Method for preparing crystal form thioamino carboxylate by taking secondary amine as raw material

Abstract

The invention relates to a method for preparing crystal form thioamino carboxylate by taking secondary amine as a raw material, namely a method for preparing the crystal form thioamino carboxylate bya one-step method through a mixed reaction of the secondary amine, carbon disulfide, metal oxide or hydroxide in water. According to the scheme, conventional reaction equipment and simplified raw materials are used for preparing a high-purity product; the method is low in water consumption, inorganic salt byproducts are not generated, and the reaction mother liquor can be recycled directly or through simple treatment.

Description

technical field [0001] The invention relates to the preparation technology of fine chemicals, in particular to a method for preparing crystalline thioaminocarboxylates from secondary amines. Background technique [0002] Thioaminocarboxylates are a class of fine chemicals that are widely used. The global annual demand is more than 50,000 tons. They are mainly used as rubber vulcanization accelerators, polymer materials and petroleum polymerization inhibitors, lubricating oil anti-wear additives, and pesticides. Wait. In specific chemical reactions, it is also used as a synergistic additive and a polymerization terminator. It is also reported to be used in the formulation of zinc-containing precursor solutions for multi-element alloy quantum dots. [0003] The disclosed preparation technology of this type of compound includes two-step alkali method and one-step method. The two-step alkali method is adopted by most production enterprises because of its high yield and mature t...

AI Technical Summary

Problems solved by technology

[0004] The disadvantage of this method is that the metathesis of the second step is a fast reaction, and the product is in the form of fine powder, which is easy to cause the inclusion of raw materials, intermediates and by-products, which affects the purity; the product system contains a large amount of sodium chloride or sodium sulfate by-products. The product needs to be desalted and washed, and the water consumption per ton of product is as high as 5m 3 The above; the mother liquor needs to be subjected to additional distillation and concentration treatment, which increases the manufacturing cost; in addition, a small amount of anions and cations will still remain in the product, which limits its application in the fields of latex, wire and cable, etc.

The disadvantage is that the activity of metal oxides in this medium system is not high, which affects the speed and degree of reaction; obviously, because of the low purity of its products, it also limits its application field

This method does not produce inorganic salt by-products. The disadvantage is that dimethylamine is stored in a high-pressure tank, and the solvent medium needs to be subjected to complicated post-treatment, and the product yield is low.

Weakness is that in described technique, 1. dimethylamine is as reaction substrate, reacts with intermediate product dimethylthioaminocarboxylic acid, promptly competes with the reaction of generating product, affects main reaction yield; Also causes mother liquor Medium ammonia nitrogen and chemical oxygen demand are relatively high, and further treatment is still required

②The solubility of zinc oxide is 1.6mg / L, and the density is 5.6g / cm 3 , the reaction activity in water is not high and it settles, which affects the product yield. Part of the zinc oxide will also be trapped in the product, which affects the purity.

The above two methods do not provide an effective technical solution

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