JPS5939846A - Preparation of anisaldehyde - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as a raw material of perfume, pharmaceuticals, agricultural chemicals, etc., in high yield and purity, by reacting methylanisole with bromine in the presence of light, and at the same time, hydrolyzing the resultant methoxybenzal bromide in the presence of a carbonate. CONSTITUTION:Methylanisole is dissolved in carbon tetrachloride at a concentration of 10-20wt% and made to react with bromine at 40-65 deg.C in the presence of light to obtain methoxybenzal bromide in high yield and purity. The product is hydrolyzed using a carbonate and water to anisaldehyde. Since the benzal bromide can be obtained in high purity as an intermediate, it is not necessary to separate the objective product by steam distillation after hydrolysis, and a high-purity objective compound can be obtained easily only by extracting directly with a proper organic solvent. Accordingly, the post-treatment of the reaction product is extremely simple, and the objective compound can be prepared at a low cost in an industrial scale.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing anisaldehyde, which is important as anisaldehyde.

More specifically, the ratio of methylanisole to carbon tetrachloride is 10~. 20% by weight dissolved in the presence of light;
Methoxybenzal bromide is produced by reacting it with bromine at a reaction temperature of 0~S'C, and anisaldehyde is produced in high yield and purity by hydrolysis using carbonate and water. It is about the method.

The most important problem with the method of the present invention is halogenation of the side chain methyl group of methylanisole, and it has been found that methoxybenzalbromide can be specifically produced in high yield and purity when bromine is used. It is based on

Regarding the halogenation of the side chain alkyl group of an aromatic alkyl compound, for example, a generally known method is to react with a halogen at the boiling point in the presence of light or peroxide in order to prevent halogenation of the aromatic ring. .

In this method, the most typical example of halogenation of the side chain alkyl group of an aromatic alkyl compound is the chlorination of toluene. .2nd edition)).

This reaction is carried out at the boiling point under sunlight or active light irradiation to prevent chlorination of the benzene nucleus.

L or L1 When trying to chlorinate the side chain methyl group by the above-mentioned known method in toluene in which the benzene nucleus is substituted with an alkoxy group as used in the present invention, the benzene nucleus is activated due to the alkoxy substituent. Compared to the chlorination of the side chain methyl group of toluene, which is unsubstituted, the selectivity is significantly poorer, and various nuclear substitution compounds including chlorides of the side chain methyl group are produced, and the desired side chain methyl group substituted product is produced. cannot be produced with good yield.

The present inventors investigated various methods for halogenation of side chain methyl groups, and found that for bromination of side chain methyl groups of alkoxy-substituted toluene, the alkoxy-substituted toluene was dissolved at 70 to 20% by weight in carbon tetrachloride. By reacting with bromine in the presence of light at a reaction temperature of 0-2C, an extremely high selectivity that would be completely unimaginable from the chlorination of the compound appears, and the methyl of the compound is specifically It was found that alkoxy-substituted benzal bromide in which the group was brominated was obtained with high purity and high yield.

Furthermore, when producing alkoxy-substituted benzaldehyde from benzal bromide using carbonate and water, since the benzal bromide is produced with high purity, it is common practice to separate it from impurities after hydrolysis. There is no need to employ the separation operation using the currently used steam distillation method, and highly pure alkoxy-substituted benzaldehyde can be easily obtained by directly extracting with a suitable organic solvent.

As described above, the method of the present invention can be said to be a very useful invention industrially, since the post-treatment in the manufacturing process is extremely simple and it can be manufactured industrially at low cost.

EXAMPLES Next, in order to clarify the present invention, the present invention will be concretely explained using examples.

Example para-methylanisole (9.29<0.73 mol) lj
Dissolve in carbon tetrachloride and stir with stirring and turn on three 300 watt tungsten lamps #5~30'C"'
C1 carbon tetrachloride/! ;09 & Ni bromine, a solution containing 2110 mol (/S mol) is gradually added dropwise.

After completion of the dropwise addition, the temperature was raised to 60-60C and stirred for about 30 minutes to complete the reaction.

After cooling the solution and distilling off carbon tetrachloride, 300 mol (3.0 mol) of calcium carbonate was added to the remaining oily substance and mixed, and the mixture was heated for about 1 hour at O'C for 2 hours, then at 100 °C. 7 at °C
Heat and stir for an hour. The solution is cooled, made slightly acidic with hydrochloric acid, and extracted with toluene.

After dehydrating the toluene layer with anhydrous sulfuric acid and IJum, the toluene is distilled off. The residual liquid was distilled off under reduced pressure to obtain 9 g of para-anisaldehyde, the desired product.

Yield fly boiling point 79-42°C/0. qtnm Name of H9 agent Kawahara 1) - Ho

Claims (1)

[Claims] A method for producing anisaldehyde from methylanisole, which comprises reacting with bromine in the presence of L1 light to produce methoxybenzalbromide, and further using a carbonate.