JPS6256955B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for industrially producing a lower aliphatic carboxylic acid ester of 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol. 2,2-dimethyl- 3-
The lower aliphatic carboxylic acid ester of methylenebicyclo[2.2.1] heptane-5-ol and the mixture of unreacted tricyclene and camphene are recovered, and then the mixture of unreacted tricyclene and camphene is added to the mixture in the presence of an acidic catalyst. After increasing the content of tricyclene in the mixture by subjecting it to the isomerization reaction described below, it is recycled as a raw material for the electrolytic oxidation reaction, and at this time, if necessary, a new mixture of tricyclene and camphuene is added to the isomerization reaction described above. The present invention relates to a method for producing a lower aliphatic carboxylic acid ester of 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol, which is supplied as a raw material for a chemical reaction or an electrolytic oxidation reaction. The lower aliphatic carboxylic acid ester of 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol has a refreshing and distinctive fresh green and balsam-like top note with slight camphor-like and mint-like top notes. It not only has a floral note with a sensory sensation, and is useful as a material for flower-like mixed fragrances, but also has a slight camphor-like and mint-like top note, and a floral note with a whistling-like sensation. It is also useful as an intermediate for the synthesis of 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol, which is useful as a raw material for flower-like perfumes (Japanese Patent Application No. 30492/1982) reference). 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptane-5-ol was obtained from Chrysanthemum
japonense ) is a monoterpene alcohol isolated from the essential oil, and is called Nojigiku alcohol [Tetrahedron Letters No. 48, 4219-4222
(1974)]. The present inventors have repeatedly studied the electrolytic oxidation of mono- and sesquiterpene hydrocarbons, and have found that Nojigik alcohol can be obtained by electrolytically oxidizing a single compound of tricyclene or camphene, and hydrolyzing the oxidation product. In addition, when camphene is used as a substrate, there are large amounts of more than 10 types of by-products such as tricyclenol, 2,2-dimethyl-3-hydroxymethylbicyclo[2.2.1] heptane-3-ol, etc. We previously reported that when tricyclene is used as a substrate, Nojigiku alcohol can be obtained with good selectivity [Matsubara et al.
See Abstracts of the 26th Symposium on Flavor, Terpene and Essential Oil Chemistry, pp. 272-274 (1982)].
Therefore, it is desirable to select tricyclene as the substrate to obtain Nojigikku alcohol. However, tricyclene is usually produced as an equilibrium mixture with camphene by isomerizing pinene in the presence of an acidic catalyst, and the boiling points of the two are very close to each other. When mass producing on a large scale, it is not easy to secure 100% pure tricyclene as a raw material substrate. As a result of further extensive research into the electrolytic oxidation of tricyclene and camphene, the present inventors found that when tricyclene and camphene are mixed and subjected to an electrolytic oxidation reaction in a lower aliphatic carboxylic acid, tricyclene is usually It is preferable to move the reaction mixture out of the reaction system or stop the reaction before substantial electrolytic oxidation of camphene occurs. Lower aliphatic carboxylic acid esters of Nojigikku alcohol can be obtained with high selectivity;
Furthermore, by isomerizing a mixture of unreacted tricyclene and camphene recovered from the reaction mixture in the presence of an acidic catalyst, the content of tricyclene in the mixture can be increased, and a mixture with an increased content of tricyclene can be obtained. It has been discovered that an additional amount of lower aliphatic carboxylic acid ester of Nojigik alcohol can be obtained with good selectivity by recycling it as a raw material for the above-mentioned electrolytic oxidation reaction, leading to the present invention. The method of the invention uses a mixture of tricyclene and camphene as substrate. The preferential electrolytic oxidation of tricyclene depends on the composition of the mixture, and the composition varies somewhat depending on the electrolytic conditions such as the electrolytic equipment used. Regarding the composition, at least in the initial stage of electrolytic oxidation, electrolytic oxidation of tricyclene proceeds with priority over electrolytic oxidation of camphuene. Such a composition can be easily determined by conducting a simple preliminary experiment regarding the electrolytic conditions of the electrolytic device used. Surprisingly, in experiments for determining such compositions, a more limited composition range is generally found in which the electrolytic oxidation of camphene is substantially suppressed and only tricyclene is selectively electrolyzed. When a mixture in this composition range (ratio of tricyclene and camphuene) is used as a substrate, the reaction of camphene is suppressed even if electrolytic oxidation is continued until a relatively high conversion rate is achieved. Carboxylic acid esters can be obtained with good selectivity and yield. For example, when using a non-diaphragm type electrolytic device, if a mixture of tricyclene and camphuene with a molar ratio of more than 2/3 is used as the substrate, the electrolytic oxidation reaction of camphene can be extremely suppressed, and tricyclene can be Selectively electrolytically oxidized. This molar ratio is approximately 2/
When a mixture of tricyclene and camphuene with a concentration lower than 3 is used as a substrate, the electrolytic oxidation reaction of both proceeds, and a large amount of by-products caused by camphuene are produced. Therefore, in such a case, it is necessary to move the reaction mixture out of the system or to stop the reaction at a relatively early stage of the reaction, before electrolysis of camphene occurs. In the present invention, a mixture of tricyclene and camphene in which tricyclene is electrolytically oxidized preferentially to camphene is prepared by isomerizing camphene, which may contain a small amount of tricyclene, in the presence of an acidic catalyst. be able to. It is industrially advantageous to carry out this isomerization reaction by isomerization distillation. Examples of the acidic catalyst include silica alumina, activated clay, p-toluenesulfonic acid, and the use of p-toluenesulfonic acid is particularly preferred. The isomerization reaction can be carried out under normal pressure or reduced pressure, and in consideration of the isomerization rate of camphene to tricyclene, it is practical to set the isomerization temperature from about 130° C. to the reflux temperature. The preferred amount of the acidic catalyst used varies depending on the type of catalyst used and the isomerization temperature, but is about 1 to 5% by weight based on camphene. For example, when p-toluenesulfonic acid is used as an acidic catalyst, at reflux temperature under normal pressure, it is about 1% by weight based on camphuene.
is preferred. The equilibrium composition of camphene and tricyclene in the presence of an acidic catalyst is approximately 8 in the ratio of the former to the latter.
However, since the boiling point of tricyclene (153℃) is lower than that of camphene (158.5-159.5℃), preferential electrolytic oxidation of tricyclene is performed by using a distillation column with 15 or more theoretical plates. For example, a mixture of the two can be obtained with a given composition of tricyclene to camphene of more than about 2/3. If a distillation column with a small number of theoretical plates is used, it is necessary to further fractionate the distillate. Note that during this isomerization distillation, bornylene, which forms a trace equilibrium composition of camphene in the presence of an acidic catalyst, is also distilled out together with tricyclene. Therefore, in order to obtain tricyclene containing almost no bornylene and camphene, it is necessary to redistill the above-mentioned isomerized distillate. 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, 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 5 mol or more, preferably 20 to 70 mol, per 1 mol of the substrate. 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, it is preferable to allow water to be present in the reaction system. When water is present in the reaction system, the electrical conductivity becomes better and the potential can be lowered significantly than in the electrolytic oxidation of tricyclene in the absence of water. It is possible to lower the electricity consumption rate in the production of acid esters. The preferred amount of water to be present is greatly influenced by the substrate concentration in the lower aliphatic carboxylic acid, and when the substrate concentration is about 3 to 10% by weight, about 1
~10% by weight, particularly a range of about 2.5 to 5% by weight. 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 and sulfates of alkali metals or alkaline earth metals such as sodium, potassium, barium, calcium, strontium, and magnesium, such as potassium propionate and sodium p-toluenesulfonate;
Phosphate, perchlorate, acetate, propionate or toluenesulfonate; ammonium salts such as ammonium sulfate, ammonium perchlorate, ammonium acetate, ammonium propionate, ammonium p-toluenesulfonate; n-butylammonium phosphate , di-n-butylammonium acetate, triethylammonium propionate, triethylammonium chloride, triethylammonium sulfate, trimethylammonium perchlorate, p-
Primary ~ having an alkyl group having 1 to 6 carbon atoms such as tetraethylammonium toluenesulfonate
Halides, sulfates of ammonium cations of tertiary amines or quaternary ammonium cations,
Phosphate, perchlorate, acetate, propionate or toluenesulfonate; Chain or cyclic amines such as trimethylamine, triethylamine, diisopropylamine, butylamine, pyrrolidine, piperazine, pyridine, picoline; Boron fluoride Boron metal salts such as sodium, sodium borochloride, etc. alone or in combination
Can be used in mixtures of more than one species. Also,
Among these supporting electrolytes, salts of lower aliphatic carboxylic acids include alkali metal hydroxides that can form salts with lower aliphatic carboxylic acids present in the system;
It can also be generated in-system by adding alkaline earth metal hydroxides, aqueous ammonia, primary to tertiary amines having alkyl groups having 1 to 6 carbon atoms, and the like. Particularly preferred supporting electrolytes include amines, lower aliphatic carboxylates, and ammonium salts. The amount of supporting electrolyte to be used varies depending on the type of supporting electrolyte and solvent used, and for example, when triethylamine is used as the supporting electrolyte, it is preferably 0.3 to 3.0 mol per 1 mol of substrate and 70 mol of acetic acid. 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 100 mA/cm ² , preferably 10 to 50 mA/cm ² , and this value can be adjusted by the terminal voltage. Although the theoretical amount of electricity is 2F/mol, it is actually preferable to use 2.5 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 50°C, it is particularly practical to carry out the reaction in the temperature range from 25 to 45°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. As mentioned above, when camphene is electrolytically oxidized, in addition to lower aliphatic carboxylic acid ester of Nojigik alcohol, lower aliphatic carboxylic acid ester of tricyclenol, etc.
Since a large amount of more than 10 types of by-products are co-produced, it is necessary to move the reaction mixture out of the reaction system or stop the reaction before substantial electrolytic oxidation of camphene occurs. From this reaction mixture, unreacted tricyclene and camphene are distilled off together with the solvent under reduced pressure, and the resulting residue is poured into water or a dilute alkaline aqueous solution, and extracted with a hydrocarbon extraction solvent such as hexane, benzene, toluene, etc. By doing so,
The desired oil component containing the lower aliphatic carboxylic acid ester of Nojigiku alcohol can be separated. In addition to the desired product, this oil may contain a small amount of by-produced lower aliphatic carboxylic acid ester of 2,2,3-trimethylbicyclo[2.2.1]heptane-3,5-diol. The lower aliphatic carboxylic acid ester of Nojigaku alcohol can be separated and obtained from this oil by a commonly used separation method such as distillation. In addition, unreacted tricyclene recovered by distilling the above reaction mixture under reduced pressure,
A mixture of camphuene and a solvent is diluted with water, for example, and then extracted with a hydrocarbon extraction solvent such as hexane, benzene, toluene, etc., and the extraction solvent is distilled off from the extract to separate unreacted tricyclene and camphuene. A mixture of can be recovered. The recovered mixture of unreacted tricyclene and camphene or a mixture to which camphuene, which may contain a small amount of tricyclene, is added is subjected to the isomerization reaction in the presence of the acidic catalyst described above to produce camphene. A mixture of tricyclene and camphene is obtained in which the electrolytic oxidation reaction is substantially suppressed and tricyclene is electrolytically oxidized preferentially, for example, a mixture of the two in which the ratio of tricyclene to camphene exceeds about 2/3, and this mixture or To this was added a mixture of tricyclene and camphene that would substantially suppress the electrolytic oxidation reaction of camphene and preferentially electrolytically oxidize tricyclene, and then electrolytically oxidize the mixture in the lower aliphatic carboxylic acid mentioned above By subjecting the reaction to the reaction and transferring the reaction mixture to the outside of the reaction system or stopping the reaction before substantial electrolytic oxidation of camphene occurs, an additional amount of lower aliphatic carboxylic acid ester of Nojigik alcohol can be obtained from this reaction mixture. can be obtained. The lower aliphatic carboxylic acid ester of Nojichoku alcohol thus obtained can be converted into Nojikik alcohol by hydrolyzing it according to a conventional method. The present invention will be specifically explained below using examples. Example 1 Isomerization step A 1-volume three-necked flask equipped with a distillation column (approximately 40 theoretical plates) with an inner diameter of 15 mm and a total length of 1 m filled with a stainless steel filler (trade name: Helipack Packkin SUS316) was charged with a commercially available Camphuen (GLC purity 79.2
%, tricyclene content 17.9%) and 4.7 g of p-toluenesulfonic acid monohydrate were added, and isomerization distillation was performed at a reflux ratio of 1/50 under normal pressure. The mixture was refluxed at an internal temperature of 158 to 165°C, and distilled at 148 to 151°C. The composition of the distillate was 74.2% tricyclene, 16.3% camphene, and 9.5% others. The total distillate amount was 340.4g. The composition of 98.0 g of pot residue was approximately 80% camphuene and 20% tricyclene. Electrolytic oxidation process 340.4 g of the above distillate, 170 g of triethylamine, and 170 ml of water were dissolved in 6800 ml of acetic acid, and this solution was placed in a box-shaped non-diaphragm electrolytic cell, using a carbon electrode, current density 40 mA/cm ² , electricity quantity 2.7 F/mol, temperature 20-29
Constant current electrolysis was carried out under conditions of ℃. After the reaction was completed, acetic acid containing unreacted tricyclene and camphene was distilled off and recovered from the reaction mixture at about 50° C. under reduced pressure. After neutralizing a small amount of acetic acid in the residual solution with an aqueous sodium carbonate solution, the reaction mixture was extracted with three portions of n-hexane, three times in total.
The extract was washed with water, dried over anhydrous magnesium sulfate, and then hexane was distilled off. The resulting oil was distilled under reduced pressure to a boiling point of 98℃/
204.2 g of acetic acid ester of Nojigikku alcohol was obtained as a 7 mmHg fraction (yield 46% based on the total amount of tricyclene and camphene). The conversion rate of tricyclene was 87%, and little camphuene was consumed. The selectivity of tricyclene for Nojigik alcohol to acetate ester was 65%. The physical properties of the obtained acetate ester of Nojigiku alcohol 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) Gas chromatography analysis (filling material OV-17, 2m, column temperature 70-250°C) of the residue in the pot after distilling off the acetate ester of Nojigik alcohol revealed that 2,2,3 - Contained 54.4 g of acetic acid diester of trimethylbicyclo[2.2.1]heptane-3,5-diol. Recovery process of unreacted tricyclene and camphuene Add 1300 ml of water to the acetic acid fraction containing unreacted tricyclene and camphuene recovered from the above reaction mixture.
was added, and then extracted using 1 portion of n-hexane 3 times in total. The extract was washed with water, dried over anhydrous magnesium sulfate, and then hexane was distilled off to obtain 122.4 g of an oily substance. This oily substance was analyzed by gas chromatography (filling material
OV-17, 2m, column temperature 70℃), the composition of this product was 27% tricyclene and 45% camphuene.
% and other 28%. Re-isomerization step: 122.4 g of the above oil and commercially available camphene (GLC
Purity 79.2%, tricyclene content 17.9%) 249.6g
was added to 98.0 g of residue from the distillation column, and an isomerization distillation was performed under the same conditions as in the above isomerization step.
340.0 g of distillate was obtained. The composition of this distillate is 74.2% tricyclene, 16.1% camphuene, and 9.7% others.
It was hot. Re-electrolytic oxidation process 340.0 g of the above distillate, 170 g of triethylamine and 170 ml of water were dissolved in 6800 ml of acetic acid, this solution was placed in a box-shaped non-melting film electrolytic cell, and a current density of 40 mA/cm ² was applied using a carbon electrode. Electricity 2.7F/mol, temperature 20~
Constant current electrolysis was performed at 29°C. After the reaction was completed, an additional 204.8 g of acetate ester of Nojigik alcohol was obtained from the reaction mixture in the same manner as in the electrolytic oxidation step (yield 47% based on the total amount of tricyclene and camphene). The conversion rate of tricyclene was 88%, and little camphuene was consumed. The selectivity of tricyclene for Nojigik alcohol to acetate ester was 65%. Reference Example 1 328.2 g of distillate (composition: 74.2% tricyclene, 16.3% camphuene, and 9.5% others) obtained by the same method as in the isomerization step of Example 1 was distilled using a distillation column with about 40 theoretical plates. Redistilled, its fraction has a composition of 92.2% tricyclene and camphene.
60.9 g of distillate containing 1.3% and 6.5% other was obtained. 0.25g of the above distillate, 0.25g of potassium acetate and water
Dissolve 0.25 ml in 10 ml of acetic acid, put this solution in a beaker-type non-diaphragm electrolytic cell, and use a carbon electrode at a current density of 35 mA/cm ² , an amount of electricity of 2.5 F/mol, and a temperature of 20 ~
Constant current electrolysis was performed at 30°C. After the reaction was completed, the reaction mixture was directly poured into 30 ml of water and extracted with 10 ml of n-hexane. The extract was washed twice with water, dried over anhydrous magnesium sulfate, and then hexane was distilled off. When the obtained oil was analyzed by gas chromatography (filling material OV-17, 2m, column temperature 70-250°C), it was found that camphene was hardly consumed and tricyclene was selectively electrolytically oxidized. The conversion rate of tricyclene was 78%, and the acetate ester of Nojigik alcohol was obtained with a selectivity of 74%. Reference Examples 2 to 8 Predetermined amounts of tricyclene (GLC purity 92.2%, camphuene content 1.3%), acetic acid, water, and supporting electrolyte shown in Table 1 were placed in a beaker-type non-diaphragm electrolytic cell, and using a carbon electrode, Constant current electrolysis was performed under conditions of a current density of 35 mA/cm ² , an amount of electricity of 2.5 F/mol, and a temperature of 20 to 30°C. After the reaction was completed, the reaction mixture was treated in the same manner as in Reference Example 1 to obtain an oily substance, and this oily substance was quantified by gas chromatography. The results are shown in Table 1.

[Table] Reference examples 9 to 11 The specified amounts of tricyclene (GLC purity 92.2%, camphuene content 1.3%), lower aliphatic carboxylic acid, water, and triethylamine shown in Table 2 were placed in a beaker-type non-diaphragm electrolytic cell. , using a carbon electrode, current density 35 mA/cm ² , quantity of electricity 2.5 F/mol, temperature 25 ~
Constant current electrolysis was performed at 30°C. After the reaction was completed, the reaction mixture was treated in the same manner as in Reference Example 1 to obtain an oily substance, and this oily substance was quantified by gas chromatography. The results are shown in Table 2.

[Table] The conversion rates of camphene in Reference Examples 9 to 11 were all less than 2%.

Claims (1)

[Claims] 1. Subjecting a mixture of tricyclene and camphene to an electrolytic oxidation reaction in a lower aliphatic carboxylic acid, and transferring the reaction mixture to the outside of the reaction system before substantial electrolytic oxidation of camphene occurs. Alternatively, the reaction is stopped and the lower aliphatic carboxylic acid ester of 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol and the mixture of unreacted tricyclene and camphene are recovered from the reaction mixture. Then, the recovered mixture of unreacted tricyclene and camphene was subjected to an isomerization reaction in the presence of an acidic catalyst to increase the tricyclene content in the mixture, and then recycled as a raw material for the electrolytic oxidation reaction. 2,2-dimethyl-3-methylenebicyclo[2.2.1]heptane, characterized in that at this time, a new mixture of tricyclene and camphene is supplied as a raw material for the isomerization reaction or electrolytic oxidation reaction as necessary. A method for producing a lower aliphatic carboxylic acid ester of -5-ol. 2. The production method according to claim 1, wherein the isomerization reaction is carried out by isomerization distillation. 3. The manufacturing method according to claim 1, wherein the electrolytic oxidation reaction is carried out in the presence of water.