Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 3

Being natural surfactants, organonitrogen bases affect the behaviour of oil disperse system in-situ conditions and upon technogenic exposure on oil fluids. In this regard, characteristics of major compounds of highly paraffinic oils and resulting asphalt-resin-paraffin deposits are important for understanding participation of these compounds in the formation of organic deposits. The work studies the distribution and composition of organonitrogen bases in highly paraffinic oil and a model of asphalt-resin-paraffin deposits obtained there from under laboratory conditions. Concentrates of high and low molecular mass bases are isolated using sedimentation techniques, extraction, and liquid adsorption chromatography on impregnated oil and sediment sorbents. High molecular mass compounds with a strongly developed alkyl skeleton prevail among highly paraffinic base oils. The fraction of these compounds is higher in sediment than in oil, which indicates their predominant participation in deposit formation. The composition of the isolated bases was characterized by IR and NMR spectroscopy, and chromatographic-mass spectrometric method. According to the structural-group analysis, average molecules of organonitrogen bases of oil and residue consist of polycyclic nucleus involving aromatic and saturated cycles with various alkyl skeletons. Average molecules of high molecular mass compounds with strongly developed alkyl substitution (the number of carbon atoms in the alkyl chain (29-32)) may contain 2-3 aromatic and 4-5 saturated cycles. Weakly alkylated (three to five carbon atoms in the alkyl chain) high molecular mass bases are more cyclical due to the development of both aromatic (K_a = 6-9) and naphthene rings (K_n = 10-13). Alkyl substituents in the structure of their average molecules are presented by methyl groups only. According to the results of chromatography-mass spectrometry studies, the composition of low molecular mass compounds of oil and asphalt-resin-paraffin deposits is characterised by identical sets of alkyl-substituted quinolines, benzo-, dibenzoquinolines, and azapyrenes, among which alkylbenzoquinolines prevail.