Molecular Structure and Thermal Analysis of Potassium Hydrogenphthalate Monohydrate

Single crystals of potassium hydrogenphthalate monohydrate, KHPhth(H ₂O), were grown from aqueous solution using a slow cooling method and the structure was determined by X-ray diffraction analysis. The crystals belong to the monoclinic space group P2₁/c. Its unit cell parameters are as follows: a = 1.1235(1), b = 0.6689(1), c = 1.1998(2) nm, β= 98.85°, V = 0.8909(1) nm³, D_c = 1.657 g/cm ³, Z = 4, F(000) = 456. The thermal decomposition of the complex was studied using differential scanning calorimetry (DSC), thermogravimetry- derivative thermogravimetry (TG-GTG) and FT-IR techniques. With a linear heat rate, the diagrams show three endothermic processes. RCOOK and K ₂CO₃ are produced at 330 and 467°C, respectively, according to FT-IR analysis.