Professor Gérard Coquerel from the University of Rouen discussed crystallisation approaches to preparing single enantiomers and in particular the use of conglomerates to allow selective crystallisation of one enantiomer from a racemic solution.  Only one in ten to fifteen compounds crystallises as a conglomerate, so in most cases this will not seem to be a viable option.   However, if the compound itself does not crystallise as a conglomerate one of it’s salts or derivatives may do, so a screen of salts and/or derivatives may reveal a compound which can be purified by crystallisation.