JPS6131090B2 - - 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',
The present invention relates to 13', 15', 16'-hexabromostearoyl)-veratrol and a method for producing the same. Conventional Technology Lacquerware is a traditional craft specializing in the East, especially Japan, and is known around the world as Japan.As is well known, lacquerware has relied on the natural lacquer sap secreted by the lacquer tree as its raw material. . 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 these reasons, the synthesis of urushiol-like substances, which are relatively easy to produce, has been devised and utilized since ancient times. Natural urushiol has the general formula (R in the formula is the number of carbon atoms having 1 to 3 double bonds.
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 can be obtained from the raw material catechol at low cost, and the alkenyl group introduced into the side chain of catechol uses a compound obtained from natural unsaturated fats. You can get it relatively easily. 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. This compound is 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 that are free of synthetic 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 be completely linear, as is the case with natural catechol. It must be in position 3 or 4.
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 linearly reacted with catechol, the addition reaction of carbon double bonds takes precedence, resulting in hydrocarbon groups branching into the catechol nucleus. In this state, the hydroxyl group of catechol also undergoes an addition reaction, resulting in the formation of an ether bond on the oxygen. This is extremely inconvenient for use as a lacquer paint that dries at room temperature. Means for Solving the Problems In order to solve these problems, the present invention
An intermediate for producing a synthetic urushiol-like substance that meets the demand 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, natural, extremely inexpensively obtained linolenic acid was obtained using the unsaturated hydrocarbon group in the side chain of the catechol nucleus as a raw material. Furthermore, in order to prevent these carbon unsaturated groups from directly adding to the catechol nucleus, it was decided to protect it with bromine. Furthermore, in order to prevent the formation of ether-like by-products, we have come to the conclusion that it is extremely appropriate to use veratrol in which the hydroxyl group of catechol is protected as a methoxy group. Specifically, the present invention relates to chemical structural formulas 4-(9', 10', 12', 13', 15', 16'
- hexabromostearoyl) - in veratrol. Furthermore, the present invention provides the reaction of veratrol (2) with 9,10,12,13,15,16-hexabromostearoyl chloride (3) in the presence of a Friedel-Crafts catalyst to obtain the above compound (1). This is due to the manufacturing method. This reaction generally uses a reaction belonging to the Friedel-Crafts reaction and is carried out in the presence of a Friedel-Crafts catalyst. As the catalyst, in addition to so-called Lewis acids such as anhydrous aluminum chloride, iron chloride, boron trifluoride, and zinc chloride, protonic acids such as hydrogen fluoride can be used. Also, suitable solvents include nitrobenzene, nitromethane, carbon disulfide, and ethylene dichloride. 9,10,12,13,15,16-hexabromostearoyl chloride (3) used in this reaction is produced by saponifying linseed oil (4) containing a large amount of linolenic acid, for example, as shown in the following formula. Bromine is added to the extracted mixed fatty acid (5), and the precipitated high-purity linolenic acid hexabromide 9, 10, 12, 13, 15, 16-hexabromostearic acid (6) is melted and an excess of It can be synthesized by adding thionyl chloride.

[Table] (3)
Effect Hydrocarbon compounds with bromine on carbon, such as linolenic acid hexabromide (6), in which the unsaturated group is protected with bromine, react with veratrol at the bromine bonding position in the presence of a Friedel-Crafts catalyst. Conventional chemical knowledge has been that it reacts with aromatic compounds such as aromatic compounds, that is, the reaction proceeds in a direction different from that of the target compound, resulting in the formation of branched compounds. However, the present invention has solved this problem by reacting the carboxylic acid group of the fatty acid polybromine compound with the veratrol nucleus in the form of acid chloride (3) as described above. If you do this,
As a result, the expected compound (1) was obtained as the acid chloride group reacts with the veratrol nucleus more quickly than the bromine group, which is abundant in the molecule. The bromine group is also preserved during the reaction process. In other words, the bromine group can be preserved even when the methoxy group of the veratrol nucleus is demethylated by further reaction using this compound (1), which has a bromine group, as an intermediate to obtain the catechol nucleus. .
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 linolenic acid is introduced in a linear manner. The present invention will be explained below based on Examples. Example 9, 10, 12, 13, 15, 16 - Synthesis of hexabromostearic acid (6) 200 g of linseed oil (4), 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 (5), 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℃). Based on elemental analysis values and infrared absorption spectra, known substances 9, 10, 12, 13, 15, 16
- Hexabromostearic acid (6). Synthesis of 9,10,12,13,15,16-hexabromostearoyl chloride (3) Add 9,10,
12, 13, 15, 16-hexabromostearic acid (6)
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 ). 4-(9′, 10′, 12′, 13′, 15′, 16′-) of the present invention
Synthesis of hexabromostearoyl)-veratrol (1) 16 ml of tetrachlorethylene, 2.3 g of anhydrous aluminum chloride (0.0148 x 1.5 mol), veratrol (2)
15.86 g (0.148 x 10 moles) were mixed, and 8.9 g (0.0148 moles) of the previously obtained 9-10-12-13-15-16-hexabromostearoyl chloride (3) was dissolved in 100 ml of tetrachloroethylene. The solution 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
℃. Elemental analysis (C, 35.32%; H, 4.30%,
Calculated value for C ₂₆ H ₃₈ O ₃ Br ₆ C, 35.57; H, 4.6
%). The infrared absorption spectrum is shown in Figure 1 (1670cm
^-1 , phenylketone; 1020cm ^-1 , veratrolφ
Absorption of _0CH3 ; 870, 810 cm ^-1 , absorption of 4-substituted veratrol). The proton NMR spectra are shown in Figure 2 (6.80, 6.95ppm (6-H), 7.52ppm (3-H),
H), 7.52, 7.64 ppm (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 (1). Effects of the Invention According to the present invention, 4-(9', 10', 12',
Since we were able to obtain 13', 15', 16'-hexabromostearoyl)-veratrol, we obtained an extremely pure synthetic urushio analog intermediate. Since this intermediate uses the known Friedel-Crafts reaction, it can be easily produced from known substances. 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, and FIG. 2 is a diagram similarly showing an NMR spectrum.

Claims (1)

[Claims] 1. Chemical structural formula 4-(9', 10', 12', 13', 15', 16'
-hexabromostearoyl) -veratrol. 2 Chemical structural formula obtained by reacting veratrol with 9,10,12,13,15,16-hexabromostearoyl chloride in the presence of a Friedel-Crafts catalyst 4-(9', 10', 12', 13', 15', 16'
-hexabromostearoyl)-veratrol production method.