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Correlation of the crystal structure and solid-state 13C NMR spectrum of pyromellitic dianhydride

✍ Scribed by Roger A. Wolfe; Willis T. Schwartz; Frank J. Dinan

Publisher
John Wiley and Sons
Year
1991
Tongue
English
Weight
335 KB
Volume
29
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The interatomic distances for crystalline pyromellitic dianhydride (PMDA) were calculated from x‐ray crystallographic data. The CP‐MAS ^13^C NMR spectrum of PMDA was found to be consistent with and accountable for in terms of these distances after literature assignment errors were corrected. An anomalous peak was observed in the differential scanning calorimetry thermogram of PMDA. The entropy change associated with this transition indicates that a two‐fold change in symmetry occurs approximately 60°C below the melting point of PMDA. Attempts to observe this transition by CP‐MAS ^13^C NMR were unsuccessful.

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