JPS6146457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to synthetic urushiol-like substances, and in particular to a novel compound 4-(9'·12'-octadecadienyl)-catechol and a method for producing the same. It is something.

(Prior art) Lacquerware is a traditional craft specific to the East, especially Japan, and is known around the world as Japan.As is well known, lacquerware relies on the natural lacquer secreted from the lacquer tree as its raw material. Ta. However, since the opening of the Meiji era, these resources have continued to deplete, and currently only 90
More than % of the total depends on imports from China. Due to these circumstances, lacquer is extremely expensive. Furthermore, research has been conducted on the synthesis of urushiol, a drying oil that makes up the majority of natural lacquer liquid, since the Meiji era, but this synthesis is extremely difficult and has not yet been solved.
Furthermore, it is considered almost impossible to produce it industrially at low cost. For these reasons, efforts have been made since ancient times to synthesize urushiol-like substances, which are relatively easy to produce.

Natural urushiol has the general formula (R in the formula is the number of carbon atoms having 1 to 3 double bonds.
o-, which represents 15 straight-chain hydrocarbon groups)
It is a mixture of homologues of alkenylcatechol. The average number of double bonds in the formula is two, but three compounds account for 50% of them. According to Professor Ichiro Miyagawa of Nagoya University, the conditions that synthetic urushiol-like substances should have, that is, the chemical structure, are generally: (a) the number of carbon atoms in the catechol side chain should be 15 or more; (b) the number of carbon atoms in the side chain should be 15 or more; The higher the degree of unsaturation, the better the drying time. (c) Chemical resistance is almost the same for those with 1 to 3 double bonds, but is poor for those with 0 double bonds. (d) Catechol nucleus It is known that there is almost no difference in the cured film due to the difference in the position of the side chain.

(Problems to be Solved by the Invention) Synthetic urushiol-like substances are compounds in which the raw material catechol can be obtained at low cost, and the alkenyl group introduced into the side chain of catechol can also be obtained from natural unsaturated fats. You can obtain it relatively easily by using . However, in this method, in the step of introducing side chains to catechol, the addition reaction of carbon double bonds to catechol takes precedence, and as a result, it is not possible to introduce alkenyl groups in a linear form, and it is not possible to introduce alkenyl groups in a branched form. Compounds are preferentially produced. As a result, many types of compounds were produced as by-products, which had to be used all at once as lacquer substitutes. Naturally, the quality was not good, and it was difficult to produce products that could be dried at room temperature. It has been used only as.

Particularly in recent years, as a result of the abnormal rise in the price of lacquerware, the price of lacquerware has become extremely expensive, and it has become difficult to use conventional low-grade products such as urushiol-like substances. There is a demand for high-grade products made of compounds that are free of .

Furthermore, in order to produce a compound with excellent performance as a urushiol analogue, it is necessary that the hydrocarbon side chain introduced into the catechol nucleus is completely linear, as is the case with natural urushiol, and that the catechol Must be in position 3 or 4 of the nucleus. Moreover, the number of double bonds of the carbon unsaturated group contained must be 2 to 3.

However, when long-chain hydrocarbons with carbon unsaturated bonds or their derivatives are reacted directly with catechol, the addition reaction of carbon double bonds takes precedence, resulting in a state in which the hydrocarbon group is branched into the catechol nucleus. As a result of the addition reaction with the hydroxyl group of catechol, an ether bond was also formed on the oxygen. This is extremely inconvenient for use as a lacquer paint that dries at room temperature.

(Means and effects for solving the problems) In order to solve these problems, the present invention
The object of the present invention is to industrially synthesize a synthetic urushiol-like substance, especially catechol having a straight-chain unsaturated alkyl group, without producing by-products, in response to the above-mentioned demand for higher quality lacquer products.

In other words, in order to obtain such a compound, linoleic acid, which can be obtained naturally at an extremely low cost, was used as a raw material for the unsaturated hydrocarbon group in the side chain of the catechol nucleus, and a linear compound in which the carbon unsaturated group was previously protected with bromine was created. was reacted with veratrol whose hydroxyl group on the catechol nucleus was protected with a methoxy group. Next, using a compound in which the veratrol nucleus was demethylated, the carbonyl group was reduced and debrominated at the same time, allowing the synthesis of the desired urushiol analog.

Specifically, the present invention relates to chemical structural formula 4-(9′・12′-octadecadienyl) represented by
- Found in catechol.

In addition, the present invention also provides the chemical structural formula for obtaining the above compound (1). The production method involves reducing 4-(9', 10', 12', 13'-tetrabrosmotearoyl)-catechol represented by the following formula with zinc in an acidic medium.

This reaction generally uses inexpensive mineral acids such as hydrochloric acid and sulfuric acid, and reduces zinc to its existence in an acidic medium. As a result, the bromine atoms on the intramolecular linear chain of 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol (2) are debrominated all at once, creating a carbon double bond. . At that time, the position and arrangement of this carbon double bond remain as it existed in linoleic acid (the double bond is 2
, all cis-type).

A further advantage of this reaction is that the carbonyl group adjacent to the aromatic ring can be reduced to a hydrocarbon group (>C=O
→＞CH ₂ ) They are to proceed at the same time.

As a result, a catechol compound having a linear hydrocarbon side chain with 18 carbon atoms containing two unsaturated groups,
4-(9'·12'-octadecadienyl)-catechol (1) is easily produced.

The reaction proceeds satisfactorily under the conditions shown above, but
Benzene, toluene,
The process can proceed more smoothly if a chemically stable solvent such as xylene is present at the same time.
Toluene is preferred when considering the boiling point of the solvent.

4-(9', 10', 12', 13'-tetrabromostearoyl)catechol (2) used in this reaction can be obtained, for example, by the process shown in the following formula. First, bromine is added to mixed fatty acid (4) extracted by saponifying linseed oil (3). Excess thionyl chloride was added to the obtained high-purity linoleic acid tetrabromide (9,10,12,13-hexabromostearic acid (5)) to form the acid chloride 9,10,12,13-tetrabromo Produces stearoyl chloride (6). After reacting this acid chloride (6) with veratrol (7) in the presence of a Friedel-Crafts catalyst, the obtained 4-(9′・10′・12′・13′-
The desired compound (2) is obtained by treating the methoxy group of (tetrabromostearoyl)-veratrol (8) with boron tribromide to demethylate it.

In this way, it is finally possible to obtain a synthetic urushiol-like substance in which a hydrocarbon side chain having 18 carbon atoms and the same unsaturated bonds as linoleic acid is introduced in a linear manner.

The present invention will be explained below based on Examples.

(Example) 9, 10, 12, 13-tetrabromostearic acid (5)
Synthesis Dissolve 250g of soybean oil (3) in 1250g of ethanol,
75 g of potassium hydroxide was mixed with an aqueous solution in a small amount of water. After heating and stirring the mixture at 80° C. for 3 hours, ethanol was distilled off under reduced pressure, and dilute sulfuric acid was added to liberate the mixed fatty acid (4).
This was extracted with ligroin, washed with brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was extracted with approx.
Concentrated to 500c.c. This was cooled to -7°C using a cryogen, and 70 c.c. of bromine was gradually added dropwise with stirring. After stirring for 1 hour, the mixture was heated to 90° C. or higher to completely dissolve the precipitate, and then filtered hot. When the filtrate is cooled, crystals precipitate. This was suction filtered, washed with an aqueous sodium sulfite solution, the crystals were air-dried, and recrystallized with ligroin.

Yield 73.6g (yield 29.2%), melting point 113.5-115℃
(Literature value 115℃). 9,10,12,13-tetrabromostearic acid, a known substance from infrared absorption spectrum
It was identified as (5).

Synthesis of 9,10,12,13-tetrabromostearoyl chloride (6) The above 9,10,12,13-tetobromostearic acid
(5) 10 g (1.704 x 10 ^-2 mol) was heated to 120°C to melt it, and 3 g (1.704 x 10 ^-2 x 1.5 mol) of thionyl chloride was added over 1 hour. The mixture was heated at 120° C. for 1 hour, and then excess thionyl chloride was distilled off under reduced pressure to obtain 9,10,12,13-tetrabromostearoyl chloride (6).

Yield over 98%. The infrared absorption spectrum matched that of a known substance.

Synthesis of 4-(9', 10', 12', 13'-tetrabromostearoyl)-veratrol (8) 21.7 g (0.0033 mol) of the above 9, 10, 12, 13-tetrabromostearoyl chloride (6) Dissolved in 20ml of carbon sulfide. Add this solution to veratrol (7)
4.5g (0.033mol), anhydrous aluminum chloride 5.3g
(0.033 x 2.2 mol) and 40 ml of carbon disulfide with stirring, 15
The reaction mixture is stirred for a period of time, and after cooling, the mixture is poured into ice water acidified with hydrochloric acid, extracted with benzene, washed with aqueous sodium bicarbonate, then with water, and then dried. Benzene is distilled off to obtain crystals.

Yield 10.1g (yield 42.6%), melting point 76-78°C.

Elemental analysis (C, 43.58%: H, 5.59%.

Calculated value for C ₂₆ H ₄₀ O ₃ Br ₄ , C, 43.36%; H,
5.59%). Infrared absorption spectrum (1660 cm ^-1 phenyl ketone; 1022 cm ^-1 , veratrol nucleus φOCH ₃ :
870, 840 cm ⁻¹ , 4-substituted veratrol). Proton NMR spectrum (6.95, 6.79ppm (6-H, J
=9.18Hz), 7.52ppm (3-H), 7.52, 7.64,
7.67 ppm (5-H; 4-substituted veratrol).

From these analysis results, the product is 4-(9′・
It was confirmed that it has the chemical structure of 10', 12', 13'-tetrabromostearoyl)-veratrol (8).

Synthesis of 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol (2) 4-(9', 10', 12',
13'-tetrabromostearoyl)-veratrol
(8) 1.853 g (2.57 x 10 ^-3 mol) was dissolved in 60 ml of dichloromethane and cooled to -60°C. To this was added 2.60 g (2.57 x 10 ^-3 x 4 moles) of boron tribromide with stirring, and the mixture was kept at the same temperature for 1 hour and then left overnight. This was poured into ice water acidified with hydrochloric acid, extracted with benzene, washed with water and brine, dried, and then the solvent was distilled off to obtain a solid product.

Yield 0.87g (yield 48.7%), melting point 110-112°C.

Elemental analysis (C, 41.64%: H, 5.23%.

Calculated value as C ₂₄ H ₃₆ O ₃ Br ₄ C, 41.65%; H,
5.25%). Infrared absorption spectrum (3200cm ^-1 , OH absorption; 1650cm ^-1 , presence of carbonyl group absorption:
1020 cm ^-1 loss of methoxy group). Disappearance of proton NMR spectrum (3.94 ppm (s, 6H, OCH ₃ ),
Presence of 6.58ppm (broad, 2H, OH). In other words, the absorption for two methoxy groups disappears, and the absorption for two OH groups disappears.
From these analytical results, it is clear that the product is 4-(9′・
It was confirmed that the chemical structure was 10', 12', 13'-tetrabromostearoyl)-catechol (2).

4-(9′・12′-octadecadienyl) of the present invention
-Synthesis of catechol (1) A mixture of 10 g of zinc powder, 6 c.c. of concentrated hydrochloric acid, and 5 c.c. of water was boiled while stirring, and the 4-(9', 10', 12' - Add 0.567 g (8.20 x 10 ^-4 mol) of 13'-tetrabromostearoyl)-catechol (2) and 10 ml of toluene, and heat under reflux for 10 hours. After cooling, separate the upper toluene layer, thoroughly extract the lower layer with ether, combine the extracts, wash with sodium bicarbonate water and brine, dry, remove the solvent and purify to obtain the desired product in the form of an oil. 0.126 g (theoretical yield 43.3%) was obtained.

Mass spectrometry (analyzed 358 _, 2932, calcd _{for C24H38O2} 358.2926).

The infrared absorption spectrum is shown in Figure 1 (4-substituted catechol, 3350 cm ^-1 , OH stretching vibration; 960,
720cm ^-1 , CH=CH).

The proton NMR spectrum is shown in Figure 2 (5.35ppm (m, 4H, -CH=CH-, J=9.6Hz,
2H, OH), 6.70ppm (3H, φ-H), 0.88~
2.75ppm (m, 29H, _-CH2 , _-CH3 ), two carbon double bonds exist in cis form).

From these analysis results, the product is 4-(9′・
It was confirmed that the chemical structure was 12'-octadecadienyl)-catechol (1).

(Effects of the Invention) According to the present invention, a carbonyl group is reduced and simultaneously debrominated using 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol.
Since we were able to obtain -(9'·12'-octadecadienyl)-catechol, an extremely pure synthetic urushiol analogue was obtained.

In fact, when a conventional synthetic urushiol-like substance containing impurities is mixed with natural urushi and used for a lacquer-based paint that dries at room temperature, the mixing ratio is 1 to 1 for Japanese urushi.
Although only 0.5 was used, when the synthetic urushiol-like substance produced according to the present invention was similarly mixed with natural lacquer, it showed the ability to form a dry coating even at a ratio of 1:1 or more. This has made it possible to provide high-quality lacquer products that can be dried at room temperature.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an infrared absorption spectrum according to an example of the present invention, and FIG. 2 is a diagram similarly showing an NMR spectrum.

Claims (1)

[Claims] 1. Chemical structural formula 4-(9′・12′-octadecadienyl) represented by
- Catechol. 2 Chemical structural formula A chemical structure obtained by reducing 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol with zinc in an acidic medium. 4-(9′・12′-octadecadienyl) represented by
- A method for producing catechol.