Derivatives of arylhydrazonic acids. Part 3: Stereochemical rearrangement of Z-oxanilo-N-dialkyl-N-arylamidrazones

Oxanilo-N¹-dialkyl-N²-arylamidrazones have been prepared by nucleophilic substitution of the chloride function of appropriate hydrazonoyl chlorides. Relative stabilities of Z- and E-isomers, calculated with the RHF/6-31G^∗ ab initio method, range between 0.7 and 2.1 kcal/mol. The Z-isomer is detected to be thermodynamically more stable for studied compounds. X-ray structure determination of 2-dimethylamino-N-phenyl-2-phenylhydrazonoacetamide revealed E- and Z-isomers (ratio 1:1) in the crystal. The different intra- and intermolecular hydrogen bond interactions, which are identified in solid state of compounds, are dissolved in polar solvents. All compounds were found to form E/Z-equilibrium in solution. In some cases E-isomers could be separated and fully characterized.     

Improvement of H/V technique by rotation of the coordinate system

In this work we investigate the application of the rotation of the coordinate system before applying denoising techniques aimed at improving the H/V spectral ratio for seismic site effects estimation. By this rotation, one can detect the direction of maximum and minimum matching between any couple of orthogonal H/V ratios. The direction of minimum matching should represent the direction of maximum anisotropy of the surface layer or a directional noise. To further improve the method, singular spectrum analysis and WASEE techniques are then applied.