G. Aridoss, K. Laali
Nov 1, 2011
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Journal
European Journal of Organic Chemistry
Abstract
A series of 5-substituted 1H-tetrazoles were synthesized through [3+2] cycloaddition reactions between nitriles RCN and NaN3 in the presence of Cu–Zn alloy nanopowder as catalyst. The 1,5-dibutyl, 1-butyl-5-hexyl, 2,5-dibutyl, and 2-butyl-5-hexyl derivatives were then used as building blocks to synthesize several novel tetrazolium ionic liquids (ILs) with EtSO4–, OTf–, and NTf2– counterions. Whereas alkylation of the 2,5-dialkyltetrazoles selectively gave the N-4 alkylated onium salts, with the 1,5-dialkyl derivatives approximately 1:1 mixtures of two tetrazolium salts were formed by alkylation at N-3 and N-4. The triflate and ethyl sulfate salts are room-temperature ILs that are hydrophilic, whereas the NTf2 salts are low-melting ILs and are hydrophobic. The resulting tetrazolium-based ionic liquids were studied by various multinuclear and 2D NMR techniques including natural abundance 15N and 1H/15N correlations.