The influence of hydrogen bonds upon diffusion of simple amines and binarymixtures of ammonia

Self diffusion coefficients of monomethylamine and trimethylamine and intra diffusion coefficients of some model mixtures containing ammonia have been measured up to pressures of 200 MPa at temperatures between the melting pre ssure curve and 423K by pulsed field gradient Spin Echo NMR. Compared to wa ter and the lower alcohols the self diffusion coefficients of pure fluid am monia shows no clear influence from hydrogen bonds in contrast to other the rmodynamic properties. Therefore the methylated substance monomethylamine h as been studied to see weather a more structured charge distribution on the molecular surface compared to ammonia is needed to hinder fast rearrangeme nts of the hydrogen bonds. For comparison also trimethylamine has been stud ied where no hydrogen bonds can be formed. Additionally binary mixtures of ammonia with methanol, benzene, trimethylamine and acetonitrile have been s tudied to see effects of intermolecular interactions.