The general procedure for the synthesis of compound (CAS:5953-85-5), compound (CAS:17356-08-0), urea and 3-methyl-1H-pyrazol-5-ol from compound (CAS:161374-07-8) was as follows: a-h of DHH (0.01 mol) was mixed with excess hydrazine hydrate (5 mL) and heated to reflux for 6 hr. . After completion of the reaction, the mixture was cooled and poured into crushed ice. The solid products a-d were collected by filtration, crystallized with ethanol and finally dried. Evaporation of the filtrate gave a solid residue, which was isolated by graded crystallization from water to obtain pyrazole and urea (a) or thiourea (b).
2.4.1. Synthesis of 3-methyl-1H-pyrazol-5-ol (13). Yield: 42-55% (based on a-h); Melting point: 221-223 °C (literature value [49]: 220-222 °C); 1H-NMR (DMSO-d6) δ (ppm): 2.47 (s, 3H, -CH3), 6.83 (s, 1H, Ar-H), 10.07 (s, 1H, OH), 12.10 (s, 1H, NH) .
