Infrared study on crystalline and amorphous phases of 2-propyn-1-ol under high pressure

Infrared spectra of 2-propyn-1-ol, a compound with a triple bond and an OH group, have been measured up to 8 GPa pressure. The liquid phase showed a phase transition around 2 GPa for a thin sample spread on KBr. The sharpening of the infrared peaks and discontinuous frequency shift indicated a transition to a crystalline phase. For a thick sample, infrared spectra showed continuous changes in peak width and frequency. The liquid transformed to an amorphous phase around 2 GPa. Polymerization occurred around 8 GPa in both the crystalline and amorphous phases. The polymerization process was a multi-step mechanism involving molecular diffusion. The diffusion step would remove the influence on the reaction of the initial molecular arrangements in the solids.