Coding of the Structural Features of Organic Compounds for the Estimation of Chromatographic Retention Indices With the USE of Additive Schemes

One of the current versions of additive schemes to estimate gas chromatographic retention indices of organic compounds not characterized by these constants assumes their structure to be assembled from simpler precursors, and subsequent arithmetical operations are performed with the known indices by the selected schemes. In order to optimize the use of such an algorithm (to confirm the correctness of the selection of structural analogs, to eliminate superposition uncertainty, etc.) it is proposed to use the linear coding system for not complete molecular structures, but only those fragments that mostly affect the chromatographic retention parameters.     

Amplification of a convective wave in a longitudinal electrostatic field

Radio Engineering Institute, Taganrog. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 8, pp. 1026–1033, August, 1989.     

Trapping of charged particles by transverse electromagnetic waves

An estimate is made of the maximum number of resonant particles interacting with a transverse plane electromagnetic wave. This estimate is based on the distribution function, in terms of integrals characterizing the motion of particles in a wave. The values found here for proton fluxes accelerated by an amplitude-modulated wave in the solar corona agree with those measured during sporadic radioemission bursts.     

Thermal transformations of 7-aryl-1,6-diazabicyclo[4.10]heptanes and 6,13-diarylperhydrodipyridazino-[1,2-<Emphasis Type="Italic">a</Emphasis>: 1′,2′-<Emphasis Type="Italic">d</Emphasis>]-1,2,4,5-tetrazines

The thermolysis of 7-aryl-1,6-diazabicyclo[4.1.0]heptanes in the absence of 1,3-dipolarophiles leads to dimers of the initially formed azomethineimines, namely, 6,13-diaryloctahydrodipyridazino[1,2-a:1′,2′ Dedicated to the memory of A. A. Potekhin. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1062–1070, July, 2008.     

Chromatography–mass spectrometry determination of alkyl methylphosphonic acids in urine

The potentials of different chromatography–mass spectrometry methods for the determination of alkyl methylphosphonic acids (AMPAs)—the chemical markers of nerve agents in urine—are compared. The gas chromatography–mass spectrometry (GC–MS) characteristics of various volatile AMPA derivatives are studied. The preference of perfluorobenzyl derivatives over methyl, trimethylsilyl and tert-butyldimethylsilyl esters for the GC–MS determination of AMPAs in urine is demonstrated. An optimal technique for the determination of AMPAs in urine is HPLC combined with high-resolution MS² mass spectrometry with the isotope–labeled forms of target compounds as internal standards. The detection limits of AMPAs in the proposed analytical procedures vary from 0.1 to 1.0 ng/mL.     

Identification of isomeric alkylarenes with the use of additive relations for the evaluation of gas-chromatographic retention indices

With the use of mono- and disubstituted C₁₄-C₁₆ alkylarenes as an example, it was found that, in many cases, the simplest additive relations for the estimation of gas-chromatographic retention indices make it possible to unambiguously identify the isomeric products of organic reactions even without the application of mass-spectrometric data. The simplest increments of different structural transformations of molecules, for example, CH₃ → C₆H₅ and H → C₆H₅, remain of importance in algorithms of this type; however, the use of procedures with no increments for the assembly of target structures is more convenient.     

An unusual result of the reaction of α-acetylene aldehydes,pyridines, and malonic acid. Synthesis and structure of novel pyridine betaines

Chemistry of Heterocyclic Compounds - 5-Aryl-2-carboxy-5-(pyridin-1-ium-1-yl)penta-2,4-dienoates, previously unknown pyridine betaines, were formed in 32–70% yields as a result of the...     

Features of the chromatography-mass spectrometric identification of condensation products of the carbonyl compounds

By the example of the condensation products of acetone with the simplest aromatic carbonyl compounds it was shown that the joint interpretation of mass spectrometric and chromatographic data in conjunction with a priori assumptions about the nature of the chemical structure allows the detection of the components of reaction mixtures that were not previously characterized by standard mass spectra or by retention indices on standard stationary phases. A necessary condition for solving such problems is creating a hypothesis about the sample composition that is possible for the expected products of the known organic reactions.