A study in desmotropy

A solid-state NMR/theoretical study of the tautomerism of 4-substituted pyrazolinones was carried out in search of new desmotropes. Thus, the systematic exploration by 13C and 15N CPMAS NMR of a series of 4-acylpyrazolin-5-ones has allowed to determine their structure in the solid state and to find a new example of desmotropy that of 1-phenyl-4-acetyl-pyrazolinone.