DE1807324B - Process for the preparation of cis which predominantly contains the trans isomer, trans-1-Menthenepoxydgemisehen - Google Patents

Description

1 2

It is already known cyclic terpene compounds The conversion of the halohydrin into the epoxide

with a single cyclic double bond through - can easily be achieved by treatment with emer base

to epoxidize organic peroxyacids.

for example 1-Menthen using Sauren ment are well known, strong bases such as

how peracetic acid are epoxidized, whereby one uses 5 alkali metal hydroxides and alkoxides, ζ B Natnum-

received bonds which were used in the manufacture of men or squid or sodium or potassium

tholen, menthone, Pipentolen, Pipenton and their methoxide or ethoxide are preferred. The base is

Esters are useful in the 1-menthen thus obtained - preferably in an amount of about 1.0 to 10.0 mol-

epoxy, however, it is essentially an equivalent per mole equivalent of halohydrin

1 1 mixture of cis and trans-1-Menthenepoxyd- io applies

isomers The trans-1-menthenepoxy isomer is a suitable analytical method for determining desirable because it is stereoselectively into the 2-mixture of the trans-cis isomer ratio in the then-1-ol can be converted, the 1-menthen intermediate obtained by an important process according to the invention for a number of other um-epoxides is based on the integration of proton dislocations represents 15 ratio in the nuclear magnetic resonance spectra

According to the present invention, a mixture of the two isomers can easily be distinguished by the processes used to produce predominantly the trans sorptions which originate from the cis, trans-1-menthenepoxydge containing the proton isomers in the 2-position of the oxirane system . The mixing created, which is characterized by the fact that cis-epoxide shows a weakly dissolved triplet in that 1-menthene with less or less than 7.17 τ, while the trans-epoxy isomer is converted into a doublet of brominous acid and the halogen ( / = 5 cP) with the center at 7.21 τ, the Intehydrm then shows in the usual way with a base gration of the peaks, which correspond to the oxirane protons of the treated isomers in a mixture,

The slight epoxidation of 1-menthene via the far-away exact ratio of the two present

Halohydnn and especially the fact that the 25 epoxy isomers

product obtained generally has a high proportion when using an optically active 1-menthen

containing trans isomers is unexpected, since the order in the process according to the invention is a corresponding

Settlement of cyclic terpene olefins such as the optically active 1-menthenepoxide obtained So

wise a-Pmen, ß-pinene or limonene, often too low yields (+) - l-menthene (H -) - l-menthene epoxide and

high yields and a large number of secondary pro- 30 (+) - l-menthen accordingly (+) - l-menthenep-

products that result from side reactions and mole- oxide, if desired according to generally known ones

Cular rearrangements are formed. Processes with both optically active isomeric

The components used in the present process can be separated

hypohalous acid is the under- The cis and trans-Menthenepoxydisomere, the

chlorous or hypobromous acid If hypobromous 35 was prepared according to the process of the invention

Acid used in the present process can be separated if used in the synthesis

The resulting epoxy may even be 90% or more of menthol to be used, especially

of the valuable trans isomers sometimes contain a high percentage of trans epoxy isomers

chlorous acid is used, the obtained one can be obtained

Epoxy contain 70 to 80% of the trans isomer 40 For a better understanding of the invention, the

The hypohalous acid is generally given in the following examples.

the method according to the invention in the quantities given in these examples is ⁰ ° C
range from about 0.1 to 3.0 mole equivalents per mole
1-Menthen used The hypochlorous used

or hypobromous acid can either be preformed 45 BeiSDiell
be or in situ m the presence of 1-menthene and
Water using suitable halogen donors

such as N-chloro- or N-bromamides or -imides, with- A solution of 41.4 g (+) - l-menthene, 150 ml

for example N-bromoacetamide, N-bromosuccimmide, water and 150 ml of dioxane is in a glass reaction

N-chlorourea or N-chlorosuccinimide, prepared 50 tion vessel, stirred 53.1 g of N-bromosuccinimide

are proportionate over a period of one hour.

The preparation of the halohydrin is added preferential manner, while the temperature carried out at 20 by adding 1-menthene is maintained with bottom up to 25 ⁰ C. The reaction mixture is stirred chlorous or hypobromous acid in an inert for 3 hours and then at 300 ml of solvent such as water, or a water-vinegar 55 water diluted The mixture is diluted with hexane to obtain acid, water-dioxane or water-tetrahydrofuran of 75.5 g of crude bromohydrm extra mixture, preferably at a temperature in the the hiert is Bromhydrm Although the use of a Lo stirred to form 1-Menreich of about 0 to 100 ⁰ C, preferably about 10 to thenepoxyd for 3 hours at 25 "C with 200 ml of 3O ⁰ C, converts 20% ^r Natnumhydroxydlosung The reactant in the epoxidation reaction is not necessary to obtain 57.8 g of the agile mixture, it is generally preferred to use a product which is mainly 1-men Use water-miscible solvent The thenepoxide is extracted with hexane The epoxide reaction of the sub-chlongen or sub-bromine is carried out by vacuum distillation with the formation of acid with 1-methylene leads to the formation of a halogen 31.4 g of pure epoxy, bp 76 to 89 ° C / 11 mm, hydrms, and this conversion is generally within 65 nff = 1.4498, [oc] f = + 52.41 °, purified The analysis half a period in the range from 10 minutes to the NMR spectrum of the distilled epoxy shows, 3 hours at the stated temperatures in the that the sample consists of 10% cis and 90% ^t r ^ans -l-Menthenwesenthchen complete epoxy

Example 2

A solution of 41.4 g of (+) - l-menthene, 150 ml of dioxane and 150 ml of water is stirred in a glass reaction vessel. 41.4 g of N-bromoacetamide are added in portions over the course of one hour, while the temperature is kept at 20 to 25 ° C. The mixture is then, as described in Example 1, with formation of 56.6 g of the product, which predominantly consists of 1-menthenepoxide consists, treated The epoxide is purified by vacuum distillation, whereby 52.5 g of remen 1-menthenepoxide, bp 74 to 90 ° C / 11 mm, nf = 1.4492, [α] ²⁴ = + 52.11 ° are formed the analysis of the NMR spectrum shows the distilled epoxide that the sample of 10% ^{C1S "1} S and 90% trans-1-Menthenepoxyd is

Example 3

A mixture of 41.4 g of 1-menthene, 150 ml of water and 150 ml acetic acid is stirred m a glass reaction vessel 40.2 g of N-chlorosuccinimide are added in portions over one hour, is while maintaining the temperature at 30 to 4O ⁰ C The The mixture is kept at 30 to 40 ^° C. for 5 hours, diluted with 250 ml of water and extracted with hexane to obtain 59.9 g of crude chlorohydrin. The crude chlorohydrin is mixed with 200 ml of 20% sodium hydroxide solution for 3 hours to form 1-menthenepoxide (50.4 g of crude material) stirred. The crude epoxide is distilled to obtain 8.4 g of pure 1-menthenepoxide, b.p. 69 to 90 ° C./1 mm, nf = 1.4562. Analysis of the NMR spectrum des epoxide shows that this consists of 22% cis and 78% of trans-1-menthenepoxide

B e 1 s ρ 1 e 1 4

Eme mixture of 120 ml of a 3-molar N-chloro urea solution, 300 ml of water, 41.1 g of 1-menthene, 30 ml of N, N, dimethylformamide and 15 ml of acetic acid is vigorously at 40 to 5O ⁰ C the mixture was stirred for 5 hours with hexane extracted to obtain 46.5 g of crude chlorohydrin The chlorohydrin is stirred for 3 hours at 20 to 25 ⁰ C with 200 ml of 20% Natnumhydroxydlosung to form 1-Menthenepoxyd (44.4 g crude material) The distillation yields 8.3 g of pure 1-menthenepoxide, boiling point 85 to 100 ° C / 11 to 12 mm, nf = 1.4564 Analysis of the NMR spectrum of the epoxide fraction shows that the sample consists of 31% cis and 69% of trans-1 -Menthenepoxide consists

Example 5

A mixture of 41.4 g of (+) - l-menthene, 3 ml of acetic acid and 300 ml of water is stirred and heated to reflux. 120 ml of a 3 molar N-chlorourea solution are added dropwise to this mixture and the reaction is refluxed for 3 hours mixture is cooled and diluted with hexane to obtain 53.9 g of crude chlorohydrin extracted treatment of the crude Chlorhydnns at 20 to 25 ⁰ C with 200 ml of a 20% Natnumhydroxydlosung ert was 44.7 g of crude material purification by vacuum distillation affords 8.7 g of 1-menthenepoxide, boiling point 75 to 100 ° C / 11mm, [a] _D = + 47.2 °, nf = 1.4551 Analysis of the NMR spectrum of the epoxide shows that the sample is 21% off consists of ice and 79% of trans-1-menthenepoxide

Example 6

Eme mixture of 41.4 g of 1-menthene, 150 ml of acetic acid, 150 ml of water and 40.2 g of N-chlorosuccmide is stirred and ^{heated to 30 to 40 °} C. for 5 hours. The mixture is mixed with hexane to give 62.9 g of crude chlorohydrin extracted, which after stirring at room temperature with 200 ml of 20% sodium hydroxide gives 54.5 g of a material containing 1-menthenepoxide. Purification by vacuum distillation gives 12.3 g of 1-menthenepoxide, b.p. 70 bis 103 ° C / 11mm, nf = 1.4450 Analysis of the NMR spectrum of the epoxide shows that the sample consists of 24% ice and 76% trans-1-menthenepoxide

Claims (2)

Patent claims: 1 process for the preparation of cis, trans-1-menthenepoxide mixtures containing predominantly the trans isomer, characterized, that 1-menthene is reacted with hypochlorous or hypobromous acid and the halohydrm obtained is then treated with a base in the customary manner 2 method according to claim 1, characterized in that that the hypochlorous or hypobromous acid m situ in the implementation with the help generated by water and a halogen donor