JPS6048491B2 - Manufacturing method of dialkoxybenzene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an advantageous method for producing dialkoxybenzene, and more particularly to a method for producing dialkoxybenzene in high yield by converting dihydroxybenzene into alkyl ether with dialkyl sulfuric acid. It is.

Dimethyl ether and diethyl ether such as catechol and hydroquinone are extremely important compounds as intermediates for medicines, fragrances, and dyes.

Various methods have been known for converting dihydroxybenzene into lower alkyl ethers.

For example, there is a method of using dialkyl sulfuric acid, alkyl halide, alcohol, etc. as an alkylating agent. Among these, a method using dialkyl sulfuric acid as an alkylating agent can be considered as a general synthesis method. This method has already been described in JP-A Nos. 51-54521, 48-57935, and 48-
13329, No. 48-56637, etc. The dialkyl sulfuric acid used for the alkylation of dihydroxybenzene is very rich in only its monoalkyl groups and is heated at 60°C.
Reacts easily even at temperatures below.

Therefore, dialkoxybenzene can be produced by using twice the molar amount of dialkyl sulfuric acid. However, this method is unsatisfactory considering that the dialkyl sulfuric acid has 00 alkylating groups.

That is, if the two alkyl groups of dialkyl sulfuric acid can be effectively utilized, very advantageous industrial production can be provided. The present inventors have obtained the knowledge described below as a result of various studies regarding the properties of dialkyl sulfuric acid and the alkylating action of dialkyl sulfuric acid.

That is, one of the alkyl groups of dialkyl sulfuric acid is highly reactive and can be used for alkylation even at temperatures below 60°C, but the monoalkyl sulfuric acid that is produced as a by-product at this time is used for alkylation. It has been found that it takes several hours to several tens of hours even at 100'C, which is the boiling point of water.

Based on these findings, the present inventor conducted various studies in order to shorten the alkylation time using monoalkyl sulfuric acid, and as a result, developed a method for involving monoalkyl sulfuric acid in the alkylation reaction in a short time by adopting specific reaction conditions. This is what we discovered.

That is, in the present invention, when alkylating an aqueous caustic solution of dihydroxybenzene or a mixture of dihydroxybenzene and a carbonate or bicarbonate of dihydroxybenzene and a caustic alkali with a dialkyl sulfuric acid, the initial reaction is carried out at a temperature of 100°C or less. The reaction system is then heated to a temperature of 100°C or higher to remove distilled components such as water from the reaction system, and the final reaction temperature is set to 110°C or higher, preferably 125°C or higher. This is a method for producing alkoxybenzene. Tr. Vses. Nauchn. Issued. In
st. Sintech. iNatural'N.
DushistykhVeshchestvl96l,
NO. ．． 5,25-30 (CA.5!.16454h1
962), monoalkyl sodium sulfate, soda ash, and catechol are mixed in the presence of a solvent, heated to 170°C, water and solvent are recovered, and the reaction is continued at the same temperature, but the present invention According to the results of studies conducted by researchers, a high temperature of 170°C is necessary, and a temperature of 110°C or higher, preferably 12°C, is required.
It was found that the reaction was completed when the generation of distillates such as water decreased at a temperature of 5°C or higher.

The method of the present invention requires a large amount of investment to raise the reaction temperature, as in the method of JP-A-51-54521. It is possible to produce dialkoxybenzene in good yield using a simple reaction apparatus without using a pressurized reaction apparatus.

When p-diethoxybenzene was produced by the method of the present invention and by the conventional method, for example, as described in one method of JP-A-48-1334, the alkylation conditions of monoalkyl sulfuric acid were changed to a temperature under water reflux. Comparing the yields when carried out, the former was 94%, while the latter was 84%. Next, a more detailed explanation will be given with reference to examples.

Example 1 Water 50TrLt and 48.9% in a 50■C four-diameter flask
102y (1.25 mol) of caustic soda and 110y (1.0 mol) of hydroquinone were added, and the temperature was adjusted to 50-60 ml.
Keep at ℃.

Next, diethyl sulfate 182y (1.2 mol) 4 was added dropwise at the same temperature. Furthermore, 48.9% caustic soda 102y (1.2
5 mol) is added, followed by water distillation at 100'C or above, and diethoxybenzene (DEB) which is steam distilled.
) and by-product ethanol are condensed out. Although the internal temperature rose as the mixture was distilled off, heating was stopped at 135° C., and after cooling slightly, water was added to the flask to dissolve the by-product Glauber's Salt, and the reaction product DEB was separated. Combined with steam distilled DEB and dried to give 1639 crude product. When this crude product was analyzed by glass chromatography, the degree was 96.5%, DEB was 157.3q (yield 9
4.6%), and monoethyl p-ethoxyphenol was not detected. The aqueous layer in which the by-product Glauber's salt was dissolved was aqueous with sulfuric acid, extracted with triol, and the triol was distilled off to obtain 1 da of p-ethoxyphenol, which is a monoethyl compound.

Example 2 In a 50■C four-diameter flask, 50ml of water, 114y (1.2 mol) of 42% caustic soda, and 110q of hydroquinone (
1.0 mol) was charged and the temperature was maintained at 55-65°C.

Next, diethyl sulfate 182y (1.2 mol) was added dropwise at the same temperature. Furthermore, 28.5 y (0.3 mol) of 42% caustic soda is added, and the temperature is then raised to 100° C. or more, and the water distilled out is steam distilled. DEB and by-product ethanol were condensed off. After raising the temperature to over 100'C, 28.5y (0.3 mol) of 42% caustic soda was added three times every 1 minute.

As the amount of components removed by distillation decreased, the internal temperature rose, but heating was stopped at 130'C and the same treatment as in Example 1 was carried out, yielding 165 Da of crude product. The purity was 96%, the DEB was 158.4y (yield 95.4%), and the amount of p-ethoxyphenol extracted from the sodium sulfate solution was 1g.
Comparative Example 1 100ml of water in a 500CC four-diameter flask1) 48.9%
Add 214 Da (2.6 mol) of caustic soda and 110 Da (1.0 mol) of hydroquinone, and bring the internal temperature to 50-60.
210 Da (1.37 mol) of diethyl sulfate was maintained at °C.
was dripped.

Then, the temperature was raised and the mixture was reacted under reflux for 8 hours, and the oil layer was separated from the water layer. A crude product of 146y was obtained by solidifying by cooling and thoroughly drying. The purity was 96% and DEB was 139y (yield 84.4%). The aqueous layer was diluted with sulfuric acid and extracted with triol to obtain 8y of p-ethoxyphenol. Comparative Example 2 Synthesis of DEB was repeated under the conditions described in JP-A-48-1332.

Claims (1)

[Claims] 1. When producing dialkoxybenzene by reacting a dialkyl sulfuric acid with an aqueous caustic solution of dihydroxybenzene or a mixture of dihydroxybenzene and a carbonate or bicarbonate of a caustic alkali, the initial reaction must first be carried out at a temperature of 100°C or less. A method for producing dialkoxybenzene, characterized in that the reaction temperature is then raised to 100°C or higher, distilled components such as water are removed from the reaction system, and the final reaction temperature is set to 110°C or higher.