Figure 4. Gibbs free-energy profile for the substitution reaction between FOX-7 and CHZ
Due to the presence of amino groups at both ends of CHZ, substitution reaction is also carried out between IM11 and the second FOX-7. In Figure 5, the amino group on the second FOX-7 is substituted by the amino group on the -NHNHC=ONHNH2 group of IM11, forming IM12. IM12 is unstable, and the bond breaking process is performed quickly, generating the NH3 molecule and the final product BADCh. Since CHZ has amino groups on both sides and there are two sites that can be substituted with FOX-7, CHZ can also easily react with two FOX-7 molecules, respectively.