Synthesis and Properties of 1,3-Dialkyl-4-nitro-1,2,3-triazolium Salts

A series of previously unknown 1,3-dialkyl-4-nitro-1,2,3-triazolium salts with the substituents of different kinds (alkyl = Me, Et, n-Pr, i-Pr, n-Bu, s-Bu, i-Amyl) were synthesized by regioselective quaternization of N2and N3-alkyl-4-nitro-1,2,3-triazoles with dialkyl sulphates in a high yield. These salts are gaining an ever-growing interest in the chemistry of energetically efficient materials, catalysts and ionic liquids. Among the two regioisomers, solely N3-substituted derivatives were found to be involved in the reaction with dialkyl sulphates. The products of N2-substitution do not enter quaternization, and this fact makes it possible to separate the mixtures of N2- and N3-isomers that exhibit close physicochemical characteristics limiting their separation by preparative techniques. The structures of the new 1,3-dialkyl-4-nitro-1,2,3-triazolium salts were proved by means of IR spectroscopy, 1H and 13C NMR spectroscopy, as well as single-crystal X-ray diffraction and elemental analysis.