Home – Home – Jornals – Chemistry for Sustainable Development 2025 number 2

The composition of fragments linked by sulphide bridges in the molecules of resin-asphaltene substances isolated from the liquid products of thermal destruction of asphaltene components of heavy high-sulphur oils from the Usinskoye and Ashalchinskoye fields in supercritical n-hexane is investigated using a complex of physicochemical methods (selective chemical degradation, IR spectroscopy, gas chromatography - mass spectrometry). The set of compounds identified in the products of C-S bond cleavage in the molecules of secondary asphaltenes and resins is largely identical to that identified in the products formed in the chemical destruction of the molecules of initial asphaltene components. They are represented by normal and branched alkanes, n-alkylcyclopentanes, n-alkylcyclohexanes, steranes, hopanes, phenylalkanes differing from each other in the position of phenyl ring in the carbon chain, diphenyls, naphthalenes, phenanthrenes, dibenzothiophenes, n-alcanoic acids, ethyl and isopropyl esters of n-alkanoic acids, and pentacyclic compounds of the oleanene series. A distinctive feature of secondary asphaltene molecules is the presence of n-alk-1-enes with an even number of carbon atoms and monocyclic aromatic hydrocarbons linked through sulphide bridges in their structure. The similarity of the set of compounds linked through sulphide bridges in the structure of initial asphaltenes and the products of their thermal decomposition under supercritical conditions is established, which suggests that the secondary asphaltenes and the resulting resins are fragments of the molecules of initial samples. These molecular fragments are linked in their structure through the least thermally stable functional groups - ether, disulphide and sulphide. The revealed differences in the pattern of molecular mass distribution for similar sulphur-bound compounds in the structure of secondary asphaltenes and resins allow us to assume that the resulting resinous components are located at the periphery of the asphaltene macromolecules of heavy high-sulphur oils.