Rate-determining nitrogen inversion in the isomerisation of isoimides to imides and azides to tetrazoles: direct observation of intermediates stabilized by trifluoroethyl groups
作者:Anthony F. Hegarty、Nuala M. Tynan、Suzanne Fergus
DOI:10.1039/b202005j
日期:2002.6.27
N→O acylgroup transfer or cyclisation. The Hammett ρ value (−0.4), obtained for the rearrangement of the imidoyl azides to the tetrazoles, compares well to other systems where the rate-determining step (nitrogen inversion) was similar. Nitrogen inversion in these imine systems is therefore significantly slower (ca. 10-fold relative to an ethyl group) in the presence of the trifluoroethyl group on nitrogen
作者:Anthony F Hegarty、Stephen J Eustace、Nuala M Tynan、Nguyen-Nguyen Pham-Tran†、Minh Tho Nguyen
DOI:10.1039/b006582j
日期:——
are not observed as products, these ions have been calculated to be the most favoured protonated forms of ylides either in the gas phase or in a continuum of solvent, irrespective of its polarity. Ab initio calculations were carried out using molecular orbital methods (HF, MP2 and CCSD(T)) with basis sets ranging from 6-31G(d) to 6-311++G(3df,2p) and density functional theory (B3LYP) in conjunction with