Investigation of copper sulfate pentahydrate dehydration by terahertz time-domain spectroscopy

Copper sulfate pentahydrate is investigated by terahertz time-domain spectroscopy. It is shown that the terahertz absorption coefficients are correlated with the particle size of the samples, as well as the heating rates of the ambient temperature. Furthermore, the water molecules of copper sulfate pentahydrate can be quantitatively characterized due to the high sensitivity of the terahertz wave to water molecules. Based on such results, the status of water incorporated in mineral opal is also characterized using terahertz time-domain spectroscopy. It indicates that terahertz technology can be considered as an efficient method to detect the dehydration of minerals.

Highly Efficient Method for Synthesis of N-Amino-2-Pyridone Derivatives in the Presence of Catalysts such as Magnesium Oxide (MgO) and Bismuth(III) Nitrate Pentahydrate (Bi(NO₃)₃·5H₂O)

Magnesium oxide (MgO) and bismuth(III) nitrate pentahydrate as highly effective catalysts which have catalyzed the three-component reaction of cyanoacetic acid hydrazide, aldehydes and malononitrile to prepare of the corresponding N-amino-2-pyridones. These catalysts are inexpensive and easily obtained, stable and storable, easily recycled and reused for several cycles with consistent activity.

SYNTHESIS OF LANSFORDITE MgCO_3·5H_2O AND ITS CRYSTAL STRUCTURE INVESTIGATION

Euhedral crystals of the uncommon low-temperature mineral lansfordite have been obtained by the synthetic method, and the crystal structure analysis has been accomplished correspondingly. The structural parameters and the general view of structure were presented for the first time. The results obtained show that the coordination configuration of two magnesium ions in the unit cell is octahedral arrangement and the coordination number is 6, but in two forms: one in the complex ion Mg（CO3）2（H2O）42- and the other in the Mg（H2O）62+. There is only a CO32- group in the structure, not three distinct groups as reported by Hill et al. previously based on the IR absorption spectrum research data. The authors of this paper believe that the exact chemical formula of lansfordite should be expressed as "Mg（H2O）6. Mg（CO3）2 （H2O）4", and MgCO3-5H2O is only a simple chemical expression.