Dissolved water analysis in saturated, unsaturated, and aromatic hydrocarbons by FTIR spectroscopy and thermal stability of dissolved water

The state of water dissolved in hydrocarbons such as n-decane (DAN), n-tetr adecane (TD), liquid paraffin (LB), 1-decene (DEN), squalene (SQ), 2,6-dime thyl-2,4,6-octatriene (TEN), benzene (BEN), toluene (TOL) and xylene (XYL) was analyzed by FTIR spectroscopy at 20 degrees C. Furthermore, the tempera ture dependence of the state of water dissolved in the hydrocarbons was inv estigated. In saturated hydrocarbons (DAN, TD, LP), a large portion of the water molec ules in cluster I (dimer-trimer mixture) seemed to exist in a state similar to that of the water molecules in the vapor phase. In unsaturated hydrocarbons (DEN, SQ, TEN), the dissolved water consisted o f cluster I, cluster II (tetramer-multimer), and cluster III (liquid water) . In aromatic hydrocarbons (BEN, TOL, XYL), the dissolved water consisted of cluster I (dimer-trimer mixture), cluster II (tetramer-multimer mixture), a nd cluster III (heptamer-octamer mixture) due to the existence of the hydro gen bond between the benzene ring and the water molecule. Cluster I in the dissolved water disappeared by vaporization of the water m olecules upon heating in the range from 40 to 80 degrees C. Large cluster I I and large cluster III in the dissolved water were gradually ruptured into smaller clusters with increasing temperature, but a little remaind at 180 degrees C.