Measurement and Correlation of Solubilities of 3‑Nitro-1,2,4-triazol-5-one (NTO) in 10 Pure Solvents and 3 Binary Solvents from 278.15 to 328.15 K

Solubilities of 3-nitro-1,2,4-triazol-5-one (NTO) were measured in 10 pure solvents (deionized water, methanol, ethanol, isopropanol, n-butanol, formic acid, ethyl acetate, acetonitrile, toluene, n-hexane) and 3 binary solvents (ethanol + water, nitric acid + water, N-methyl pyrrolidone + water) from 278.15 to 328.15 K using gravimetric methods. The measured solubility data in pure solvents were fitted by a polynomial empirical equation, the van’t Hoff equation, and the modified Apelblat equation, among which the modified Apelblat equation is the best empirical model for correlating the solubility of NTO in pure solvents. The modified Apelblat equation, the CNIBS/R-K equation, and the Jouyban–Acree equation were adopted to correlate the experimental solubility data in three binary solvents. In binary solvents, all fitted results agree well with the measured solubilities of NTO. This work can provide guidance for further crystallization researches of NTO.