Journal of the American Chemical Society 2007-05-16

Gas-phase tautomeric equilibrium of 4-hydroxypyrimidine with its ketonic forms: a free jet millimeterwave spectroscopy study.

Raquel Sanchez, B Michela Giuliano, Sonia Melandri, Laura B Favero, Walther Caminati

Index: J. Am. Chem. Soc. 129(19) , 6287-90, (2007)

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Abstract

4-Hydroxypyrimidine (4HP) has two conformational forms (the hydroxyl hydrogen cis or trans with respect to the adjacent nitrogen), which are in tautomeric equilibrium with two ketonic forms, 4-pyrimidinone (4PO) and 6-pyrimidinone (6PO). We have investigated the free jet absorption millimeterwave spectrum of this system, assigning the rotational spectra of 4HPcis and 4PO; the latter species is more stable by 2.0(9) kJ/mol. No lines corresponding to the trans isomer of 4-hydroxypyridine and to 6PO have been observed.