Method for preparing methyl o-anisate

Abstract

The invention discloses a method for preparing methyl o-anisate. The method comprises the following steps: based on salicylic acid as a starting raw material, acetone as a solvent, anhydrous potassium carbonate as a catalyst and dimethyl sulfate as a methylation reagent, stirring and reacting for 5-10 hours at the controlled temperature of 45-50 DEG C; after reaction is finished, cooling, filtering and recovering potassium salt; and recovering acetone by distilling filtrate under room pressure, and distilling under reduced pressure to obtain the product methyl o-anisate. The method is a one-step method for synthesizing methyl o-anisate, thus reaction period is shortened, and energy consumption is greatly reduced; the product potassium salt (potassium sulfate) can be sold, and waste slag is not generated; potassium carbonate is adopted for catalytic reaction, potassium carbonate has high activity and conversion rate reaching more than 99%, and waste liquid and residue are hardly generated; recovered acetone can serve as the solvent to be directly used for reaction, thus cost is low; and prepared methyl o-anisate has high content being more than or equal to 99.5% (GC (gas chromatograph)), good quality, low salicylic acid content being less than or equal to 0.1% and low moisture content being less than or equal to 0.3%. The method disclosed by the invention has the advantages of good practicability, and better economic benefits and social benefits.

Description

technical field [0001] The invention belongs to the technical field of organic compound synthesis, in particular to a method for preparing methyl o-methoxybenzoate. Background technique [0002] Methyl o-methoxybenzoate is currently used in the industry as follows: salicylic acid is methylated with sulfuric acid diformic acid and water is used as a solvent under alkaline conditions, and then acid is separated to obtain o-methoxybenzoic acid. After drying, it is esterified with methanol by concentrated sulfuric acid, recovers methanol, washes with water, and separates to obtain the crude product of methyl o-methoxybenzoate, which is then subjected to high vacuum distillation to obtain o-methoxybenzoate Methyl benzoate. The disadvantages of this process include: 1) Because dimethyl sulfate is easily decomposed under alkaline conditions, the amount of dimethyl sulfate used in the process is relatively large; 2) The conversion rate of the methylation reaction is low, and the in...

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Problems solved by technology

The disadvantages of this process include: 1) Because dimethyl sulfate is easily decomposed under alkaline conditions, the amount of dimethyl sulfate used in the process is relatively large; 2) The conversion rate of the methylation reaction is low, and the intermediate o-methoxy The separation of benzoic acid is difficult, and the purity is low, the general content is about 90%; 3) A large amount of acidic saline wastewater is generated during the acid separation of the product; 4) Concentrated sulfuric acid is used as a catalyst for the esterification reaction, and a large amount of acidic wastewater is also generated in the post-treatment; 5) Due to the low content of the intermediate o-methoxybenzoic acid, the quality of the final product methyl o-methoxybenzoate is poor, the product content is about 98%, and more waste liquid and residue are produced after distillation