Temperature effects on the hydrogen-bond patterns in 4-piperidinecarboxylic acid.

Abstract

A temperature-controlled X-ray powder diffraction experiment, complemented with TGA and DSC analysis, allowed us to follow changes in the molecular conformation and hydrogen-bond patterns of 4-piperidinecarboxylic acid. The presence of three phases is confirmed. Phase 1 represents the monohydrated form of 4-piperidinecarboxylic acid, which exists from room temperature to 359 K, where dehydration occurs. Phase 2 measured at 363 K corresponds to an anhydrous form of the acid. At ca 458 K the onset of a second, more gradual transition is observed, which ends at around 543 K. Phase 3 measured at 543 K is a high-temperature anhydrous form of the acid. The structures of phases 2 and 3 were solved from synchrotron powder diffraction data by simulated annealing using the DASH program and refined by the Rietveld method. The phase changes are accompanied by modification of the hydrogen-bond patterns and of the torsional orientation of the terminal carboxylate group. This group makes a 49 degrees rotation about the C1-C2 bond during the first transition.

• Authors: Asiloé J Mora, Edward E Avila, Gerzon E Delgado, Andrew N Fitch, Michela Brunelli
• Journal: Acta crystallographica. Section B, Structural science (Acta Crystallogr B) Vol. 61 Issue Pt 1 Pg. 96-102 (Feb 2005) ISSN: 0108-7681 [Print] United States
• PMID: 15659862 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carboxylic Acids
• Piperidines
• 4-piperidinecarboxylic acid

Topics

• Calorimetry, Differential Scanning
• Carboxylic Acids (chemistry)
• Hydrogen Bonding
• Models, Molecular
• Molecular Structure
• Phase Transition
• Piperidines (chemistry)
• Temperature
• Thermogravimetry
• X-Ray Diffraction