Equilibria of the 5-substituted-1,2-acylated tetrazoles and imidoyl azides
Equilibrium of acylated-5-alkyloxy (aryloxy) tetrazoles and acylated-imidoyl azides was measured by (1)H NMR and/or IR spectroscopy. In nonpolar solvents the relatively weakly electron-withdrawing acyl group (CO(2)CH(3)) favored acylation at the 2-position of the 5-substituted tetrazoles. Moderately electron-withdrawing groups (CO(2)CH(2)CCl(3), CO(2)CCl(3)) move the equilibrium to the side of 1-acyl-5-substituted tetrazole. Strong electron-withdrawing groups (CN, SO(2)CH(3), SO(2)CF(3)) favored the formation of the azide. The rate of isomerization of tetrazoles and the azide increases at higher concentrations and polarity of the solvent. In solid phase or in the nonpolar solvent (diethyl ether), only one of the three isomers is present, its structure depending on the nature of the substituents at the 1 or 2 positions of tetrazoles.
Dabbagh
HA
College of Chemistry, Isfahan University of Technology, Isfahan, 8415 Islamic Republic of Iran, Iran, and Department of Chemistry, New Mexico State University, Las Cruces, New Mexico, 88003-0001, USA.
Lwowski
W