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

We report optimized synthetic procedures to cis-TMCDA and cis-cyclohexane-1,2-diamine. Our new two-step approach is an efficient and low-cost method for synthesizing the ligand cis-TMCDA. In the preparation of cis-cyclohexane-1,2-diamine, the crystallization of the unexpected intermediate cis-cyclohexane-1,2-diammonium hydrogensulfate ethylsulfate made the subsequent reactions easier in their workup, as nickel(II) chloride impurities were eliminated.