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双氰胺(dicyandiamide)又称氰基胍(cyanoglmnjdine),是合成新型材料如密胺塑料和药物如巴比土酸盐和胍基衍生物等的主要原料,应用十分广泛。然而,关于双氰胺的取代反应,特别是四取代反应的研究工作还未见报道。我们在此报道在相转移催化条件下双氰胺取代反应的研究工作。 在一般条件下双氰胺很难发生四取代反应,Suyama等曾尝试用非直接烷基化的方法来制取双氰胺的四取代产物,但未获成功,这也是至今未见报道的原因之一。我们认为,双氰胺进行四取代反应的困难在于其发生取代反应后增加了取代基与氰亚氨基的立体位阻效应,阻碍了进一步的反应。我们尝试使用相转移催化剂来克服上述困难。实验结果表明,相转移催化剂对于这一反应具有异常的活性。在碱的水溶液-甲苯中加入相转移催化剂(如四丁基溴化铵、三乙基苄基氯化铵TEBA等),双氰胺与卤代物(RX)可顺利地进行烷基化反应,得到很好的结果。
Dicyandiamide (dicyandiamide), also known as cyanoglmnjdine, is widely used in the synthesis of new materials such as melamine plastics and drugs such as barbiturates and guanidino derivatives. However, the research on the substitution reaction of dicyandiamide, especially the tetra-substituted reaction has not been reported yet. We report here the work on the dicyandiamide substitution reaction under phase transfer catalysis. Under normal conditions, dicyandiamide is hard to undergo tetrasubstitution. Suyama et al. Tried to produce dicyandiamide tetrasubstituted by non-direct alkylation method, but this has not been reported yet. one. In our opinion, dicyandiamide is more susceptible to tetrasubstituted reactions because of the increased steric hindrance of the substituents to the cyanoimino groups after the substitution reaction, hindering further reaction. We try to use phase transfer catalyst to overcome the above difficulties. The experimental results show that the phase transfer catalyst has an unusual activity for this reaction. Addition of a phase transfer catalyst (such as tetrabutylammonium bromide, triethylbenzylammonium chloride, TEBA, etc.) to the alkali aqueous solution - toluene, the dicyandiamide and the halide (RX) can be smoothly alkylated, Get good results.