John W. Larsen

A rapid and convenient method for measuring the swelling of coals by solvents

Abstract The volumetric swelling procedure developed by Liotta was applied to a pair of coals using 10 solvents. The results were compared with the results of gravimetric swelling experiments. Good straight-line correlations having slopes of 0.93 (Bruceton coal) and 1.01 (III. No. 6 coal) were observed. The much more rapid and convenient volumetric swelling procedure gives the same results as the gravimetric procedure. Additionally, no correction for pore volume is necessary with the volumetric procedure. From plots of the gravimetric vs. volumetric swells, the accessbile pore volumes of the coals can be determined. They are 21% and 15% for Bruceton and III. No. 6 coals, respectively.

Effect of aqueous alcoholic solvents on counterion-binding to CTAB micelles

Two theories have been proposed to explain the effects of alcohols on micelles: on dealing primarily with the solubilization of alcohols in micelles and the other with the effects of the alcohols on the solvent structure. In an effort to shed more light on the effects of alcohol solutes on micelles, the authors examined the effect of methanol, ethanol, isopropanol, and t-butanol on the degree of dissociation of micelles over a wide range of alcohol concentration. At low alcohol concentrations, the alteration of micelle structure caused by solubilization of the alcohols is more important than the effects due to modification of the water structure by the alcohols, as indicated by a decrease in the amount of Br/sup -/ bound to CTAB micelles as the alcohol concentration increases. This behavior undergoes a sudden reversal at 0.1 to 0.2 mole fraction alcohol. The reason for this reversal is not clear. (38 refs.)

Coal swelling in binary solvent mixtures: Pyridine—chlorobenzene and N,N-dimethylaniline—alcohol

Illinois No. 6 coal has been swollen in pyridine—chlorobenzene mixture and the composition of the solvent inside the coal measured. Pyridine disrupts the non-covalent crosslinks in coal, so the addition of very small amounts of pyridine leads to an enormous increase in the uptake of chlorobenzene by the coal. The sites which interact specifically with pyridine can be titrated by measuring the composition of the solvent absorbed by the coal. Bruceton coal has been swollen by mixtures of alcohols with N,N-dimethylaniline. About the same amount of methanol, ethanol, and propanol are absorbed by pyridine-extracted coal, suggesting the existence of specific sites for alcohol binding. Significantly less t-butanol is bound, presumably due to steric effects. The swelling behaviour of extracted and unextracted coals are quite different, since pyridine extraction destroys many non-covalent crosslinks. The interactions of these solvents with coal are very sensitive to the ability of the solvents to interact specifically with the coal and, in doing so, to destroy non-covalent crosslinks.

Internal rearrangement of hydrogen during heating of coals with phenol

Abstract Heating either Bruceton or Wyodak coal with phenol results in the thermal depolymerization of the coal yielding pyridine-soluble products and an insoluble residue. The depolymerization is accompanied by extensive rearrangements of hydrogen within the coals producing a soluble material enriched in hydrogen and a residue which is hydrogen poor. The hydrogen shuttle in Wyodak coal has a different temperature dependence than does the depolymerization, being favoured at higher temperatures. The H C ratio of the soluble products increased with increasing conversion. Relatively small amounts ( ca . 5%) of the products at high conversion are derived from phenol.

Reactions of coal in acidic phenol. Model compound studies

The cleavage of a series of methylene- and ether-linked aromatics has been studied in phenol acidified with p-toluenesulfonic acid as model processes for the acidic ‘depolymerization’ of coals. Methylenelinked unactivated aromatics do not react during refluxing for 24 h, whereas cleavage sometimes occurs if the aromatic moiety has electron-donating substituents. Benzylic ethers are cleaved, but also undergo a variety of condensation reactions. The failure of the acid-catalysed depolymerization of coals in phenol may be due either to the lack of cleavable bonds in the coal or to internal condensation reactions which compete with the depolymerization.

The molecular weight distribution of coal extracts. Coalification is not a condensation polymerization

Abstract The pyridine extracts from Bruceton and Illinois No. 6 coals were fractionated using gel permeation chromatography and the molecular weight of each fraction was measured using vapor pressure osmometry. If, as has been suggested, coalification is a simple condensation polymerization from a mixture of monomers with gel formation, then as the molecular weight of the components increase, their concentration should decrease. Exactly the opposite behavior is observed. The number average molecular weights for the Bruceton and Illinois No. 6 extracts respectively are 860 daltons and 1100 daltons while the corresponding weight average molecular weights calculated from the molecular weight distribution are 2300 daltons and 2700 daltons.

Ionic hydrogenations using boron trifluoride hydrate. Reductions of polycyclic aromatics

Results obtained using the boron trifluoride monohydrate and triethylsilane pair are reported. The following compounds did not undergo hydrogenation: naphthalene, phenanthrene, 1-methylnaphthalene, ..beta..-naphthalenethiol, phenol, anisole, toluene, and benzene. These compounds were reduced and their reaction products were tabulated: anthracene, naphthacene, 1-hydroxynaphthalene, 2-hydroxynaphthalene, 1-methoxynaphthalene, 2-metholxynaphthalene, 1-naphthalenethiol, ..cap alpha..-tetralone, 2-acetonaphthalene, and adamantanone. Measurements were made using gas chromatography, mass spectra, and NMR. The mechanism of this kind of reaction appears to be protonation followed by hydride abstraction which is rate determining.

Effect of solvent swelling on diffusion rates in bituminous coal

The Diels-Alder reaction of maleic anhydride with Illinois No. 6 and Bruceton coals is much slower than with anthracene and depends on the square root of time, establishing that the rate of this reaction is diffusion controlled. The rate of this reaction was measured for these two coals swollen with a number of different solvents. The rate of reaction and thus the rate of diffusion of maleic anhydride into the coals was independent of the degree of swelling of the coals.

Kinetic study of the depolymerization of Bruceton coal

Abstract The depolymerization of coals using phenol and p-toluenesulphonic acid, was studied.In this reaction the acid ‘catalyst’ is destroyed, its rate of destruction being different for different coals. A kinetic study of the depolymerization of Bruceton coal under conditions of gradually declining acid concentration has been carried out. Parameters which were monitored include the weight increase of the products, the solubility of the products in benzene-ethanol, the extractability of the products into pyridine, the amount of colloidal material present in the pyridine-extractables, and the molecular weight distribution of the pyridine-soluble products. Under the conditions used, the reaction produces primarily polymeric products from coal. The molecular weight distribution of the pyridine-soluble material seems to undergo no major changes with reaction time.

Spatial distribution of oxygen in coals. Development of a tin labelling reaction and Mössbauer studies

Abstract All of the hydroxyl groups in Illinois No. 6 and Rawhide (Wyodak) coals have been converted to their-O-SnBu 3 derivatives by reacting with ( n - Bu 3 Sn ) 2 0 in refluxing toluene. The Sn Mossbauer spectra of the coal derivatives show that almost all of the tin is trigonal bipyramidal, which requires the presence nearby of a heteroatom for co-ordination to the tin. If this observed geometry occurs in the parent coal, in spite of the large size of the introduced derivatizing group, then the hydroxyl groups of the coal are paired with another heteroatom and most are hydrogen bonded in the solid.