Simultaneous XRD-DSC measurements of water-2-propanol at sub-zero temperatures.

A simultaneous low-temperature X-ray powder-diffractometric (XRD)-DSC technique was applied to the solid state and melting process of frozen aqueous solutions of 2-propanol. 1H NMR spectra were also obtained at low temperatures. The chemical shifts of the CH3 proton and the CH proton can be classified into four temperature regions: higher than -20 degrees C, around -20 degrees C, -50 to -20 degrees C, and lower than -50 degrees C.