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Reactions of Pittsburgh No. 8 Coal with Maleic Anhydride. Evidence for the Existence of Reactive Diene Structures in Coal
journal contribution
posted on 1998-07-30, 00:00 authored by John W. Larsen, Deanna Metka Quay, James E. RobertsThe reaction between 13C-labeled maleic anhydride and Pittsburgh No. 8 coal has been
investigated by NMR. The occurrence of the following reactions has been ruled out: ene reaction,
maleic anhydride polymerization, ester formation, radical addition, electron transfer, and physical
entrapment. Michael addition to −SH has been demonstrated in model systems, but does not
occur with −OH groups and cannot explain the observed 10−20% (wt) incorporation of maleic
anhydride. All data are consistent with the occurrence of Diels−Alder reactions. There are not
enough reactive dienes in any coal structure model to yield the large maleic anhydride
incorporations observed. Either current coal structures are seriously incorrect or this coal is
exhibiting strongly enhanced reactivity whose origin is not understood.