Home – Home – Jornals – Chemistry for Sustainable Development 2024 number 1

Gas chromatography with mass spectrometric detection (GC-MS) was used to study the composition of bromides obtained upon selective cleavage (chemolysis) of the C-O bond of ether/ester bridges under the action of BBr₃ in oil components from ten oil and natural bitumen samples. It is shown that most of the samples under study demonstrate the absence of mono- and dibromides of alkanes, alkylcyclohexanes, pregnanes and steranes, cheilanthanes and hopanes in the products of chemolysis. Monobromides of n-alkanes have been identified only in the products of chemolysis of oil components isolated from maltha of the Ashalchinskoye oilfield and the products of its biodegradation under laboratory conditions. In total, the identified products of selective cleavage of ether/ester bridges include mono- and dibromides of alkylbenzenes: mainly (С₁₃-С₂₂)-alkyltrimethylbenzenes, (С₁-С₇)-naphthalenes, phenanthrene, dibenzothiophene and their homologues. Monobromides of C₆-biphenyl, C₄-tetralin, dibromides of (C₂-C₆)-benzothiophenes, (C₂-C₅)-biphenyls, C₁-tetralin, fluorene, and C₂-fluorene have been also identified. Tribromides of (С₂-С₄)-naphthalenes, С₂-phenanthrene, and (С₁-С₂)-fluorenes have been identified in a limited number of samples. In chemolysis products, dibromides occur more rarely than monobromides, while tribromides are much less common than dibromides. The results obtained indicate that the above-mentioned compounds are partially present in oils as structural fragments connected with other fragments of the oil components through one or much less often through two or three ether/ester bridges. The list of structural fragments linked via ether/ester bridges, their composition and relative content differ in oil components of different oil and natural bitumen samples. Ethyl esters of aliphatic acids from C₁₂ to C₃₂, with a clear predominance of even acids and a maximum corresponding to C₁₆ and C₁₈, have been identified in the products of chemolysis of almost all samples.