The pyrazole esters (n= 2) are known to be hydrolyzed in the presence of bases [1–3]. We found that pyrazole esters I–III (n= 1) are hydrolyzed with water in the absence of bases. 15 h. Yield 2.8 g (68%). The isomers molar ratio is 3: 5–3: 1, respectively. White crystals, mp 160–163 C (water). IR spectrum, ν, cm–1: 1530 (ring), 1680 (C= O), 3100–3400 (COOH). 1Н NMR spectrum (DMSO-d6), δ, ppm (J, Hz): 2.19 s (3H, 3-CH3), 2.22 s (3H, 5-CH3), 4.70 s ...
