title: Diffusion studies of dihydroxybenzene isomers in water-alcohol systems.
abstract: Nuclear magnetic resonance diffusion studies can be used to identify different compounds in a mixture. However, because the diffusion coefficient is primarily dependent on the effective hydrodynamic radius, it is particularly difficult to resolve compounds with similar size and structure, such as isomers, on the basis of diffusion. Differential solution interactions between species in certain solutions can afford possibilities for separation. In the present study, the self-diffusion of the three isomers of dihydroxybenzene (i.e., (1,2-) catechol, (1,3-) resorcinol, and (1,4-) hydroquinone) was studied in water, aqueous monohydric alcohols (i.e., ethanol, 1-propanol, tert-butanol), and aqueous ethylene glycol. These systems allowed the effects of isomerism and differential solvent interactions on diffusion to be examined. It was found that, while in aqueous solution these isomers had the same diffusion coefficient, in water-monohydric alcohol systems the diffusion coefficient of catechol differed from those of resorcinol and hydroquinone. The separation was found to increase at higher concentrations of monohydric alcohols. The underlying chemical reasons for these differences were investigated.
authors: Nanoscale Organisation and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors: Dale J
authors: DJ
authors: Codling
authors: Gang
authors: G
authors: Zheng
authors: Tim
authors: T
authors: Stait-Gardner
authors: Shu
authors: S
authors: Yang
authors: Mathias
authors: M
authors: Nilsson
authors: William S
authors: WS
authors: Price