JPS6146456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to synthetic urushiol analogues, and in particular to novel compounds 4-(9', 12', 15'-octadecatrienyl)-catechol and its This relates to a manufacturing method.

(Prior art) Lacquerware is a traditional craft specializing in the East, especially Japan, and is known worldwide as Japan.As is well known, lacquerware relies on the natural lacquer sap 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
The country relies on imports from China for more than % of its total production. 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.
Moreover, 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 is preferably 15 or more; (b) the number of carbon atoms in the side chain is good; 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 linear unsaturated alkyl group, which does not produce a wide product, in response to the above-mentioned demand for high-quality lacquer products.

That is, in order to obtain such a compound, linolenic acid, which is naturally obtained 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 It is found in 4-(9', 12', 15'-octadecatrienyl)-catechol, which is represented by

In addition, the present invention also provides the chemical structural formula for obtaining the above compound (1). 4-(9', 10', 12', 13', 15', 16'
-hexabromostearoyl)-catechol is reduced 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, 4-(9', 10', 12', 13', 15', 16'
-hexabromostearoyl)-catechol (2), the bromine atoms on the linear chain within the molecule are debrominated all at once to form a carbon double bond. At this time, the carbon double bonds are restored in the same position and configuration as they were in linolenic acid (three double bonds, all in cis form).

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 having 18 carbon atoms and containing 3 unsaturated groups,
4-(9'.12'.15'-octadecatrienyl)-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′・
15',16'-hexabromostearoyl)-catechol (2) 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). The obtained high-purity linoleic acid hexabromide (9, 10, 12, 13, 15, 16
- Adding excess thionyl chloride to hexabromostearic acid (5)) produces acid chloride 9, 10, 12, 13, 15,
16-hexabromostearoyl chloride (6) is produced. After reacting this acid chloride (6) with veratrol (7) in the presence of a Friedel-Crafts catalyst, the obtained 4-(9', 10', 12', 13', 15', 16'- The desired compound (2) is obtained by treating the methoxy group of hexabromostearoyl)-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 having the same unsaturated bonds as linolenic acid is introduced in a linear manner.

The present invention will be explained below based on Examples.

(Example) Synthesis of 9, 10, 12, 13, 15, 16-hexabromostearic acid (5) 200 g of linseed oil (3), 50% potassium hydroxide aqueous solution
200 c.c. and ethanol 160 c.c. were mixed and boiled for 3 hours. Ethanol was distilled off under reduced pressure, diluted with water, and excess dilute sulfuric acid was added to liberate the mixed fatty acid (4), which was boiled and stirred until it became transparent. After cooling, ether 900
cc, thoroughly washed with water, and dried over anhydrous sodium sulfate. The filtrate was cooled between -10°C and -30°C, and 80 c.c. of bromine was added dropwise. After leaving it overnight,
The precipitate was filtered, washed with ether, and the crystals were dried. Recrystallized from benzene.

Yield 63.5g (yield 32%), melting point 181.5-183℃
(Literature value 183℃). 9, 10, 12, 13, 15, 16- of known substances based on elemental analysis values and infrared absorption spectra.
It was identified as hexabromostearic acid (5).

Synthesis of 9,10,12,13,15,16-hexabromostearoyl chloride (6) Add 9,10,
12, 13, 15, 16-hexabromostearic acid (5)
Add 8.4 g (0.0148 mol), heat to 120°C, add 4 g (0.0148 x 2.3 mol) of thionyl chloride,
The reaction was allowed to proceed for 1 hour. After the reaction was completed, excess thionyl chloride and 1,2-dichloroethylene were distilled off under reduced pressure. The yield was quantitative. Its chemical structure was confirmed by the infrared absorption spectrum (disappearance of COOH group absorption; clear appearance of acid chloride absorption at 1795 cm ^{-1 )} .

Synthesis of 4-(9', 10', 12', 13', 15', 16'-hexabromostearoyl)-veratrol (8) 16 ml of tetrachlorethylene, 2.3 g (0.0148 x 1.5 mol) of anhydrous aluminum chloride, veratrol (7 )
Mix 15.86 g (0.0148 x 10 moles) and add
A solution prepared by dissolving 8.9 g (0.0148 mol) of the previously obtained 9,10,12,13,15,16-hexabromostearoyl chloride (6) in 100 ml of tetrachloroethylene was added dropwise. The mixture was reacted by heating at 120°C for 50 hours while stirring, and after cooling, the mixture was poured into ice water containing diluted hydrochloric acid and extracted with chloroform. After washing with water, diluted sodium hydroxide solution, and brine, and drying, the solvent was removed. The residue was washed with methanol to remove veratrol, and the remaining solid was purified by recrystallization from benzene.

Yield 2.04g (yield 15.8%), melting point 151.5-152.5°C.

Elemental analysis (C, 35.32%; H, 4.30%,
Calculated value C as C ₂₆ H ₃₈ O ₃ Br ₆ , 35.57%; H,
4.36%).

Infrared absorption spectrum (1670 cm ^-1 , phenyl ketone; 1020 cm ^-1 , absorption of veratrol angle φOCH ₃ ;
870, 810 cm ⁻¹ , absorption of 4-substituted veratrol).

Proton NMR spectrum (6.80, 6.95ppm (6
-H), 7.52ppm (3-H), 7.52, 7.64ppm (5
-H); 4-substituted veratrol).

^13C -NMR spectrum (110.1ppm, d, _C6 ;
110.3ppm, d, C ₃ ; 122.6ppm, d, C ₅ ;
130.4ppm, s, C ₄ ; 149.1ppm, s, C ₁ ;
153.2ppm, s, C ₂ ) From these analysis results, the product is 4-(9′・
It was confirmed that it has the chemical structure of 10', 12', 13', 15', 16'-hexabromostearoyl)-veratrol (8).

Synthesis of 4-(9', 10', 12', 13', 15', 16'-hexabromostearoyl)-catechol (2) 4-(9', 10', 12 obtained as above) ′・
1.71 g (1.95 x 10 ^-3 mol) of 13', 15', 16'-hexabromostearoyl)-veratrol (8) was dissolved in 30 ml of dichloromethane and cooled to -70 to -80°C. A solution of 1.95 g (1.95 x 10 ^-3 x 4 moles) of boron tribromide dissolved in 7 ml of dichloromethane was added dropwise to the mixture at the same temperature while stirring, and the mixture was left overnight. A solid target product was obtained by pouring into ice water acidified with hydrochloric acid. After washing with water and drying, it was recrystallized from chloroform.

Yield 0.87g (yield 52.3%), melting point 175-176°C.

Elemental analysis (C, 31.75%; H, 3.94%,
Calculated value for C ₂₄ H ₃₄ O ₃ Br ₆ , C, 33.92%; H,
4.03% Infrared absorption spectrum (3300cm ^-1 , OH absorption;
1650 cm ^-1 , carbonyl group absorption; 4-substituted catechol absorption occurred at 810 and 870 cm ^-1 , and methoxy group absorption at 1020 cm ^-1 disappeared).

From these analysis results, the product is 4-(9′・
It was confirmed that the chemical structure was 10', 12', 13', 15', 16'-hexabromostearoyl)-caterol (2).

Synthesis of 4-(9', 12', 15'-octadecatrienyl)-catechol of the present invention Mix 15 g of zinc powder and 1.5 g of mercuric chloride, add 15 ml of toluene and the previously obtained 4-(9'・10′・12′・
Add 0.867 g (1.02 x 10 ^-3 mol) of 13', 15', 16'-hexabromostearoyl)-catechol.
Add a mixture of 36 ml of concentrated hydrochloric acid (D ¹⁵ ₄ 1.18) and 10 ml of water with vigorous stirring and reflux for 24 hours. After cooling, separate the upper toluene layer, thoroughly extract the lower layer with ether, combine the extracts, wash with sodium bicarbonate water and water, dry, remove the solvent and purify to obtain the target product in the form of an oil. 0.167g (yield 46%) was obtained.

Elemental analysis value (C, 80.82%; H, 11.03%,
Calculated value as C ₂₄ H ₃₆ O ₂ C, 80.85%; H, 10.18
%).

The infrared absorption spectrum is shown in Figure 1 (4-substituted catechol), and the proton NMR spectrum is shown in Figure 2.
As shown in the figure (5.36ppm, m, 6H, -CH=CH-,
J=10Hz, cis type).

^13C -NMR spectrum (115.6ppm, d, _C6 ;
115.7ppm, d, C ₃ ; 120.8ppm, d, C ₅ ; 136.
Zppm, s, C ₄ ; 141.2ppm, s, C ₄ ;
143.3ppm, s, C ₂ ; 127.1ppm, d, C ₁₀ ′;
127.7ppm, d, C ₁₅ ′; 128.3ppm, d, C ₁₂ ′,
_{13′130.3ppm} , d, C ₉ ′; 131.9ppm, d, C ₁₆ ′).

Mass spectrometry (analytical value m/e, 356.2717, calculated value m/e, 356.2716).

From these analysis results, the product is 4-(9′・
12′・15′-octadecatrienyl)-catechol
It was confirmed that it has the chemical structure (1).

(Effect of the invention) According to the present invention, 4-(9', 10', 12', 13',
Using 15', 16'-hexabromostearoyl)-catechol, 4-(9', 12', 15'-octadecatrienyl)-catechol can be obtained by reducing the carbonyl group and debrominating it at the same time. Therefore, extremely pure synthetic urushiol analogs can be 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 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′・15′-octadecatrienyl)-catechol represented by 2 Chemical structural formula 4-(9', 10', 12', 13', 15', 16'
- hexabromostearoyl) - chemical structure formed by reducing catechol with zinc in an acidic medium A method for producing 4-(9', 12', 15'-octadecatrienyl)-catechol represented by