Spectroscopic and differential scanning calorimetric studies of the order-disorder phase transition in bicyclononanone

The phase transition in bicyclononanone, C9H14O, has been examined using differential scanning calorimetry, variable-temperature vibrational spectroscopy, and proton spin-lattice relaxation time measurements. The high-temperature phase is disordered and the low-temperature phase either has an orthorhombic crystal with D-2 or C-2 upsilon symmetry or is tetragonal with D-2d symmetry. The barrier to rotation in the low-temperature phase between 250 and 300 K is 45.1 kJ mol(-1). In the high-temperature phase, two relaxation processes were observed, with activation energies of 11.7 (300-330 K) and 7.7 kJ mol(-1) (>330 K). (C) 1998 Academic Press.