ZI) can be reduced to the OH group in a further reaction, e.g. using complex hydrides such as lithium aluminum hydride or lithium or sodium borohydride. The alcohols (Z2) are obtained in this way.

CH ₃ OH

I I

CH ₃ -C-CH2-CH (CH ₃ ) -CH2-CH = CR ¹ -CR ² (Z2)

I.

CH ₃

The alcohols (Z2) are then converted into the esters (Ia) by esterification with short-chain carboxylic acids or by reaction with e.g. Dimethyl carbonate or diethyl carbonate is converted into the carbonates (Ib) or by etherification according to Williamson, if desired in the presence of a phase transfer catalyst, into the allyl ethers (Ic).

CH ₃ OR ³

I I

CH3-C-CH2-CH (CH ₃ ) -CH ₂ -CH = CR ¹ -CR ² (Ia: R3 = acyl group;

| Ib: R ³ = alkoxycarbonyl groups;

CH3 Ic: R ³ = alkyl group)

The compounds (I) can then be purified by customary methods, for example by distillation. The compounds (I) according to the invention have remarkable olfactory properties, such as are very sought after in the fragrance industry, namely sandalwood-like or green with very complex shades and great charisma. The compounds of type (Ia) are characterized by their sandal scent, while the compounds of type (Ib) have fresh green notes.

Another object of the invention is therefore the use of the compounds of general formula (I) as fragrances.

From a perfume perspective, sandalwood oil is particularly valued and valuable. It is obtained by steam distillation from the heartwood of sandalwood, a tropical semi-parasite that occurs in India and Malysia. Heartwood appears after about ten years and only begins to develop more quickly in twenty-year-old trees. Fully grown trees are cleared at the age of 30 to 60 years because the roots are particularly rich in fragrant heartwood [cf. E. T. Morris, Dragoco Report 1983 (30) 40]. It is therefore understandable that fragrance research is constantly striving to develop suitable substitutes for natural sapwood oil.

Substituted mono-, bi- or tricyclic systems represent the large number of fragrances known from the state of the art with a scent of soft wood. This also applies to α- and β-santalol, the main constituents of natural sandalwood oil. The applicant is only aware of one example of a commercially available non-cyclic sand fragrance which is marketed under the trade name 0syrol ( ^TR ) and which is a 2,6-dimethyl-2-methoxy-6-hydroxy-octane (US Pat. No. 3,963,648). Japanese patent application JP 90/282339 describes noncyclic alcohols with a sandal scent, for example tetramethyldecan-4-en-3-ol.

German patent application DE 3245047 describes aliphatic alcohols and esters which have fruity and in particular pear-like fragrance notes or ambrette-woody, flowery and balm-like fragrance notes. Particular emphasis is placed on 5,7,7-trimethyloctyl propionate, whose fruity, pear-like note is particularly emphasized. The odor profile of the compounds (I) is original and novel. In perfume compositions, the compounds (I) enhance the harmony and charisma as well as the adhesion, the dosage being matched to the desired fragrance note taking into account the other constituents of the composition.

The fact that the trimethylhexanal derivatives (Ia) have sandal notes or the derivatives (Ib) green notes could not be predicted and is therefore a further confirmation of the general experience that the olfactory properties of known odoriferous substances do not necessarily lead to conclusions about the Allow properties of structurally related compounds, because neither the mechanism of fragrance perception nor the influence of the chemical structure on fragrance perception have been sufficiently researched, so it cannot normally be predicted whether a change in the structure of known odoriferous substances will ever change the olfactory properties and whether these changes are judged positively or negatively.

Because of their odor profile, the compounds of the formula (I) are particularly suitable for modifying and enhancing known compositions. Particularly to be emphasized is their extraordinary olfactory strength, which generally contributes to the refinement of the composition.

^• The compounds of formula (I) can be combined with numerous known fragrance ingredients, for example other fragrances of natural, synthetic or partially synthetic origin, essential oils and plant extracts. The range of natural fragrances can include both volatile, medium and low volatile components and that of synthetic fragrances includes representatives from practically all classes of substances. Examples are:

(a) Natural products such as tree moss absolute, basil oil, agricultural oils such as bergamot oil, mandarin oil, etc., mastic absolute, myrtle oil, pal arosa oil, patchouli oil, petitgrain oil, wormwood oil, myrrh oil, olibanum oil

(b) Alcohols such as farnesol, geraniol, linalool, nerol, phenylethyl alcohol, rhodinol, cinnamon alcohol, Sandalore [3-meth l-5- (2.2.3-trimethylcyclopent-3-en-l-yl) pentan-2-ol ], Sandela [3-isocamphyl- (5) -cyclohexanol], (c) aldehydes, such as citral, Helional ^R, α-hexyl cinnamic aldehyde, hydroxycitronellal lal _r Lilial ^R [p-tert-butyl-α-methyldihydrozimtaldehyd], methylnonyl acetaldehyde,

(d) ketones such as allyl ionone, ionone, β-ionone, isoraldein, methyl ionone,

(e) esters such as allylphenoxyacetate, benzyl salicylate, cinna yl propionate, citronellyl acetate, citronellyl ethoxylate, decyl acetate, dimethylbenzylcarbyl acetate, ethyl acetoacetate, hexenyl isobutyrate, linalyl acetate, methyl dihydrojasyl acetate, cyclohexyl acetate, vetiver hexyl acetate

(f) Lactones such as f-undecalactone, l-0xaspiro [4.4] nonan-2-one, as well as various other components often used in perfumery such as ketone musk, indole, p-menthan-8-thiol-3-one, methyleugenol, A broxan.

Also noteworthy is the way in which the compounds of structure (I), in particular (Ia), round off and harmonize the olfactory notes of a wide range of known compositions, but without dominating in an unpleasant manner.

Some of the compounds according to the invention contain chiral centers, so that these compounds can exist in different spatial forms. In the context of conventional syntheses, the compounds according to the invention are obtained as mixtures of the corresponding isomers and are used as such as fragrances.

The usable proportions of the compounds according to the invention or their mixtures in fragrance compositions range from 1 to 70 percent by weight, based on the mixture as a whole. Mixtures of the compounds (I) according to the invention and compositions of this type can be used for perfuming cosmetic preparations such as lotions, creams, shampoos, soaps, ointments, powders, aerosols, toothpastes, mouthwashes, deodorants as well as in alcoholic perfumery (eg Eaux de Cologne , Eau de toilette, extras) can be used. There is also an application for perfuming technical products such as detergents and cleaning agents, fabric softeners and textile treatment agents or tobacco. To perfume these various products, the compositions are added to them in an olfactory effective amount, in particular in a concentration of 0.05 to 2 percent by weight, based on the entire product. These values However, they are not intended to represent any limit values, since the experienced perfumer can achieve effects with even lower concentrations or build new types of complexes with even higher doses.

The following examples are intended to explain the subject matter of the invention and are not to be interpreted as restrictive.

B e i s p i e l e

1. Production of the preliminary stages

(a) 4,7,9,9-tetramethy1-4-decen-3-one:

In a 250 ml three-necked flask, 46.5 g of 3,5,5-trimethylhexanal (Hoechst) were mixed with 140.1 g of diethyl ketone (3-pentanone) and 40 g of aluminum oxide / potassium fluoride (with nitrogen and stirring) prepared by suspending 20 g Al2O3 in 40 g 50% aqueous KF solution and subsequent concentration to constant weight). The mixture was stirred at 60 ° C for 4 hours and at 90 ° C for 6 hours. The starting aldehyde was then completely converted. The catalyst was filtered off, the filtrate was distilled in a high vacuum on a Rotavapor and then on a Vigreux column. 53 g of crude product were obtained. The fine distillation gave 30.1 g of the product with a boiling point of 77-80 ° C./0.02 mbar and a purity of 90% determined by gas chromatography.

(b) 4,7,9,9-tetramethyl-4-decen-3-ol:

5 g of sodium borohydride were suspended in 100 ml of ethanol in a 250 ml three-necked flask. 29.3 g of 4,7,9,9-tetramethyl-4-decen-3-one were dissolved in 80 ml of ethanol and metered continuously into the stirred suspension in 15 minutes. The temperature of the reaction mixture rose to about 30 ° C. The mixture was then refluxed for 20 minutes. After cooling, the mixture was poured into a saturated ammonium chloride solution / ice mixture for workup and extracted several times with ether. The combined organic phases were washed neutral with water, dried over potassium carbonate and concentrated. The subsequent Kugelrohr distillation in a high vacuum at 0.08 mbar and an air bath temperature of 150 ° C. yielded 23.8 g of crude product, which was purified by a rotary belt distillation. The main run of 18.6 g went over at a head temperature of 71 - 75 ° C / 0.02 mbar. 2. Preparation of the compounds I according to the invention

2.1. Type (Ia) compounds

Example 1; 4,7,9,9-tetramethyl-4-decen-3-yl ~ formate

A solution of 30 g of 4,7,9,9-tetramethyl-4-decen-3-ol in 32 g of 99% formic acid was stirred into a 250 ml three-necked flask at room temperature. A further 20 g of formic acid were then added to the mixture and the mixture was stirred again at room temperature for 16 hours. The excess of formic acid was distilled off in a water jet vacuum and the residue was fractionally distilled on a rotating column. The main run of 7.1 g of the ester went under a high vacuum at 0.02 mbar and a head temperature of 82-85 ° C. The gas chromatographic content of the desired compound was approximately 90%. The IR spectrum (film on NaCl) showed adsorption bands at 2954, 1728 (ester-CO band), 1364 and 1169 cm ^-1 (C-0 vibration).

Smell: fruity, woody, balsamic, sandal note

2.2. Type (Ib) compounds

Example 2: 4,7,9,9-tetraπtethyl-4-decen-3-yl-ethyl carbonate

In a 250 ml three-necked flask with Dean-Starck water separator attachment, 31.9 g of 4,7,9,9-tetramethyl-4-decen-3-ol were mixed with 62 g of diethyl carbonate and 3 g of sodium methoxide (30% in methanol ) added. The mixture is heated to 90 ° C. with stirring and the ethanol formed in the course of the reaction is distilled off via the water separator. To remove the catalyst, the mixture is washed twice with sodium sulfate solution. After the water phase had been separated off, the organic phase was transferred to a still and the excess diethyl carbonate was removed by distillation. Distillation of the residue through a 30 cm Vigreux column gave 14 g of the pro at a top temperature of 92-93 ° C./0.05 mbar. product with a GC purity of 95.3%. The IR spectrum (film on NaCl) shows bands at 2954, 1745 (carbonate-C = 0), 1369 and 1258 cm " ¹ (C-0 vibrations).

Smell: very natural note of freshly cut grass

Composition example

Odor characteristic: floral (rose)

990

( ^a ) DPG = dipropylene glycol

The addition of 10 parts of compound Ib (from example 2) brings about a more harmonious, uniform odor that comes closer to the natural rose scent than the original composition.

Claims

Patent claims 1. Trimethylhexanal derivatives of the general formula (I) CH ₃ l CH3-C-CH2-CH (CH ₃ ) -CH ₂ -CH = CRl-CH-R ² (I) I ^• I CH3 OR ³ wherein the radicals R * and R ² independently of one another are an alkyl group having 1 to 3 C atoms and R ^{3 is} an alkyl, acyl or alkoxycarbonyl group having 1 to 3 C atoms. 2. Trimethylhexanal derivatives according to claim 1, wherein the radicals R ¹ and R ² independently of one another stand for an alkyl group having 1 to 2 carbon atoms. 3. trimethylhexanal derivatives according to claim 1 or 2, wherein the radical R ^{3 is} an alkoxycarbonyl radical. 4. Process for the preparation of trimethylhexanal derivatives of the general formula (I), CH3 I CH3-C-CH2-CH (CH ₃ ) -CH ₂ -CH = CRl-CH-R ² (I) I [ CH3 0R ³ wherein the radicals R ¹ and R ² independently of one another are an alkyl group with 1 to 3 C atoms and R ^{3 is} an alkyl, acyl or alkoxycarbonyl group with 1 to 3 C atoms, by dehydrating base-catalyzed aldol condensation of 3.5, 5-trimethylhexanal with the corresponding short-chain aliphatic ketones, their reduction, for example with complex hydrides, to the corresponding alcohols and finally their derivatization to the corresponding esters (Ia), carbonates (Ib) or allyl ethers (Ic). 5. Use of trimethylhexanal derivatives according to one of claims 1 to 4 as fragrances. 6. Fragrance compositions containing a trimethylhexanal derivative of the formula (I) according to Claims 1 to 4 in an amount of 1-70% by weight, based on the overall composition. 7. Use of mixtures of trimethylhexanal derivatives of the formula I according to claim 1 to 4 as fragrances in cosmetic preparations, technical products or alcoholic perfumery.