4-Amino-5-phenyl-4H-1,2,4-triazole-3-thiol

Synthesis of 4[amino]-5-phenyl-4H-1,2,4-triazole-3-thiol: A suspension of potassium salt dithiocarbazinate (4.44g, 0.02M), hydrazine hydrate (2ml, 0.04M) and water (80ml) was refluxed for 3 hrs. The color of the reaction mixture changed to green, hydrogen sulphide was evolved and a homogenous solution resulted. A white solid was precipitated by dilution with cold water (100ml) and acidification with concentrated hydrochloric acid. The product was filtered, washed with cold water (2×30 ml) and recrystallised from ethanol in 42 % yield.
Melting point : 198 -200°C.
IR (KBr cm-1): 943 (N-C-S str), 1278 (N-N-C str), 3365(N-H str), 696 (C-S str), 3082 (Ar CH str), 1446 (C-N str).
NMR (ppm): 7.7 (m, 5H, Ar-H), 7.9 (s, 2H, NH2), 14.6(s, 1H, S-H).

Journal of Heterocyclic Chemistry, 13, p. 925, 1976 DOI: 10.1002/jhet.5570130450
The Journal of Organic Chemistry, 47, p. 2757, 1982 DOI: 10.1021/jo00135a014