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[Chemical Knowledge]：Production and manufacturing method and process flow of dimethoxybenzene

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Dimethoxybenzene (Dimethoxybenzene) is an important chemical raw material, widely used in medicine, pesticides, spices and other fields. There are two main manufacturing methods: one is obtained by the reaction of phenol with dimethyl sulfate, and the other is obtained by the methylation reaction of benzene with methanol in the presence of an acidic catalyst. This article will detail these two manufacturing methods.

1. phenol and dimethyl sulfate reaction method

1. raw material preparation

phenol: colorless needle crystal, a special smell, soluble in hot water, ethanol, ether and other organic solvents.
dimethyl sulfate: colorless transparent liquid, pungent odor, soluble in water and organic solvents.

2. reaction principle

under the action of alkaline catalyst, phenol and dimethyl sulfate substitution reaction, generating dimethoxybenzene.

3. Operation

(1) Phenol is mixed with an alkaline catalyst and heated to a certain temperature.
(2) Dimethyl sulfate is slowly added dropwise, the dropping rate is controlled, and the reaction temperature is kept stable. After the dropwise addition of
(3) was completed, the reaction was continued for a certain period of time and then cooled to room temperature.
(4) The pH is adjusted to neutral with an acid to separate unreacted phenol and sodium sulfate salt.
(5) The organic phase was washed with distilled water, dried and then distilled to collect the fraction of dimethoxybenzene.

4. Precautions

(1) Dimethyl sulfate is toxic, and the dripping speed should be strictly controlled during operation to avoid local overheating.
(2) It is necessary to maintain an alkaline environment during the reaction to promote the reaction.
(3) The temperature should be controlled during distillation to avoid the decomposition of dimethoxybenzene.

2. benzene and methanol methylation reaction method

1. raw material preparation

benzene: colorless transparent liquid, has a special smell, insoluble in water, soluble in organic solvents.
methanol: colorless transparent liquid, alcohol smell, soluble in water and organic solvents.
acid catalyst: such as sulfuric acid, phosphoric acid, etc.

2. reaction principle

in the presence of acidic catalyst, benzene and methanol methylation reaction, the generation of dimethoxy benzene.

3. Operation Step

(1) Benzene, methanol and acidic catalyst are mixed and heated to a certain temperature.
(2) Stir continuously during the reaction to maintain the uniformity of the reaction solution.
(3) After completion of the reaction, the reaction mixture is cooled to room temperature, and the pH value is adjusted to neutral with a base.
(4) Unreacted benzene and methanol were separated, and the organic phase was washed with distilled water and dried.
(5) Distillation is carried out to collect the fraction of dimethoxybenzene.

4. Precautions

(1) The choice of acid catalyst has an important influence on the reaction speed and selectivity, and the appropriate catalyst should be selected according to the specific situation.
(2) It is necessary to maintain a certain temperature and pressure during the reaction to promote the reaction.
(3) The temperature should be controlled during distillation to avoid the decomposition of dimethoxybenzene.
dimethoxybenzene can be obtained
the above two manufacturing methods, but each has its own advantages and disadvantages. The raw materials of the reaction method of phenol and dimethyl sulfate are easy to obtain and the operation is relatively simple, but dimethyl sulfate is toxic and requires strict control of operating conditions. The raw materials for the methylation reaction of benzene and methanol are green and environmentally friendly, but the reaction conditions are harsh and require higher temperatures and pressures. In actual production, the appropriate manufacturing method can be selected according to the specific situation.

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