Kinetic characterization of a transient reaction by degeneration of the precursor mechanism: Application to the synthesis of 3,4-diazabicyclo[4.3.0]non- 2-ene

Article abstract of DOI:10.1002/kin.20072

The rate of the oxidation of N-amino-3-azabicyclo[3.3.0]octane by chloramine has been studied by GC and HPLC between pH 10.5 and 13.5. The second-order reaction exhibits specific acid catalysis. The formation of N,N′-azo-3-azabicyclo(3.3.0)octane or 3,4-diazabicyclo(4.3.0)non-2-ene is pH, concentration, and temperature dependent. In alkaline media, the exclusive formation of 3,4-diazabicyclo[4.3,0]non-2-ene is observed. Kinetic studies show that the oxidation of N-amino-3-azabicyclo[3.3.0]octane by chloramine is a multi-step process with the initial formation of a diazene-type intermediate, which is converted by hydroxide ions into 3,4-diazabicyclo[4.3.0]non-2-ene. Because it was not possible to follow the rate of change of the intermediate concentration, to determine the kinetics of 3,4diazabicyclo[4.3.0]non-2-ene formation, a procedure based on the degeneration of the precursor process was adopted. An appropriate mathematical treatment allowed a quantitative interpretation of all the phenomena observed over the given pH interval. The activation parameters were determined.