A complete analysis of a crude oil C-2-carbazole fraction by H-1 NMR spectroscopy

A new approach for a complete analysis of petroleum C-2 carbazoles has been developed. C-2 carbazole subfraction isolated from crude oil using liquid chromatography on silica gel and preparative reverse-phase HPLC, was invest igated by proton nuclear magnetic resonance spectroscopy and gas chromatogr aphy. As an example, the analysis of C-2 carbazoles from the Van-Yagansk oi l (Upper Jurassic, West Siberia province) is reported. The isolated subfrac tion included all C-2 carbazoles and also a part of some of the least retai nable C-3 carbazoles. Dimethylcarbazoles have been determined in the C-2 su bfraction as the predominant type of isomers. Ethyl-, i-propyl-. methylethy l- and n-propylcarbazoles were determined in low abundances. Distribution o f 1-, 2- and 3- (jointly), 4-ethylcarbazoles was determined. All the dimeth ylcarbazoles were determined in the oil, with the content of 4,5-dimethylca rbazole being negligible. (C) 1998 Elsevier Science Ltd. All rights reserve d.