Two-dimensional near-infrared correlation spectroscopy study the methanol in acidic pH region

The effect of pH on the structure of methanol was investigated by FT-NIR (Fourier transform near-infrared) spectroscopy and generalized two-dimensional (2D) correlation spectroscopy. pH perturbed 2D correlation spectra are calculated for the spectra in the 5500–4000, 7500–5500 cm−1 regions at different pH values. We observed that the stretching of CH3 was shifted because of the direct interaction of the CH3 group of methanol with the OH group of water, the change of free OH is more sensitive to pH than the cyclic dimmer and CH·O.