Negative ion mass spectrometry and stereochemistry of organic compounds. 7. Phenoxybenzyl esters of 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-carboxylic acid

Conclusions The stereospecific fragmentation of 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid -cyano-3-phenoxybenzyl ester was found under conditions of resonant capture of electrons of epithermal energies with dissociation of HCN. The stereospecific collection of fragment ions allows not only the identification of one of the diastereoisomers, but also the quantitative (5%) determination of it in a mixture of racemates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 291–294, February, 1989.     

Identification of the type and parameters of fastening from the natural frequencies of a fastened rod

A rod can be fastened in a number of ways. If the rod ends are inaccessible to visual observation, the question arises of whether it is possible to determine the type and parameters of their fastening from sound vibrations induced by an impact on the rod. In this connection, a possible statement of the problem is as follows: to identify the type and parameters of fastening on both ends of a homogeneous rod from its natural frequencies. In other words, it is necessary to determine the type of fastening of each of the ends of a homogeneous rod (clamping, free support, elastic support, elastic fixing, floating fixing, or free end) and its parameters (the stiffness coefficients of springs for elastic fixing). The duality and stability of the solution to this problem is demonstrated. A method of solving this problem with the use of 9 natural frequencies is proposed. The results of numerical experiments on reconstructing various types of fastening from 9 natural frequencies are presented.     

Fragmentation of valine and proline in resonant free electron capture reactions

The processes of resonant electron capture by molecules of valine and proline were studied. The main dissociative decay channels of molecular ions and the structures of fragment ions were established. The reactions of simple bond cleavage and H-shift rearrangement processes were revealed. The dissociative electron attachment cross-sections for [M - H]^? ions were measured in the region of 1.25 eV. The metastable decay of [M - H]^? ions were found in the energy region of 4.5?C8 eV. The structures of decomposing parent ions were determined using the statistical model of metastable fragmentation.