Glen B. Brons

Oxidative weathering of Illinois No.6 coal

The exposure of freshly-mined Illinois No.6 bituminous coal (Monterey Mine No.1) to atmospheric oxygen at ambient conditions resulted in a slow oxidation reaction which appeared to be complete within two months to produce an oxidized coal product with ≈26% more organically bound oxygen than the fresh coal. An oxygen functional group analysis was performed to determine the carboxylic acid, hydroxyl and ether group content of the coal before, during and after the reaction. Infrared analysis showed no carbonyl production; however, ether functionality was being produced. O-methylation reactions which employed isotopically labelled methyl groups (both C-13 and deuterium) were used to identify and quantify O-H and CO2H sites in the weathering coal samples. It was found that these acidic groups were not the products of oxidative weathering. Essentially all of the chemically incorporated oxygen eventually formed ether linkages. In a related study on this coal, hydroperoxide was detected as a transient intermediate in the early stages of the oxidation. A mechanism is proposed which involves the simultaneous formation under mild temperatures of a hydroperoxide and a carbon radical that undergoes a radical displacement producing the ether product directly. Solvent swelling studies revealed that these ethers act as cross-linking agents in the coal structure. The more highly cross-linked coal structure that resulted from weathering was responsible for the destruction of the plastic properties of this bituminous coal.

Prediction of gas chromatographic response factors by the PLS method

Abstract “Dietz” response factors (RF) have been measured under standard conditions for 100 substituted benzenes and pyridines. The data have been treated by the partial least squares (PLS) method, using as explanatory variables the molecular weight together with structural features such as the numbers of atoms of each element and of multiple bonds, functional groups, etc. The “Dietz” RF are explained to 84% of the variance by three PLS components. It is shown that Dietz RF can be predicted from the structural formulae for many classes of compounds with an average deviation of 0.05 within the model and 0.09 out of the model. This should be of considerable utility in the quantitative analysis of complex product mixtures by GC/MS, especially for those cases where some or all of the products are unavailable. The PREDICT.EXE program for the PC and Fortran code, PREDICT.FOR, as well as the raw data set used to derive the model are included on disk.

Bitumen chemical changes during aquathermolytic treatments of Cold Lake tar sands

Abstract Cold Lake tar sand samples have been treated in the laboratory in neutral water and caustic brine at 250 ± 3 °C for up to 75 days to simulate the environment during the steam-displacement process used to recover heavy oil (bitumen) from subterranean reservoirs. Observed chemical changes in the isolated bitumen fractions include volatiles generation and asphaltene reduction, both of which affect the viscosity of the oil. Maximum volatiles levels, and minimum viscosities and asphaltene concentrations, were achieved in a 30 to 50 day time-frame. Longer term treatments showed a reversal of these changes. The generated volatiles from the 50 day treatments were isolated and determined to be mostly olefinic in nature. These olefins can then undergo proposed addition reactions that would be consistent with the changes observed for the properties of the whole bitumen.

Unprecedented pyridine ring CC bond cleavages by formic acid.

Abstract Formic acid at 350°C converts pyridine and 4-methylpyridine into products deriving from both αβ and βγ CC bond cleavages of the pyridine ring.