Production method of p-tolualdehyde

Abstract

The invention relates to a production method of p-tolualdehyde. The method comprises the steps of: pumping a p-xylylene dichloride low-boiling-point compound containing p-methylbenzylidene into a rectifying tower, collecting a p-methylbenzylidene finished product and p-xylylene dichloride finished product fractions; putting the p-methylbenzylidene finished product into an acidolysis reaction kettle, and adding a catalyst and water at the same time; at the end of acidolysis, conveying the lower layer acid water to an acid water storage tank, and pumping an upper layer oil phase into an alkaline hydrolysis kettle; putting Na2CO3 into the alkaline hydrolysis kettle to carry out alkaline hydrolysis reaction, and then pumping the upper layer oil phase into a coarse distillation tower; conducting coarse distillation: subjecting the upper layer oil phase to pressure reduced distillation; performing rectification: putting the collected overhead distillate into the rectifying tower to perform pressure reduced rectification, and collecting 90-115DEG C/30mmHg fractions, thus obtaining a p-tolualdehyde finished product with purity of 99%. The production method of p-tolualdehyde provided by the invention can fully recycle p-methylbenzylidene, realizes zero discharge of process wastewater, has high yield, and can lower the production cost.

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...

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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

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