The
static gravimetric method was used to measure the
solubility of 17-α hydroxyprogesterone (OHP) in 13 pure solvents
ranging from 278.15 to 323.15 K. The results indicate that the experimental
solubility of OHP increases with increasing temperature. The experimental
solubility data were correlated by the selected van’t Hoff
model, λh model, modified Apelblat model, Yaws
model, and nonrandom two-liquid (NRTL) model. The fitting results
show that the Yaws model can give better correlation results by fitting
13 different pure solvent systems. Based on the NRTL equation, the
thermodynamic analysis of solubility data showed that the mixing process
was spontaneous. The Hansen solubility parameters (HSPs) and solvent
effect were applied to explore these solubility characteristics. Finally,
the thermodynamic properties Δsol
H°, Δsol
S°, Δsol
G°, %ξH, and %ξTS were calculated by the van’t Hoff model equation.
The results showed that Δsol
H°,
Δsol
S°, and Δsol
G° are all positive values, indicating that
the dissolution of OHP in the selected solvent is an endothermic reaction
with increasing entropy.