29639-03-0Relevant academic research and scientific papers
Novel and efficient synthesis of 4-substituted-1,2,4-triazolidine-3,5- diones from anilines
Mallakpour, Shadpour,Rafiee, Zahra
, p. 1927 - 1934 (2008/02/04)
A simple and efficient three-step synthetic procedure for the preparation of 4-substituted phenyl derivatives of 1,2,4-triazolidindiones (urazoles), starting from anilines, has been developed. In this method, aniline derivatives were reacted with 4-nitrophenyl chloroformate to provide corresponding carbamate derivatives. In the second step, semicarbazide derivatives were prepared from these carbamates by reaction with ethyl carbazate. The cyclization reaction of corresponding semicarbazides furnished 1,2,4-triazolidindiones in high yields. Copyright Taylor & Francis Group, LLC.
Nucleophilic substitution reactions of phenyl chloroformates
Yew, Kyoung Han,Koh, Han Joong,Lee, Hai Whang,Lee, Ikchoon
, p. 2263 - 2268 (2007/10/03)
Methanolysis and aminolysis of phenyl chloroformates in acetonitrile have been investigated.The rates are slow due to initial-state stabilization by strong resonance electron donation from the phenoxy group.In both reactions the large positive values of ρY = 0.8-1.6 and low ΔH(excit.) and ΔS(excit.) values show that the transition state is strongly associative with little bond breaking.This mechanism is supported by the relatively large solvent isotope effect, kMeOH/kMeOD = ca. 2.3-2.5, and by the relatively strong inverse secondary kinetic isotope effect, kH/kD =/ca. 0.74-0.94, involving deuteriated aniline nuclephiles, in addition to a negative value of ρXY.The dependence on aniline basicity, βx(βnuc) =/ca. 0.8, and the ρX values of -2.3 are similar to those corresponding values for the reactions of benzoyl chlorides which have been predicted to react by an associative SN2 mechanism.These observations are consistent with a concerted displacement mechanism for the methanolysis and aminolysis of phenyl chloroformates.
