Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (3): 412-418.doi: 10.3866/PKU.WHXB201501122

• THERMODYNAMICS, KINETICS, AND STRUCTURAL CHEMISTRY • Previous Articles     Next Articles

Low Temperature Heat Capacities of Uracil and 5-Bromouracil

ZHANG Xiao-Ye1,2, XUE Bin1, CHENG Ze1,2, TAN Zhi-Cheng2, SHI Quan2   

  1. 1. School of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003, Liaoning Province, P. R. China;
    2. Dalian National Laboratory for Clean Energy, Liaoning Province Key Laboratory of Thermochemistry for Energy and Materials, Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning Province, P. R. China
  • Received:2014-11-25 Revised:2015-01-12 Published:2015-03-06
  • Contact: SHI Quan, XUE Bin E-mail:shiquan@dicp.ac.cn;xue-b@163.com

Abstract:

The heat capacities of uracil and 5-bromouracil were measured using a quantum design physical property measurement system (PPMS) in the temperature range of 1.9-300 K. The experimental results indicate that the heat capacities of the two compounds increase with increasing temperature, and no thermal anomalies are observed across the whole temperature range studied. The heat capacity values of 5-bromouracil are larger than those of uracil as it has a higher molecular weight but a similar molecular structure. The heat capacities were fitted to theoretical models and the thermodynamic functions were calculated based on the curve fitting. The standardmolecular entropies at 298.15 K were determined to be (132.48±1.32) and (165.39±1.65) J·K-1·mol-1 for uracil and 5-bromouracil, respectively.

Key words: Uracil, 5-Bromouracil, Heat capacity, Physical property measurement system, Thermodynamic function

MSC2000: 

  • O641