Production method of p-tolualdehyde

Abstract

The invention relates to a production method of p-tolualdehyde. The production method comprises the following steps: sucking p-methylbenzylidene-containing p-xylylene dichloride into a rectifying tower under a low boiling condition, and collecting a p-methylbenzylidene finished product and a p-xylylene dichloride finished product fraction; feeding the p-methylbenzylidene finished product into an acidolysis reaction kettle, and adding a catalyst and water at the same time; after acidolysis is completed, conveying acid water on the lower layer into an acid water storage tank, and sucking an oil phase on the upper layer into an alkaline hydrolysis kettle; feeding Na2CO3 into the alkaline hydrolysis kettle, and sucking an oil phase on the upper layer into a crude distillation tower after alkaline hydrolysis reaction is completed; performing coarse distillation: performing decompression distillation on the oil phase on the upper layer; performing rectification: feeding collected fractions at the top of the tower into the rectifying tower for decompression rectification, and collecting a fraction at the temperature of 100 to 110 DEG C per 30 mmHg to obtain a p-tolualdehyde finished product with the purity of 99 percent. According to the production method of the p-tolualdehyde, the p-methylbenzylidene can be fully recycled, and zero discharge of process wastewater can be realized; the yield is high; the production cost can be reduced.

Description

technical field [0001] The invention relates to a production method of p-tolualdehyde, which belongs to the field of chemical industry. Background technique [0002] P-tolualdehyde is an important organic chemical intermediate. It is an important intermediate in flavors and fragrances, synthetic fibers, pharmaceutical synthesis, whitening agents and other products. It is also used in plastic nucleating agents, terephthalic acid raw materials and coal Asphalt modifier, etc., the market demand is increasing day by day. [0003] The current synthesis methods mainly include direct oxidation, electrochemical method and Sommeler reaction. Direct oxidation is to use oxidant to directly oxidize p-xylene to prepare p-tolualdehyde, but its selectivity is poor, the yield is low (8%-9%), the product separation is difficult, and the product quality is not good, and the three wastes are serious and difficult to handle. [0004] The electrochemical method is to oxidize p-xylene in the el...

AI Technical Summary

Problems solved by technology

In the production process of p-tolualdehyde, nearly 20% of black viscous by-products are produced. The by-products have complex structures and properties, and are difficult to recycle. They can only be buried or burned, polluting the environment

Moreover, in the process of preparing p-tolualdehyde in the Sommeler reaction, a large amount of production process wastewater will be produced, the production process wastewater COD is high, biochemical treatment is difficult, and water pollution is serious