Proton Magnetic Resonance Spectrum of 2-Chloroaniline-15N. Long-range Coupling Constants to Amino Protons from all Ring Protons

The p.m.r. spectra of 2-chloroaniline and 2-chloroaniline- 15 N in benzene and toluene solutions are analyzed at 60 and 100 MHz under conditions where the amino protons are exchanging intermolecularly and also where they are not exchanging. The spectrum of 2-chloroaniline-H 15 ND in the absence of amino proton exchange is observed between −48 and 80 °C. In all situations fast rotation about the C—N bond evidently occurs. Long-range couplings of the amino protons to all ring protons are observed and their signs are determined. The nonplanarity of the amino group is discussed in terms of the long-range couplings, of the one-bond 15 N–H couplings, and of the two-bond H–H couplings in the amino group. The signs and magnitudes of the coupling constants between the ring protons and 15 N are also determined.