JPS5848525B2 - What's going on? - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for isomerizing unsaturated compounds.

More specifically, the present invention performs an isomerization reaction between the cis and trans forms of aliphatic or cycloaliphatic ketones, alcohols, or esters having an unsaturated hydrocarbon chain in which both the cis and trans forms are present. The present invention relates to a method for isomerizing unsaturated compounds, which comprises heating in the presence of ruthenium acetylacetonate, ruthenium glyoximate or ruthenium stearate as a catalyst.

In general, many double bond isomerization reactions are already known.
It is broadly classified into the following three methods.

(A) A method in which double bonds are chemically treated and then isomerized when converted into double bonds again.

(B) A method using photoreaction.

(Q: Method using a catalyst.

(4) Specifically, the method involves subjecting double bonds to addition reactions such as epoxidation, halogenation, halohydrination, thioetherification, and sulfonation, and then removing them to form double bonds. , J. W-Cornforth et al. Chem-Soc. 1 9 5 9112~1
27 and 2539-2547, it has been applied to the stereospecific synthesis of squalene, and K. B
- S harpress et al. J-AmerChem.
This method is used for the synthesis of trans-cyclooctene, as reported in Soc-, 94, 6538 (1972).

This method has the disadvantages of using expensive reagents, which cannot be reused, and having complicated operations.

The photoreaction of method (B) has a low reaction temperature and is an effective method that can change the isomer ratio of cis-two-trans forms simply by irradiating ultraviolet rays.

Of course, the selectivity can be improved by adding a photosensitizer or using a solvent.

However, in order to achieve high selectivity, a diluent must be used to
It has the disadvantage that the reaction must be carried out at a low concentration of ~10%.

(The method using a catalyst in method 0 is the most preferred method when carried out industrially, and acidic catalysts, basic catalysts, transition metal catalysts, etc. can be used.

When an acidic catalyst or a basic catalyst is used, in addition to cis-trans isomerization, side reactions such as movement of the double bond position and/or production of high molecular weight products are involved.

For isomerization reaction using transition metal catalyst, M-Orc
"Advances in Cataly" written by hin
sis” vol 1 6, Academic P
ress, New York (1 9 6 6
) As described in P2, hydrogen-adsorbed palladium, Raney nickel, cobalt carbonyl, iron carbonyl, etc. are generally used.

Also recently C-D. Weis et al. described an isomerization reaction using a rhodium catalyst in Helv Chim Acta. ,
57, 856-863 (1974),
All of these involve a shift in the position of the double bond, which does not meet the intent of the present invention.

It is known that heating in the presence of certain ruthenium compounds moves the position of the double bond [for example, T-D-
J. D' Silva et T e trahedro
n, vol, 30, 1015-1018 (197
4)).

However, according to the present invention, aliphatic or cycloaliphatic ketones, alcohols or esters having unsaturated hydrocarbon chains, in which cis-trans isomers may exist, can be converted into ruthenium acetylacetonate, ruthenium glyoximate or ruthenium stearate. It was discovered that isomerization between the cis and trans forms selectively proceeds by heating in the presence of , and the present invention was achieved based on this discovery.

The reaction is a thermal equilibrium reaction, and the equilibrium ratio of the cis form and the trans form of the olefin, for example, in the case of an isolated two-substituted double bond, is usually 5 to 10 to 95 to 90, leaning towards the trans form.

Further, the isolated tri-substituted olefin and the isolated tetra-substituted olefin are inclined to the trans form at a ratio of 40-45 to 60-55.

The cyclic compound olefin has an 8-membered ring with a cis form of 95
% or more, and in the 12-membered ring, the cis type is about 70%,
Furthermore, as the ring becomes larger, the cis form decreases and the trans form increases.

Examples of the compounds that can be used in carrying out the present invention include the following compounds.

2-hexen-1-ol 3-hexen-1-ol; 3,7-dimethyl-2,6-octadien-1-ol: 3,7,11-trimethyl 2,6,10-dodecatrien-1-ol: 3.7.11~trimethyl-1.
6,10-dodecatrien-3-ol: 6,10-dimethyl-5,9-undecadien-2-one: 6,10
・101 trimethyldodeca-3-en-2-one; 6・
10-dimethyl-10-methoxydode-3-ene-2
-one; ethyl 5,9-dimethyl-4,8-decadienoate: 5,9,13-trimethyl-4,8,12-tetradetrienoate; 2-methyl-5,9,13-trimethyl-4・Ethyl 8.12-tetradetrienoate:
2-cyclohexyl-5,9,13-trimethyl-4.
8.12-tetrade-ethyl trienoate: 3.7.11-trimethyl-2.4.10-methyl 2.4.10-decatrienoate: α
and β-santalol, jasmone, methyl jasmonate, and the like.

All of these unsaturated compounds whose cis and trans forms deviate from the thermal equilibrium composition are considered as raw materials.

In order to prevent the position of the double polymer bond from shifting, it is preferable that the catalyst does not take the form of ruthenium hydride.

Particularly preferred catalysts are ruthenium acetylacetonate and ruthenium glyoximate.

The catalyst is usually o.o. It can be used in the range of ooi to 20 wt%, preferably 0.01 to 1.0 wt%, and the reaction temperature is from about 50 °C to about 300 °C,
The temperature is preferably 150 to 210°C.

Although the reaction can be carried out under an air atmosphere, it is preferably carried out under an inert gas atmosphere.

Although the reaction solvent is not particularly necessary, a solvent that is stable under the above reaction conditions and does not participate in the reaction, such as a saturated hydrocarbon such as squalane, may be used as the solvent.

The reaction is not necessarily continued until an equilibrium composition is obtained, and may be terminated midway.

Furthermore, if the target product has a lower boiling point than the raw material, it is also possible to shift the equilibrium toward the production system by performing distillation while performing the isomerization reaction, and obtain the target product almost quantitatively.

If the catalyst is not separated after the reaction, there is a risk that a reverse isomerization reaction will occur, for example, when precision distillation is performed in the next step to separate the cis and trans forms.

Therefore, the reaction solution was subjected to simple distillation as a catalyst separation step.
Preferably, the distillate is subjected to precision distillation and the residue containing the catalyst is reused in the isomerization reaction.

Of course, it is also possible to chemically deactivate the catalyst or physically adsorb it.

Examples will be described in detail below.

Example 1 Cis-geranylacetone (6,10-dimethyl 5,9-
Undecadien-2-one) 50P and ruthenium acetylacetonate (hereinafter abbreviated as Ru(AA)3) 0.15'? and heated to 190° C. under nitrogen atmosphere.

The reaction solution was subjected to gas chromatography (PEG-20M
**10 to Chromosorbw (AW)
% loading: Column temperature 160°C: Carrier gas He 1.
7k9/c4).

The conversion rate of the cis isomer after 2 hours of reaction was 32%, and the selectivity of the generated trans isomer was 99%.

After a further 5 hours, the conversion rate of the cis isomer was 41%, and the selectivity of the generated trans isomer was 97.4%.

Examples 2 to 4 Similar to Example 1, Ru(AA
Table 1 shows the results when 0.3% by weight of )3 was added and the reaction temperature was varied.

Example 5 Transgeranylacetone 50 as in Example 1
fKRu (AA)3 0.1'i? was added, and the reaction was carried out at 200° C. under a nitrogen atmosphere.

The conversion rate of trans-geranylacetone after 3.5 hours was 29.6%, and the selectivity of the produced cis-geranylacetone was 98.9%.

The conversion rate after 15 hours was 35.7%, and the selectivity was 97.2%.

Example 6 Nerol (3,7-dimethyl-2,6-octadiene-
1-ol) 501 and ruthenium (III) stearate}0. =l and heated to 170°C under nitrogen atmosphere.

The conversion rate of nerol after 5 hours of reaction was 42.7%,
The selectivity of the produced trans isomer, ie, geraniol, was 94.4%.

Example 7 Cis-α-santalol 10f? and Ruthenium (II
I) Glyoxime} 0. The mixture of 1 f is heated to 165° C. under an argon atmosphere and the reaction is carried out for 6 hours.

When the reaction solution was analyzed by gas chromatography, the conversion rate of the cis isomer was 30.6%, and the selectivity of the trans isomer was 96%.
．． It was 8%.

Example 8 Transjasmon 1 0 0? KRu (A
A) 30.5? When the reaction mixture was heated at 160° C. for 3 hours under a nitrogen atmosphere, a composition having a ratio of cis to trans isomers of approximately 5:95 was obtained.

The reactor is directly connected to a distillation column having about 30 theoretical plates, the bottom temperature of the column is maintained at about 160° C., the reflux ratio is set to 10, and vacuum distillation is carried out over a long period of time.

Distillate 9 3. The composition ratio of 3gr was 91:9 between cis and trans isomers.

Example 9 △3-}7th △5-cis-6,10-dimethyl-3
・5.9-Untekatrien-2-on 20g Ru
(AA) Add 30.0 1P and 190℃ under nitrogen atmosphere
The reaction was carried out by heating.

When the reaction solution was analyzed by gas chromatography, △1trans △1trans-6,10-dimethyl-3 was newly found.
- It was confirmed that a peak of 5,9-untecatrien-2-one was generated.

Note that no formation of Δ3-cis form was observed.

The conversion rate of the Δ5-cis isomer after 2 hours of reaction was 23.0%, and the selectivity of the produced Δ5-trans isomer was 98.7%.

The conversion rate after a further 6 hours was 32.6%, and the selectivity was 97.1%.

Example 10 △4・△8-cis, R to farnesyl ethyl acetate 101
u (AA)30.0 1 5? was added and heated to 185° C. under a nitrogen atmosphere to carry out the reaction.

The conversion rate of △4/△8-cis isomer after 3 hours of reaction is 36.4
%, and the Δ4-trans Δ8-cis form of the product, Δ4
The selectivity for the -cis Δ8-trans isomer and the Δ4/Δ8-trans isomer was 98.2%.

The ratio of (Δ4 trans, Δ8 cis isomer + Δ4-cis, Δ8-trans isomer) to (Δ4/Δ8-trans isomer) was 8:1.

After a further 8 hours, the conversion rate of △4・△8-cis isomer was 62.0
%, and the selectivity of the above three isomers was 97.0% tare.

Furthermore (△4-trans, △8-cis body ten △4-trans,
The ratio of Δ8-cis form) to (Δ4Δ8-trans form) was approximately 45:15.

Claims (1)

[Claims] 1 Ruthenium acetylacetate is used as a catalyst in the isomerization reaction between the cis-to-trans form of an aliphatic or alicyclic ketone alcohol or ester having an unsaturated hydrocarbon chain in which both the cis form and the trans form are present. A method for isomerizing an unsaturated compound, characterized by heating with ruthenium ester, ruthenium glyoximate or ruthenium stearate.