  Synchrotron X-ray diffraction measurements have been conducted on aqueous
mixtures of propan-2-ol (a.k.a. isopropanol, or 2-propanol), for alcohol
contents between 10 and 90 molar %, from room temperature down to 230 K.
Molecular dynamics simulations, by using an all-atom parametrization of the
propan-2-ol molecule and the well-known TIP4P/2005 water model, were able to
provide semi-quantitative descriptions of the measured total structure factors.
Various quantities related to hydrogen bonding, like hydrogen bond numbers,
size distribution of cyclic entities and cluster size distributions, have been
determined from the particle co-ordinates obtained from the simulations. The
percolation threshold at room temperature could be estimated to be between
isopropanol concentrations of 62 and 74 molar %, whereas at very low
temperature, calculations yielded a value above 90 molar %.
