Search

Experimental data of hydrolytic polymerization of lanthanide ions in aqueous solution were treated by graphic method, computer fitting and pq analysis, species present were ascertained and hydrolysis constants obtained. Ln (OH)2+ and Ln2 (OH)24+ predominated in the species of all hydrolysis products. When the first and the second hydrolysis constants were plotted against radii and effective nuclear charge of lanthanide ions, the curves obtained conformed with the “three-division groups” rule. Correlation between hydrolysis constants of Ln2 (OH)24+ and other hydrolysis constants is linear. Using the above empirical correlations we calculated hydrolysis constants of all lanthanide ions and obtained satisfactory results which showed good regularity for hydrolysis of lanthanide ions and thus systematized all data of the reaction.

Bonding mechanism of cis-Pt(NH_3)_2Cl_2 with DNA has been studied by CNDO/2 cal- culation.The computed results of the six models considered indicated that from the point of view of overlap population Q)(AB)and two atoms energy E_(AB),the most favorable bonding form was that between platinum and two N_7 atoms,from guanines(G)to form [(NH_3)_2PtG_2]~(2+).Thus,intrastrand cross-linkage mechanism which had been previously proposed by some authors was confirmed by our calculation.Chelation mechanism could not completely be excluded.Under certain conditions, it was possible for platinum to combine with a guanine through its N_7 and O(C_6)to form a chelate, but it was unstable as compared with [(NH_3)_2PtG_3]~(2+). Although the intrastrand cross-linkage mechanism is favored by our calculation,the question of how such a mode of combination hampers replication of DNA remains to be solved.

Sodium silicate in solution has been studed by ~(29)Si NMR spectroscopy. It was found that for solution of sodium silicate with mole number equal to 1, as the concentration of the solution lowered, the degree of polymerization decreased and the relative concentration of monosilicate anion increased, the lower the concen- tration of silicate solution, the more the relative concentration of monosilicate. It was also found that the regular changes of chemical shift δ and spin lattice relaxation time T_1 of various species of silicon and added salt effect on sodium silicate solution varied with mole number and concentration of the silicate in solution.

The solid state reaction of sodium nitrate and iron (III) oxalate in hydrogen atmosphere was investigated by gas chromatography, Mossbauer spectroscopy and X-ray diffraction. The results show that there is no reaction below 240°C between them while iron (III) Oxalate decomposes itself into α-FeC2O4 and gives off CO2 and H2O peaks at 180°C. The reaction takes place at 260—300°C when sodium nitrate oxidizes α-FeC2O4 to Fe (III) compound and releases large amount of CO2 and a little NO and O2. Different mole proportions and particle sizes of reactants have no obvious effect on solid state reaction. Because of the catalyzing effect of Fe (III) compound, sodium nitrate and its reduction product, sodium nitrite decomposes at 380—500°C and Fe (III) compound is transformed into γ-Fe2O3 at 460°C.

Some properties and thermal decomposition of iron (III) oxalate supported on HZSM-5 and HY zeolites have been studied by GC, IR, and Mossbauer spectroscopy methods. Thermal decomposition of unsupported iron (III) oxalate took place in two stages: as indicated by peak α (giving CO2) and peak γ (yielding CO and CO2), but for iron (III) oxalate supported on zeolites, an additional peak β (producing CO and CO2) appeared as a result of the interaction between C2O42− and Al3+. At 500°C Fe2(C2O4)3-HZSM-5 system produced α-Fe in H2 due to the weak interaction between the salt and the support. For Fe2(C2O4)3-HY system in H2, at 500° the solid products consisted of α-Fe and a little highly dispersed Fe (0) together with Fe (II) and F(III) oxides, which were difficult to be reduced.

Thermal decomposition of nitrourea salts (K, Na, Ag, Ba) was studied in hydrogen atmosphere, helium atmosphere and vacuum by gas chromatography and mass spectrometry. The evolution of dinitrogen oxide, water, hydrazine, nitrogen dioxide and the formation of cyanate salts during thermodecomposition of nitrourea salts in helium and hydrogen were confirmed. In vacuum the evolved gaseous products changed to dinitrogen oxide, water, nitrogen monoxide, nitrogen gas indicating that interreaction between evolved gaseous products occurred. The same solid products – cyanate salts – are formed showing vacuum having no effects upon the decomposition mechanism.