Temperature-dependent Raman spectroscopy of anilinium chloride near phase transition

The existence of various solid phases of organic ammonium halides, due to the presence of hydrogen bonding, has long been established but is limited to alkyl ammonium halides. On the other hand, the presence of such phase transitions was eluded in case of anilinium chloride. In the present work, we have undertaken a systematic temperature dependent Raman spectroscopic study on anilinium chloride, in the range 300–100–350 K. Spectral variation in the low frequency (100–400 cm−1) and high frequency (2500–3700 cm−1) regions around 350 and 260 K shows the signature of the phase transitions in this compound. These phase transitions were reversible in nature. The latter transition is in agreement with DSC measurements.