Hydrogen donor density

Formic acid, anhydrous (M.W. 46.03, m.p. 8.5°, b.p. 100.8°, density 1.22), or a 90% aqueous solution, is an excellent hydrogen donor in catalytic hydrogen transfer carried out by heating in the presence of copper [77] or nickel [77]. Also its salt with triethylamine is used for the same purpose in the presence of palladium [72, 73], Conjugated double bonds, triple bonds, aromatic rings and nitro compounds are hydrogenated in this way. 

BPA reaction in water or methanol yielded solvation products in addition to those observed from pyrolysis neat and thermolysis in the hydrogen donor solvent, tetralin. BPA conversion passed through a minimum at a reduced solvent density of 0.6 and 0.1 for reaction in methanol and water, respectively. Results qualitatively similar to those observed in Figures 2 and 4 have been noted previously for... 

Amestica and Wolf (12) in a study closely related to the one described herein, measured the conversion of Illinois No. 6 coal in toluene and ethanol. Their results clearly showed that conversions increased with temperature and solvent density but were not detailed enough to show the time dependence of the conversion. However, a result important to this study was that toluene converts coal to liquids without significantly reacting itself. After reaction, 98% of the toluene used was recovered versus only 73 -85% of the ethanol in runs using it. Ethanol is a hydrogen donor and reacts extensively with the coal. While toluene probably reacts with coal to a small extent, its effect was primarily physical in nature. As such, it is a good candidate for studying the effects of a supercritical solvent on coal liquefaction kinetics since the enhancement effect of supercritical conditions is physical in nature. 

Except for the case of t-butanol (260), < >(H2) approaches unity at intermittent light conditions. This means that in steady illumination experiments a considerable part of the H atoms disappear in combination reactions. The high radical density (at low hydrogen donor concentration) is reached by the high absorption coefficient of the Hg vapor. Some minor products are thought to originate from "atomic cracking" reactions 74. 

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