EP2925712A1

EP2925712A1 - Method for producing cyclohexyl-substituted tertiary alkanols

Info

Publication number: EP2925712A1
Application number: EP13802553.1A
Authority: EP
Inventors: Stefan Rüdenauer; Ralf Pelzer; Klaus Ebel; Martin Bock
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2012-11-27
Filing date: 2013-11-26
Publication date: 2015-10-07
Also published as: WO2014082978A1

Abstract

The present invention relates to a process for the preparation of compounds of formula (Ia) by the reaction of styrene with a secondary alkanol and the hydrogenation of the obtained phenyl-substituted tertiary alkanol. The invention further relates to compounds of formula (Ia) and to the use of such compounds as fragrances and to compositions containing the compounds of formulae (Ia) and (Ib).

Description

The present invention relates to a process for the preparation of cyclohexyl-substituted tertiary alkanols, and to the use of such compounds as perfume.

Fragrances are used in a variety of technical products and household products to cover unwanted odors or for olfactory improvement. Floral notes are of great interest, especially when used in detergents and cleaners. It is important for such uses that the fragrances not only have a pleasant odor, but also remain chemically stable over a longer period of time and can be incorporated into the corresponding product in a technically good manner. It is also desirable to have the lowest possible production process for the fragrances.

4-Cyclohexyl-2-methyl-2-butanol, also referred to as coranol, is a fragrance with lily-of-the-valley fragrance, the use of which as a component of fragrance compositions was first described in US 4,701,278. Preparation methods for 4-cyclohexyl-2-methyl-2-butanol have been described by Okazawa et al. (Can J. Chem., 60 (1982), 2180-93) and Ebel et al. (WO 201 1/1 17360) described.

Basically, there is a constant need for new fragrances to supplement the already available fragrance range. In the search for new fragrances which meet the abovementioned requirements, it has now surprisingly been found that cyclohexyl-substituted tertiary alkanols, such as 1-cyclohexyl-3-methyl-3-pentanol and its longer-chain analogs, possess interesting olfactory properties. 1 - Cyclohexyl-3-methyl-3-pentanol has, in addition to a pleasant note of lavender (similar to coranol, tetrahydrolinalool) additionally fruity aspects.

Furthermore, a new process for preparing such compounds has been found. Synthesis routes to give 1-cyclohexyl-3-methyl-3-pentanol are described by Daziauskas (Chemiya, Technika, Fizine Geografiya (4): 35-42, 1967) and Nazarov and Nagibina (Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya: 83- 89, 1946). However, these production routes are multi-step and would therefore be associated with high costs in practical implementation on an industrial scale. The present invention provides a process for the preparation of a compound of the formula (Ia)

ready, comprising: a) the reaction of styrene with a compound of the formula (II)

O H

to obtain a compound of formula (Ia), and

b) the heterogeneous-catalytic hydrogenation of the compound of the formula (Ia) to the compound of the formula (Ia).

Unless otherwise indicated, in the compounds of the formulas (Ia), (Ib), (II), (IIa), (IIIb), (IV) and (V) described hereinbelow and independently, R and R ^{2 are} independent selected from among groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) _y , where either x and y are each 1 or one of the variables x and y is 1 and the other is 0. Preferably, R ¹ and R ^{2 are} independently selected from C 1-7 -alkyl, C 3-7 -cycloalkyl and C 4-7 -cycloalkylalkyl. In this case, R ¹ and R ² together comprise a total of 3 to 1 1 carbon atoms, in particular 3 to 8 carbon atoms, preferably 3 to 5 carbon atoms and more preferably 3 carbon atoms.

As used herein, Ci-7-alkyl is a linear or branched alkyl radical having 1 to 7 carbon atoms. Examples of linear C 1-7 -alkyl are methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl, examples of branched C 1-7 -alkyl are isopropyl, sec-butyl, tert-butyl, iso- Hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl and 2-ethylbutyl.

As used herein, C3-7 cycloalkyl is a cycloalkyl radical of from 3 to 7 carbon atoms in total, which is bonded through one of the carbon ring atoms. This Cycloalkyl radical is unsubstituted or substituted with 1, 2 or 3 Ci-7-alkyl radicals as defined above, with the proviso that the cycloalkyl radical in total (ie including any alkyl substituents) comprises not more than 7 carbon atoms. Examples of an unsubstituted C 3-7 cycloalkyl are cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

As used herein, C4-7 cycloalkylalkyl is a linear or branched alkyl radical substituted with a cycloalkyl group and comprising 4 to 7 carbon atoms in total (i.e., including the cycloalkyl substituent). Examples of C4-7 cycloalkylalkyl are cyclohexylmethyl, cyclopentylmethyl and 1-cyclopentylethyl.

According to a preferred aspect of the invention, R ¹ and R ^{2 are} independently selected from C 1-7 -alkyl and C 3-7 -cycloalkyl. The respective compounds within a particular of the described reaction pathways (hereinafter also referred to as "corresponding compounds") carry the same R ¹ and R ² .

A preferred embodiment of the invention relates to a process for preparing 1-cyclohexyl-3-methyl-3-pentanol, comprising:

a) the reaction of styrene with 2-butanol to give 3-methyl-1-phenyl-3-pentanol, and

b) the heterogeneous-catalytic hydrogenation of 3-methyl-1-phenyl-3-pentanol to 1-cyclohexyl-3-methyl-3-pentanol.

In further embodiments of the process according to the invention, the compound of the formula (Ia) is selected from 1-cyclohexyl-3-methyl-3-hexanol, 1-cyclohexyl-3-methyl-3-heptanol, 1-cyclohexyl-3-methyl-3- octanol, 1-cyclohexyl-3-methyl-3-nonanol, 1-cyclohexyl-3,4-dimethyl-3-octanol, 1-cyclohexyl-3,5-dimethyl-3-octanol, 1-cyclohexyl-3,6- dimethyl-3-octanol, 1-cyclohexyl-3,7-dimethyl-3-octanol, 1-cyclohexyl-3,4,4-trimethyl-3-heptanol, 1-cyclohexyl-3,5,5-trimethyl-3- heptanol, 1-cyclohexyl-3,6,6-trimethyl-3-heptanol, 1-cyclohexyl-5-ethyl-3-methyl-3-heptanol, 1-cyclohexyl-3,5-dimethyl-3-heptanol, 2, 4-dicyclohexyl-2-methyl-2-butanol, 1-cyclohexyl-4-cyclopentyl-3-methyl-3-pentanol, 1-cyclohexyl-3-ethyl-3-hexanol, 1-cyclohexyl-3-ethyl-3- heptanol, 1-cyclohexyl-3-ethyl-3-octanol and 1-cyclohexyl-3-ethyl-3-nonanol.

The process for preparing the compound of formula (Ia) can be represented by the following reaction scheme:

The invention thus relates to a process for preparing a compound of the formula (Ia) with the steps described here and below and in the claims.

The method has a number of advantages. It allows a highly atom economical production of a compound of formula (Ia) from very inexpensive basic chemicals, does not require any elaborate work-up steps and is therefore relatively inexpensive. The use of expensive and dangerous reagents such as methyllithium is not required.

Both step a) and step b) can be carried out easily on an industrial scale and provide the respective products with high selectivity and good yields. In step a) of the process according to the invention, a secondary alkanol of the formula (II) is reacted with styrene. In this case, a corresponding phenyl-substituted tertiary alkanol of the formula (IIIa) forms as well as by-products, inter alia, toluene and ethylbenzene, which, however, can be separated off from the target product, for example by distillation.

Furthermore, in step a), in addition to the compound of the formula (IIIa), the corresponding (ie the same R ¹ , R ² ) methyl-substituted alkanol of the formula (IIIb)

from which, by heterogeneous catalytic hydrogenation, the compound of the formula (Ib)

arises. The methyl-substituted alkanol of the formula (IIIb) is presumably formed by reaction of the compound of the formula (II) with .alpha.-methyl-styrene which can be formed in a free-radical reaction from styrene and ethylbenzene according to the following scheme:

In view of the selectivity of the reaction, it has proven advantageous to carry out the reaction in step a) under supercritical conditions. This is understood to mean reaction conditions in which at least one of the components of the reaction mixture, preferably the compound of the formula (II), is in the supercritical state. Accordingly, according to a preferred embodiment of the process according to the invention, the reaction in step a) takes place under conditions in which the compound of the formula (II) is in the supercritical state. For example, in the case of 2-butanol, the critical temperature _{Tc is} 263 ° C and the critical pressure _{Pc is} 4.2 MPa. Supercritical conditions can be adjusted by the skilled person by varying pressure and temperature.

The temperature required for a sufficient rate of reaction of styrene with a compound of formula (II) is usually at least (T _c + 15) ° C, often at least (T _c + 65) ° C and especially at least (T _c + 85) ° C, where T _{c is} the critical temperature of the compound of formula (II) used. In order to achieve a sufficient selectivity of the reaction, it has proven to be advantageous if the temperature in the reaction in step a) does not exceed a value of (T _c + 265) ° C, in particular (T _c + 165) ° C. The reaction in step a) is preferably carried out at elevated pressure, which is generally in the range from 5 to 50 MPa, often in the range from 10 to 30 MPa and in particular in the range from 15 to 25 MPa. The reaction preferably takes place under the autogenous pressure of the reaction mixture prevailing at the desired reaction temperature.

The reaction time naturally depends on the chosen conditions and the desired conversion and is usually in the range from 30 s to 4 h, in particular in the range from 3 min to 3 h and especially in the range from 5 min to 2.5 h. In one embodiment of the invention, the reaction time is in the range of 0.5 to 4 h, in particular in the range of 1 to 3 h and especially in the range of 1, 5 to 2.5 h. As a rule, the reaction is carried out to the extent that at least 80%, in particular at least 90%, of the reaction residue used in the deficit, which is preferably styrene, has reacted. It has proven particularly advantageous to carry out the reaction in step a) at elevated temperatures, ie above (T _c + 65) ° C., in particular above (T _c + 85) ° C., preferably in the range (T _c + 1 15). ° C and (T _c + 165) ° C. This allows short reaction times, which are usually in the range of 30 s to 30 min, in particular in the range of 3 min to 20 min and especially in the range of 5 min to 15 min. In this way, good selectivities with respect to the target product can be achieved even with high conversion of styrene. In view of the selectivity of the reaction, it has proved to be advantageous to carry out the reaction in step a) in the substantial or complete absence of catalysts, such as free-radical initiators, acids or transition metal compounds. Substantial absence means that the concentration of any catalysts is less than 1 g / kg (<1000 ppm), especially less 0.1 g / kg (<100 ppm) based on the total weight of the reaction mixture.

The reaction of styrene with a compound of the formula (II) in step a) can be carried out in bulk or in a suitable, ie reaction-inert, diluent. Suitable inert diluents are aprotic organic solvents which have no ethylenically unsaturated double bond, such as aliphatic and alicyclic ethers having preferably 4, 5 or 6 carbon atoms, for example diethyl ether, 1, 2-dimethoxyethane, bis (2-methoxyethyl) ether, 2 Methyltetrahydrofuran and especially tetrahydrofuran; aliphatic and cycloaliphatic saturated hydrocarbons having preferably 5 to 8 carbon atoms, for example pentane, hexane, heptane or octane; Alkyl esters of aliphatic carboxylic acids having preferably 4 to 8 carbon atoms and mixtures of the abovementioned solvents. The reaction in step a) preferably takes place in substance, ie essentially no starting materials other than styrene and the compound of the formula (II), such as, for example, inert solvents, are used for the reaction. Essentially, it means here that styrene and the compound of the formula (II) account for at least 95% by weight, in particular at least 99% by weight, based on the total amount of the components used in step a). In addition, the reactants used for the reaction, ie styrene and the compound of formula (II), production-related small amounts of impurities such as water, ethylbenzene, toluene and the like may contain, the impurities usually less than 5 wt .-%, in particular less account for 1 wt .-%, based on the total amount of the reactants. In particular, the water content of the reactants used in step a) is not more than 1 wt .-%, based on the total amount of the reactants. With regard to the selectivity of the reaction, it has proved to be advantageous if, in the reaction according to step a), a compound of the formula (II) is used in large excess, based on styrene, and / or ensures that in the reaction tion zone in which styrene and the compound of formula (II) are brought into contact under reaction conditions, a large excess of the compound of formula (II), based on the styrene present in the reaction zone is present. As a rule, in step a) styrene and the compound of the formula (II) are added in a molar ratio of styrene to compound of the formula (II) of at most 1: 5, preferably at most 1:10, in particular at most 1: 30, particularly preferably at most 1:40 and especially at most 1:50 pm. With regard to an efficient reaction procedure, it is advantageous if, in step a), styrene and compound of the formula (II) are in a molar ratio in the range from 1: 5 to 1: 200, preferably in the range from 1:10 to 1: 200 , in particular in the range from 1: 30 to 1: 150 or in the range from 1: 30 to 1: 130, more preferably in the range from 1:40 to 1: 100 and especially in the range from 1:50 to 1:90.

The reaction in step a) can be carried out batchwise (so-called batch mode), i. The styrene and the compound of the formula (II) are initially charged in the desired molar ratio in a suitable reactor and brought to the desired reaction conditions and kept under reaction conditions up to the desired conversion. The reaction in step a) can also be carried out in the so-called semi-batch mode, i. the main amount, generally at least 80%, in particular at least 90%, of one or both reactants is added to the reactor continuously or in portions over a relatively long period of time, generally at least 50% of the total reaction time. For example, at least 80%, especially at least 90%, of the compound of formula (II) used may optionally be introduced together with a portion of the styrene and at least 80%, in particular at least 90%, of the styrene used be fed to the reaction under reaction conditions.

The reaction in step a) can also be carried out continuously, ie styrene and compound of the formula (II) are fed continuously in the desired molar ratio into a reaction zone and the reaction mixture is withdrawn continuously from the reaction zone. The rate at which styrene and compound of the formula (II) are fed to the reaction zone depends on the desired residence time, which in turn depends on the reactor geometry in a known manner and corresponds to the reaction time given above. The reaction in step a) can in principle be carried out in all reactors which are suitable for the chosen reaction conditions, preferably in autoclaves which may have devices for mixing the reactants, or in reaction tubes.

In order to keep the molar ratio of styrene to compound of the formula (II) low during the reaction and at the same time to allow an efficient reaction, it has proved advantageous to use at least 80%, in particular at least 90%, of the compound used in step a) of the formula (II) optionally together with a partial amount of the styrene and at least 80%, in particular at least 90% of the styrene used in step a) of the reaction in step a) under reaction conditions feeds. The addition of the styrene may be carried out in portions or preferably continuously. The rate at which styrene is fed in is thereby preferably chosen such that the molar ratio of the unreacted styrene fed into the reaction zone or the reactor to the compound of the formula (II) in the reaction zone is less than 1 during the reaction : 10, in particular not more than 1:40 and especially not more than 1: 50, and for example is in the range from 1:10 to 1: 2000, preferably in the range from 1:40 to 1: 1500 and in particular in the range from 1:50 to 1: 1000. In a continuous reaction procedure, it is therefore preferable to feed styrene and compound of the formula (II) in the abovementioned molar ratios to the reactor or the reaction zone. In a particular embodiment of the invention, the rate at which styrene is fed in is preferably chosen such that the molar ratio of the styrene fed into the reaction zone or reactor to the compound of formula (II) in the reaction zone is in the range of 1 : 10 to 1: 130, in particular in the range from 1:20 to 1: 120, more preferably in the range from 1:40 to 1: 100 and especially in the range from 1:50 to 1:90. This applies in particular also in the case of continuous reaction control for the molar ratios of styrene and compound of the formula (II) fed to the reactor or the reaction zone.

The reaction mixture obtained in step a) can be worked up in a manner known per se or, if appropriate after removal of the compound of the formula (II), used directly as such in step b) of the process according to the invention. In general, it has proved to be advantageous to work up the reaction mixture obtained in step a), for example extractively or by distillation or by a combination of these measures. In one embodiment of the process according to the invention, the reaction mixture obtained in step a) is worked up by distillation to give the desired compound of formula (IIIa) or the desired composition consisting essentially of the compound of formula (IIIa) and the corresponding compound of the formula (IIIb), as the middle fraction of light and high boilers separated. If an excess of compound of the formula (II) is used, the low-boiling fraction, which consists predominantly of compound of the formula (II), can be recycled to the process. As a rule, the compound of the formula (II) is substantially removed before step b), so that the proportion of compound of the formula (II) in the educt used for the hydrogenation in step b) is less than 20% by weight, in particular not more than 10 wt .-%, based on the total amount of starting material in step b). Depending on the embodiment of the distillation, the substantially pure compound of the formula (IIIa) is obtained (purity of at least 95% by weight, in particular at least 98% by weight and especially at least 99% by weight or at least 99.5% by weight. ) or a composition consisting essentially, ie at least 95 wt .-%, in particular at least 98 wt .-% and especially at least 99 wt .-% or at least 99.5 wt .-% of compound of the formula (IIIa) and corresponding compound of the formula (IIIb), wherein the weight ratio of the compound of the formula (IIIa) to the corresponding compound of the formula (IIIb) is typically in the range from 50: 1 to 1000: 1. Both the pure compound of the formula (IIIa) and the composition can be used in the subsequent hydrogenation according to step b). This produces the corresponding pure compound of the formula (Ia) (purity at least 95% by weight, in particular at least 98% by weight and especially at least 99% by weight or at least 99.5% by weight) or the corresponding composition from the compound of the formula (Ia) and the compound of the formula (Ib) (purity and weight ratio of the compounds of the formulas (Ia) and (Ib) essentially as defined above for the compounds of the formulas (IIIa) and (IIIb)).

The hydrogenation is expediently carried out on a catalyst suitable for the nuclear hydrogenation of aromatic substances, which is also referred to below simply as a catalyst. Suitable catalysts are in principle all catalysts which are known to be suitable for the ring hydrogenation of aromatics, ie catalysts which catalyze the hydrogenation of phenyl groups to cyclohexyl groups. These are usually catalysts containing at least one active metal from Group VIIIB of the Periodic Table (CAS version), such as palladium, platinum, cobalt, nickel, rhodium, iridium, ruthenium, in particular ruthenium, rhodium or nickel, or a Mixture of two or more thereof, optionally in combination with one or more other active metals. Preferred further active metals are selected from groups IB or VIIB of the periodic table (CAS version). Under the likewise usable metals of subgroups IB and / or VIIB are, for example, copper and / or rhenium.

The catalysts may be full catalysts or, preferably, support catalysts. Suitable support materials are, for example, activated carbon, silicon carbide, silicon dioxide, aluminum oxide, magnesium oxide, titanium dioxide, zirconium oxide, aluminosilicates and mixtures of these support materials. The amount of active metal is usually 0.05 to 10 wt .-%, often 0.1 to 7 wt .-% and in particular 0.1 to 5 wt .-%, based on the total weight of the supported catalyst, in particular, if the active metal is a noble metal such as rhodium, ruthenium, platinum, palladium or iridium. In the case of catalysts which contain cobalt and / or nickel as active metals, the amount of active metal can be up to 100% by weight and is usually in the range from 1 to 100% by weight, in particular from 10 to 90% by weight the total weight of the catalyst.

The supported catalysts can be used in the form of a powder. As a rule, such a powder has particle sizes in the range from 1 to 200 μm, in particular from 1 to 100 μm. Powdered catalysts are particularly suitable when the catalyst is suspended in the reaction mixture to be hydrogenated (suspension mode). When using the catalysts in fixed catalyst beds, it is usual to use moldings which are e.g. are obtainable by extrusion, extrusion or tableting and which are e.g. may have the form of spheres, tablets, cylinders, strands, rings or hollow cylinders, stars and the like. The dimensions of these moldings usually range from 0.5 mm to 25 mm. Frequently, catalyst strands with strand diameters of 1, 0 to 5 mm and

Strand lengths of 2 to 25 mm used. With smaller strands generally higher activities can be achieved, but these often do not show sufficient mechanical stability in the hydrogenation process. Therefore, very particularly preferably strands with strand diameters in the range of 1, 5 to 3 mm are used. Also preferred are spherical support materials with ball diameters in the range of 1 to 10 mm, in particular 2 to 6 mm.

Preferred catalysts are those which comprise at least one active metal selected from ruthenium, rhodium and nickel, optionally in combination with one or more further active metals selected from groups IB, VIIB and VI 11 B of the periodic table (CAS version) ,

Particularly preferred catalysts are ruthenium-containing catalysts. These contain ruthenium as the active metal, optionally in combination with one or more additional active metals. Preferred further active metals are selected from Groups IB, VIIB and VII IB of the Periodic Table (CAS version). The catalysts may be full catalysts or, preferably, supported catalysts. Examples of further active metals from the group VI 11 B are, for example, platinum, rhodium, palladium, iridium, cobalt and nickel, which can also be used as a mixture of two or more thereof. Among the metals of subgroups IB and / or VIIB which can likewise be used, for example copper and / or rhenium are suitable. Ruthenium is preferably used alone as active metal or together with platinum or iridium as active metal; With very particular preference ruthenium is used alone as the active metal.

Particular preference is given to ruthenium-containing catalysts in which the ruthenium and the optionally present further active metals are arranged on a support material (ruthenium-containing supported catalysts). Suitable support materials for the ruthenium-containing supported catalysts are in principle the abovementioned support materials. Preference is given to silicon dioxide-containing carrier materials, in particular those which have a silicon dioxide content of at least 90% by weight, based on the total weight of the carrier material. Likewise preferred are alumina-containing carrier materials, in particular those which have a content of aluminum oxide (calculated as Al 2 O 3) of at least 90% by weight, based on the total weight of the carrier material. The support materials preferably have a BET specific surface area, determined by N 2 adsorption according to DIN 66131, of at least 30 m ² / g, in particular 50 to 1000 m ² / g. The amount of active metal is usually 0.05 to 10 wt .-%, preferably 0.1 to 3 wt .-% and in particular 0.1 to 1 wt .-%, based on the total weight of the ruthenium-containing supported catalyst.

Suitable ruthenium-containing catalysts are, for example, those described in US Pat. No. 3,027,398, DE 4407091, EP 258789, EP 813906, EP 1420012, WO 99/32427, WO 00/78704, WO 02/100536, WO 03/103830, WO 2005/61 105, US Pat. WO 2005/61 106, WO 2006/136541 and WO201 1082991 mentioned catalysts. With respect to the catalysts disclosed therein, reference is made to these documents.

Also preferred catalysts are rhodium-containing catalysts. These contain rhodium as active metal, optionally in combination with one or more further active metals. Preferred further active metals are selected from the groups IB, VIIB or VI 11 B of the periodic table (CAS version). The catalysts may be solid catalysts or, preferably, supported catalysts. Examples of further active metals from the group VI 11 B are, for example, platinum, palladium iridium, cobalt and nickel, which may also be used as a mixture of two or more thereof. Among the metals of subgroups IB and / or VIIB which can likewise be used, for example copper and / or rhenium are suitable. In these catalysts, rhodium is used alone as the active metal or together with platinum or iridium as the active metal; most preferably, rhodium is used alone as the active metal. Suitable rhodium-containing catalysts are known, for example, from the publications mentioned above for ruthenium-containing catalysts, can be prepared by the procedures given there or are commercially available, for example the catalyst Escat 34 from Engelhard. For rhodium-containing supported catalysts, the abovementioned support materials can be considered. Preference is given to silicon dioxide-containing carrier materials, in particular those which have a silicon dioxide content of at least 90% by weight, based on the total weight of the carrier material. Also preferred are alumina-containing support materials, in particular those having a content of alumina (calculated as Al2O3) of at least 90 wt .-%, based on the total weight of the support material. The amount of active metal is usually 0.05 to 10 wt .-%, based on the total weight of the rhodium-containing supported catalyst. Also preferred catalysts are nickel-containing catalysts. These contain nickel as the active metal, optionally in combination with one or more further active metals. Preferred further active metals are selected from Groups IB, VIIB or VIIIB of the Periodic Table (CAS version). The catalysts may be solid catalysts or, preferably, supported catalysts. Examples of further active metals from group VIIIB are, for example, platinum, palladium, iridium and cobalt, which can also be used as a mixture of two or more thereof. Among the metals of subgroups IB and / or VIIB which can likewise be used, for example copper and / or rhenium are suitable. In these catalysts, nickel is preferably used alone as the active metal. Suitable nickel-containing catalysts are commercially available, for example the catalyst Ni5249P from BASF SE. For nickel-containing supported catalysts, in principle, the abovementioned support materials come into consideration. Preference is given to silica, alumina and magnesium oxide-containing support materials, in particular those which consist of at least 90 wt .-% of such materials. The amount of active metal is usually 1 to 90 wt .-%, preferably 10 to 80 wt .-% and in particular 30 to 70 wt .-%, based on the total weight of the nickel-containing supported catalyst. Preference is also given to those nickel-containing catalysts which consist essentially exclusively of active metal, ie whose amount of active metal is more than 90% by weight, for example 90 to 100% by weight. According to a particularly preferred embodiment, a shell catalyst is used, in particular a shell catalyst which comprises ruthenium alone or together with at least one further active metal of subgroups IB, VIIB or VIIIB of the Periodic Table of the Elements in the abovementioned amounts. Such shell catalysts are known, in particular, from WO 2006/136541 and in the unpublished EP 09179201.0.

Such a shell catalyst is a supported catalyst in which the predominant amount of the active metal contained in the catalyst is in the vicinity of the surface of the catalyst. In particular, at least 60% by weight, more preferably at least 80% by weight, in each case based on the total amount of the active metal, up to a penetration depth of at most 200 μm, ie. in a dish with a maximum distance of 200 μm to the surface of the catalyst particles. In contrast, there is no or only a very small amount of the active metal in the interior (core) of the catalyst. In the process according to the invention, it is very particularly preferable to use a coated catalyst in which no active metal can be detected inside the catalyst, ie. Active metal is present only in the outermost shell, for example in a zone up to a penetration depth of 100 to 200 μm. The above-mentioned data can be determined by means of SEM (scanning electron microscopy), EPMA

(electron probe microanalysis) - EDXS (energy dispersive X-ray spectroscopy) are determined and represent averaged values. Further information on the above measuring methods and techniques, for example, "Spectroscopy in Catalyst" by JW Niemantsverdriet, VCH, 1995 taken become. For further details regarding the penetration depth of active metal, reference is made to WO 2006/136541, in particular to page 7, lines 6 to 12.

Preferred coated catalysts have a content of active metal in the range of 0.05 to 1 wt.%, In particular 0.1 to 0.5 wt .-%, particularly preferably 0.25 to 0.35 wt .-%, each based on the Total weight of the catalyst.

For the hydrogenation according to the invention in step b), shell catalysts with a support material based on silicon dioxide, in general amorphous silicon dioxide, are particularly preferred. The term "amorphous" is understood in this context that the proportion of crystalline silicon dioxide phases makes up less than 10% by weight of the support material. However, the support materials used for the preparation of the catalysts may have superstructures, which are formed by regular arrangement of pores in the carrier material. Suitable support materials are in principle amorphous silicon dioxide types which are at least 90 Wt .-% consist of silicon dioxide, wherein the remaining 10 wt .-%, preferably not more than 5 wt .-%, of the support material may also be another oxidic material, for example MgO, CaO, ΤΊΟ2, ZrÜ2, Fe2Ü3 and / or alkali metal oxide. In a preferred embodiment of the coated catalyst, the support material is halogen-free, in particular chlorine-free, ie the content of halogen in the support material is less than 500 ppm by weight, for example in the range from 0 to 400 ppm by weight. Thus, preference is given to a coated catalyst which contains less than 0.05% by weight of halide (determined by ionic chromatography), based on the total weight of the catalyst. Preference is given to support materials which have a specific surface area in the range from 30 to 700 m ² / g, preferably from 30 to 450 m ² / g (BET surface area to DIN 66131). Suitable amorphous support materials based on silicon dioxide are familiar to the person skilled in the art and commercially available (see, for example, OW Flörke, "Silica" in U-IImann's Encyclopedia of Industrial Chemistry, 6th Edition on CD-ROM). They may have been both natural and artificial. Examples of suitable amorphous support materials based on silica are silica gels,

Diatomaceous earth, pyrogenic silicas and precipitated silicas. In a preferred embodiment of the invention, the catalysts used silica gels as support materials. Depending on the configuration of the shell catalyst, the support material may have different shapes. If the process according to the invention in which the shell catalysts are used is designed as a suspension process, the support material in the form of a finely divided powder will usually be used to prepare the catalysts used. The powder preferably has particle sizes in the range from 1 to 200 μm, in particular from 1 to 100 μm. When using the coated catalyst according to the invention in fixed catalyst beds, moldings are usually used, as described above, from the support material.

In a particularly preferred embodiment, the support material of the coated catalyst used, which is in particular a support material based on silicon dioxide, a pore volume in the range of 0.6 to

1, 0 ml / g, preferably in the range of 0.65 to 0.9 ml / g, for example from 0.7 to 0.8 ml / g, determined by Hg porosimetry (DIN 66133), and a BET surface area in the range 280 to 500 m ² / g, preferably in the range of 280 to 400 m ² / g, most preferably in the range of 300 to 350 m ² / g. In shell-type catalysts of this type, at least 90% of the pores present preferably have a diameter of 6 to 12 nm, preferably 7 to 11 nm, particularly preferably 8 to 10 nm. The pore diameter can be determined by methods known to those skilled in the art, for example by Hg porosimetry or N 2 physisorption. In a preferred embodiment, at least 95%, particularly preferably at least 98%, the pores present a pore diameter of 6 to 12 nm, preferably 7 to 1 1 nm, more preferably 8 to 10 nm, on. In a preferred embodiment, there are no pores in these shell catalysts which are smaller than 5 nm. Furthermore, there are preferably no pores in these shell catalysts which are greater than 25 nm, in particular greater than 15 nm. In this context, "no pores" means that no pores with these diameters are found by conventional measuring methods, for example Hg porosimetry or IS physisorption. In preferred coated catalysts, the dispersity of the active metal is preferably from 30 to 60% and more preferably from 30 to 50%. Methods for measuring the dispersity of the active metal are known in the art, including, for example, the pulse desorption, in which the determination of the noble metal dispersion (specific metal surface, crystallite size) is carried out with a CO pulse method (DIN 66136 (1 -3)).

The hydrogenation process according to the invention can be carried out in the liquid phase or in the gas phase. The hydrogenation process according to the invention is preferably carried out in the liquid phase.

The hydrogenation process according to the invention can be carried out both in the presence and in the absence of a solvent or diluent, ie it is not absolutely necessary to carry out the hydrogenation in solution. The solvent or diluent used may be any suitable solvent or diluent. Suitable solvents or diluents are in principle those which are able to dissolve the organic compound to be hydrogenated as completely as possible or completely mix with it and which are inert under the hydrogenation conditions, ie are not hydrogenated. Examples of suitable solvents are cyclic and acyclic ethers having preferably 4 to 8 carbon atoms, for example tetrahydrofuran, dioxane, methyl tert-butyl ether, dimethoxyethane, dimethoxypropane, dimethyldiethylene glycol, aliphatic alcohols having preferably 1 to 6 carbon atoms, such as methanol , Ethanol, n- or isopropanol, n-, 2-, iso- or tert-butanol, carboxylic esters of aliphatic carboxylic acids having preferably 3 to 8 carbon atoms such as methyl acetate, ethyl acetate, acetic acid propyl ester or butyl acetate, methyl propionate, ethyl propionate, butyl propionate and aliphatic ether alcohols such as methoxypropanol and cycloaliphatic compounds such as cyclohexane, methylcyclohexane and dimethylcyclohexane. The amount of solvent or diluent used is not particularly limited and can be freely selected as needed, with at However, use of a solvent, such amounts are preferred, which lead to a 3 to 70 wt .-% solution of the intended organic compound for hydrogenation. In one embodiment of the invention, step b) according to the invention is carried out in bulk.

The actual hydrogenation is usually carried out in analogy to the known hydrogenation for the hydrogenation of organic compounds having hydrogenatable groups, preferably for the hydrogenation of a carbocyclic aromatic group to the corresponding carbocyclic aliphatic group, as described in the aforementioned prior art. For this purpose, the organic compound as a liquid phase or gas phase, preferably as a liquid phase, brought into contact with the catalyst in the presence of hydrogen. The liquid phase can be passed over a catalyst fluidized bed (fluid bed mode) or a fixed catalyst bed (fixed bed mode).

The hydrogenation can be configured both continuously and discontinuously, wherein the continuous process procedure is preferred. Preferably, the process according to the invention is carried out in trickle-bed reactors or in flooded mode according to the fixed-bed procedure, with the implementation in trickle-bed reactors being particularly preferred. In particular, here the compound to be hydrogenated in substance, i. largely absence of organic diluents used (solvent content preferably <10%). The hydrogen can be passed both in cocurrent with the solution of the educt to be hydrogenated and in countercurrent over the catalyst. The hydrogenation can also be carried out batchwise by the batch procedure. In this case, the hydrogenation is preferably carried out in an organic solvent or diluent. In a batchwise implementation of the process according to the invention, the catalyst is typically used in such an amount in step b) that the concentration of ruthenium in the reaction mixture used for the hydrogenation in the range of 10 to 10,000 ppm, especially in the range of 50 to 5000 ppm, especially in the range of 100 to 1000 ppm.

The hydrogenation is typically carried out at a hydrogen pressure in the range of 5 to 50 MPa, in particular in the range of 10 to 30 MPa. The hydrogen can be fed as such, or diluted with an inert, for example nitrogen or argon in the reactor. The hydrogenation in step b) is typically carried out at temperatures above 50 ° C, in particular in the range of 100 to 250 ° C. Apparatuses suitable for carrying out the hydrogenation are known to the person skilled in the art and are directed primarily according to the mode of operation. Suitable apparatuses for carrying out a hydrogenation after the hydrogenation on the catalyst fluidized bed and on the fixed catalyst bed are, for example, from Ullmanns Enzyklopadie der Technischen Chemie, 4th Edition, Volume 13, p. 135 ff., And from PN Rylander, "Hydrogenation and Dehydrogenation" in Ullmann's Encyclopedia of Industrial Chemistry, 5th ed. On CD-ROM.

Compounds of the formula (Ia) in which R ¹ and R ² independently of one another are of groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) _y , where either x and y are each 1 or one of the variables x and y 1 and the other is O, are selected and R ¹ and R ² together comprise a total of 4 to 1 1 carbon atoms, 5 to 1 1 carbon atoms, in particular 4 to 8 carbon atoms and preferably 4 or 5 carbon atoms are also provided by the invention. When R ¹ and R ² together comprise a total of 4 carbon atoms, then R ¹ and R ^{2 are} preferably each ethyl. Compounds of the formula (Ia) according to the invention can therefore be selected, for example, from 1-cyclohexyl-3-methyl-3-heptanol, 1-cyclohexyl-3-methyl-3-octanol, 1 -

Cyclohexyl-3-methyl-3-nonanol, 1-cyclohexyl-3,4-dimethyl-3-octanol, 1-cyclohexyl-3,5-dimethyl-3-octanol, 1-cyclohexyl-3,6-dimethyl-3 octanol, 1-cyclohexyl-3,7-dimethyl-3-octanol, 1-cyclohexyl-3,4,4-trimethyl-3-heptanol, 1-cyclohexyl-3,5,5-trimethyl-3-heptanol, 1 - Cyclohexyl-3,6,6-trimethyl-3-heptanol, 1-cyclohexyl-5-ethyl-3-methyl-3-heptanol, 1-cyclohexyl-3,5-dimethyl-3-heptanol, 2,4-dicyclohexyl 2-methyl-2-butanol, 1-cyclohexyl-4-cyclopentyl-3-methyl-3-pentanol, 1-cyclohexyl-3-ethyl-3-hexanol, 1-cyclohexyl-3-ethyl-3-heptanol, 1 - Cyclohexyl-3-ethyl-3-octanol and 1-cyclohexyl-3-ethyl-3-nonanol. The present invention further provides compositions comprising a compound of formula (Ia)

and a compound of the formula (Ib)

where R ¹ and R ^{2 are} independently selected from groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) _y , as defined above, and R ¹ and R ² together represent a total of 3 to 1 1 carbon atoms, especially 3 to 8 carbon atoms, preferably 3 to 5 carbon atoms and more preferably 3 carbon atoms.

In these compositions, the weight ratio of the compound (s) of formula (Ia) to compound (s) of formula (Ib) is typically in the range of 50: 1 to 1000: 1. Such compositions may also contain small amounts of a corresponding compound of the formula (IV)

and optionally a formula (V)

contained by overreduction of the corresponding compounds of formula (IIIa) or compounds of formula (IIIb). The proportion by weight of the total amount of the compound of formula (IV) and optionally of the compound of formula (V) is usually not 10 wt .-%, in particular 5 wt .-%, based on the corresponding compound of formula (la) if present, is in the range from 0.01 to 10% by weight, in particular in the range from 0.01 to 5% by weight, based on the corresponding compound of the formula (Ia). It is of course also possible to separate compounds of formula (IV) and optionally present compounds of formula (V), for example by distillation, so that the total amount of compound of formula (IV) and optionally present compound of formula (V) less than 1 wt .-%, in particular less than 0.5 wt .-% or less than 0.1 wt .-%, based on the corresponding compound of formula (la), is. A particular composition are concentrates, ie, compositions that are substantially, ie at least 95%, more preferably at least 98% and especially at least 99% or at least 99.5% by weight of a compound of formula (Ia) and small amounts of corresponding compound of formula (Ib), eg compositions wherein the weight ratio of the compound of formula (Ia) to the corresponding compound of formula (Ib) is in the range of 50: 1 to 1000: 1 ,

These concentrates may contain corresponding compounds of the formula (IV) and, if appropriate, corresponding compounds of the formula (V) in the abovementioned amounts. Compositions in which the weight ratio of the compound of the formula (Ia) to the corresponding compound of the formula (Ib) is outside the ranges mentioned here can be obtained by mixing the compound of the formula (Ia) with the desired amount of compound of the formula (Ib ) getting produced. Such compositions are of course also subject of the present invention.

A compound of formula (Ib) may be prepared from a corresponding compound of formula (IIIb) in analogy to step b), i. by a process comprising a heterogeneous-catalytic hydrogenation of the compound of formula (IIIb). The information given above for the hydrogenation in step b) is taken in full reference to the hydrogenation of the compound of formula (IIIb).

In this case, it is possible to initially prepare a compound of the formula (IIIb) in a targeted manner and then to subject it to a heterogeneous-catalytic hydrogenation in analogy to the previously described step b). A compound of the formula (IIIb) can be prepared in a targeted manner by reacting α-methylstyrene with a corresponding compound of the formula (II) under the conditions mentioned above for step a).

However, it is also possible to proceed by first preparing a composition of a compound of the formula (IIIa) and of a corresponding compound of the formula (IIIb), for example in the manner described above for step a), this composition of a heterogeneous catalytic Hydrogenation in analogy to the step b) described above, and the composition thereby obtained, which contains a corresponding compound of formula (Ia) and a corresponding compound of formula (Ib), separates by distillation into its constituents. The distillation can be carried out in analogy to conventional fractional distillation processes. Suitable devices for this purpose are familiar to the expert. The necessary conditions can be determined by routine experimentation. As a rule, the distillation is carried out under reduced pressure. In the compounds of the formulas (Ia) and (Ib) according to the invention, in which R ¹ and R ^{2 are} different, the chiral carbon atom bearing the hydroxyl group may have a different configuration. Accordingly, the present invention also relates to the individual enantiomers and enantiomer mixtures, for example a racemate, of the compounds of the formula (Ia) or of the formula (Ib) according to the invention. The enantiomers can be separated by well-known methods, for example by crystallization, by chiral column chromatography, or by conversion to diastereomers, which are separated by conventional chromatography and distillation techniques and then converted back to the now enantiomerically pure starting materials. In addition, the compounds of the formula (Ib) according to the invention may have a different configuration on the chiral carbon atom bearing the cyclohexyl group. Accordingly, the present invention also relates to individual diastereomers and diastereomer mixtures of the compounds of the formula (Ib) according to the invention. The diastereomers, because of their different physical properties, can be separated by conventional methods, such as chromatography and distillation techniques.

Compounds of the formulas (Ia) and (Ib) as well as the compositions and concentrates likewise described here are odorous substances which can be used as fragrances or flavorings and in particular in cosmetic products, laundry detergents and hard surface cleaners.

The invention thus also relates to cosmetic compositions, laundry detergents and hard surface cleaners, comprising:

i. one or more compound (s) of the formula (Ia), in particular those in which R ¹ and R ² together comprise a total of 3 to 8 carbon atoms and preferably 3 to 5 carbon atoms, more preferably 1-cyclohexyl-3-methyl-3 pentanol, or

ii. a composition comprising a compound of the formula (Ia) and a corresponding compound of the formula (Ib), especially those in which R ¹ and R ² together comprise a total of 3 to 8 carbon atoms and preferably 3 to 5 carbon atoms, more preferably where R is ^{1 is} methyl and R ^{2 is} ethyl. Preference is given to the compound (s) i. or composition ii. contained as additives, ie such cosmetic products, laundry detergents or hard surface cleaning agents contain in addition to i. or ii. Substances or compositions of matter which are suitable for use as cosmetic products, laundry detergents or hard surface cleaners. Examples of suitable cosmetic agents are in principle all cosmetic compositions which usually contain fragrances. These include Eaux-de-Parfum, Eaux-de-Toilette, Eaux-de-Cologne, after-shave products such as lotions and creams, pre-shave products, perfumed towelettes, depilatory creams and lotions, tanning creams and lotions, hair care products such as Shampoos, hair conditioners, hair fixatives, hair gels, hair toners, hair waxes, hair sprays, mousses, hair mousses, top fluids, perming agents, hair colorants and bleaching agents or hot oil treatments, and also skin cleansers such as soaps, washing gels, shower gels, body care preparations such as skin creams, oils, lotions, and the like, such as hands, face, or foot care products, sunscreens, deodorants and antiperspirants, skin disinfectants, insect repellents, and decorative cosmetic products. Depending on the field of application, the cosmetic compositions can be formulated as aqueous or alcoholic liquid, oil, (aerosol) spray, (aerosol) foam, mousse, gel, gel spray, cream, lotion, powder, tabs, or wax.

Detergents include agents for cleaning and / or disinfecting surfaces, such as household cleaners, neutral cleaners, toilet cleaners, floor cleaners, carpet cleaners, window cleaners, polishes, furniture care products, liquid and solid dishwashing detergents, liquid and solid machine dishwashing detergents, as well as Cleaning or treatment of textiles such as solid, semi-solid or liquid laundry detergents, laundry aftertreatment agents, softeners, ironing aids, textile removers, fabric preconditioners, laundry soaps, washing tablets and the like.

Further, the compounds and compositions of the present invention may be used as a perfume ingredient in other perfume-containing products such as air cleaners, lamp oils, candles, room air improvers, WC bricks, and the like.

The compound of the formula (Ia) in the compositions, cosmetic agents, textile detergents, cleaning compositions and uses according to the invention can be selected, for example, from 1-cyclohexyl-3-methyl-3-pentanol, 1-cyclohexyl-3-methyl-3-hexanol, 1 -Cyclohexyl-3-methyl-3-heptanol, 1-cyclohexyl-3-methyl-3-octanol, 1-cyclohexyl-3-methyl-3-nonanol, 1-cyclohexyl-3,4-dimethyl-3-octanol, 1 -

Cyclohexyl-3,5-dimethyl-3-octanol, 1-cyclohexyl-3,6-dimethyl-3-octanol, 1-cyclohexyl-3,7-dimethyl-3-octanol, 1-cyclohexyl-3,4,4- trimethyl-3-heptanol, 1-cyclohexyl-3,5,5-trimethyl-3-heptanol, 1-cyclohexyl-3,6,6-trimethyl-3-heptanol, 1-cyclohexyl-5-ethyl-3-methyl 3-heptanol, 1-cyclohexyl-3,5-dimethyl-3-heptanol, 2,4-dicyclohexyl-2-methyl-2- butanol, 1-cyclohexyl-4-cyclopentyl-3-methyl-3-pentanol, 1-cyclohexyl-3-ethyl-3-hexanol, 1-cyclohexyl-3-ethyl-3-heptanol, 1-cyclohexyl-3-ethyl 3-octanol and 1-cyclohexyl-3-ethyl-3-nonanol. The invention will be explained in more detail with reference to the following examples:

Example 1: Preparation of the hydrogenation catalyst

The carrier material used was a spherical SiO 2 carrier (type AF125 from BASF SE) with a spherical diameter of 3 to 5 mm and a shaking density of 0.49 kg / l. The BET surface area was 337 m ² / g, the water absorption (WA) at 0.83 ml / g. For impregnation, a 14.25 wt .-% solution of ruthenium (III) acetate in acetic acid (from Umicore). 200 g of carrier were placed in a round bottom flask. 15 g of the ruthenium acetate

Solution was diluted to 150 ml with distilled water (90% WA). The support material was placed in the distillation flask of a rotary evaporator and the first quarter of the solution was pumped onto the support material at a gentle vacuum at 3 to 6 rpm. After completion of the addition, the support was left in a rotary evaporator at 3 to 6 rpm for a further 10 minutes to homogenize the catalyst. This impregnation homogenization step was repeated three times until all the solution had been applied to the support. The thus treated support material was dried in a rotary kiln at 140 ° C, then for 3 h at 200 ° C in a stream of hydrogen (20 l / h H ₂ , 10 l / h N ₂ ) and passivated at 25 ° C (5% air in N2, 2 h). The novel catalyst A obtained in this way contained 0.34% by weight of ruthenium, based on the total weight of the catalyst.

Step a) - Example 2: Preparation of 3-methyl-1-phenyl-3-pentanol The reaction of styrene and 2-butanol was carried out in a continuously operated laboratory plant. This included a 300 ml autoclave operated under pressure control. Thus, the removal amount corresponded at any time of the entry amount. The withdrawn reaction mixture was cooled, vented and collected in a discharge vessel.

A solution of styrene in 2-butanol (20 wt .-%, 100 g / h) was pumped continuously through the laboratory system at an average temperature of 390 ° C in the reactor. The conversion of styrene was 84.0% and in the steady state, 14.7 g / h of 3-methyl-1-phenyl-3-pentanol were obtained. Step b) - Example 3: Preparation of 1-cyclohexyl-3-methyl-3-pentanol

In a 300 ml autoclave were added 5.6 g of 3-methyl-1-phenyl-3-pentanol dissolved in 94.4 g of tetrahydrofuran and 1.6 g of a catalyst prepared according to Example 1 (0.35% ruthenium on silica). submitted. The autoclave was purged three times with nitrogen and then hydrogenated for 10 hours at 160 ° C and 160 bar hydrogen pressure. The effluent was analyzed by gas chromatography (polydimethylsiloxane DB1, 30 m, internal diameter: 0.25 mm, film thickness: 0.25 μm, 50 ° C., 5 minutes isothermal, -6 ° C./min, 290 ° C., 219 minutes isothermal) , The conversion was 99.9%, the selectivity at 93%.

Claims

claims

1 . Process for the preparation of a compound of formula (Ia)

comprising: a) the reaction of styrene with a compound of the formula (II)

O H

wherein a compound of the formula (IIIa)

and the heterogeneously catalytic hydrogenation of the compound of the formula (IIIa) Compound of the formula (Ia) in which R ¹ and R ² independently of one another are of groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) y, wherein either x and y are each 1 or one of the variables x and y is 1 and the other is 0, and in particular selected from Ci-7-alkyl, C3-7-cycloalkyl and C4-7-cycloalkylalkyl, and

R ¹ and R ² together comprise a total of 3 to 1 1 carbon atoms.

2. The method of claim 1, wherein the reaction in step a) under

Conditions in which the compound of formula (II) is in the supercritical state.

3. The method according to claim 1 or 2, wherein in step a) further comprises a

Compound of formula (IIIb)

obtained, which is hydrogenated in step b) heterogeneously catalytically to a compound of formula (Ib)

Method according to one of the preceding claims, wherein the reaction in step a) at a temperature, in the range of 250 to 500 ° C and a pressure in the range of 5 to 50 MPa. 5. The method according to any one of the preceding claims, wherein the molar ratio of the styrene used in step a) to the compound used in step a) of the formula (II) in the range of 1: 5 to 1: 200. 6. The method according to any one of the preceding claims, wherein the catalyst used in step b) contains at least one selected from palladium, platinum, cobalt, nickel, rhodium, iridium, ruthenium active metal.

7. The method of claim 6, wherein the catalyst used in step b) contains ruthenium as the active metal.

8. The method according to claim 6 or 7, wherein the catalyst used in step b) contains at least one further active metal of the subgroups IB, VII B or VIIIB of the Periodic Table of the Elements (CAS version). 9. The method according to any one of the preceding claims, wherein one carries out step b) in trickle mode. 10. The method according to any one of the preceding claims, wherein R ^{1 is} methyl and R ^{2 is} ethyl.

1 1. Compound of the formula (Ia)

where R ¹ and R ² independently of one another are groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) y, where either x and y are each 1 or one of the variables x and y 1 and the other 0 is, and in particular among Ci-7-alkyl, C3-7-cycloalkyl and C4-7-cycloalkylalkyl selected and

R ¹ and R ² either together comprise a total of 5 to 1 1 carbon atoms or are each ethyl.

12. Composition containing a compound of the formula (Ia)

and a compound of the formula (Ib)

R ¹ and R ² together comprise a total of 3 to 1 1 carbon atoms.

13. The composition of claim 12, wherein R ^{1 is} methyl and R ^{2 is} ethyl.

14. Use of a compound of the formula (Ia)

wherein R ¹ and R ^{2 are} independently selected from groups of the formula (C 3-7 cycloalkyl) _x - (C 1-7 alkyl) y, where either x and y are each 1 or one of Variables x and y are 1 and the other is 0, and especially under Ci-7-alkyl, C3-7-

Cycloalkyl and C4-7-cycloalkylalkyl are selected and

R ¹ and R ² together comprise a total of 3 to 1 1 carbon atoms, as a fragrance, in cosmetic products, in laundry detergents or in

Cleaning agents for hard surfaces.

15. Cosmetic, textile or hard surface cleaners containing a compound of formula (Ia)

where R ¹ and R ² independently of one another are groups of the formula (C 3-7 -cycloalkyl) _x - (C 1-7 -alkyl) y, where either x and y are each 1 or one of the variables x and y 1 and the other 0 is, and in particular among Ci-7-alkyl, C3 cycloalkyl and C4-7-cycloalkylalkyl selected and

R ¹ and R ² together comprise a total of 3 to 1 1 carbon atoms.