Kinetics of dehydrohalogenation of N-chloro-3-azabicyclo[3,3,0]octane in alkaline medium. NMR and ES/MS evidence of the dimerization of 3-azabicyclo[3,3,0]oct-2-ene

The formation of 3-azabicyclo3,3,0]oct-2-ene in the course of the synthesis of N-amino-3-azabicyclo3,3,0]octane using the Raschig process results from the following two consecutive reactions: chlorine transfer between the monochloramine and the 3-azabicyclo3,3,0]octane followed by a dehydrohalogenation of the substituted haloamine. The kinetics of the reaction were studied by HPLC and UV as a function of temperature (15 to 44°C), and the concentrations of NaOH (0.1 to 1 M) and the chlorinated derivative (1 to 4×10⁻³ M). The reaction is bimolecular (k=103×10⁻⁶ M⁻¹ s⁻¹; ΔH^0#=89 kJ mol⁻¹; and ΔS^0#=−33.6 J mol⁻¹ K⁻¹) and has an E2 mechanism. The spectral data of 3-azabicyclo3,3,0]oct-2-ene were determined. IR, NMR, and ES/MS analysis show dimerization of the water-soluble monomer into a white insoluble dimer. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 129–136, 1998.