DE2161084C3 - Mixtures of the acetals of a- and ß-sinensals and isomeric acetals of similar structure and a process for their production - Google Patents

Description

The invention relates to mixtures of the acetals of the «- and / 3-sinensals and isomeric acetals of analogous structure, as well as a process for the preparation of these compounds,
They are therefore mixtures of isomeric acetals of the general formulas I a and I b

R'-O

R ² - θ ' R ¹ -O

R ² - O

CH-

CH

CH ₁

C = CH-CH ₂ -CH ₂ -

CH ₃

C = CH-CH, -CH,

CH ₃

-C = CH-CH, -CH = C- CH = CH,

CH ₃ CH ₃

Γ H

-C = CH-CH, -CH, -C-CH = CH ₂

(I af

(Ib)

in which R ¹ and R ² each denote aliphatic hydrocarbon radicals with 1 to 4 carbon atoms or R ¹ and R ² together denote an alkylene group with 2 to 5 carbon atoms and η denotes the numbers 0.1 or 2

The new compounds have aromas and flavors with a tangerine and orange effect found strong interest in the beverage industry, as they are more stable due to their chemical constitution are considered to be the relatively unstable natural orange fragrances and flavors SinensaL

The fact that there is a great need for odorous and aromatic substances with tangerine and orange effects results from the large number of publications on constitution and attempts at the synthetic production of the natural odorous and aromatic substances of oranges, «- and the jS-Sinensal (compare e.g. A. Thomas, J. Amer. Chem. Soc. 91 [1969J 3281; G. _J5 Büchi etaL, HeIv. Chim. Acta 50 [1967], 2440; E. Bertele et al, HeIv. Chim. Acta 50 [ 1967J 2445; DT-OS 17 68 659; DT-OS 17 93 710; DT-OS 17 93 711 and DT-OS 17 68 793). Despite the countless attempts, the fully synthetic production of <x- and j9-Sinensal according to the prior art could not be realized in a simple manner with satisfactory yields. The known processes for the production of sinensalen are largely based on natural substances such as ocimene and / or myrcene, which are usually not always present or are not present in sufficient quantities, or from compounds that are difficult to access synthetically, such as trans-farnese. In contrast, you get the coveted sinensals by simple acid hydrolysis from the acetals according to the invention of the formulas Ia and Ib * in which η stands for the number 1, which in turn can be produced fully synthetically in a relatively simple manner from intermediates available in the art. So for the production of Sinensalacetalen according to the simple process of the present invention, a mixture of the isomeric phosphonium salts 4-methylene-5-hexene-1 and 4-methyl-3,5-hexadiene-1-triphenylphosphonium iodide and 2-methyl-2- hepten-6-on-l-al-acetal necessary. Said mixture can be obtained from acetobutyrolactone, which is technically readily available as an intermediate for the production of vitamin Bi, by ring splitting with HCl, Grignard vinylation of the 1-halopentanone- (4) obtained and reaction with triphenylphosphine. The 2-methyl-2-hepten-6-one-1-al-acetal can be obtained from the 2-methyl-2-hydroxy-3-buten-1-al-dimethyl acetal, which is readily available as an intermediate product in a technical vitamin A synthesis Reacting with phosgene to the acetals of 2-methyl-4-halogen-2-butene-1-than, reacting the same with an alkali compound of an acetoacetic ester and subsequent alkaline thermal cleavage of the COOR ³ * group can be obtained.

In addition to the new acetals of the general formulas Ia and Ib, the invention relates to a Process for the preparation of the same, which is characterized in that in a manner known per se

a) a mixture of the isomeric phosphonium salts of the general formulas IHa and IHb

CH ₂ - P ⁺ (C ₆ H ₅ J ₃ · Χ "

-CH, -CH, -C = CH

-I ₂ - ^ n ₂

CH ₃ -CH ₂ -CH = C-CH = CH ₂

CH,

CH,

CH ₂ -CH ₂ -C = CH CH ₂

Il

-CH ₂ -CH ₂ -C-CH = CH ₂

(HIa)

(III b)

P ⁺ (C ₆ H ₅ ), · Χ "

in which X is chlorine, bromine or iodine and ρ stands for the numbers 0 or 1, in an inert organic solvent with an approximately equimolar amount of a strong base and

5 6

b) the triphenylphosphin-ylenes obtained with acetals of the general formula II

R <- O

CH

C = CH-CH, -CH,

-C = O

R ² -O

in which R ¹ and R ^{2 have} the meaning given above and m stands for the numbers O or 1. The isomeric phosphonium salts IHa and IHb are prepared in a simple manner by reacting triphenylphosphine with the corresponding halogen compounds of the formulas IVa and IVb.

CH,

CH ₃
CH ₂ -CH ₂ -C = CH CH ₃
CH ₂ -CH = C-CH = CH ₂

(IVa)

CH, -X

CHv-CH, -C = CH

The bromine or iodine compounds are preferably used here, since the conversion of the chlorine products is accompanied by increased formation of by-products. The reaction is carried out in an inert solvent such as benzene, toluene, xylene or ligroin at temperatures from 40 to 200 ^° C., preferably from 50 to 150 ^° C. The residence time is between one and 50 hours, preferably between 10 and 30 hours. The phosphonium salts obtained usually precipitate out of the reaction mixture in crystalline or oily form. Conversion and yield are mostly quantitative.

The halogen compounds IVa and IVb can be obtained in a simple manner by Grignard vinylation of 1-halopentanone- (4) or l-halogen ^ -methyl-nona ^ - en-8-one, subsequent elimination of water from the alcohol obtained and, if appropriate, transfer of the chloride into the bromine or iodine compound. Examples of making this Pre-products are given in the experimental part (Examples 1 a to Id and 2a to 2e).

The acetals of the formula II are acetals of methylgiyoxal and of 2-methyl-2-hepten-6-on-1-al in CH ₂

Il

CHv-CH, -C - CH = CH,

(IVb)

Consideration.

The acetals of 2-methyl-2-hepten-6-one-l-aIs can, for example, be prepared in a simple manner by reacting acetals of 2-methyl-4-halogen-2-butene-l-as with an alkali compound of an acetoacetic ester and subsequent alkaline-thermal cleavage of the -COOR ³ group from the 2-methyl-2-hepten-S-carbalkoxy-δ-on-1-al-acetals obtained.

The acetals of methylglyoxal can be, for example by oxidation of acetone with nitrosyl chloride and trapping of the resulting methylglyoxal obtained by acetalization.

Triggers for implementing the method according to the invention or suspended firstly treating the mixture of the isomeric phosphonium salts in an inert organic solvent and then added to this solution or suspension at temperatures from -50 to + 100 ⁰ C, preferably -20 to +20 ⁰ C, approximately molar Add amounts of strong base. A strong red coloration of the reaction mixture shows the formation of the corresponding triphenylphosphin-ylene. Va and Vb on

CH-

CH ₁
CH, -CH, -C = CH

P (C ₆ H ₅ J ₃

CH

CH,
CH, -CH, -C = CH

P (Q ₁ H ₅ ).,

Inert solvents are hydrocarbons such as benzene and toluene, ethers such as diethyl ether, Ethylene glycol dimethyl ether and tetrahydrofuran as well as strongly polar solvents such as dimethylformamide, N-methylpyrrolidone and alcohols such as methanol and Äihanolin.

CH ₃
-CH ₂ - CH = C - CH = CH ₂

TI ²

T-CH ₂ -CH ₂ -C-CH = CH ₂

(Va)

(Vb)

Strong bases that can be used are, for example, butyllithium and methylmagnesium chloride. Sodium or Potassium alcoholate, sodium hydride and sodium or Called potassium hydroxide.

The triphenylphosphin-ylenc obtained do not need to be isolated for further reaction.

The Ylene solution is added then at temperatures from 0 to 100 ° C, preferably 10 to 70 ° C, the acetals of the formula II too. The reaction between the ylenes and the acetals is usually instantaneous. Towards the end of the reaction is the reaction mixture colored yellow.

To achieve the most complete implementation possible the Ylene is used in a slight stoichiometric excess (about 5 to 10%).

The reaction mixture is worked up in the customary manner. For example, you put the obtained Reaction mixture with water, extracted with petroleum ether, filtered from sparingly soluble triphenylphosphine oxide from and isolates the process products by distillation.

The isomer mixtures obtained generally contain about 50 to 80%. preferably 60 to 70%, of the methylene compound Ib in addition to about 20 to 50%, preferably 30 to 40%, of acetals of the formula Ia.

The free aldehydes can easily be obtained from the mixture of the acetals of the formulas la and Ib by acid hydrolysis getting produced.

The acid hydrolysis takes place in a manner known per se. For example, the acetals become useful with 0.01 to 1 mole of a mineral acid such as sulfuric acid or hydrochloric acid, or an organic acid such as Formic acid. p-toluenesulfonic acid or acetic acid, per Mol acetal added in the form of a 1 to 20% solution and with intensive mixing 0.5 to 5, preferably 2 to 3 hours at temperatures of 10 heated to 50 ° C.

In the case of hydrolysis, it is advisable to add a solubilizer to the reaction mixture. As a solubilizer are lower aliphatic alcohols such as methanol, ethanol and propanol as well as cycloaliphatic Ethers such as tetrahydrofuran and dioxane are particularly suitable. The aldehydes obtained can be customary Way, for example by extraction after gentle neutralization of the reaction mixture, for. B. with an alkali bicarbonate or sodium carbonate, and distilling off the extractant.

In the hydrolysis of mixtures of the acetals of 2-methyl-6-methylene-octa-2.7-diene-1-as or 2,6-dimethyl-octa-2.5,7-triene-1-as In addition to the corresponding free aldehydes, 2,6-dimethylocta-2,4,6-trien-1-al is formed to a large extent by shifting the double bond with its chain of conjugated double bonds. The orange odor of the isomer mixture obtained is significantly more intense than that of the <x and /? - Sinensal.

With the aid of the process described, a series of mixtures of isomeric acetals were produced for the first time accessible, which have found interest as fragrances and flavorings with an orange effect.

The mixtures of acetals of 2,6-dimethyllO-methylene-dodeca-ie.ll-triene-l-al. Which can be prepared in a simple way and with good yields and 2,6,10-trimethyl-dodeca-2,63, ll-tetraen-1-al open a new one very advantageous way of obtaining the natural orange fragrances that are very popular in the food industry and flavoring agents α- and /? - Sinensal.

example 1
a) 1 -Chlor-4-methyl-hexen- (5) -ol- (4)

To 2.7 liters of a 1.25 molar solution of vinyl magnesium chloride in tetrahydrofuran at 10 to 20 ° C within one hour 300 g (2.5 mol) of 1-chloro-pentanone (4) added with stirring. The mixture is then left at room temperature for about 5 hours react again. Then, while cooling with ice, 500 ml of water are added from the precipitated salt

-, filtered off, the filtrate under reduced pressure concentrated and the residue is distilled over 5 g of calcium carbonate. 335 g of 1-chloro-4-methyl-hexen- (5) -ol- (4) are obtained, which corresponds to a yield of 90% of theory.

κ. Kp.o.15 = 51 ⁰ C; η ■; = 1.4653.

b) 1 -Chlor-4-methylen-hexen- (5) and
I -Chlor-4-methyl-hexadiene- (3.5)

100 g of adipic acid are suspended in 300 g of paraffin, oil and heated the mixture to 160 to 170 ° C at 80 Torr. With stirring, 850 g of 1-chloro-4-methyl-hexcn (5) -ol- (4) are added to this mixture over the course of 6 hours. At the same time, the process product and the water formed are distilled off. After the _ "> Reaction, the water is separated off and the organic phase is purified by distillation. It 614 g (yield: 82% of theory) of a mixture are obtained which, according to nuclear magnetic resonance spectra 66% 1-chloro-4-methylene-hexen-(5), 27% trans-1 -.'-. Chloro-4-methyl-hexadiene- (3.5) and 7% cis-l-chloro-4-methyl-hexadiene- (3.5) contains.

Bp) ,, = 58 to 78 ° C: n = 1.4305.

c) l-) od-4-methylene-hexene (5) and
l-iodine-4-methyl-hexadiene- (3.5)

39 g (0.3 mol) of the chloride mixture prepared according to Ib are dissolved in 75OmI acetone, treated with 225 g (1.5MoI) sodium iodide and, with stirring, 30 Heated to the boil for hours. After cooling it will

.-, filtered off, the filtrate at 25 ° C under reduced The pressure is concentrated, the residue is treated with about 0.5 l of ether and the insoluble salts are washed with Removed water and sodium thiosulphate solution. The ethereal solution is then poured over sodium sulfate

■ iii fat dried and after filtration under reduced Pressure restricted. In the subsequent fractional distillation of the residue, 56 g of one are obtained Mixture of l-Jcd-4-methy! En-hexene- (5) and l-iodine-4-methyl-hexadiene- (3.5), that in the isomer combination

• »Settlement corresponds to the starting material (yield: 84% of theory).

Bp 4 to 5 = 33 to 35 ° C; η = 1.5573.

d) 4-methylene-5-hexene-1 - and
4-methyl-3,5-hexadiene-1-triphenylphosphonium iodide

66 g (0.3 mol) of the isomer mixture prepared according to Ic are dissolved in 130 ml of benzene, 158 g of triphenylphosphine are added and, with stirring, 30 Hours heated to 55 to 65 ° C. Then the r> benzene solution is decanted, the residue with 200 ml of benzene are added, the mixture is stirred for about 1 hour and separated off and the phosphonium salt thus obtained is dried. The yield is almost quantitative.

M.p. = 141 to 144 ° C

"" e) 2,6-Dimethyl-1O-methylene-dodeca-2,6,11 -triene-

l-al-butylene- (13) -acetal and

2,6,1O-TrimethyI-dodeca-2,6,9,11 -tetraen-

1 -al-butylene- (l 3) acetal

f.-, 172 g (0.356MoI) of the phosphonium salt prepared according to 1d are suspended in 500 ml of toluene and mixed with 152 g of a 15% n-butyl lithium within one hour at temperatures from -10 to -5 ° C.

solution (0.356 mol) in η-hexane. The reaction is then allowed to continue for about 1 hour at 19 ° to 20 ° C. and then 68 g (0.32 mol) of 2-methyl-2-hepten-6-one-1-al-butylene- (1,3) acetal are added drop by drop. Thereafter, the previously red solution is colored or pale yellow, ϊ for secondary reaction heats the reaction mixture for about 3 hours at 60 to 70 ⁰ C. After cooling, 500 ml of ice water is added, extracted several times with hexane, the combined organic phases washed with water and the solvents are removed under reduced pressure. In the fractional distillation of the residue that remains, 66 g of a mixture which consists of about 66% 2,6-dimethyl-10-methylene-dodeca-2,6.11-triene-al-butylene- (1,3) -acetal are obtained and about 34% 2,6,10-trimethyl- η dodeca-2.6,9,1 1-tetraene-1-al-butylene- (1,3) acetal. This corresponds to a yield of 71% of theory.
B.p.oDi = 120 to 129 ° C; n; = 1.5030.

f \ ~ - fl-Cinencal

"'" "-" JIi

58 g (0.2 mol) of the acetal mixture prepared according to Ie are dissolved in 150 ml of dioxane, and 25 ml of I nH ₂ SO4 are added. The mixture is then stirred for about 3 hours at 30 ^° C. It is then neutralized with soda and the dioxane under reduced r. Distilled pressure. About 200 ml of ether are added to the residue obtained, washed with water and the ether is removed under reduced pressure. A yellow oil with a strong smell of orange is obtained, from which 39 g of 0-Sinensal are obtained in fractional distillation. This corresponds to a yield of 89% of theory.

Bp 005 = 96 to 100 ° C; π ■■ = 1.5143.

According to NMR spectra, the mixture contains 66% of the / Msomers (methylene compound) and 34% of the λ-iso r, meren.

Example 2

a) I -ChloM-methyl-nona ^ -en-e-one

149 g (1 mol) of the 1-chloro-4- ₄ »methyl-hexen- (5) -ol- (4) prepared according to la, to which 2 g of triethylamine have been added, are added dropwise at 50 to 55 ° C. with 77 ml (1 mol) of diketene added. The reaction is then allowed to continue for about 15 hours and the acetoacetate is then heated to 140 to 170.degree. When the elimination of carbon dioxide has ended (approx. 19.51), the cooled reaction mixture is taken up in ether, washed neutral with sodium bicarbonate solution and the solvent is removed under reduced pressure. In the fractional distillation of the residue obtained, 113 g of l-ChloM-methyl-nona ^ -en-e-one are obtained. This corresponds to a yield of 60% of theory.
= 82 to 85 ° C; fl? = 1.4764.

b) 1 -ChloM.e-dimethyl-deca - ^ - dien-e-ol

55

The vinyl Grignardation of the ketone described under 2a according to Example la gives the l-chlorine ^^ - dimethyl-deca ^^ - dien-e-ol roughly 90% yield.

Kp.o.001 = 87-88 ⁰ C; η s = 1.4828.

c) l-chloro ^ methyl-e-methylen-deca - ^ - diene and l-chloro- ^ e-dimethyl-deca- ^ J ^ -triene

When the alcohol prepared according to 2b is dehydrated with adipic acid according to Example Ib, a mixture of l-chloro ^ methyl-e-methylene-deca ^^ - diene and l-chloro-4,8-dimethyl-deca ^, 7.9 is obtained -triene in about 80% yield.

Bp 0.1; = 87 to 95'C; n = 1.5104.
According to the NMR spectrum, this mixture contains about 65% of the O-form (methylene compound).

d) l-iodine-4-methyl-8-methylene-deca-4,9-diene and
l-! od-4,8-dimethyl-deca-4,7,9-triene

When the isomer mixture prepared according to 2c is reacted analogously to Ic, the mixture is obtained from 1-iodo-4-methyl-8-methylene-deca-4,9-diene and 1-iodo-4,8-dimethyl-deca-4,7,9-triene in about 80% yield.

Κρ. _οοη , = 83 to 88 "C; n = 1.5483.

e) 4-methyl-8-methylene-deca-4,9-diene-1 - and
4,8-dimethyl-deca-4,7,9-triene-1-phosphonium iodide

The isomer mixture prepared according to 2d and triphenylphosphine are obtained analogously to Example Id the corresponding phosphonium salts in oily form. The yield is 92% of theory.

f) 2,6-Dimethyl-10-methylen-dodeca-2,6,11 -triene-

1-al-dimethyl-acetal and

2,6,10-trimethyl-dodeca-2,6,9,11 -tetraen-1 -al-

dimethyl acetal

80 g (0.145 mole) of the phosphonium salt produced according to 2e are suspended in 300 ml of toluene and, at - 15 to - 10 ⁰ C with 64 g of 15% strength n-butyllithium solution (0.145 mol in hexane) was added over 30 minutes. The mixture is left for about 1 hour at 10 to 20 ⁰ C and then added to react for the red solution 17 g (0.14 mol) of methylglyoxal dimethyl acetal to. The color changes to yellow. The mixture is left for about 1 hour at 60 to 70 ⁰ C to react further, then, after cooling, 300 ml of ice water to the mixture is extracted several times with hexane and distilled, after washing with water, the solvent off under reduced pressure. The residue is fractionally distilled, 28 g of Λ, / 2-Sinensal-dimethylacetal being obtained. The yield is 75% of theory.

Kp.0.02 = 110 to 114 ⁰ C; π {· = 1.4985.

The ß-isomer (methylene compound) is according to the NMR spectrum included to approx. 65%.

In the case of the acid-catalyzed hydrolysis according to Example If, about 85% strength is obtained therefrom Yield.

Example 3

a) 2-methyl-6-methylene-octa-2,7-diene

1 -al-dimethylacetal and
2,6-dimethyl-octa-2,5,7-triene-1-al-dimethylacetal

220 g (0.0456 mol) of the phosphonium salt mixture prepared according to Example Id are suspended in 600 ml of toluene and 194.5 g of a 15% n-butyllithium solution (0.456 mol) in hexane are added at -10 to -5 ° C The reaction is allowed to continue for about 2 hours at 10 to 20 ° C. and 53 g (0.45 mol) of methylglyoxal dimethyl acetal are then added dropwise to the mixture at 10 to 20 ° C. The color changes from red to yellow. The mixture is then stirred for about 2 hours at 60 to 70 ^° C., after cooling, about 500 ml of ice water are added and the mixture is extracted several times with hexane. The combined organic solutions are washed salt-free with water and concentrated under reduced pressure. The residue that remains is fractionated, with 73 g of a mixture consisting of approx. 65% 2-methyl-6-methylene-octa-2,7-diene. lal-dimethylacetal and approx. 35% 2,6-dimethyl-octa-24.7-

Lrien-I -al-dimethyl-acetal can be obtained. The yield is 83% of theory.

Kp.n.) = 78 to 86 ⁰ C; π = 1.4899.

b) 2-methyl-6-methylene-octa-2,7-dien-1-al,

2,6-dimethyl-octa-2,5,7-triene-1-al and

2,6-dimethyl-octa-2,4,6-trien-1-al

17 g of the acetal mixture obtained according to 3a are dissolved in 30 ml of methanol, with 10 ml of a 0.5 η-sulfuric acid was added and the mixture was stirred for one hour at room temperature. You then move with sodium carbonate until the solution reacts neutrally, the methanol is distilled off under reduced pressure, takes up the residue in ether and washes out with water. After the ether has been distilled off fractionally distilled, 11 g of an aldehyde mixture, consisting of 2-methyl-6-methylen-octa-2,7-dien-1-al, 2,6-dimethyl-octa-2,5,7-trien-1-al and 2,6-dimethyl-octa-2,4,6-triene-1 -al receives. The yield here is 85% of theory. The orarigengerucri this one Connection is more intense than that of the * -, j3-Sinensals.

M.p. 0.15 = 72-73 ° C; / J: '= 1.5910.

According to the IR and NMR spectrum, this hydrolysis largely results in a double bond shift 2,6-dimethyl-octa-2,4,6-triene-1-aleine.

Example 4

a) 2,6,10-trimethyl-l 4-methylene-hexadeca-

2,6,10,15-tetraene-1-al-butylene- (1,3) -acetal and

2,6,10,14-tetramethyl-hexadeca-2,6,10,13,15-pentaen-

1-al-butylene- (1,3) acetal

2-methyl-2-hepten-6-one-l-al-butylene- (1,3) acetal
is reacted with the phosphonium salt prepared in Example 2e according to Example 2f. The above-mentioned mixture of the double bond isomers is obtained in about 65% yield. According to the NMR spectrum, about 65% of the methylene compound is present.
Kp.o.ooi = 153 to 161 ° C; n: '= 1.5145.

b) 2,6,10-trimethyl-14-methylene-hexadeca-

2,6,10,15-tetraen-1-al and

2,6,10,14-tetramethyl-hexadeca-

2,6,10,13,15-pentaen-1-al

In the acid-catalyzed hydrolysis of the acetal mixture 4a according to Example If, the corresponding ones are obtained Aldehyde in a yield of 85% of theory. Kp.o.ooi = 131 to 137 ° C; n = 1.5250.

Example 5

a) 172 g (0.356 mol) of the phosphonium salt prepared according to Example 1 d are suspended in 500 ml of toluene and within one hour at temperatures of -10 to -5 ° C with 152 g of a 15% n-butyllithium solution (0.356 mol) in η-hexane added. Then allowed for about 1 hour at 10 to 20 ⁰ C, and then returns to react for 64 g (0.32 mol) of 2-methyl-2-hepten-6-one-l-al-propylene (1,2) acetal drop by drop. The previously red solution is then only slightly yellow in color. For post-reaction, the reaction mixture is heated to 60 to 70 ° C. for about 3 hours. After cooling, 500 ml of ice water are added, the mixture is extracted several times with hexane, the combined organic phases are washed out with water and the solvents are removed under reduced pressure. In the fractional distillation of the residue that remains, a mixture is obtained which consists of approx. 66% 2,6-dimethyl-10-methylene-dodeca-2,6, l 1-triene-l-al-propylene- (l, 2 ) acetal and about 34% 2,6,10-trimethyl-dodeca-2,6,9,11-tetraene-1-al-propylene- (1,2) -acetal.

B.p. 05 = 115 to 124 ⁰ C; n / = 1.5028.

b) If one works as described in Example 5a, but uses instead of 64 g (0.32 mol) of 2-methyl-2-hepten-6-one-l-al-propylene- (l, 2) -acetal 68.7 g (0.32 mol) of 2-methyl-2-hepten-6-one-l-al-diethylacetal, a mixture is obtained which consists of about 66% 2,6-dimethyl-10-methylene dodeca-2,6,11 -trien-1 -al-diethylacetal and 34% 2,6,10-trimethyl-dodeca-2,6,9,1 1-tetraene-1-al-diethylacetal consists.

Kp.o.oi = 114 to 12O ⁰ C; η / = 1.4987.

c) The procedure is as described in Example 5a, but instead of 64 g (0.32 mol) of 2-methyl-2-hepten-6-one-1-al-propylene- (1,2) acetal 74.4 is used g (0.32 mol) of 2-methyl-2-hepten-6-one-la! -di-n-propyl acetal, a mixture is obtained which consists of about 66% 2,6-dimethyl-10-methylene dodeca-2,6,11 -triene-1-al-din-propyl acetal and 34% 2,6,10-trimethyl-iodeca-2,6,9,11-tetraene-1-al-di-n-propyl acetal .
B.p. 01 = 122 to 132 ° C; π - = 1.5025.

Claims (1)

Claims; I, mixtures of isomeric acetates of the formulas Ia and Ib R ¹ -O R ² -OR ¹ -O CH- CH, C = CH-CH ₂ -CH ₁ CH ₃ CH, -C = CH-CH ₂ -CH = C-CH = CH ₂ (Ia) R ² -O CH- CH, C = CH- CH -, - CH, - CH ₃ CH, -C = CH-CH ₂ -CH ₂ -C-CH = CH, (Ib) in which R ¹ and R ² each denote aliphatic hydrocarbon radicals with 1 to 4 carbon atoms or R ¹ and R ² together denote an alkyl group with 2 to S carbon atoms and η denotes the numbers 0.1 or 2. 2. Process for the preparation of the mixtures of isomeric acetals of the formulas I a and I b R ¹ -O CH CH ₃ C = CH-CH ₂ -CH ₂ CH ₃ CH ₃ -C = CH-CH ₂ -CH = C-CH = CH ₂ (Ia) R ² -OR ¹ -O R ² - O CH - CH ₁ -C = CH-CH ₂ -CH ₂ CH, -C = CH-CH ₂ -CH ₂ -C-CH = CH ₂ (Ib) in which R ¹ and R ² each represent aliphatic hydrocarbon radicals with 1 to 4 carbon atoms or R ¹ and R ² together represent an alkylene group with 2 to S carbon atoms and η represents the numbers 0.1 or 2, characterized that in a known manner a) a mixture of the isomeric phosphonium salts of the general formula HIa and IHb CH ₂ - CH ₃ Ί CH _{3 :} CH ₂ -CH ₂ -C = CH-L-CH ₂ - CH = C-CH = CH ₂ P ⁺ (C ₆ H ₅ J ₃ CH, CH ₁ CH ₂ -CH ₂ -C = CH CH ₂ Il / "" »Ti r * . f ~ * U - / "» LI 2 ν_Γΐ2 ~ ^- ν-- ^ _ΓΊ ^ 112 P ⁺ (C ₆ H ₅ J ₃ in which X is chlorine, bromine or iodine and ρ door is the numbers 0 or 1, in an inert organic solvent with an approximately equimolar amount of a strong base and b) the triphenylphosphinylene obtained with acetals of the general formula II R ¹ -O CH CH ₃ C = CH-CH ₂ -CH ₂ CH ₃ -C = O R ² —O in which R ¹ and R ^{2 have} the meaning given above and m stands for the numbers 0 or I, is converted.