Synthesis of cis-TMCDA: Optimization and characterization of a key intermediate

► cis-TMCDA is synthesized from cyclohexane-1,2-diamine (mixture of diastereomers) in a two-step procedure or via cis-cyclohexane-1,2-diamine. ► Both procedures contain separation of diastereomers with nickel(II) chloride. ► In the synthesis of cis-cyclohexane-1,2-diamine, crystallization of the unexpected cyclohexane-1,2-diammonium hydrogensulfate ethylsulfate facilitates further reaction steps.