Miscibility Isotope Effect in Ethylene Glycol-Nitromethane System

摘要

Recently an extensive study of the thermodynamic properties of ethylene glycol+nitromethane mixtures has been reported by Salvi and Van Hook.Apart from the PVT properties of protio and deutrio ethylene glycols (CH_2OH)_2 and (CH_2OD)_2 they investigated H/D isotope effects on critical demixing in ethylene glycolitrometha-ne solutions and found a moderate effect on the miscibility of ethylene glycol and nitromethane.This isotope shift in the upper critical solution temperature (UCST),equal to DELTAT_C=T_C(D)-T_C(H)=2.03 K,means that deuteration of ethylene glycol in OH group makes the miscibility worse.This observation is compatible with the general Rabinovich approach [2],which states that deuteration in polar groups should worsen the miscibility,whereas the deuteration of nonpolar groups leads to an improvement of the miscibility.However,the recent results on binary mixtures involving deuterated nitromethane [3,4] revealed that in these cases the miscibility is worse as well.Therefore,we decided to extend the measurements on deuterated nitro-methane/ethylene glycol system to verify this behaviour.