Green Process Development Of NBPT And Its Derivatives

NBPT is one of the effective soil urease inhibitors which has many advantages such as high activity,bargain price,low toxicity,easy to be degraded,no residual and non-pollution. This paper studied the green synthesis techniques of NBPT.Ethyl acetate was selected as the recrystallization solvent.After re-use the mother liquid 5 times,the average yield of NBPT was 70%and purity was 97.4%.New HPLC methods with two routine mobile phases were developed for the determination of NBPT.Methodâ… :λ=210nm,acetonitrile-water(30:70),pH=3.8,column temperature 30℃,flow rate 1.0 mL/min,injection volume 20μL;linear relation equation y=3×10⁷×-152839,R²=0.9945;average recovery 99.4%;detection limit 7.93×10^-6 mg/mL; RSD of precision 1.27%.Methodâ…¡:λ=220nm,methanol-water(40:60),pH=3.54,others were same as method I;linear relation equation y=9×10⁶x+6041.3,R²=0.9994;average recovery 99.7%;detection limit 2.57×10^-5mg/mL;RSD of precision 0.12%.This article emphatically studied the preparation of NBPT.A two-pot process has been developed in this subject.THF was adopted as solvent.The acid-accepter was TEA.The optimum conditions were obtained by the methods of 4 factors and 3 levels orthogonal test. The optimum technological conditions were:The reaction temperature of the second step was 5℃;the first step was 0℃;TEA:PSCl₃=1:1;NBA:PSCl₃=1.03:1.Under these process conditions the average yield of NBPT was 96.5%and purity was 86.2%.The average recovery of TEA was 93.8%.N-cyclohexylthiophosphoric triamide was synthesized through the two-pot method yield 63.4%,purity 89.1%.Mother liquor reuse to recycle TEA,the average yield of the recycled TEA was 88.3%and purity was 99.2%.The one-pot method synthesis of NBPT was established.Two-pot method conditions were used in one-pot method,with this method the process was briefied,the procedure was simplied and the cost of NBPT was further reduced,also a much better yield of the recycling solvent was gaved.Using this method the average yield of NBPT was 95.7%,purity was 84.9%.N-(n-propyl)thiophosphoric triamide,N-isobutylthiophosphoric triamide,and N-benzylthiophosphoric triamide were synthesized by one-pot method,yield of them were 97.3%,89.6%,91.2%,purity were 93.3%%,85.1%,81.8%.