DE1951883C3 - Process for the preparation of penta-2,4-dien-1-alene and new compounds of this class of compounds - Google Patents

Description

C CH CHO

ι, c c

HI

R ₃

(I) HO R ₁

ίο \ |

C CH

R ₂ C

(II)

in which Ri stands for a hydrogen atom or, like R2, a hydrocarbon radical with up to 40 carbon atoms which can contain oxygen atoms as heteroatoms, Ri and R ₂ together with the carbon atoms which they substitute can also denote a 5- to 7-membered ring and R3 stands for stands for an alkyl radical, characterized in that propargyl alcohols of the general formula

in which Ri and R _{2 have} the meaning given, with Λ-formyl carboxylic acid esters of the general formula

OH
R ₄ OC-C CHO

C CH

αϊ)

in which Ri and R _{2 have} the meaning given, with Λ-formyl carboxylic acid esters of the general formula

R ₄ OC C CHO

R ₃

(III)

in which Rj has the meaning given and R4 for is an alkyl radical, is reacted at temperatures of 100 to 350 ° C.

2. 2,5,9-trimethyldeca-2,4,9-triene-1-al.

3. 9-methoxy-2,5,9-trimethyldeca-2,4-diene-1-al.

4. 2,5,9-trimethyldeca-2,4-dien-1-al.

5. 2,5,9,13-tetramethyltetradeca-2,4,8,11-tetraen-1-al.

6. 6-ethyl-2-methyldeca-2,4-diene-1-al.

The invention relates to a process for the preparation of penta-2,4-dien-1-alene by reaction of substituted propargyl alcohols with α-formyl carboxylic acid esters. The invention also relates to new penta-2,4-diene-1-aIe.

It has been found that penta-2,4-diene-1-ales of the general formula

CH CHO

(i)

R ₃

has and R4 is an alkyl radical in which R 3 is as defined above, at temperatures of 100 to 350 ⁰ C.

The new process has the advantage that a large number of penta-2,4-dien-1-alene is easily accessible.
The process also has the advantage that it proceeds with good yields.

Preferred starting materials il are those in which Ri stands for a hydrogen atom or, like R _2, an aliphatic hydrocarbon radical with 1 to 40 carbon atoms, a 5- to 8-membered, cycloaliphatic hydrocarbon radical with 6 to 8 carbon atoms, an araliphatic hydrocarbon radical with up to 8 carbon atoms, in particular represents a benzyl radical or a phenyl or naphthyl radical. The hydrocarbon radicals may contain oxygen atoms as heteroatoms, e.g. B. as aldehyde, keto, alkoxy or carbalkoxy groups, especially as alkoxy groups. In particularly preferred starting materials II, Ri denotes a hydrogen atom or, like R2, an aliphatic hydrocarbon radical with 1 to 32 carbon atoms which can have 1 to 2 alkoxy groups with 1 to 4 carbon atoms as substituents, a cyclohexyl radical, a benzyl radical or a phenyl radical. In the particularly preferred starting materials II, Ri and R ₂ together can also denote a 6-membered ring. Starting materials II in which Ri is a methyl group and R _{2 is} a group of the general formulas are of particular industrial importance

55

CH ₃

H - (- CH ₂ -CH-CH ₂ -CH ₂ - ^ -

or

H-

- C - CH ₂ -CH ₂

CH ₃
-CH ₂ -C = CH-CH ₂ -

in which Ri stands for a hydrogen atom or is like R ₂ , where η is an integer from 1 to 8.

Suitable starting materials are, for example

3,7-dimethyl-oct-7-en-1-yn-3-ol,

7-methoxy-3,7-dimethyl-oct-1-yn-3-oL

SJ-dimethyl-oct-ö-en-1-yn-S-ol;

Dehydronerolidol, 4-AUIyI-OCt-l-in-3-oI or

Dehydroisophytol,

S-methyl-pent-1-yn-a-ol,

3-methyl-but-1-yn-3-oI,

Ethynylcyclohexanol and ethynylcydooctanol.

In the preferred starting materials III, R ₃ denotes an alkyl radical with 1 to 12 hydrocarbon atoms, in particular with 1 to 4 carbon atoms, and R ₄ denotes an alkyl radical with 1 to 4 carbon atoms. Suitable starting materials are, for example

a-formylpropionic acid methyl ester,

a-formylpropionic acid n-butyl ester,

a-formylbutyric acid methyl ester,

a-formylbutyric acid n-butyl ester and

«-Formyloctanecarboxylic acid methyl ester.
It is advantageous to use 1 to 5 moles of the starting material III per mole of starting material II. Particularly good results are obtained if one uses per mol of starting material III, 2 to 2.5 mols of starting material III

The reaction is carried out at temperatures of 100 to 350 ^° C. Temperatures of 120 to 220 ° C. have proven particularly useful. In general, the reaction is carried out at normal pressure. However, it is also possible to use pressures of 130 mbar to 10 bar.

In general, no solvents are used for the reaction, but it is also possible to use solvents and diluents, e.g. B. inert high-boiling hydrocarbons such as perhydro- and tetrahydronaphthalene, dimethylformamide and N-methylpyrrolidone.

The process according to the invention is carried out, for example, by placing in a reaction vessel the starting materials II and III in the given ratio, optionally together with a solvent presented and heated to the temperatures described Since in this reaction alcohol and Carbon dioxide are split off, the end of which is easy to determine. The reaction mixture is then optionally after removing solvents by known methods, e.g. B. by fractional distillation, worked up Unreacted starting materials can be fed back into the reaction. It is possible to carry out the reaction continuously in a simple manner.

The compounds produced according to the invention are fragrances, and they are also suitable for production of biologically active compounds.

The method of the invention is illustrated by the following examples:

example 1

A mixture of 76
and 87 g of a-formylpropionate was heated to 160 ⁰ C. The cleaved methanol wild over a column continuously distilled off during the reaction increases the temperature up to 230 "C After about 3 hours the reaction is complete The reaction mixture is worked up by fractional distillation 71 g (76% of theory) of 2,5,9-trimethyldeca-2,4,9-trien-1-al with a boiling point of 98 to 99 ° C. at 0.013 mbar with a refractive index η I ⁵ = 1.5299 are obtained. The process product has a pronounced fruity note that is reminiscent of raspberries

Example 2

A mixture of 92 g of 7-methoxy-3,7-dimethyl-oct-lin-3-ol and 87 g of a-formylpropionate, as described in Example 1 for 5 hours at temperatures of 150 to 200 ⁰ C heated by fractional distillation of the reaction mixture, 79 g (74% of theory) of 9-methoxy-2,5,9-trimethyldeca-2,4-dien-1-al with a boiling point of 109 to 12 ° C. at 0.7 mbar with a refractive index ni ^} = 1 are obtained , 5165.

Example 3

A mixture of 77 g of 3,7-dimethyl-oct-l-yn-3-ol and 87 g of methyl Λ-formylpropionate is heated to temperatures of 155 to 210 ° C. for 3 hours, as described in Example 1. By fractional distillation, from the reaction mixture 69 g (73% of theory) of 2,5,9-Trimethyldeca-2,4-dien-l-ai of boiling point 78 to 81 ⁰ C at 0.24 mbar with the refractive index /? £? = 1.5132.

Example 4

A mixture of 110 g and 87 g Dehydronerolidol a-formylpropionate, as described in Example 1 for 2 hours at 180 to 200 ⁰ C is heated from the reaction mixture obtained by fractional distillation in a yield of 63% 2,5,9,13 -Tetramethyltetradeca ^ AS.ll-tetraen-l-al from the boiling point 125 to 127 ° C at 0.03 mbar with the refractive index / j | ⁵ = 1.5190.

Example 5

A mixture of 77 g of 4-ethyl-oct-l-en-3-ol and 87 g of a-formylpropionate was heated for 5 hours at temperatures of 145 to 22O ⁰ C. Fractional distillation gives the reaction mixture in a yield of 68% 6-ethyl-2-methyldeca-2,4-dien-1-al with a boiling point of 74 to 78 ° C. at 0.3 mbar with a refractive index n " -1 , 5148.

Claims (1)

Patent claims: 1. Process for the preparation of penta-2,4-diene-1 -den of the general formula denotes a hydrocarbon radical with 1 to 40 carbon atoms which can contain oxygen atoms as heteroatoms, R] and R ₂ together with the carbon atoms which they substitute can also form a 5- to 7-membered ring and R3 represents an alkyl radical, advantageously obtained if one propargyl alcohols of the general formula