JPH0568454B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a method for synthesizing benzyl ether and derivatives thereof (hereinafter collectively referred to as benzyl ethers) in a short time and in high yield by a one-step reaction. (Prior art and its problems) As a method for synthesizing benzyl ethers, benzyl halides or their nuclear substituted products (hereinafter collectively referred to as benzyl halides) are reacted with an alkali metal salt of acetic acid to produce benzyl esters. The benzyl esters are then hydrolyzed to produce benzyl alcohols, and then the benzyl alcohols and benzyl halides are subjected to alkali metal hydroxylation in an organic solvent other than alcohol that has good affinity for water. There is a method of obtaining benzyl ethers by heating and stirring them together with an aqueous solution for a long period of time. However, the above synthesis method requires multiple steps for the reaction and is complicated to operate, and when a benzyl halide derivative having a heat-reactive substituent is used as a raw material, the product cannot be formed by heating for a long time. There were problems such as a decrease in yield due to decomposition, polymerization, and generation of by-products. In particular, when a benzyl halide derivative having a heat-reactive substituent is used as a raw material, the synthesized product often becomes a heat-reactive compound, and the reaction takes an unnecessarily long time at high temperatures. It is difficult to control the reaction time to obtain the desired compound in high yield, as if the reaction time is too short, the yield will be low. It was hot. (Means for solving the problem) The inventors of the present invention solved the above problem by intensively studying the reaction mechanism at each stage, and found that by using a specific solvent, the reaction can be performed in one step, and by using a specific catalyst. It has been discovered that benzyl ethers can be synthesized in a short time and in high yield by using these in combination, and the present invention has been completed. That is, the present invention provides a method for producing benzyl ethers, which is characterized by reacting benzyl halides with an aqueous alkali metal hydroxide solution in at least one solvent selected from dimethyl sulfoxide and dimethyl formamide in the presence of a phase transfer catalyst. This is a synthesis method. The benzyl halides used in the present invention have the general formula

[Mechanism of action and effects]

According to the present invention, the following reaction mechanism (1) is considered to exist.

[Chemical formula] (However, K is an alkali metal.) That is, by using a specified solvent and a phase transfer catalyst, benzyl chloride and alkali metal hydroxide aqueous solution can form the formula (1) at the interface between the solvent layer and the water layer. The reaction takes place quickly. That is, benzyl chloride a undergoes hydrolysis to become benzyl alcohol b, which becomes an alkali metal salt c, and the benzyl alkoxy anion attacks the benzylic carbon of unreacted benzyl chloride a′ as shown by the arrow in formula (1). This leads to the formation of an ether bond, resulting in a one-step reaction to form benzyl ether d. This is clearer than the fact that benzyl alcohol b, which is a reaction intermediate, is obtained as a reaction by-product. In particular, in the present invention, by using a phase transfer catalyst, the individual reactions described above are quickly completed, thereby suppressing the production of by-products, decomposition products, etc., and increasing the yield. Therefore, even when using a raw material having a heat-reactive substituent, the desired product can be obtained with a high yield of 70% or more. (Examples) Hereinafter, the present invention will be described in detail based on Examples. Example 1 2 equipped with reflux condenser, stir bar and thermometer
900 g of dimethyl sulfoxide in a three-necked flask.
ml and heated the dimethyl sulfoxide externally to 100°C using an oil bath. 380 g of chloromethylstyrene was added to this solvent, and then a solution of 170 g of potassium hydroxide and 2 g of tetrabutylammonium bromide dissolved in 400 ml of water was added all at once.
Thereafter, the reaction temperature was maintained at 100°C and stirring was continued for 15 minutes to complete the reaction. After the reaction was completed, the flask was cooled on ice. Then, the precipitate generated by the reaction was separated, the liquid was transferred to a separating funnel, 500 ml of diethyl ether and 500 ml of water were added, shaken well, and the aqueous layer and organic layer were separated.The lower aqueous layer was removed. . 500 ml of water was added to the separating funnel in which only the organic layer remained to wash the organic layer. After performing this operation three times, the organic layer was transferred to Erlenmeyer flask No. 1, and a small amount of anhydrous magnesium sulfate was added to the flask. The drying agent was separated, and diethyl ether was removed from the liquid under reduced pressure to obtain the desired product, orange bisvinylbenzyl ether. The yield and structure of the product were confirmed using gas chromatography and mass spectrometry. As a result, the yield of the target product, bisvinylbenzyl ether, was 70%, and the by-product, vinylbenzyl alcohol, was 25%. Example 2 Example 1 was prepared using 138 g of benzyl chloride as the raw material benzyl halide, a solution of 58 g of potassium hydroxide and 1 g of tetrabutylammonium bromide dissolved in 200 ml of water, and 900 ml of dimethyl sulfoxide.
The reaction was carried out under the same conditions. As a result, dibenzyl ether and benzyl alcohol were obtained in a yield of 80% and 20%, respectively. Example 3 380g of chloromethylstyrene, potassium hydroxide
A reaction was carried out under the same conditions as in Example 1 using 140 g of dibenzo 18-crown 6 as a phase transfer catalyst dissolved in 400 ml of water and 900 ml of dimethyl sulfoxide. The result is 50% bisvinylbenzyl ether and 40% vinylbenzyl alcohol.
% yield. Example 4 Using 138 g of benzyl chloride as the raw material benzyl halide, Example 1 was prepared using a solution of 58 g of potassium hydroxide and 1 g of tetrabutylammonium bromide dissolved in 200 ml of water and 900 ml of dimethylformamide.
The reaction was carried out under the same conditions. As a result, the yields of benzyl ether and benzyl alcohol were 80% and 20%, respectively. Comparative example 1 138g of benzyl chloride, 50g of potassium hydroxide
g and 1 g of tetrabutylammonium bromide to 200 g of water.
ml and various organic solvents (tetrahydrofuran, dioxane, diethyl ether, n-hexane, benzene, acetonitrile) as reaction solvents under the same conditions as Example 1, the target product was not obtained. , resulting in raw material recovery. Further, even when the reaction time was extended to 6 hours, the desired dibenzyl ether product was not obtained. Comparative Example 2 When the reaction time was changed from 15 minutes to 2 hours under the reaction conditions of Example 1 and a phase transfer catalyst was not used, an orange elastic solid (vinyl benzyl ether polymer) was produced and the target product was not obtained. A certain benzyl ether compound could not be obtained.

Claims (1)

[Claims] 1. In the presence of a phase transfer catalyst in at least one solvent selected from dimethyl sulfoxide and dimethyl formamide, a compound of the general formula [Formula] (wherein R ₁ and R ₂ are hydrogen or alkyl, R A method for synthesizing benzyl ethers, which comprises reacting benzyl halides ( ₃ is hydrogen, X is halogen) with an aqueous alkali metal hydroxide solution. 2. The synthesis method according to claim 1, wherein the benzyl halide is used in an amount of 10 to 50 parts by weight per 100 parts by weight of at least one of dimethyl sulfoxide and dimethyl formamide. 3. A patent in which the aqueous alkali metal hydroxide solution is an aqueous solution containing 20% by weight or more of alkali metal hydroxide, and the alkali metal hydroxide in the aqueous solution is 30 to 60 parts by weight based on 100 parts by weight of the benzyl halide derivative. A synthesis method according to claim 1. 4. The synthesis method according to claim 1, wherein the phase transfer catalyst is used in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the benzyl halide.