Disentangling the Thermochemical and Thermodynamic Properties of Triadimefon

Abstract

Triadimefon is a widely used systemic triazole fungicide, yet its heat capacity and enthalpy of solution, which are key thermodynamic data for reactor heat transfer design, formulation process optimization, and environmental fate modeling, remain unreported. Herein, the molar heat capacity (Cp,m) of triadimefon was measured by differential scanning calorimetry (DSC) using the sapphire three-step method over the range 283.15–333.15 K. The temperature dependence of Cp,m is well described by a cubic polynomial, and Cp,m at 298.15 K is 359.23 J mol–1 K–1. The thermodynamic functions HT – H298.15 K and ST – S298.15 K were derived from the experimental heat-capacity data. These quantities, together with Cp,m, were also calculated by density functional theory. The calculated values are slightly lower than the experimental ones, with relative deviations ranging from 8.70 to 10.25%. To further understand its solution behavior, the dissolution of triadimefon in N,N-dimethylformamide was investigated at 298.15 K. The process is endothermic, with a molar dissolution enthalpy of 15.71 ± 0.13 kJ mol–1. An empirical relationship between dissolution enthalpy and molality is established, with the dissolution kinetics described by dαdt=10−2.42(1−α)0.80. The present thermochemical and kinetic results of triadimefon afford reliable bases of physical and chemical properties for formulation development, recrystallization process optimization, and environmental behavior assessment.