Standard Nonpolar Phases Research Articles

Ambiguousness of GC-MS identification of spiro[2.4]hepta-4,6-diene in natural objects

The publications on the GC-MS identification of spiro[2.4]hepta-4,6-diene in various natural objects were critically considered. Significant similarity of the mass spectra and coincidence of the GC retention indices on standard nonpolar phases of spiro[2.4]hepta-4,6-diene (761±3) and its isomer (toluene, 760±8) do not allow one to assert that the spirocyclic hydrocarbon was found in all the cases. Additional analytical parameters should be applied to differentiate such isomers.

Evolution of structure and magnetic properties for BaFe11.9Al0.1O19 hexaferrite in a wide temperature range

M-type BaFe11.9Al0.1O19 hexaferrite was successfully synthesized by solid state reactions. Precision investigations of crystal and magnetic structures of BaFe11.9Al0.1O19 powder by neutron diffraction in the temperature range 4.2–730K have been performed. Magnetic and electrical properties investigations were carried out in the wide temperature range. Neutron powder diffraction data were successfully refined in approximation for both space groups (SG): centrosymmetric #194 (standard non-polar phase) and non-centrosymmetric #186 (polar phase). It has been shown that at low temperatures (below room temperature) better fitting results (value χ2) were for the polar phase (SG: #186) or for the two phases coexistence (SG: #186 and SG: #194). At high temperatures (400–730K) better fitting results were for SG: #194. It was established coexistence of the dual ferroic properties (specific magnetization and spontaneous polarization) at room temperature. Strong correlation between magnetic and electrical subsystems was demonstrated (magnetoelectrical effect). Temperature dependences of the spontaneous polarization, specific magnetization and magnetoelectrical effect were investigated.

Interpretation of Retention Indices in Gas Chromatography for Establishing Structures of Isomeric Products of Alkylarenes Radical Chlorination

By an example of previously uncharacterized products obtained by alkylarenes radical chlorinationwas demonstrated that combination of various interpretation methods applied to the retention indices (RI) inthe gas chromatography on the standard nonpolar phases (comparison of RI of products, initialcompounds, characteristics of succession of the chromatographic elution of the structural isomers with theuse of estimation of molecular dynamic parameters, application of the additive schemes to RI calculation, and using of structural analogy CH3↔Cl for testing the results obtained) permitted unambiguous identification of the structure even without data of mass spectrometry.