Eur. Phys. J. Special Topics 226, 849-855 (2017)
https://doi.org/10.1140/epjst/e2016-60187-0

Regular Article

A new polymorph of 4′-hydroxyvalerophenone revealed by thermoanalytical and X-ray diffraction studies

¹ Centro de Química e Bioquímica e Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1649-016 Lisboa, Portugal
² Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal

^a e-mail: memp@fc.ul.pt

Received: 27 July 2016
Revised: 18 October 2016
Published online: 18 April 2017

Abstract

A new polymorph of 1-(4-hydroxyphenyl)pentan-1-one (4′-hydroxyvalerophenone, HVP) was identified by using differential scanning calorimetry, hot stage microscopy, and X-ray powder diffraction. This novel crystal form (form II) was obtained by crystallization from melt. It has a fusion temperature of T_fus = 324.3 ± 0.2 K and an enthalpy of fusion Δ_fusH_m^o = 18.14±0.18 kJ·mol⁻¹. These values are significantly lower than those observed for the previously known phase (form I, monoclinic, space group P2₁/c, T_fus = 335.6 ± 0.7 K; Δ_fusH_m^o = 26.67±0.04 kJ·mol⁻¹), which can be prepared by crystallization from ethanol. The results here obtained, therefore, suggest that form I is thermodynamically more stable than the newly identified form II and, furthermore, that the two polymorphs are monotropically related.