JPS6131089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to intermediates for producing synthetic urushiol-like substances, and in particular to novel compounds 4-(9', 10', 12',
The present invention relates to 13'-tetrabromostearoyl)-catechol and a method for producing the same.

Conventional Technology Lacquerware is a traditional craft specializing in the East, especially Japan, and is known worldwide as Japan.As is well known, lacquerware has relied on a small amount of natural lacquer sap from the lacquer tree as its raw material. . However, since the opening of the Meiji era, these resources have been depleted, and currently 90% of them have been depleted.
For the above, we rely 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, 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.
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 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. 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 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. Furthermore, the phenolic hydroxyl group must be of the o-dihydroxybenzene type, that is, the catechol type.

However, when a long-chain hydrocarbon having a carbon unsaturated bond or its derivative is subjected to a linear chain reaction with catechol, the addition reaction of the carbon double bond takes priority. As a result, the hydrocarbon group is bound to the catechol nucleus in a branched state, and as a result of an addition reaction to the hydroxyl group of catechol, an ether bond is also usually formed on the oxygen. It was also considered to protect the hydroxyl group with a methoxy group. However, there are many compounds containing methoxy groups in naturally occurring essential oils, and it has been common knowledge that fairly harsh conditions must 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 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.

In other words, in order to obtain such an intermediate, linoleic 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'-tetrabromostearoyl)-veratrol is represented by

In addition, the present invention provides the chemical structural formula: The method involves treating 4-(9', 10', 12', 13'-tetrabromostearoyl)-veratrol 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. −80℃
The demethylation reaction proceeds rapidly even at extremely low temperatures.

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′-tetrabromostearoyl)-veratrol (2) used in this reaction is
For example, it can be obtained by a process as shown in the following formula. First, bromine is added to mixed fatty acid (4) extracted by saponifying soybean oil (3) containing a large amount of glycerin ester of linoleic acid. 9,10,12,13-tetrabromostearoyl chloride was produced by adding excess thionyl chloride to the obtained high-purity linoleic acid tetrabromide (9,10,12,13-tetrabromostearic acid (5)). (6) and veratrol (7) are reacted in the presence of a Friedel-Crafts catalyst to obtain the target compound (2).

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 concentrated to about 500 c.c. This was cooled to -7℃ with a cryogen, and the bromine
70 c.c. was gradually added while 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℃). From the infrared absorption spectrum, it was identified as 9,10,12,13-tetrabromostearic acid (5), a known substance.

Synthesis of 9,10,12,13-tetrabromostearoyl chloride (6) 10 g (1.704×10 ^-2 mol) of the above 9,10,12,13-tetrabromostearic acid (5) was heated to 120°C and melted. Then, 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 (2) 21.7 g (0.033 mol) of the above 9, 10, 12, 13-tetrabromostearoyl chloride (6) was Dissolved in 20ml of carbon sulfide. Add this solution to veratrol (7)
4.5g (0.038mol), anhydrous aluminum chloride 5.3g
(0.033×2.2 mol) and carbon disulfide (40 ml) with stirring. Boil under reflux for 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 φ
OCH 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 (2).

Synthesis of 4-(9′・10′・12′・13′-tetrabromostearoyl)-catechol (1) of the present invention 4-(9′・10′・12′・
13′-tetrabromostearoyl)-latrol(2)
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%).

The infrared absorption spectrum is shown in Figure 1 (3200cm
^-1 , OH absorption; 1650 cm ^-1 , presence of carbonyl group absorption; 1020 cm ^-1 methoxy group absorption disappeared).

The proton NMR spectrum is shown in Figure 2 (disappearance of 3.94 ppm (S, 6H, OCH ₃ ), 6.58 ppm
Presence of (broad, 2H, OH). That is, the absorption for two methoxy groups disappeared, and the absorption for two OH groups newly appeared).

From these analysis results, the product is 4-(9′・
It was confirmed that the chemical structure was 10', 12', 13'-tetrabromostearoyl)-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'-tetrabromostearoyl)-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, and FIG. 2 is a diagram similarly showing an NMR spectrum.

Claims (1)

[Claims] 1. Chemical structural formula 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol represented by 2 Chemical structural formula A chemical structural formula obtained by treating 4-(9', 10', 12', 13'-tetrabromostearoyl)-veratrol with boron tribromide, represented by A method for producing 4-(9', 10', 12', 13'-tetrabromostearoyl)-catechol represented by: