How does microwave irradiation affect aqueous solutions of polar solutes?

Abstract

We employed an empirical molecular mechanical model and non-equilibrium molecular dynamics simulations to investigate the structure of aqueous solutions of some prototypical polar compounds upon microwave heating. Microwave irradiation has been taken into account implicitly by performing simulations at a rotational temperature exceeding the translational one (Tr>Tt). We studied aqueous solutions of 5 polar compounds (acetone, acetaldehyde, dimethylether, methanol, and acetonitrile), which have been recently classified as hydroneutral or hydrophilic, depending on their hydration number determined experimentally via dielectric spectroscopy. We have shown that the two groups of polar compounds could indeed be distinguished also based on the changes in their hydration upon a Tr increase. Moreover, we have clearly demonstrated the crucial effects of mass and charge distribution in a solute molecule on its hydration properties under the studied non-equilibrium microwave conditions.