Vernon F. Raaen

Thermal cleavage of chemical bonds in selected coal-related structures☆

Abstract Solvent-refined coal is produced in processes in which coal is heated with hydrogen-donor solvents. From it, oil, asphaltene, and preasphaltene fractions can be separated. The sizes of the molecules in these fractions are smaller than the sizes of those in the starting coal; the smaller sizes result from bond-breaking reactions. We have investigated the bond-breaking processes by determining what kinds of bonds rupture when each of a large number of carefully selected model compounds was subjected to the conditions of asphaltene formation. Both tetralin and vitrinite from Illinois No. 6 coal were used as hydrogen donors. The products of chemical breakdown of the model compounds are presented in several Tables. Relative rates of cleavage of some selected compounds were also determined. The information obtained is discussed in relation to structural features of coal.

Retention of pyridine-14C and other 14C-labelled amines by Illinois No. 6 coal

Abstract When Illinois No. 6 whole coal or vitrain is extracted with pyridine- 14 C, the extracts and solid residues retain 12–20% and 9–16%, respectively (at temperatures of 23 and 130 °C) of the pyridine- 14 C. Repeated treatment of the extracts with benzene, followed by filtration and drying at 0.1 Pa for 48 h removes only 20–25% of the labelled amine, although 92–98% of the latter is exchangeable with unlabelled pyridine. The solid residues exhibit similar behaviour. Tetrahydroquinoline- 14 C (THQ- 14 C) was used to extract Illinois No. 6 vitrain at 270 °C; the soluble and insoluble fractions after exhaustive drying retained 18% and 15%, respectively, of the THQ- 14 C which could not be exchanged (from the soluble fraction) with a mixture of unlabelled THQ and quinoline. Ethylenediamine- 14 C (EDA- 14 C) was also used to extract Illinois No. 6 vitrain. The retention of EDA- 14 C was temperature-dependent (10% retained in 20 h at 120 °C, followed by 1 h at 150 °C). Following three exchanges with unlabelled EDA, all but 2.6% of the EDA- 14 C was removed.

The Effect of Ring Substituents on the Isotope Effects in Reactions of Carbonyl‐C14 Esters and Ketones

The variations of the isotope fractionation factor k14/k12 with changes in ring substituents, reaction temperature, solvent, concentration, and the alcohol group have been studied for the saponification of ethyl benzoates (α‐carbon‐14). The variations of the k14/k12 ratio with changes in temperature and ring substituents have been studied for the formation of the 2,4‐dinitrophenylhydrazones of acetophenones (α‐carbon‐14).

New method for isotopic labelling of organic compounds involving organoboranes

The use of organoboranes in the syntheses of labelled materials offers a convenient and mild alternative to traditional methods; a variety of 14C-labelled materials have been synthesized in good radiochemical yields utilizing organoboranes.

The Reaction of Carbon-14-Labeled Reagents with Coal

The reasons for carrying out the research presented here were threefold: 1) to allow carbon-14-labeled reagents to react with coal and with coal-derived materials at low temperatures and thus to estimate a) the reagents1 value in determining which functions are present in the original coal or b) have been added or removed during coal reactions; 2) to allow carbon-14-labeled compounds (containing structures similar to those known to be present in coal) to react with coal at or above 400°, then to determine the fates of these compounds using the carbon-14 as a tracer. In this way it was hoped conclusions could be drawn as to how the same kind of moiety behaves in the coal structure; and 3) to elucidate the mechanisms of the thermal reactions of the above-mentioned labeled compounds with coal.