Accessible Unlicensed Requires Authentication Published by Oldenbourg Wissenschaftsverlag June 3, 2013

The Structure and Dynamic Properties of 1H-Pyrazole-4-Carboxylic Acids in the Solid State

Lourdes Infantes, M. Ángeles García, Concepción López, Rosa M. Claramunt and José Elguero


The structure of three simple pyrazole-4-carboxylic acids unsubstituted in position 1 (NH derivatives) 1H-pyrazole-4-carboxylic acid (1), 3(5)-methyl-1H-pyrazole-4-carboxylic acid (2) and 3,5-dimethyl-1H-pyrazole-4-carboxylic acid (3) are discussed based on crystallographic results (two new structures) and solid-state NMR (CPMAS). Compounds 1 and 3 present polymorphism and one of the polymorphs of each compound shows solid-state proton transfer (SSPT). Compound 2 presents tautomerism that has been studied by NMR, both in the solid-state and in solution at low temperature.

* Correspondence address: CSIC, Instituto de Quimica-Fisica 'Rocasolano', Serrano 119, Dep. de Cristalografía y Biología Estructural, 28006 Madrid, Spanien,

Published Online: 2013-6-3
Published in Print: 2013-6-1

© by Oldenbourg Wissenschaftsverlag, München, Germany