Dielectric and conductivity studies of stereo-selectively synthesized d- and l-nor-ephedrine

The stereo isomers, d - and l -phenyl propanolamine hydrochloride (nor-ephedrine) were stereo-selectively synthesized from benzaldehyde and nitroethane followed by catalytic reduction using hydrogen and Raney nickel. The nor-ephedrine was characterized by UV, IR, and LC/MS analysis. The purity of the synthesized nor-ephedrine hydrochlorides was analyzed using HPLC. Resolution of d - and l -isomer of PPA hydrochloride was carried out using the resolving agent, d -3-formyl-2,2,5,5-tetramethyl-1,3-thiazolidine-4-carboxylicacid. Optical rotation was found to be ±36°. The temperature and frequency dependence of dielectric constant, dielectric loss, and conductivity of d - and l -isomers of nor-ephedrine were studied over a range of frequency (50 Hz–5 MHz) and temperature (40–140 °C). It was found that d -isomer possesses higher dielectric constant and AC conductivity values compared to l -isomer. The band gap of 1.35 and 1.69 eV for d - and l -isomers, respectively, indicates that these two compounds behave as organic semiconductor materials.