Viedma ripening

rdf:langString Viedma ripening

rdf:langString Viedma ripening or attrition-enhanced deracemization is a chiral symmetry breaking phenomenon observed in solid/liquid mixtures of enantiomorphous (racemic conglomerate) crystals that are subjected to comminution. It can be classified in the wider area of spontaneous symmetry breaking phenomena observed in chemistry and physics. It was discovered in 2005 by geologist Cristobal Viedma, who used glass beads and a magnetic stirrer to enable particle breakage of a racemic mixture of enantiomorphous sodium chlorate crystals in contact with their saturated solution in water. A sigmoidal (autocatalytic) increase in the solid-phase enantiomeric excess of the mixture was obtained, eventually leading to homochirality, i.e. the complete disappearance of one of the chiral species. Since the original discovery, Viedma ripening has been observed in a variety of intrinsically chiral organic compounds that exhibit conglomerate crystallization and are able to inter-convert in the liquid via racemization reactions. It is also regarded as a potential new technique to separate enantiomers of chiral molecules in the pharmaceutical and fine chemical industries (chiral resolution).