Continuous production method for N-NBPT

Abstract

The invention relates to a production method for chemical fertilizer urease inhibitors, in particular to a continuous production method for N-NBPT. The continuous production method comprises the following steps: mixing thiophosphoryl chloride and dichloromethane for stirring; cooling; then dropwise adding a mixed solution of n-butylamine and dichloromethane, and acid bounded reaction agents simultaneously; preserving heat for 0.5-6 hours after dropwise adding to obtain a reaction solution, wherein the acid bounded reaction agents are ammonium hydroxides or ammonia gases; filtering and layering the obtained reaction solution; introducing the ammonia gases into the underlayer reaction solution for an ammonolysis reaction; centrifuging, filtering and concentrating the reaction solution obtained after the ammonolysis reaction; recrystallizing to obtain the product. According to the invention, other auxiliary raw materials are not needed except for raw materials used for producing the product; the continuous production method needs no purification in the tremendously optimized reaction process, has a mild reaction condition and no other by-products, and has the advantages of high production efficiency, mild reaction condition, high yield, good quality, less three wastes, fully utilized resources and the like.

Description

Technical field [0001] The invention relates to a method for producing a chemical fertilizer urease inhibitor, in particular to a method for continuous production of N-butyl thiophosphoric triamide. Background technique [0002] N-Butylthiophosphoric triamide is one of the effective soil urease inhibitors in agriculture, and it can be formulated with urea in a certain proportion of compound fertilizer. On the one hand, it can inhibit the activity of urease, slow down the hydrolysis rate of urea, make urea easily absorbed by plants, and greatly improve the utilization rate of urea. On the other hand, it can also provide phosphorus, sulfur, nitrogen and other elements to improve the soil. U.S. Patent No. 4,530,714, Chinese Patent No. CN101370753, etc. have reported the application of N-butyl thiophosphoric triamide as a urease inhibitor in urea and urea-based compound fertilizers. [0003] N-Butylthiophosphoric triamide mainly has the following synthetic methods: [0004] (1) Two-st...

AI Technical Summary

Problems solved by technology

However, this process also has the disadvantages of long reaction time, strong triethylamine odor, low recovery rate, difficulty in post-treatment separation and purification, cumbersome operation steps and the need for pressurization when passing ammonia.

Chinese patent CN101503424 discloses a method for preparing N-n-butylthiophosphoric triamide by one-pot method, which also uses tetrahydrofuran as a solvent, triethylamine as an acid-binding agent, and reacts with ammonia under normal pressure, but there is still a reaction time Long, centrifuged separation reaction by-products of solid ammonium chloride, tetrahydrofuran and triethylamine loss and other issues

Chinese patent CN101759717 also uses triethylamine as an acid-binding agent and chloroform as a solvent. After passing through the ammonia, it is directly concentrated to obtain a crude product, which needs to be reacted under nitrogen protection, and how to remove ammonium chloride, triethylamine and chloroform. Not mentioned

However, the ammonia reaction in the second step of the method is still a batch reaction, which is not conducive to the continuous and large-scale production of the whole process, and the solvent used and the excess n-butylamine have low boiling points, large losses, and high costs.

[0007] In a word, the current various processes for producing N-n-butylthiophosphoric triamide still have shortcomings such as low production efficiency, high cost, and serious waste. The green production process of N-n-butylthiophosphoric triamide with less environmental pollution still has important industrial value

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