Abstract
In order to develop an effective separation process for catecholamine (CA), a basic investigation on solvent extraction of dopamine (DA), adrenaline (Ad) and noradrenaline (NA) from hydrochloric acid solution and their stripping is conducted at 30°C employing bis(2-ethylhexyl) hydrogen phosphate (D2EHPA) in chloroform, n-hexane and toluene as the organic diluents. From the dependencies of the distribution ratios on the concentrations of reactant species, i.e. CA, hydrogen ion and D2EHPA, it is elucidated that CA (RNH2) is extracted with D2EHPA (HR′) according to the ion exchange mechanism, as the complex type, RNH3R′(HR′)3, and the equilibrium constants (Kex, CA) for the extraction reactions are also evaluated. The quantitative structure property relationship (QSPR) of Kex, CA values for each organic diluent is discussed using molecular modeling with semi-empirical molecular orbital calculations considering the solvent effect.
