Method for producing methyl benzoate using benzoic acid containing sodium chloride as raw materials

Abstract

The invention discloses a method for producing methyl benzoate by using a benzoic acid containing sodium chloride as raw materials. The method comprises the following steps: mixing side products of the benzoic acid containing sodium chloride and excessive methanol in an esterifying kettle, at the same time, adding an organic catalyst and an inorganic catalyst to the esterifying kettle, performing warming and stirring at the same time, when the temperature is raised to 100 DEG C, performing heat preservation and continuously dropwise adding methanol for 4 hours, and maintaining the methanol in an excessive reaction state; after stopping dropwise adding, firstly, distilling off the methanol, then distilling off the methyl benzoate, and performing caustic washing, water washing, and dehydrating so as to obtain the finished methyl benzoate. The method disclosed by the invention adopts the jointed effects of the organic catalyst and the inorganic catalyst, and the usage amount of the organic catalyst only accounts for 5-10% of the usage amount of a single catalyst in the prior art, so that the production cost is substantially reduced; raffinate in the bottom of the kettle is recycled, and the yield of the methyl benzoate is further increased without generating hazardous wastes, so that the expense for handling the hazardous wastes is reduced.

Description

technical field [0001] The invention relates to a method for producing methyl benzoate by recycling benzoic acid, a by-product in the production process of chemical products. In particular, a method for the recovery and utilization of by-product benzoic acid containing sodium chloride to produce methyl benzoate is provided, which is especially suitable for the production of benzoic acid (containing sodium chloride) as a by-product in the process of dibenzoylmethane Recycling to produce methyl benzoate. Background technique [0002] Benzoic acid is also known as benzoic acid. Benzoic acid is generally used as a medicine or preservative to inhibit the growth of fungi, bacteria, and mold. It is usually applied on the skin when it is used as medicine to treat skin diseases such as ringworm. Used in synthetic fiber, resin, paint, rubber, tobacco industry. [0003] In the production process, if the by-product benzoic acid is not recycled, it will have a serious negative impact ...

AI Technical Summary

Problems solved by technology

The process of producing dibenzoylmethane is divided into condensation, pickling, alkali washing, water washing, concentration, crystallization and other processes. In the pickling process, some methyl benzoate will be hydrolyzed to produce benzoic acid. During alkali washing, benzoic acid and The alkali reacts to produce sodium benzoate. When the separated sodium benzoate is neutralized with hydrochloric acid to recover benzoic acid, the filtered benzoic acid contains part of brine. When the recovered benzoic acid is used to produce methyl benzoate, sodium chloride poisons the catalyst , that is, p-toluenesulfonic acid generates its salt (sodium p-toluenesulfonate), which makes it lose its catalytic effect. Therefore, a large amount of p-toluenesulfonic acid is consumed in the actual production process, which greatly increases the production cost and produces a lot of danger. waste

If only concentrated sulfuric acid is used as a catalyst, the amount of sulfuric acid will be large, and serious corrosion will occur, and a large amount of alkali will be used for neutralization, which will affect the service life of the equipment and increase the production cost