Separation of Enantiomers of Alanine from Racemic Mixture by Polycrystalline Metal Surfaces - A Spectroelectrochemical Approach

ABSTRACT:Spectroelectrochemicalinvestigation of racemic alanine on polycrystalline metal surfaces was studied in 1M LiClO₄ medium, to achieve cost effective separation of biologically important molecules from the racemic mixture. Analysis of the FTIR spectrum of racemic alanine in 1M LiClO₄ indicated degradation of the same. Upon prolonged exposure in LiClO₄, byproducts from degradation of alanine increasedin concentration as also observed from UV-Vis spectroscopy. Cyclic Voltammetry studies unraveled different adsorption behaviors on different metal surfaces for the racemic and the enantiomeric solution of alanine. Further FTIR analysis of the alanine solution after Cyclic Voltammetry revealed possible presence of cyanide (-C≡N) and terminal alkyne as byproducts. As predicted by Monte Carlo simulations earlier, Circular Dichroism implied the dextro rotation ofthe racemic alanine solution after Cyclic Voltammetry. These results support the preferential adsorption of L-alanine over D-alanine from racemic mixture that could be attributed to the umbrella inversion of the molecule after adsorption on the metal surface in presence of applied electric field in the LiClO₄ environment. A plausible mechanism for the formation of terminal alkyne and -C≡N byproducts had also been attempted.