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