JPH0218396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cyclic terpene hydrocarbon, and more specifically, the general formula (-1) (In the formula, n means an integer of 0 or 1.) Chain terpene alcohol and/or general formula (-2) (In the formula, n is as defined above.) A general formula () characterized in that a chain terpene alcohol represented by the formula (wherein n is as defined above) is subjected to a dehydration cyclization reaction by applying electricity in the presence of an electrolyte. (where n is as defined above, Z ¹ and Z ²
one is a hydrogen atom and the other together with Z represents a single bond, two of X ¹ , X ² and X ³ are hydrogen atoms and the remaining one together with X represents a single bond represents. ) The present invention relates to a method for producing a cyclic terpene hydrocarbon shown in the following.

The cyclic terpene hydrocarbon represented by the general formula () is not only used as an aroma component of perfumes, but is also useful as a synthetic intermediate for aroma components of other perfumes, cosmetic base materials, pharmaceuticals, and the like. For example, limonene, terpinolene, and bisabolene are known as active ingredients in deodorants and fragrances.

Conventionally, methods for producing cyclic terpene hydrocarbons from chain terpene alcohols include, for example, a method for obtaining limonene by treating nerol or geraniol with a 2-fluoropyridinium salt in the presence of tri-n-butylamine, and a method for obtaining limonene by treating nerol or geraniol with a 2-fluoropyridinium salt in the presence of tri-n-butylamine. A method is known in which bisabolene is obtained by treating the presence of tri-n-butylamine with 2-fluorobenzothiazolium salt [Mukaiyama et al.
Chemistry Letters, 1137 (1976) and Chemistry
Letters, 1169 (1977)], the preparation of onium salts such as 2-fluoropyridinium salts and 2-fluorobenzothiazolium salts used in these methods is not easy.

As a result of research on the cyclization reaction of chain terpene alcohols, the present inventors found that the general formula (-1)
The above general formula () can be obtained by electrolytically reacting the chain terpene alcohol represented by the above general formula (-2) or the above general formula (-2).
The inventors have discovered that the cyclic terpene hydrocarbon represented by the formula can be easily obtained, leading to the present invention.

The dehydration cyclization reaction in the present invention is carried out by applying electricity in the presence of an electrolyte. Examples of electrolytes include perchlorates or boron tetrafluoride salts of alkali metals or alkaline earth metals such as lithium, sodium, potassium, calcium, and barium; tetraethylammonium salts of perchloric acid;
Examples include quaternary ammonium salts such as tetrabutylammonium salts. The amount of electrolyte used varies depending on the electrolyte used, but for example, when using lithium perchlorate as the electrolyte,
Approximately per mole of raw material chain terpene alcohol
It is 0.1 to 10 times the mole, preferably about 1 to 5 times the mole. The dehydration cyclization reaction is preferably carried out in a solvent in order to increase the reaction rate and reaction selectivity. Examples of solvents include chain or cyclic ethers such as diethyl ether, dimethoxyethane, diethoxyethane, and tetrahydrofuran; lower fatty acid esters such as ethyl formate, methyl acetate, ethyl acetate, methyl propionate, and methyl valerate; acetone, methyl ethyl ketone, and methyl Lower aliphatic ketones such as isobutyl ketone; carbonic acid esters of lower aliphatic alcohols such as dimethyl carbonate and diethyl carbonate; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, and carbon tetrachloride can be used. , especially tetrahydrofuran. In addition, electricity is applied in these solvents and in the presence of the above electrolyte,
In systems where strong acids are generated, for example in ethereal solvents such as tetrahydrofuran, electrolytes such as alkali metal perchlorates such as lithium perchlorate or quaternary ammonium salts of perchloric acids such as tetraethylammonium perchlorate. is present, the dehydration cyclization reaction of the chain terpene alcohol represented by the general formula (-1) or the chain terpene alcohol represented by the general formula (-2) tends to occur, and the target can be achieved with a good yield. A product is obtained. Further, the dehydration cyclization reaction in the present invention is easily affected by temperature, and the yield of the product decreases as the temperature decreases. Preferably, the reaction is carried out at a temperature range of room temperature to about 80°C.

As electrodes, those commonly used in electrolytic reactions such as gold, platinum, titanium plated with gold or platinum, carbon; or nickel, titanium-nickel, stainless steel, lead, copper, or oxides thereof can be used. However, electrodes that give good results in terms of reaction yield and selectivity are platinum, carbon, nickel, stainless steel, and lead. The current density is about 1~
The range is 500mA/cm ² and the amount of electricity required is approx.
Although a small amount such as 0.01 to 1 F/mol is sufficient, the current density and amount of electricity required for the cyclodehydration reaction in the present invention vary depending on the reaction conditions employed. For example, the current density required for the cyclodehydration reaction of (E)nerolidol at 58°C using lithium perchlorate as an electrolyte in tetrahydrofuran solvent is
It is 3.3mA/cm ² and the quantity of electricity is 0.28F/mol.

The chain terpene alcohol represented by the general formula (-1) used as a raw material in the present invention or the general formula (
Examples of the chain terpene alcohol represented by -2) include geraniol, nerol, linalool, (E,E) falnesol, (E,Z) falnesol, and (E)nerolidol.

After the reaction is complete, the reaction mixture is poured into water, aqueous sodium bicarbonate, etc., then extracted with an organic solvent such as hexane, and the solvent is distilled off from the extract to carbonize the cyclic terpene represented by the general formula (). Hydrogen can be separated and obtained. Note that cyclic terpene hydrocarbons are usually recovered as a mixture of positional isomers regarding double bonds. Each isomer can be easily obtained by subjecting this mixture to a separation operation such as distillation.

The present invention will be specifically explained below using examples.

Example 1 (E) Nerolidol 100mg in a 30ml test tube
(0.45mmol) and lithium perchlorate 350mg
(3.28 mmol) was weighed out, 8 ml of purified tetrahydrofuran was added thereto, and the mixture was stirred to form a homogeneous solution.
A platinum electrode (1.5 x 2 cm ² ) was attached to this branched test tube, and while the reaction temperature was maintained at 58°C, the flow rate was 3.3 mA/cm ^{2 .}
Electrify for 20 minutes at a constant current (amount of electricity: 0.28F/mol)
I did this. After the reaction was completed, saturated sodium bicarbonate solution was added to the reaction mixture. The organic layer was concentrated under reduced pressure, and this was combined with the n-hexane extract (extracted twice) from the aqueous layer. This mixture was washed once with saturated brine, dried over anhydrous sodium sulfate, and then The solvent was distilled off under reduced pressure to obtain 108.3 mg of an oil. This oil was purified using a silica gel column to obtain 84.0 mg of a colorless oil. As a result of analyzing this product by gas chromatography (SE-30, 6m, 160℃), α-bisabolene represented by formula (-1), β-bisabolene represented by formula (-2), and formula (-3 ) was found to be obtained at yields of 36%, 18%, and 18%, respectively. Compounds corresponding to peaks representing these organisms were separated by gas chromatography, and each compound was confirmed by IR analysis and NMR analysis.

α-Bisabolene IR (Neat): 2960 (CH ₃ ), 2910 (CH ₂ ), 2840,
1600, 1440, 1376, 1100, 875 cm ^{-1 1} H-NMR (CDCl ₃ ) δ: 1.56-1.80 (m, 13H,
CH ₃ , CH-); 1.88-2.36 (m, 6H, -
CH ₂ ―); 2.71 (t, J = 7.7Hz, 2H, ―CH ₂
--); 5.00-5.28 (m, 2H, --CH=C);
5.34-5.52 (m, 1H, -CH=C) β-bisabolene IR (solv, CHCl ₃ ): 2960 (CH ₃ ), 2920 (CH ₂ ),
2845, 1640 (C=C), 1450, 1435, 1376,
895cm ^{-1 1} H-NMR (CDCl ₃ ) δ: 1.58 to 1.76 (m, 11H,
CH ₃ , ―CH ₂ ―); 1.84 to 2.16 (m, 9H, ―
CH ₂ ―, CH―); 4.80 (s, 2H, H ₂ C=C
); 5.00-5.28 (m, 1H, -CH=C);
5.32-5.52 (m, 1H, -CH=C) γ-bisabolene IR (solv, CHCl ₃ ): 2960, 2910, 2840, 1525,
1510, 1450, 1430, 1375, 1225, 1195 cm ^- 1 ¹ H-NMR (CDCl ₃ ) δ: 1.58-1.84 (m, 12H,
CH ₃ ); 1.85-2.16 (m, 6H, -CH ₂ -);
2.32 (t, J=6.6Hz, 2H, -CH ₂ -); 2.64
~2.88 (m, 2H, -CH ₂ -); 5.00 ~ 5.28 (m,
1H, -CH=C); 5.30~5.56 (m, 1m, -
CH=C) Example 2 In a 30 ml test tube with a branch, (E, E) 100 mg (0.45 mmol) of falnesol and 350 ml of lithium perchlorate.
mg (3.28 mmol) was weighed out, 8 ml of purified tetrahydrofuran was added thereto, and the mixture was stirred to form a homogeneous solution. A platinum electrode (1.5 x 2 cm ² ) was attached to this branched test tube, and while maintaining the reaction temperature at 60°C,
Electrify for 10 minutes at a constant current of 3.3mA/ ^cm2 (working energy:
0.14F/mol). After the reaction was completed, saturated sodium bicarbonate solution was added to the reaction mixture. The organic layer was concentrated under reduced pressure, and this was combined with the n-hexane extract (extracted twice) from the aqueous layer. This mixture was washed once with saturated brine, dried over anhydrous sodium sulfate, and then 94.4 mg of oil was obtained by distilling off the solvent under reduced pressure.
I got it. This oil was purified using a silica gel column to obtain 91.1 mg of a colorless oil. As a result of analyzing this substance by gas chromatography, α-
Bisabolene (-1), β-bisabolene (-2)
and γ-bisabolene (-3) with a yield of 37%,
It was observed that this was obtained in 18% and 17%.

Example 3 100 mg (0.45 mmol) of (E,Z) falnesol and 350 ml of lithium perchlorate in a 30 ml test tube with a branch.
mg (3.28 mmol) was weighed out, 8 ml of purified tetrahydrofuran was added thereto, and the mixture was stirred to form a homogeneous solution. A platinum electrode (1.5 x 2 cm ² ) was attached to this branched test tube, and while maintaining the reaction temperature at 58°C,
Electrify for 15 minutes at a constant current of 3.3mA/ ^cm2 (amount of electricity:
0.21F/mol). After the reaction was completed, the reaction mixture was treated in the same manner as in Example 1 to obtain 88.6 mg of a colorless oil. Analysis of this product by gas chromatography revealed that α-bisabolene (-1), β-bisabolene (-2), and γ-bisabolene (-3) were found in yields of 40%, 18%, and 19%, respectively.
It was recognized that this was obtained.

Example 4 100mg of geraniol in a 30ml test tube
(0.65mmol) and lithium perchlorate 346mg
(3.25 mmol) was weighed out, 8 ml of purified tetrahydrofuran was added thereto, and the mixture was stirred to form a homogeneous solution.
A platinum electrode (1.5 x 2 cm ² ) was attached to this branched test tube, and while the reaction temperature was maintained at 60°C, the flow rate was 3.3 mA/cm ^{2 .}
Electrify for 15 minutes at a constant current (amount of electricity: 0.21F/mol)
I did this. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, washed once with water, dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to obtain 88.3 mg of a yellow oil. This oil was purified using a very short silica gel column to obtain 64.5 mg of a colorless oil. As a result of analyzing this product by gas chromatography, it was found that limonene represented by formula (-4) and terpinolene represented by formula (-5) were obtained in yields of 23% and 41%, respectively. Compounds corresponding to the peaks representing these products were separated by gas chromatography, and each compound was confirmed because its physical property values matched those of existing limonene and terpinolene.

Claims (1)

[Claims] 1. General formula (In the formula, n means an integer of 0 or 1.) Chain terpene alcohol and/or general formula (In the formula, n is as defined above.) A general formula characterized in that a chain terpene alcohol represented by (where n is as defined above, Z ¹ and Z ²
One of them is a hydrogen atom and the other together with Z represents a single bond, two of X ¹ , X ² and X ³ are hydrogen atoms and the remaining one together with X represents a single bond. Represents a bond. ) A method for producing a cyclic terpene hydrocarbon. 2. The method for producing a cyclic terpene hydrocarbon according to claim 1, wherein n is 1 in the general formula.