Conformational studies by dynamic nuclear magnetic resonance. Part 16. The mechanism of tautomerism in triazenes
作者:Lodovico Lunazzi、Giorgio Panciera、Maurizio Guerra
DOI:10.1039/p29800000052
日期:——
The kinetics of tautomerism of triazenes, R1NH–NNR2⇌ R1NN–NHR2, have been determined by means of line-shape analysis of the 1H n.m.r. spectra at various temperatures. When R1= R2= Me the equilibrium reaction is second-order whereas when R1= Me, R2= Ph or when R1= R2=p-MeC6H4 the reaction follows a first-order course. Thermodynamic activation parameters have been determined for both situations for a
三氮烯的互变异构现象的动力学,R 1 NH-N NR 2 ⇌ - [R 1 ñ N-二NHR 2,已经由线形状分析测定1在各种温度下H核磁共振光谱。当R 1 = R 2 = Me时,平衡反应是二阶的;而当R 1 = Me时,R 2 = Ph或当R 1 = R 2 = p -MeC 6 H 4时反应遵循一阶过程。对于两种溶剂,在两种情况下均已确定了热力学活化参数。理论上的INDO计算有助于理解当脂族被芳族取代基取代时,从双分子反应路径向单分子反应路径的转变。与理论电荷总体分析的结论一致,没有溶剂效应提示了一种根本机理。
Pseudo-rotation of spin-labelled phosphoranes formed by cyclisation of triazenylphosphoranyl radicals
作者:John C. Brand、Brian P. Roberts
DOI:10.1039/c39810001107
日期:——
Triazenylphosphoranylradicals undergo cyclisation to give paramagnetic phosphoranes and the rapid pseudo-rotation of the latter can be monitored by e.s.r. spectroscopy.
三氮烯基膦烷基被环化以产生顺磁性磷烷,并且后者的快速假旋转可以通过电子能谱法监测。
Goldschmidt; Holm, Chemische Berichte, 1888, vol. 21, p. 1016
作者:Goldschmidt、Holm
DOI:——
日期:——
Novel triazenes and triazolines from the base-catalyzed hydrolysis of 1,3-dialkyl-3-acyltriazenes
作者:Richard H. Smith、Brian D. Wladkowski、Julie A. Herling、Timothy D. Pfaltzgraff、Jesse E. Taylor、Erin J. Thompson、Brunon Pruski、John R. Klose、Christopher J. Michejda
DOI:10.1021/jo00050a016
日期:1992.11
The products and mechanism of hydrolytic decomposition of a series of 1,3-dialkyl-3-acyltriazenes were studied in alkaline buffers. In general the mechanism of decomposition involves deacylation leading to the formation of the parent 1,3-dialkyltriazene. The solvent deuterium isotope effect (k(H2O)/k(D2O)) is less than 1.0, indicating specific base catalysis. A plausible mechanistic explanation is rapid reversible attack by hydroxide ion, followed by rate-limiting heterolysis of the N(l)-acyl bond. The resultant, 1,3-dialkyltriazene is somewhat unstable under the reaction conditions and undergoes subsequent hydrolysis, a reaction previously shown to be specific acid-catalyzed. When the N(l) alkyl group is 2-chloroethyl, unusual products are obtained. For the 3-acetyl and 3-carbethoxy derivatives, the initial deacylation product, 1-(2-chloroethyl)-3-methyltriazene, efficiently cyclizes to form 1-methyltriazoline. The 3-(methylcarbamoyl) derivative does not deacylate, but instead undergoes dehydrohalogenation to 1-vinyl-3-methyl-3-(methylcarbamoyl)triazene.