Malvina Farcasiu

Fractionation and structural characterization of coal liquids

Abstract A method of characterizing coal liquids in terms of fractions of different chemical functionality is described. This method is based on Chromatographic fractionation of both benzene-soluble and pyridine-soluble components by sequential elution with specific solvents on silica gel columns (SESC). The paper presents the theoretical criteria for choosing the conditions and the sequence of elution solvents, the methods used to establish the chemical structure, and model compound comparisons.

New characterization techniques for coal-derived liquids☆

Abstract Development of understanding of the chemistry of coal liquefaction is often limited by the tools available to study compositional change. This paper discusses several new and useful techniques for characterization of coal-derived liquids. A single method of analysis is shown to be much less informative than the combined results from several methods. In particular, combinations of liquid chromatography, gas chromatography, and field ionization mass spectroscopy (FIMS) are shown to be particularly useful. Liquid chromatography offers a convenient method to isolate chemically distinct fractions of both distillates and non-dstillates which on subsequent further characterization can yield insight into understanding the chemistry involved in coal liquefaction. Through sophisticated data manipulation mechanistic information can be gained via FIMS which would be nearly impossible to achieve using other characterization tools.

Reactions of coals and coal liquids with a liquid superacid

Abstract A series of chemical bonds which are strong enough to make coals and coal liquids unreactive during thermal liquefaction processes are reactive under the conditions of strong acid catalyzed reactions. We studied reactions of coals and coal liquids with small aromatic molecules in the presence of trifluoromethanesulfonic acid and identified some of these chemical bonds. Examples of such bonds are C ar C aliph and C ar C aliph C ar . We identified the presence of significant amounts of monoaromatic phenols (mainly methyl and ethyl substituted) bound to the rest of coal or coal liquid aromatic structures with methylene bridges. The importance of the relative concentration of reactant:acid is discussed based on data with model compounds.

Adamantane rearrangement mechanisms. 1,2-trimethylenenorbornanes

Abstract Unexpected differences in the aluminium bromide-catalyzed rearrangement behaviour of 1,2- endo -trimethylenenorbornane ( 1 ) and its 1,2- exo -isomer ( 2 ) are interpreted. Isotopic labelling studies indicate that reversible abstraction of the tertiary 2- endo hydride in 2 does not occur. Instead, rearrangement to 6 is favored. The label scrambling in the final product, adamantane ( 8 ), is attributed to degenerate isomerization in the proto-adamantyl precursor, 7 .