Efficient Isomeric Enrichment in Cocrystals of Cyclohexanediamines and Low Molecular Weight Diols

Cis and trans isomers of cyclohexanediamines are separated by cocrystallization with low molecular weight diols: 1,4-benzenedimethanol and cis- and trans-1,4-cyclohexanedimethanol. In six out of seven cocrystals formed, significant enrichment of one cyclohexanediamine enantiomer is achieved in a simple and efficient process. Crystal structures are examined to reveal the origin of this high degree of selectivity.