High-pressure induced conformational and phase transformations of 1,4-dioxane probed by Raman spectroscopy

Abstract Pressure induced conformational and phase transformations of 1,4-dioxane has been investigated up to 37.6 GPa using Raman spectra. Three solid high pressure phases are identified during compression by the observation of markedly different Raman patterns as well as different pressure dependences of characteristic Raman modes. At 1.3 GPa, the liquid 1,4-dioxane finally transforms to solid phase I. Subsequent increasing pressure to 11.4 GPa, the second solid phase presents marked as solid phase II. Above 33.8 GPa, another high pressure structure, solid phase III, is identified. In addition, the influence of high pressure on conformational behavior of 1,4-dioxane has also been discussed. The results show the chair conformer exists in all state of 1,4-dioxane, no matter liquid or solid phase. But 1,4 twist-boat conformation only presents in solid phase I and phase III, while 2,5 twist-boat conformation just exists in solid phase II. Moreover, the formation of hydrogen bond-like C–H⋯O interactions and its response to the extreme condition are also confirmed. Finally, the phase transitions under high pressure are reversible.