JPH028032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2,2-dimethyl-3-methylenebicyclo[2,2,1]heptan-5-ol or its lower aliphatic carboxylic acid ester. Alternatively, camphene is electrolytically oxidized in a lower aliphatic carboxylic acid, the oxidation product is hydrolyzed as necessary, and the resulting 2,2-dimethyl-3-methylenebicyclo[2,
2,2-dimethyl-3-methylenebicyclo[2,2,1]heptan-5-ol or a lower aliphatic carboxylic acid ester thereof, characterized in that 2,1] heptan-5-ol or a lower aliphatic carboxylic acid ester thereof is separated The present invention relates to a method for producing an aliphatic carboxylic acid ester.

2,2-dimethyl-3-methylenebicyclo[2,2,1]heptan-5-ol is a monoterpene alcohol isolated from the essential oil of Chrysanthemum japonense by Matsubara et al. is called Nojigiku alcohol; Tetrahedron Letters No. 48, 4219-4222
(1974)], it has the aroma of Noji chrysanthemum and is useful as an aroma component in perfumes. This lower aliphatic carboxylic acid ester of Nojigiku alcohol also has an elegant flower-like aroma and is useful as an aroma component of fragrances.

Conventionally, it has been reported that Nojigiku alcohol is synthesized by chlorinating camphene with chlorine gas, then acetoxylating it with potassium acetate, and further hydrolyzing it [DLDull
et al., J.Org.Chem., 29, 3095 (1964)], this method is not necessarily satisfactory in terms of yield, selectivity, etc. In addition, camphenyl aldehyde, borneol, 2β-camphenyl alcohol, etc. can be obtained by electrolytically oxidizing camphene or tricyclene using lithium acetate as a supporting electrolyte and a stainless steel electrode, and then saponifying the product. It has been reported that [Matsubara et al., Abstracts of the 16th Symposium on Flavor, Terpene and Essential Oil Chemistry, pp. 111-112 (1972)], the electrolytic oxidation reaction or saponification reaction There is no report that Nojigiku alcohol or its ester was produced.

As a result of extensive research into the electrolytic oxidation of mono- and sesquiterpene hydrocarbons, the present inventors found that when electrolytically oxidized in tricyclene and/or camphene lower aliphatic carboxylic acid, the lower aliphatic carboxylic acid ester of Nojigik alcohol is highly selective. We found that this lower aliphatic carboxylic acid ester of Nojigiku alcohol can be easily derived into Nojikiku alcohol by hydrolysis,
This led to the present invention.

In the method of the present invention, tricyclene,
Although camphene or a mixture thereof can be used, the target compound can be obtained with the highest selectivity when tricyclene is used as a substrate. The electrolytic oxidation reaction is carried out in lower aliphatic carboxylic acids. Examples of lower aliphatic carboxylic acids include acetic acid,
Examples include propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, and the use of acetic acid is particularly preferred. These lower aliphatic carboxylic acids are used as solvents and also act as reaction reagents, so according to the electrolytic oxidation reaction of the present invention, esters of Nojigik alcohol corresponding to the lower aliphatic carboxylic acids used can be obtained. . The amount of lower aliphatic carboxylic acid used is per mole of substrate.
The amount is 20 to 100 mol, preferably 40 to 80 mol. Note that a solvent such as methyl acetate or ethyl acetate that does not inhibit the electrolytic oxidation reaction may be present in the reaction system. Further, when the electrolytic oxidation reaction of the present invention is carried out in a system where water is present, nojigikku alcohol is produced in addition to the above-mentioned ester, and a mixture of the two is obtained.

In the electrolytic oxidation reaction of the present invention, it is preferable to use a suitable supporting electrolyte. The supporting electrolyte is preferably one that is non-reactive with the substrate or reaction product and does not inhibit the electrolytic oxidation reaction, such as potassium chloride, magnesium sulfate, barium phosphate, lithium perchlorate, sodium perchlorate, potassium acetate, and strontium acetate. , halides, sulfates, phosphates, perchlorates, acetates of alkali metals or alkaline earth metals such as sodium, potassium, barium, calcium, strontium, magnesium, such as sodium p-toluenesulfonate, or toluenesulfonic acid. Salt; ammonium sulfate, ammonium perchlorate, ammonium acetate,
Ammonium salts such as ammonium p-toluenesulfonate; carbon atoms such as n-butylammonium phosphate, di-n-butylammonium acetate, triethylammonium chloride, triethylammonium sulfate, trimethylammonium perchlorate, and tetraethylammonium p-toluenesulfonate; ~
Halides, sulfates, phosphates of primary to quaternary ammonium cations having 6 alkyl groups,
perchlorate, acetate or toluenesulfonate;
Chain or cyclic amines such as trimethylamine, triethylamine, diisopropylamine, butylamine, pyrrolidine, piperazine, pyridine, picoline; boron metal salts such as sodium borofluoride and sodium borochloride alone or in combination Can be used in mixtures of more than one species. Particularly preferred supporting electrolytes include amines and ammonium salts. The amount of supporting electrolyte used varies depending on the type of supporting electrolyte and solvent used and the required current density. For example, when tetraethylammonium p-toluenesulfonate is used as the supporting electrolyte, 1 mol of substrate, acetic acid It is preferably 0.1 to 1.0 mol per 70 mol.

Since the electrolytic oxidation reaction of the present invention is carried out in a lower aliphatic carboxylic acid, acid-resistant electrodes such as gold, platinum, titanium plated with gold or platinum, carbon, or lead peroxide are preferably used. Materials which give particularly good results in terms of reaction yield and selectivity are carbon, platinum or titanium plated with platinum. The current density is in the range of 5 to 50 mA/cm ² , preferably 10 to 20 mA/cm ² , and this value can be adjusted by adjusting the terminal voltage. The theoretical amount of electricity is
Although it is 2F/mol, it is actually preferable to use 3.0 to 4.5F/mol to increase the conversion rate of Nojigikku alcohol to lower aliphatic carboxylic acid ester. Although the reaction is possible over a relatively wide range of temperatures, such as from 10 to 45°C, it is particularly practical to carry out the reaction in the temperature range from 15 to 25°C. Incidentally, if a reaction at a constant temperature is desired, the reaction system may be cooled or heated by conventional means.

The electrolytic oxidation reaction in the present invention can be carried out continuously or batchwise. After the electrolytic oxidation reaction, for example, the reaction mixture or the residue obtained by distilling off the solvent from it under reduced pressure is poured into water or a dilute alkaline aqueous solution, and this is extracted with a suitable solvent such as hexane to achieve the desired purpose. It is possible to separate the lower aliphatic carboxylic acid ester of Nojichoku alcohol or the oil containing this and Nojichoku alcohol. In addition to the target product, this oil contains by-produced 3,5-diacetoxycamphane, 3,5-
3,5- such as dipropionyloxycamphane
May contain small amounts of diacyloxycamphane. A lower aliphatic carboxylic acid ester of Nojichoku alcohol or this and Nojichoku alcohol can be separated and obtained from this oil by a commonly used separation method such as distillation.

The lower aliphatic carboxylic acid ester of Nojichoku alcohol obtained by the electrolytic oxidation reaction can be made into Nojichoku alcohol by hydrolyzing it according to a conventional method with or without isolation and purification.

The present invention will be specifically explained below using examples.

Example 1 1.36 g of tricyclene (GLC purity 100%) and 2.50 g of tetraethylammonium p-toluenesulfonate as a supporting electrolyte were dissolved in 40 ml of acetic acid, this solution was placed in a beaker-type membraneless cell, and a current density was adjusted using a carbon electrode. 10mA/cm ² , current flow 4F/mol,
Constant current electrolysis was performed at a temperature of 20-29°C.
After the reaction was completed, acetic acid was distilled off from the reaction mixture at about 40°C under reduced pressure, and the remaining small amount of acetic acid was neutralized with an aqueous potassium carbonate solution. Extraction was performed using 150 ml. The extract was washed with water, dried over anhydrous magnesium sulfate, and then the hexane was distilled off to obtain 1.25 g of an oily substance. Next, dissolve this oil in 50ml of ethanol, and add 10ml of 2N caustic soda to this.
was added, and the resulting mixture was heated under reflux for 1.5 hours.
Ethanol was distilled off from the reaction mixture under reduced pressure, and the residual oil was poured into water, which was extracted with n-hexane. After washing the extract with water and drying with anhydrous magnesium sulfate, expulsion distillation was performed and FID-
1.02 g of crude Nojigiku alcohol with a GLC distribution ratio of 57% was obtained. Furthermore, by recrystallizing this crude Nojigiku alcohol from ethanol,
0.30 g of Nojigiku alcohol was obtained as white crystals with a temperature of 55 to 57.5°C. The physical properties of this product are shown below.

IR spectrum (cm ^-1 ): 3320, 2960, 1660,
1050, 1030, 880 NMR spectrum (90MHz) δ ^CDCl3 _ppn : 0.95, 1.02 (each s, 6H); 2.61 (BS, 1H); 3.7-3.9 (m, 1H); 4.64, 4.85 (each s, 2H) Implemented Example 2 Add 1.32 g of tricyclene (GLC purity 100%) and 1.56 g of triethylamine as a supporting electrolyte to 40 g of acetic acid.
This solution was placed in a beaker-type non-diaphragm cell, and constant current electrolysis was performed using a carbon electrode at a current density of 10 mA/cm ² , a current flow rate of 4 F/mol, and a temperature of 20 to 29°C. After the reaction was completed, the same procedure as in Example 1 was carried out to obtain 1.25 g of an oily substance. Then,
This oily substance was hydrolyzed in the same manner as in Example 1, and then distilled to obtain a FID-GLC distribution ratio of 57%.
0.98 g of crude Nojigiku alcohol having the following properties was obtained.
This crude Nojigiku alcohol was recrystallized from ethanol to obtain 0.51 g of white crystals of Nojikiku alcohol.

Example 3 2.72 g of camphene (GLC purity 100%) and 5.02 g of tetraethylammonium p-toluenesulfonate as a supporting electrolyte were dissolved in 80 ml of acetic acid, placed in a beaker-type membraneless cell, and using a carbon electrode at a current density of 10 mA. /cm ² , current flow 4F/mol, temperature
Constant current electrolysis was performed at 29°C. After the reaction is completed, the oily substance is removed by the same treatment as in Example 1.
2.62g was obtained. Next, this oily substance was hydrolyzed in the same manner as in Example 1, and then distilled to obtain
2.65 g of crude Nojigiku alcohol with a FID-GLC distribution ratio of 19% was obtained. This crude Nojigiku alcohol was recrystallized from ethanol to obtain 0.43 g of white crystals of Nojikiku alcohol.

Example 4 1.36 g of tricyclene (GLC purity 100%) was electrolytically oxidized in the same manner as in Example 1, and 1.30 g of an oil containing acetic acid ester of Nojigik alcohol was obtained by the same extraction operation from the resulting reaction mixture. . By distilling this oil under reduced pressure, bp.98℃/
0.73 g of acetic acid ester of Nojigiku alcohol was obtained as a 7 mmHg fraction. The physical properties of this product are shown below.

IR spectrum (cm ^-1 ): 2980, 1740, 1660,
1380, 1250, 1230, 1030, 890 NMR spectrum (90MHz) δ ^CDCl3 _ppn : 0.98, 1.02 (each s, 6H); 2.00 (s, 3H); 2.75 (BS, 1H); 4.5-4.7 (m, 1H) ; 4.70, 4.95 (each s, 2H) Example 5 A similar electrolytic oxidation reaction was carried out in Example 1 using 40 ml of propionic acid instead of 40 ml of acetic acid, and from the resulting reaction mixture, Nojigi 1.32 g of an oil containing propionic ester of alcohol was obtained. By distilling this oil under reduced pressure, the propionic acid ester of Nojigik alcohol was obtained as a fraction of bp.101℃/7mmHg.
0.81g was obtained. The physical properties of this product are shown below.

IR spectrum (cm ^-1 ): 2980, 1740, 1660,
1180, 1020, 890 NMR spectrum (90MHz) δ ^CDCl3 _ppn : 1.00, 1.04 (each s, 6H); 1.10 (t, 3H); 2.27 (q, 2H); 2.75 (bs, 1H); 4.5-4.7 (m , 1H); 4.70, 4.96 (each s, 2H)

Claims (1)

[Scope of Claims] 1. Electrolytic oxidation of tricyclene and/or camphene in a lower aliphatic carboxylic acid, hydrolysis of the oxidation product as necessary, and then the produced 2,2-dimethyl-3-methylenebicyclo[2 , 2,1] 2,2- characterized by separating heptan-5-ol or its lower aliphatic carboxylic acid ester
Dimethyl-3-methylenebicyclo[2,2,1]
A method for producing heptane-5-ol or a lower aliphatic carboxylic acid ester thereof.