MD simulation study of the diffusion and local structure of <Emphasis Type="Italic">n</Emphasis>-alkanes in liquid and supercritical methanol at infinite dilution
1.School of Chemistry and Chemical Engineering,Hainan Normal University,Haikou,People’s Republic of China;2.School of Pharmacy,Guangdong Pharmaceutical University,Guangzhou,People’s Republic of China;3.Hainan Entry-Exit Inspection and Quarantine Technology Center,Haikou,People’s Republic of China;4.KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering,Sun Yat-sen University,Guangzhou,People’s Republic of China
Abstract:
The diffusion coefficients of 14 n-alkanes (ranging from methane to n-tetradecane) in liquid and supercritical methanol at infinite dilution (at a pressure of 10.5 MPa and at temperatures of 299 K and 515 K) were deduced via molecular dynamics simulations. Values for the radial distribution function, coordination number, and number of hydrogen bonds were then calculated to explore the local structure of each fluid. The flexibility of the n-alkane (as characterized by the computed dihedral distribution, end-to-end distance, and radius of gyration) was found to be a major influence and hydrogen bonding to be a minor influence on the local structure. Hydrogen bonding reduces the flexibility of the n-alkane, whereas increasing the temperature enhances its flexibility, with temperature having a greater effect than hydrogen bonding on flexibility.
Graphical abstract The flexibility of the alkane is a major influence and the hydrogen bonding is a minor influence on the first solvation shell; the coordination numbers of long-chain n-alkanes in the first solvation shell are rather low
