Viatcheslav V. Takhistov

Alkylated and chlorinated polysulfides detected in sediments of the Eastern Gulf of Finland

Sediments collected in October 1997 from four locations in the Eastern Gulf of Finland were studied for organic pollutants. Extraction of samples with methylene chloride followed by a concentration procedure and high resolution GC coupled with low resolution mass spectrometric analysis revealed the presence of nearly 200 organic compounds. As a first result, we present data concerning six organosulfur compounds, not previously known as environmental chemicals. One of the compounds was identified as bis(dichloromethyl) disulfide. The other five previously unknown substances were deduced from their mass spectra to be bis(dichloromethyl)trisulfide, 1,1,2-trichlorodimethyl disulfide, dichloromethyl thiylsulfenyl chloride, tetrathiacyclopentane and a structurally unidentified alkylpolysulfide which possibly also contains oxygen.

Thermochemistry of organic and heteroorganic species. Part V. Photoionization studies of isomerization and fragmentation of polysubstituted cyclopropenes: 3-methyl-3-acetyl- and related compounds

Appearance energies for molecular and some fragment ions from 3-methyl-3-acetyl-, 1,2-dimethyl-3-acetyl-, 1,2-dimethyl-3-hydroxycarbonyl- and 1,3-dimethyl-2-(1-methyl)vinylcyclopropenes and model compounds 2,3-dimethylfuran and 1-methylindene were measured by photoionization mass spectrometry. It was shown that, in all cases, the structure of the [M – Me]+ ion does not correspond to the expected structures of substituted cyclopropenium ions. Possible schemes for formation of [M – Me]+ ions are given. Isodesmic reactions were systematically applied for calculation of the heats of formation for 35 possible C5H5O+ isomers from 3-methyl-3-acetyl-cyclopropene. In addition, the heats of formation for more than 30 other unsaturated ions and free radicals were estimated with the help of series of isodesmic reactions. A new value of 160 kJ mol−1, as compared with the currently used value of 215.5 kJ mol−1, for the cyclopropylmethyl free radical is suggested. The publication represents the further development of the methodology for the heat of formation estimation procedure for even-electron ions and free radicals.

Thermochemistry of organic and heteroorganic species. Part IV. Photoionization studies of isomerization and fragmentation of poly-substituted cyclopropenes. 3-Methyl-3-ethynyl- and tetrachlorocyclopropene

Appearance energies of [M – Me]+ ions from p-ethylphenylacetylene, 1-methyl-1-phenylcyclopropane and 3-methyl-3-ethynylcyclopropene and of [M – Cl]+ ions from tetrachlorocyclopropene were measured by photoionization mass spectrometry. The heats of formation 1040.5, 864, 1268 and 1041 kJ mol−1 were obtained for ethynyl- and vinyltropylium and ethynyl- and trichlorocyclopropenium ions, respectively. Using these and some literature data and the series of isodesmic reactions, the heats of formation of seven substituted cyclopropenium ions and four propargylic ions were derived.

Mass spectrometric identification of novel polychlorinated phenyl salicylates in sediments of a river contaminated by industrial wastes

Analyses of chlorinated aromatic contaminants in industrially polluted sediments of the Kymijoki River, South-East Finland, were extended to the search of previously unknown pollutants by gas chromatography/mass spectrometry. In the fraction of persistent organochlorines, a series of substances were identified as octa- to tetra-chlorinated phenyl esters of 2-hydroxybenzoic acids (most probably all polychlorinated phenyl salicylates). All their mass spectra were previously unknown and interpreted by fragmentation rules, appearance energy calculations and simulation.

Thermochemistry of Organic and Heteroorganic Species. Part IX. Photoionization Studies of Isomerization and Fragmentation of Polysubstituted Cyclopropenes: Phenyl-Substituted Cyclopropenes:

Ionization and appearance energies of some fragment ions from 1,2,3-trimethy1-3-phenyl-, 3-methyl-1,2,3-triphenyl-, 1,2-diphenyl-3-methoxycarbonyl-, 1,2,3-triphenyl-3-methoxycarbonyl- and 1,3,3-triphenyl-2-methoxycarbonyl-cyclopropenes were measured by photoionization mass spectrometry. It was shown that in none of these compounds did the fragment ions possess the expected stable substituted cyclopropenium ion structure. Accordingly, possible schemes of molecular ion isomerization are given. The enthalpies of formation of nearly 50 substituted cyclopropenium ions, and ions of related structure, were estimated using series of isodesmic reactions. This publication, together with the previous works of the authors in this Journal, demonstrates the general methodology for estimation of the enthalpy of formation for even-electron ions. It is suggested that the present methodology can provide a good alternative to other estimation or computation procedures applied to the thermochemistry of ions.

Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. I.

Structures of six cyclic polysulfides, previously unkown as organic environmental pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography (GC) coupled to mass spectrometry. High-resolution mass spectrometry measurements of the isotopic composition of four compounds could be done to confirm their molecular formulae. Total low-resolution mass spectrometry spectra were used to elucidate structures of all six compounds by a thermochemical approach, application of fragmentation rules and by ICLU simulation of the spectra. The compounds were found to be (in the order of GC retention) 1,2,4-trithiacycloheptane, tetrathiacyclopentane, 1,2,4,5-tetrathiacyclohexane, 1,2,3,4-tetrathiacycloheptane, 1,2,3,4-tetrathiacyclohexane and 1,2,4,6-tetrathiacyclooctane.