JPH0768160B2 - Method for producing alkoxymethylbenzaldehyde - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing alkoxymethylbenzaldehyde. More specifically, it relates to a method for producing an alkoxymethylbenzaldehyde, which comprises reacting α, α, α'-trichloroxylene with a lower alcohol in the presence of an alkaline substance, and then removing the lower alcohol under acidic conditions.

Alkoxymethylbenzaldehyde is a compound having an alkoxymethyl group and an aldehyde group in one molecule, and is very useful, for example, as a phenol resin raw material and a crosslinking agent.

[Conventional technology]

Regarding the conventional method for producing alkoxymethylbenzaldehyde, for example, CA 102 131585 describes a method for synthesizing p-methoxymethylbenzaldehyde from p-methoxymethylbrombenzene by a Grignard reaction, but this method is not industrial. I can not say. That is, the reality is that there is still no satisfactory industrial production method of alkoxymethylbenzaldehyde.

[Problems to be Solved by the Invention]

An object of the present invention is to provide an industrial production method of alkoxymethylbenzaldehyde.

[Means for solving the problem]

The present inventors have earnestly studied to achieve the above object, and finally arrived at the present invention.

That is, the present invention is a method for producing an alkoxymethylbenzaldehyde characterized by reacting α, α, α'-trichloroxylene with a lower alcohol in the presence of an alkaline substance, and then removing the lower alcohol under acidic conditions.

The present invention will be described in more detail below.

α, α, α′-trichloroxylene means α, α, α ′
-Trichloro-p-xylene or α, α, α'-trichloro-o-xylene or α, α, α'-trichloro-m
-Xylene. This α, α, α'-trichloroxylene is produced by a chlorination reaction of p-xylene or o-xylene or m-xylene. For example, p-xylene or o-xylene or m-xylene can be produced by allowing molecular chlorine to act under irradiation of light or in the presence of a peroxide radical generator or an azo radical generator. It is generally well known that the chlorination reaction of xylene is a sequential reaction, and the product can be controlled by the molar ratio of chlorine and xylene. α, α, α'-trichloroxylene is contained in the reaction mixture in the largest amount when the molar ratio of chlorine to xylene is about 3, but in order to increase the yield of α, α, α'-trichloroxylene It is also possible to control the molar ratio to 3 or less and to recycle low boiling components. In order to take out α, α, α'-trichloroxylene from such a reaction mixture, a distillation method or a crystallization method can be generally adopted, but the reaction mixture can be used as it is without purification.

The lower alcohol used in the present invention is methanol,
They are ethanol, 1-propanol and 2-propanol. The lower alcohol may be at least the number of moles of chlorine contained in α, α, α'-trichloroxylene, but industrially 1.5 times or more is suitable.

The alkaline substance is lithium hydroxide, lithium carbonate, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, calcium hydroxide or calcium carbonate. These alkaline substances are usually used alone, but may be used as a mixture of two or more kinds. The alkaline substance may be used in the form of a solid having a high purity or an aqueous solution having a low purity. The alkaline substance may be at least more than the number of moles of chlorine contained in α, α, α'-trichloroxylene.

In the present invention, α, α, α'-trichloroxylene is mixed with a lower alcohol in advance and then an alkaline substance is sequentially added, or α, α, α'-trichloroxylene is sequentially mixed with a lower alcohol and an alkaline substance. A method of adding, or a method of simultaneously adding α, α, α′-trichloroxylene, a lower alcohol and an alkaline substance is adopted.

The reaction temperature can be arbitrarily selected within the range of 0 to 200 ° C., and the reaction pressure is usually atmospheric pressure or pressurized. For example, it is industrially advantageous to use the reaction heat of α, α, α'-trichloroxylene and a lower alcohol, and further to reflux the lower alcohol to control the temperature to the boiling point of the lower alcohol at normal pressure.

In the present invention, it is necessary to react α, α, α′-trichloroxylene with a lower alcohol and then remove the lower alcohol under acidic conditions. The acidic condition is pH 5 or less, preferably pH 4 or less. The acidic substance is not particularly limited as long as it is an acidic substance usually used in the art, and for example, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid,
Butyric acid, oxalic acid, p-toluenesulfonic acid, dimethyl sulfate,
Examples include diethyl sulfate and acidic ion exchange resins.

In the present invention, lower alcohol is removed after acidification to produce alkoxymethylbenzaldehyde. The distillation method is the most advantageous method for removing the lower alcohol. The pressure during distillation is normal pressure or reduced pressure.

In order to recover high-purity alkoxymethylbenzaldehyde from the alkoxymethylbenzaldehyde-containing liquid obtained as described above, the lower alcohol is removed by distillation to separate the liquid, so that only the aqueous layer should be removed. Furthermore, a high-purity alkoxymethylbenzaldehyde can be produced by removing other impurities by distillation purification.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

〔Example〕

Example 1 900 g of methanol and 500 g of 25% sodium hydroxide aqueous solution were charged in a glass reactor equipped with a stirrer and a reflux condenser, and a reaction mixture obtained by chlorinating p-xylene in the presence of ultraviolet rays was purified by distillation. 200 g of α, α, α'-trichloro-p-xylene thus obtained (α, α, α'-trichloro-p
-Xylene 90% by weight, α, α'-dichloro-p-xylene 5% by weight, α, α, α ', α'-tetrachloro-p-
Xylene (2% by weight, other 3% by weight) was added dropwise over 1 hour. Further, the mixture was reacted at 65 ° C. for 3 hours while refluxing methanol. Then, after filtering and removing the salt, the pH was adjusted to 2 with 1N hydrochloric acid. Next, when the methanol was distilled off with a rotary evaporator, the water layer was removed because the liquid was separated into two layers. When the oil layer was analyzed by gas chromatography,
The purity of p-methoxymethylbenzaldehyde was 88%. The results are shown in Table 1.

Examples 2 to 5, Comparative Example 1 Alkoxymethylbenzaldehyde was synthesized in the same manner as in Example 1 except for the conditions shown in Table 1. The results are shown in Table 1.

Purification Example The methoxymethylbenzaldehyde having a purity of 88% obtained in Example 1 was purified by distillation in a glass tray distillation column. 95% pure methoxymethylbenzaldehyde was obtained.

[Effects of the Invention] According to the present invention, a characteristic compound having an alkoxymethyl group and an aldehyde group in the molecule can be obtained in high purity and high yield, which is very useful industrially.

Claims (3)

[Claims] 1. A method for producing an alkoxymethylbenzaldehyde, which comprises reacting α, α, α′-trichloroxylene with a lower alcohol in the presence of an alkaline substance, and then removing the lower alcohol under acidic conditions. 2. α, α, α'-trichloroxylene is α,
The method for producing an alkoxymethylbenzaldehyde according to claim 1, which is α, α'-trichloro-p-xylene. 3. The method for producing an alkoxymethylbenzaldehyde according to claim 1, wherein the lower alcohol is methanol.