Manufacturing Method of Anisole
Anisole, also known as phenylmethoxybenzene or phenoxymethane, is a colorless, transparent liquid with a special aroma. It is mainly used as a solvent, a flavor and a pharmaceutical intermediate. In the field of raw materials for chemical production, there are two main manufacturing methods for anisole: one is prepared by the reaction between benzyl alcohol and dimethyl sulfate, and the other is prepared by the esterification reaction between benzoic acid and methanol. This article will introduce these two manufacturing methods in detail.
I. Preparation of anisole by reaction between benzyl alcohol and dimethyl sulfate
The principle of this method is that the etherification reaction between benzyl alcohol and dimethyl sulfate occurs under the action of alkaline catalyst to produce anisole. The specific operation steps are as follows:
1. Mix benzyl alcohol with alkaline catalyst (e.g. sodium hydroxide or potassium hydroxide) and heat to a certain temperature.
2. Slowly add dimethyl sulfate dropwise, controlling the rate of dropwise acceleration to keep the reaction temperature stable.
3. At the end of the reaction, cool to room temperature, wash the reaction solution with an acidic aqueous solution and isolate the anisole.
4. Purify the anisole by distillation and collect the fractions with boiling point at 154-156°C.
The advantage of this method is that the raw materials are easily available and the operation steps are relatively simple. However, it should be noted that dimethyl sulfate is a toxic compound, and the operation requires strict control of safety conditions.
II. Preparation of anisole by esterification reaction of benzoic acid and methanol
The principle of this method is that benzoic acid and methanol under the action of acidic catalyst undergo esterification reaction to produce methyl benzoate, and then methyl benzoate and methanol under acidic conditions undergo etherification reaction to produce anisole. The specific operation steps are as follows:
1. Mix benzoic acid with methanol, add acidic catalyst (such as sulfuric acid or hydrochloric acid), and heat and reflux for a certain time.
2. At the end of the reaction, cool to room temperature, separate out the unreacted methanol and the generated water to obtain methyl benzoate.
3. Methyl benzoate is mixed with methanol, acid catalyst is added and heated to reflux for a certain time.
4. At the end of the reaction, cool to room temperature, absorb the unreacted methanol and acid catalyst with alkaline absorbent, and isolate the anisole.
5. The anisole is purified by distillation and the fractions with boiling points at 154-156°C are collected.
The advantage of this method is that it avoids the use of toxic dimethyl sulfate, but the procedure is relatively complicated and requires more steps and raw materials.
Whichever method is used to prepare anisole, the reaction conditions need to be strictly controlled to ensure product quality and safety. At the same time, the waste generated in the production process needs to be properly disposed of to avoid pollution of the environment.
In conclusion, there are two main methods for the manufacture of anisole, namely, through the reaction of benzyl alcohol with dimethyl sulfate and through the esterification reaction of benzoic acid and methanol. Different methods have different advantages and disadvantages and operation requirements, so choose the suitable method for preparation according to the specific production conditions and needs.
