Chemical Science International Journal

Single crystals of racemic barium tartrate monohydrate, BaC₄H₄O₆·H₂O, were grown at 308 K by a gel method using silica gel as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (monoclinic P2₁/c) and structural parameters were determined at room temperature. The crystal structure consisted of BaO₉ and BaO₁₀ polyhedra, two independent C₄H₄O₆ molecules, and O–H···O and C–H···O hydrogen bonds between adjacent H₂O or C₄H₄O₆ molecules. Weight losses due to thermal decomposition of racemic BaC₄H₄O₆·H₂O were found to occur in the temperature range of 300–1550 K. We suggested that the weight losses were caused by the evaporation of bound water molecules and the evolution of H₂CO, H₂, CO, and O₂ gases from the two C₄H₄O₆ molecules, and that the residual chalky white and black substances that remained as a mixture in the vessel after decomposition were barium oxide (BaO) and barium monocarbide (BaC), respectively.