JPS6127379B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to intermediates for the production of synthetic urushiol-like substances, and in particular to novel compounds 4-(9', 10', 12',
This invention relates to 13', 15', 16'-hexabromostearoyl)-catechol and its production method. (Conventional technology) Lacquerware is a traditional craft specializing in the East, especially Japan, and is known worldwide as Japan.As is well known, the raw material for lacquerware is the natural lacquer secreted by the lacquer tree. I've been doing it. 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, much less how to produce it industrially at low cost. is considered almost impossible. For this reason,
Since ancient times, the synthesis of urushiol-like substances, which are relatively easy to produce, has been devised and utilized. Natural urushiol has the general formula (R in the formula is the number of carbon atoms having 1 to 3 double bonds.
0 (representing 15 straight-chain hydrocarbon groups)
- A mixture of homologs of alkenylcatechols.
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. (c) Chemical resistance is almost the same for materials with 1 to 3 double bonds, but is poor for materials with 0 double bonds. (d) It is known that there is almost no difference in the cured film due to the difference in the position of the side chain in the catechol nucleus. (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, making it impossible 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 consisting of unaccompanied compounds. 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 in a completely linear form, 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. Furthermore, the phenolic hydrogen group must be of the 0-dihydroxybenzene type, ie of the catechol type. However, when long-chain hydrocarbons with carbon unsaturated bonds or their derivatives are directly reacted with catechol, the addition reaction of carbon double bonds takes precedence, resulting in the hydrocarbon group branching into the catechol nucleus. As a result of the addition reaction with the hydroxyl group of catechol, an ether bond was usually formed on the oxygen. It was also considered to protect the hydroxyl group with a methoxy group. However, many naturally occurring essential oils contain methoxy groups;
It was common knowledge that fairly harsh conditions had to be used to convert these into phenols by hydrolysis. For example, heating to 150-200℃ in concentrated hydrobromic acid for long periods of time, or using expensive and unstable hydroiodic acid, requires similarly harsh reaction conditions, so the intramolecular structure These methods cannot be applied to compounds that have delicate and easily changeable parts. (Means and effects for solving the problems) In order to solve these problems, the present invention
An intermediate for producing synthetic urushiol-like substances that meet the demands for higher quality lacquer products as mentioned above.
In particular, the object of the present invention is to provide an intermediate for industrially synthesizing catechol having a linear unsaturated alkyl group without producing by-products. That is, in order to obtain such an intermediate, 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 chain with the carbon unsaturated group previously protected with bromine was used. The compound was reacted with veratrol, the hydroxyl group of the catechol nucleus protected with a methoxy group. By demethylation using this reaction compound, the desired intermediate having a catechol nucleus could be obtained. Specifically, the present invention relates to chemical structural formulas 4-(9', 10', 12', 13', 15', 16'
- hexabromostearoyl) - in veratrol. In addition, the present invention provides the chemical structural formula: 4-(9', 10', 12', 13', 15', 16'
-hexabromostearoyl)-veratrol is treated with boron tribromide. According to this method, boron tribromide can be applied at an extremely low temperature, and the veratrol compound (2) can be extremely easily demethylated to obtain the compound (1) of the present invention. Moreover, the highly functional bromine moiety undergoes no structural change at all. It is more preferable that the reaction temperature is low in order to eliminate the risk of side reactions occurring as the reaction temperature increases. Even at extremely low temperatures such as -80°C, the demethylation reaction proceeds rapidly. In addition, AlCl ₃ etc. can be used in addition to boron tribromide for the demethylation reaction, but by-products are likely to be generated and furthermore, it is necessary to remove them with a solvent.
The process becomes complicated. In contrast, boron tribromide, although expensive, can be easily removed by treatment with water. 4-(9′・10′・12′・13′・
15',16'-hexabromostearoyl)-veratrol (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 linolenic acid hexabromide (9, 10, 12, 13, 15,
9, 10, 12, 13, 15, produced by adding excess thionyl chloride to 16-hexabromostearic acid (5))
16-hexabromostearoyl chloride (6),
The target compound (2) is obtained by reacting with veratrol (7) in the presence of a Friedel-Crafts catalyst.

[Table] A synthetic urushiol-like substance can be obtained in which a hydrocarbon side chain with 18 carbon atoms and an unsaturated bond 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, excess dilute sulfuric acid was added, and the liberated mixed fatty acid (4) was boiled and stirred until it became transparent. After cooling, ether 900c.c.
The extract was extracted with water, 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 standing 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
°C (literature value 183 °C). From elemental analysis values and infrared absorption spectra, known substances 9, 10, 12, 13,
It was identified as 15,16-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 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 (2) 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 salt, 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℃. 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 nucleus 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, _C2 ). 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 (2). 4-(9′, 10′, 12′, 13′, 15′, 16′-) of the present invention
Synthesis of 4-(9′・10′・12′・
1.71 g (1.95 x 10 ^-3 mol) of 13', 15', 16'-hexabromostearoyl)-veratrol (2) 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
℃. Elemental analysis (C, 31.75%; H, 3.97%,
Calculated value for C ₂₄ H ₃₄ O ₃ Br ₆ , C, 33.92%; H,
4.03%). The infrared absorption spectrum is shown in Figure 1 (3300cm
^-1 , OH absorption; 1650 cm ^-1 , carbonyl group absorption; 4-substituted catechol absorption at 810 and 870 cm ^-1 , and methoxy group absorption at 1020 cm ^-1 disappeared) From these analysis results, it was determined that the formation The object is 4−(9′・
It was confirmed that the chemical structure was 10', 12', 13', 15', 16'-hexabromostearoyl)-catechol (1). (Effects of the Invention) According to the present invention, the methyl group of the veratrol nucleus is easily demethylated, and the unsaturated hydrocarbon group of the side chain of the catechol nucleus is protected with bromine.
Since we were able to obtain 12', 13', 15', 16'-hexabromostearoyl)-catechol, an extremely pure synthetic urushiol analogue intermediate was obtained. Moreover, since a single compound can be produced without any by-products, the synthetic urushiol-like substance finally obtained using this as a raw material does not contain any impurities. 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 using the present invention as an intermediate was similarly mixed with natural urushi, it showed the ability to form a dry coating film 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.

Claims (1)

[Claims] 1. Chemical structural formula 4-(9′, 10′, 12′, 13′, 15′, 16
′−
hexabromostearoyl)-catechol. 2 Chemical structural formula 4-(9′, 10′, 12′, 13′, 15′, 16
′−
hexabromostearoyl) - chemical structure consisting of veratrol repaired with boron tribromide 4-(9', 10', 12', 13', 15', 16'
-Hexabromostearoyl)-catechol production method.