JPH101451A - Production of 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and simply obtain the subject compound useful as an intermediate for medicines, etc., in high purity and yield by a new method reacting a specific Vilsmeier reagent with a (substituted)-catechol. SOLUTION: A Vilsmeier reagent prepared from dimethylformamide and phosphorus oxychloride is reacted with a (substituted) catechol of formula I (R is H or an alkyl), preferably at 100-120 deg.C to provide the objective compound of formula II. Specifically, for example, the (substituted) catechol is added to the Vilsmeier reagent prepared by reacting dimethylformamide with phosphorus oxychloride in 1:1 molar ratio and the catechol is reacted with the reagent for 4 hours, the resultant product is cooled and poured into water and extracted and concentrated with chloroform and the concentrate is recrystallized by using n-hexane. Furthermore, the Vilsmeier reagent is reacted with the (substituted) catechol usually in (1 to 2):1 molar ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4 useful as an intermediate for food additives, pharmaceuticals and electronic materials.
-A method for synthesizing hydroxybenzaldehyde with high purity, high yield and a simple method.

[0002]

2. Description of the Related Art Conventionally, 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde has been prepared by using catechol and chloroform.
It is synthesized by the Eimer-Tiemann reaction (Ber. 9, 1268 (1876)). However, this reaction is usually used for the reaction having a phenolic hydroxyl group, and the aldehyde group is preferentially added to the o-position of catechol. In order to obtain the compound (1), it was necessary to separate a by-product compound in which an aldehyde group was introduced at the o-position of catechol. However, this separation method is complicated, so that the yield of the compound of the present invention is low and it has been difficult to selectively synthesize it.

[0003]

DISCLOSURE OF THE INVENTION The present invention is directed to a process for preparing 3,4-dihydroxybenzaldehyde or 3
An object of the present invention is to provide a novel method for synthesizing -alkyloxy-4-hydroxybenzaldehyde with high purity, high yield and a simple method.

[0004]

The object of the present invention is to react (1) a Vilsmeier reagent prepared from dimethylformamide and phosphorus oxychloride with a catechol or a substituted catechol represented by the following general formula (II). A process for producing 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde represented by the following general formula (I),

[0005]

Embedded image

In the formula, R represents a hydrogen atom or an alkyl group. (2) The reaction temperature of 80 to 150 ° C., wherein the 3,4-dihydroxybenzaldehyde or 3- A process for producing alkyloxy-4-hydroxybenzaldehyde.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail. The Vilsmeier reagent used in the present invention is N, N-
A methyleneiminium compound which is obtained by reacting dimethylformamide and phosphoryl chloride in a molar ratio of 1: 1 and using N, N-dimethylformamide in excess as required and using it as a solvent, usually called a Vilsmeier complex It is. In the present invention, the desired compound is obtained by reacting the thus-prepared Vilsmeier reagent with the catechol or substituted catechol represented by the above general formula (II). If the reaction temperature is too low, it is difficult to react, and if it is too high, a by-product is formed.
~ 120 ° C is applied. The Vilsmeier reagent and catechol or substituted catechol are usually reacted in a molar ratio of 1 to 2: 1.

In the general formula (I), R is a hydrogen atom or an alkyl group such as a methyl group, an ethyl group or a propyl group, preferably a hydrogen atom, a methyl group or an ethyl group.

Next, an example of a method for producing the compound of the present invention will be described. Dimethylformamide and phosphorus oxychloride:
Catechol or substituted catechol was added to the Vilsmeier reagent adjusted to 1, reacted at 80 to 120 ° C. for 4 hours, cooled, poured into water, extracted with chloroform, concentrated, and recrystallized with n-hexane to obtain the desired product. 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4
-Hydroxybenzaldehyde can be obtained in high yield and high purity.

[0010]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Example 1 Synthesis of 3,4-dihydroxybenzaldehyde: Phosphorus oxychloride 1 in 50 ml of dimethylformamide
5.3 g (0.1 mol) are added dropwise at 10 ° C. After dropping, 11.0 g (0.1 mol) of catechol was added, and 12
The temperature is raised to 0 ° C. and the reaction is carried out at the same temperature for 4 hours. After completion of the reaction, the reaction solution is cooled to room temperature, poured into 500 ml of water, and stirred for 1 hour. Next, 200 ml of chloroform is added and the mixture is extracted and concentrated. 100 ml of n-hexane was added to the concentrate, and the solution was completely dissolved at 50 ° C.
The crystals were separated by filtration and dried to obtain 11.0 g (yield: 80%) of the desired product.
The results of elemental analysis with a purity of 99% or more and a melting point of 152.0 to 155.0 ° C are as follows.

Example 2 Synthesis of 4-hydroxy-3-methoxybenzaldehyde: To 50 ml of dimethylformamide, 15.3 g (0.1 mol) of phosphorus oxychloride is added dropwise at 10 ° C. 12.4 g of 2-methoxyphenol (0.
1 mol), heated to 120 ° C., and reacted at the same temperature for 4 hours. After completion of the reaction, the reaction solution is cooled to room temperature,
Inject into milliliter and stir for 1 hour. Next, 200 ml of chloroform was added, and the mixture was extracted and concentrated. 100 ml of n-hexane was added, and the mixture was completely dissolved at 50 ° C.
I got Melting point: 80.0 to 84.0 ° C The results of elemental analysis are as follows.

Example 3 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was changed to 50 ° C., and it took more than 20 hours to complete the reaction.

[0013]

According to the present invention, 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde can be efficiently produced in a high yield, a high purity and a simple method. it can.

Claims (2)

[Claims] 1. A method of reacting a Vilsmeier reagent prepared from dimethylformamide and phosphorus oxychloride with a catechol or a substituted catechol represented by the following general formula (II): A method for producing 4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde. Embedded image In the formula, R represents a hydrogen atom or an alkyl group. 2. The method for producing 3,4-dihydroxybenzaldehyde or 3-alkyloxy-4-hydroxybenzaldehyde according to claim 1, wherein the reaction temperature is 80 to 150 ° C.