有机碱催化CO_2与伯胺反应合成N,N′-二取代脲

以有机碱为催化剂,CO2与伯胺反应合成了N,N′-二取代脲;考察了有机碱种类、伯胺碳链长度、反应温度、CO2压力、反应时间、催化剂用量对合成反应的影响。实验结果表明,随伯胺碳链的增长,催化剂的碱性增强,N,N′-二取代脲的收率增加;脂肪族N,N′-二取代脲的收率明显高于芳香族N,N′-二取代脲。在所选用的有机碱中,1,5,7-三氮杂双环[4.4.0]葵-5-烯(TBD)催化剂的活性最高。以正丁胺为反应基质、TBD为催化剂,合成N,N′-二丁脲的最佳反应条件为:反应温度180℃,CO2压力10.0M Pa,反应时间10h,TBD摩尔分数5.0%(基于正丁胺);在此条件下,N,N′-二丁脲的收率为81.8%;红外光谱表征结果表明,合成的产物为N,N′-二丁脲。

Synthesis of N,N′-Disubstituted Ureas from Carbon Dioxide and Primary Amine over Organic Base Catalysts

N,N′-Disubstituted ureas,used as intermediates for synthesis of pesticides,resin precursors and carbamates,were synthesized from carbon dioxide and primary amines(namely n-propylamine,n-butylamine,n-amylamine,n-hexylamine,benzylamine and aniline) over organic base catalysts.Effects of organic base types,carbon chain length of primary amine,carbon dioxide pressure,catalyst dosage,reaction temperature and time on the synthesis were investigated.Yield of N,N′-disubstituted ureas increases along with carbon chain length of primary amine and catalyst basicity.Yields of aliphatic N,N′-disubstituted ureas are much higher than those of aromatic N,N′-disubstituted ureas. Under optimal conditions: n-butylamine as primary amine,1,5,7-triazabicyclodec-5-ene(TBD) as catalyst,reaction temperature 180 ℃,time 10 h,CO2 pressure 10.0 MPa,TBD mole fraction 5.0%(based on n-butylamine),yield of N,N′-dibutylurea is 81.8%.The prepared N,N′-dibutylurea was separated from products and identified by IR spectrometry.