The combustion energy of thioproline was determined
by the precision rotating-bomb calorimeter at 298.15 K to be ΔcU= –2469.301.44 kJ mol–1.
From the results and other auxiliary quantities, the standard molar enthalpy
of combustion and the standard molar enthalpy of formation of thioproline
were calculated to be ΔcHmθC4H7NO2S,
(s), 298.15 K= –2469.921.44 kJ mol–1
and ΔfHmθC4H7NO2S, (s), 298.15K= –401.331.54
Authors:Y. Xu-Wu, Z. Hang-Guo, S. Wu-Juan, W. Xiao-Yan, and G. Sheng-Li
The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine.
Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy,
ΔcU, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy
of combustion, ΔcHmθ, and the standard molar of formation of the complex, ΔfHmθ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively.
Authors:Y. Wang, Q. Fan, P. Li, X. Zheng, J. Xu, Y. Jin, and W. Wu
The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated
under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic
strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III)
uptake on soil, however at low pH values, the influence of anions was following the order: Cl− ≈ NO3− > ClO4−. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7,
the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes
in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed
outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.
Authors:H. Ding, Y. Niu, Y. Xu, W. Yang, S. Yuan, Z. Qin, and X. Wu
Solvent extraction of protactinium with tri-iso-octyl-amine (TIOA) in xylene, benzene, carbon tetrachloride and chloroform
from HCl, HF, HNO3, HClO4 and H2SO4 media was studied using 233Pa as a radiotracer. The extraction efficiencies of protactinium were determined as a function of shaking time, concentrations
of mineral acids in aqueous phase, extractant concentrations and diluents in organic phase. The extraction mechanism was discussed.
The results show that the extracted species in the organic phase is [(R3N−H)nPa(OH)xCl
Authors:W.-Y. Liu, Sh.-L. Xie, X.-Zh. Xu, Ch.-Y. Wu, and F. Feng
Oroxylin A (5,7-dihydroxy-6-methoxyflavone), which has showed multiple pharmacological effects, was semi-synthesized chemically as a pharmaceutical agent. Its impurities, degradation products and their formation pathways remain unknown. In the present study, two impurities (5,6,7-trihydroxyflavone, 5-hydroxy-6,7-dimethoxytlavone) and a degradation product (5,7-dihydroxy-8-methoxyflavone) in Oroxylin A bulk drug substance were identified, and their formation pathways were proposed. A reversed phase liquid chromatographic method for the simultaneous determination of Oroxylin A and the three compounds was developed on a C18 column using methanol-acetonitrile-0.1% acetic acid (54:23:23, v/v/v) as the mobile phase. The detection was performed at 271 nm. The method was validated to be robust, precise, specific and linear between 4 and 40 μg mL−1; the limits of detection and quantification of Oroxylin A were 0.01 and 0.04 μg mL−1, respectively. The developed method was found to be suitable to check the quality of bulk samples of Oroxylin A at the time of batch release and also during its stability studies (long term and accelerated stability).
Authors:Z. Fengqi, G. Hongxu, L. Yang, H. Rongzu, C. Pei, G. Sheng-li, Y. Xu-wu, and S. Qizhen
The constant-volume combustion energies of
the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine
(2HDNPPb(s) and 4HDNPP(s)),
were determined as –4441.922.43 and –4515.741.92
kJ mol–1 , respectively, at 298.15 K. Their
standard enthalpies of combustion, Δcm
H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K), and standard enthalpies of formation,
Δrm H θ(2HDNPPb(s) and 4HDNPPb(s),
298.15 K) were as –4425.812.43, –4499.631.92 kJ
mol–1 and –870.432.76, –796.652.32
kJ mol–1 , respectively. As two combustion
catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the
pressure exponent of RDX–CMDB propellant.