The single electron chemistry of coals (open access)

The single electron chemistry of coals

TCNQ Charge Transfer Complexes with Coals. TCNQ can be readily deposited in coals from pyridine solution. IR spectra of TCNQ and TCNQ in Illinois No. 6 coal are shown in Fig. 1. It is clear that the stretching frequency has been shifted by the full 44 cm[sup [minus]1] caused by the transfer of a single electron. Similar behavior has been observed with a variety of coals, including lignites, subbituminous and a range of bituminous coals. There are two possible explanations for the observed shift. The simplest explanation is that there exist in coals structures which are excellent single electron donors capable of transferring an electron to TCNQ in the ground state. All of the TCNQ dissolved in the coal is shifted. No uncomplexed TCNQ remains in the sample, as demonstrated by the absence of the unaltered CN stretch at 2227 cm[sup [minus]1]. The spectrum shown is for TCNQ in coal in a molar concentration equivalent to approximately 20% of the PNA systems in this coal as deduced from the NMR studies of Solum et al. (1989). It is highly unlikely that 20% of the PNA systems in coal are such good electron donors that the charge transfer complex would have …
Date: July 24, 1990
Creator: Larsen, John W. & Flowers, Robert A., II
System: The UNT Digital Library
The single electron chemistry of coals, January 1, 1990--March 30, 1990 (open access)

The single electron chemistry of coals, January 1, 1990--March 30, 1990

The Wyodak, Upper Freeport and Pocahontas No. 3 samples containing DPPD display a decrease in spin density as compared to the starting coals. Coincident with this decrease is a loss or decrease of the narrow inertinite signal in the esr spectrum of these coals. The Pittsburgh No. 8 coal sample containing DPPD also displays a loss of spin density as compared to the starting coal but there is no change in the esr spectrum. These results compare well with earlier work involving 4-vinylpyridine and the same coal samples. We discovered the presence of poly(4-vinylpyridine) in our coal samples and a concurrent loss of inertinite radical density. It is possible that the inertinite radicals may initiate the polymerization or in the present work may abstract hydrogen from DPPD. No C=N stretch was displayed in the IR spectrum to substantiate this claim.
Date: April 16, 1990
Creator: Larsen, John W. & Flowers, Robert A., II
System: The UNT Digital Library