DE4236887A1 - New 3-(4-methylphenyl(-2-(ar)alkylpropanal cpds. - prepn. from 3-(4-methylphenyl)-2-(ar)alkylpropan-1-ol cpds. and used in perfumes - Google Patents

Abstract

3-(4-methylphenyl)-2-(ar)alkylpropanals of formula (I) are claimed. R = 3-10C alkyl, (substd.) 6-10C aryl, or 7-10C araliphatic gp. USE/ADVANTAGE - Use of (I) as component of perfumes is claimed. (I R = CH3) have an orange-citrus note, and the process provides a simple, economical prepn. of cpds. with different underlying notes.

Description

The present invention relates to aldehydes of general formula I so as a method for their production and their application. R can do this the meaning of optionally branched alkyl radicals or cycloalkyl radicals, of optionally substituted aryl radicals, such as. As the phenyl group, or of ara liphatic radicals, such as. As the benzyl group.

The compound of the formula I where R =CH ₃ is a desired odoriferous substance which is used in the perfume industry (compare Ullmann's Encyclopedia of Ind. Chem. Vol. A1, page 343).

The representation of the above compounds is usually about an aldol condensation of 4-methylbenzaldehyde with corresponding alipha or araliphatic aldehydes, with alkali hydroxide or alkali alcoholate is used as the base (see L. Appell, Cosmetics, Fragran ces and Flavors, First Edition, 1982, Novox Inc. 372; GB-PS 798 901, U.S. Patent 1,844,013; U.S. Patent 2,875,131; and EP-A 0 392 258).

The resulting 3-aryl-2- (ar) alkyl propenals are then with catalytically excited hydrogen to the corresponding saturated Al hydrogenated dehydrated.

The substituted benzaldehydes are known in the art in general by oxidation of the corresponding alkylbenzenes - be it electrochemically (U.S. Patent 3,985,809), with oxygen (R.A. Sheldon, J. Kochi, Metal-Cataly zed Oxidations of Org. Compounds, Academic Press 1981, 315) or above a halogenation followed by hydrolysis - prepared. This Her Positioning methods are complex and associated with high costs.

In the electrochemical oxidation and in the air oxidation of Me Methyl aromatics are used metal salts that are difficult to dispose of.  

In addition, the aromatic aldehydes are only obtained in acceptable selectivity if the conversion of the reaction is limited to less than 50% remains. The space / time yields of these methods are therefore low.

In the specific case of 4-methylbenzaldehyde, the electrochemical and the air oxidation, starting from p-xylene, particularly poorly applicable, since both methyl groups of p-xylene can be oxidized. Also the way via the chlorination of p-xylene separates completely, since p-xylene is not se can be chlorinated selectively to 4-methylbenzal chloride.

Furthermore, compounds of the formula I where R =CH ₃ and C ₂ H _{5 were} prepared by reacting toluene with methacrolein or ethacrolein in a direct manner (Bull Soc Soc. Fr., [1961], 1194, DE-PS 11 45 161). However, this stoichiometric amounts of Lewis catalysts are benö taken, the yield of the reaction is only about 20%.

Another approach for the preparation of compounds of formula I be is in getting them out of the corresponding formula II alcohols to gain selective oxidation.

The starting compounds of the formula II and an advantageous process for their preparation are the subject of patent application P. , , (= O.Z. 4694) with the same filing date.

In compounds of the formula II, R may have the meaning of optionally branched Alkyl radicals or cycloalkyl radicals, of optionally substituted aryl radicals, such as As the phenyl group, or of araliphatic radicals, such as. B. the benzyl group. Compounds of formula II can be in good Yields by Aldol condensation of Terephthalaldehydsäuremethylester with aliphatic or araliphatic aldehydes and subsequent hydrie tion of the condensation product are made on Kupferchromit. Terephthalaldehydsäuremethylester is in turn a by-product of Terephthalic acid dimethyl ester production and thus readily available.  

Aliphatic and araliphatic aldehydes can be synthesized by Dehy tion of the corresponding alcohols in the gas phase. This naturally requires high temperatures (Houben Weyl 4 (2), 333) [1955]).

Methods of selective oxidations of primary alcohols to the corre sponding aldehydes under mild conditions and using bil Volatile oxidants are barely known. The Swern oxidation (Milos, Hudlicky, Oxidations in Organic Chemistry, [1990], American Chemical Society, 145) is suitable, for example, only for laboratory conversions, since the necessary agents, dimethyl sulfoxide and oxalyl chloride, expensive Che must be used and stoichiometric.

In industrial chemistry, catalytic processes are sought, in those with cheap oxidants primary alcohols selectively to the Aldehydes can be oxidized.

From the publication by Anelli et al. (J. Org. Chem. 52, 2559 [1987]) is known to be primary alcohols at low temperatures (0 to 5 ° C) selectively with sodium hypochlorite to the aldehydes when, as a catalyst, a 2,2,6,6-tetramethylpiperidine-N-oxyl-deri vat of formula III is used.

In a two-phase system of water and methylene chloride, the kata lysator of formula III in the organic phase and the cocatalyst Potassium bromide is dissolved in the aqueous phase, the substrate is pre-exposed sets. A 2.5% sodium hypochlorite solution combined with sodium hydrogencar carbonate has been brought to a pH of about 8.6, is at 0 to 5 ° C added dropwise.  

Also primary alcohols that substitute in α-position with a heterocycle were oxidized under the above conditions to the aldehydes, but not sodium bicarbonate, but a hydrogen / dihydro genphosphate buffer was used; see EP-A 316,763. In this case however, a 14% sodium hypochlorite solution could be used which improved the space / tent yield. But also in this procedure For the reaction of 1 mol of starting material, 600 ml of water and 600 ml of methyl were used chloride plus the water volume of the sodium hypochlorite solution be forces.

In addition, the oxidation of 4-chloro-butanol to 4-chlorobutanal is under the latter conditions have been described (EP-A 340 703).

Potassium bromide is also an essential co-product in other publications. Catalyst for the oxidation of primary alcohols by means of 2,2,6,6-Te tramethylpiperidine N-oxyl derivatives and sodium hypochlorite to the aldehyde den (Anelli et al., J. Org. Chem. 54, 2970 [1989]; Sharzewski et al., Tetrahedron Lett. 2177 [1990]).

For the previously described process for the oxidation of primary alcohol len to the aldehydes by sodium hypochlorite by means of 2,2,6,6-tetrame Thylpiperidin-N-oxylderivaten is characteristic that on the one hand large Solvents and on the other hand potassium bromide required as cocatalyst wherein the potassium bromide in an aqueous phase together with the organic phase is submitted.

The compound of formula I with R = CH ₃ (JASMORANGE®) has an orange-like citrus note. It is desirable to find variants of this citrus note with different subnotes.

It was the object of the invention, further 3- (4-methylphenyl) -2- (ar) alkyl Propanals with good fragrance properties and a method for their Preparation starting from 3- (4-methylphenyl) -2- (ar) alkyl Propan-1-olene (formula II) is simple and economical.  

This problem was solved by providing the invention Compounds of the formula I and their preparation by catalytic Oxi dation of compounds of formula II.

The invention provides 3- (4-methylphenyl) -2- (ar) alkylpropanals of general formula I

where R is a straight-chain or branched alkyl radical having 3 to 10 C Atoms, an unsubstituted or substituted aryl radical having 6 to 10 C atoms or an araliphatic radical having 7 to 10 carbon atoms.

Another object of the invention is a process for the preparation of 3- (4-methylphenyl) -2- (ar) alkylpropanals of general formula I.

wherein R is a straight-chain or branched alkyl radical having 1 to 10 C Atoms, an unsubstituted or substituted aryl radical having 6 to 10 C atoms or an araliphatic radical having 7 to 10 carbon atoms meaning tet, which is characterized in that 3- (4-methylphenyl-2- (ar) alkylpropan-1-ols of the formula II

wherein R is a straight-chain or branched alkyl radical having 1 to 10 C Atoms, an unsubstituted aryl radical having 6 to 10 carbon atoms or a araliphatic radical having 7 to 10 carbon atoms, in the presence of 2,2,6,6-Tetramethylpiperidin-N-oxyl derivatives of the formula III

and organic solvents with sodium hypochlorite and sodium hydrogen carbonate added.

In the process according to the invention, sodium hypochlorite is referred to as oxida tion agent and a piperidine derivative of the formula III as a catalyst be uses. Preferably, the compound III is used with X = OH, since these in a simple manner by catalytic oxidation of Triacetonaminalkohol is available (DE-OS 42 19 459). Surprisingly, it was found that Alcohols of the general formula II according to a highly simplified method using sodium hypochlorite and a 2,2,6,6-tetramethylpiperidine N-oxyl as a catalyst in good yields selectively to the aldehydes of the formula I. can be implemented.

The solvents used are methyl tert-butyl ether, butyl chloride, toluene or other water immiscible compounds. The solvents amount is already sufficient with about 250 g per mole of alcohol and thus considerably smaller than in the aforementioned publications and godparents th.

Furthermore, no two-phase mixture is presented, but only the Lö solution of the alcohol and the 2,2,6,6-tetramethyl-piperidine-N-oxyls in the organic solvents. Sodium hypochlorite will be beneficial as about 13% solution, which also 20 mol% sodium bicarbonate (relative to the substrate) and used at about 0 to 5 ° C within added dropwise for about 1 h.

Surprisingly, the presence of potassium bromide in the form of a aqueous second phase, which is in contact with the organic phase is not necessary for the reaction. This reduces the size  Reaction volume considerably. In addition, one avoids bromide in Ab water.

Another object is finally the use of erfindungsge MAESSEN compounds as fragrance component.

example 1 3- (4-methylphenyl) -2-methylpropanal

In a 2 liter three-necked flask, a mixture of 250 g of methyl tert-bu Tylether, 164 g (1 mol) of 3- (4-methylphenyl) -2-methylpropan-1-ol, 1.7 g (10 mmol) 2,2,6,6-tetramethyl-4-hydroxy-piperidine-N-oxyl and 15 g (180 mmol) of sodium bicarbonate at 0 to 5 ° C presented. Under With rapid stirring, 750 g (1.3 mol) of 13% Na Na are added within 1 h added triumhypochloritlösung. You stop the emotion, leave on room temp warming up and separates the upper organic phase. After drying tion of the organic phase over sodium sulfate, the MTB ether abde quenched and the residue fractionated in vacuo. The yield of 3- (4- Methylphenyl) -2-methylpropanal is 130 g (80%), boiling point: 96 ° C at 1 mbar.

Example 2 3- (4-methylphenyl) -2-ethylpropanal

In a 2 liter three-necked flask, a mixture of 250 g of methyl tert-bu Tylether, 178 g (1 mol) of 3- (4-methylphenyl) -2-ethyl-propan-1-ol, 1.7 g (10 mmol) 2,2,6,6-tetramethyl-4-hydroxy-piperidine-N-oxyl and 15 g (180 mmol) of sodium bicarbonate at 0 to 5 ° C presented. Under With rapid stirring, 750 g (1.3 mol) of 13% Na Na are added within 1 h added triumhypochloritlösung. You stop the emotion, leave on room temp warming up and separates the upper organic phase. After drying tion of the organic phase over sodium sulfate, the MTB ether abde quenched and the residue fractionated in vacuo. The yield of 3- (4- Methylphenyl) -2-ethylpropanal is 139 g (80%), boiling point: 97 ° C at 1 mbar.  

Example 3 3- (4-methylphenyl) -2-isopropylpropanal

A mixture of 250 g of methyl tert-butyl ether, 192 g (1 mol) of 3- (4-methylphenyl) -2-isopropylpropan-1-ol, 1.7 g (10 mmol) is placed in a 2 l three-necked flask. 2,2,6,6-tetramethyl-4-hydroxy-piperidine-N-oxyl and 15 g (180 mmol) of sodium bicarbonate at 0 to 5 ° C presented. With rapid stirring is added within 1 h 750 g (1.3 mol) of 13% sodium triumhypochloritlösung added. Stirring is stopped, the mixture is allowed to warm to room temperature and the upper organic phase is separated off. After drying the organic phase over sodium sulfate, the MTB ether is distilled off and the residue is fractionated in vacuo. The yield of 3- (4-methylphenyl) -2-isopropylpropanal is 148 g (78%), boiling point:
100 ° C at 2.5 mbar.

Example 4 3- (4-methylphenyl) -2-heptylpropanal

In a 2 liter three-necked flask, a mixture of 250 g of methyl tert-bu Tylether, 248 g (1 mol) of 3- (4-methylphenyl) -2-heptylpropan-1-ol, 1.7 g (10 mmol) 2,2,6,6-tetramethyl-4-hydroxy-piperidine-N-oxyl and 15 g (180 mmol) sodium bicarbonate at 0 to 5 ° C presented. Under fast Stirring is added within 1 h 750 g (1.3 mol) of 13% sodium hypo chlorite solution added. Stop stirring, let it warm to room temperature warm and separate the upper organic phase. After drying the organic phase over sodium sulfate, the MTB ether is distilled off and the residue is fractionated in vacuo. The yield of 3- (4-methylphenyl) - 2-heptylpropanal is 200 g (81%), boiling point: 150 ° C at 0.2 mbar.

Example 5 3- (4-methylphenyl) -2-benzylpropanal

In a 2 liter three-necked flask, a mixture of 250 g of methyl tert-bu tyl ether, 240 g (1 mol) of 3- (4-methylphenyl) -2-benzylpropan-1-ol, 1.7 g (10 mmol) 2,2,6,6-tetramethyl-4-hydroxy-piperidine-N-oxyl and 15 g (180 mmol) sodium bicarbonate at 0 to 5 ° C presented. Under fast Stirring is added within 1 h 750 g (1.3 mol) of 13% sodium hypo chlorite solution added. Stop stirring, let it warm to room temperature warm and separate the upper organic phase. After drying the  organic phase over sodium sulfate, the MTB ether is distilled off and the residue is fractionated in vacuo. The yield of 3- (4-methylphenyl) - 2-benzylpropanal is 190 g (80%), boiling point: 145 ° C at 0.2 mbar.

Example 6 - Application example

Using 3- (4-methylphenyl-2-butylpropanal, a compo produced with a citrus note:

limonene 83 parts by weight cis-ocimene 35 parts by weight 3- (4-methylphenyl) -2-butylpropanal 392 parts by weight linalool 8 parts by weight isopulegol 21 parts by weight α-bergamotene 1 part by weight caryophyllene 4 parts by weight citronellyl 25 parts by weight neral 6 parts by weight geranial 8 parts by weight Citronellol 170 parts by weight Geranylacetat 3 parts by weight nerol 3 parts by weight elemol 21 parts by weight eugenol 6 parts by weight geraniol 214 parts by weight 1000 parts by weight

3- (4-methylphenyl) -2-butylpropanal has a fresh-agry note with subtle, jasmine undertone. She gives the above composition a fresh, aldehydic appearance.

Claims (3)

1. 3- (4-methylphenyl) -2- (ar) alkylpropanals of the general formula I. wherein R is a straight-chain or branched alkyl radical having 3 to 10 carbon atoms, an unsubstituted or substituted aryl radical having 6 to 10 carbon atoms or an araliphatic radical having 7 to 10 carbon atoms. 2. A process for the preparation of 3- (4-methylphenyl) -2- (ar) alkylpropana len the general formula I. where R is a straight-chain or branched alkyl radical having 1 to 10 C atoms, an unsubstituted or substituted aryl radical having 6 to 10 C atoms or an araliphatic radical having 7 to 10 C atoms, which is characterized in that 4-Methylphenyl nyl-2- (ar) alkylpropan-1-ols of the formula II where R is a straight-chain or branched alkyl radical having 1 to 10 C atoms, an unsubstituted aryl radical having 6 to 10 C atoms or an araliphatic radical having 7 to 10 C atoms, in the presence of 2,2,6,6- Tetramethylpiperidine N-oxyl derivatives of the formula III and organic solvents with sodium hypochlorite and Natriumhydro gencarbonat added. 3. Use of 3- (4-methylphenyl) -2- (ar) alkylpropanals according to claim 1 as fragrance component.