Two groups of triazolium salts based on the central triazole ring isomer
Triazolium salts are chemical compounds based on the substitutedtriazole structural element. They are composed of a cation based on a heterocyclic five-membered ring with three nitrogen atoms, two of which are functionalized and a corresponding counterion (anion). Depending on the arrangement of the three nitrogen atoms the triazolium salts are divided into two isomers, namely 1,3,4-trisubstituted-1,2,3-triazolium salts as well as 1,2,4-triazolium salts. They are precursors for the preparation of N-heterocylcic carbenes.[1]
1,3,4-trisubstituted-1,2,3-triaolium salts can be synthesized from 3,4-disubsituted-1,2,4-triazol molecule by quaternization of the 1 nitrogen. This quaternization can be done by reaction with alkyl iodides (or other alkyl halide, albeit less yield is generally observed due to less reactivity, alkyl fluoride are rarely seen as they are mostly unreactive) yielding the corresponding 1,3,4-trisubstituted 1,2,3-triazolium salt with iodine. Similarly 1,3,5-trisubstituted-1,2,3-triazolium salts can be obtained from 3,5-disubsituted-1,2,4-triazol.
1,4-disubstituted 1,2,4-triaolium salts can be synthesized from 4-subsituted 1,2,4-triazol molecule by quaternization of the 1 nitrogen. This quaternization can be done by reaction with alkyl iodides (or other alkyl halide, albeit less yield is generally observed due to less reactivity, alkyl fluoride are rarely seen as they are mostly unreactive) yielding the corresponding 1,4-disubstituted 1,2,4-triazolium salt with iodine.
