NMR spectroscopy in environmental chemistry:1H and13C NMR parameters of tricyclic polychlorinated C10 hydrocarbons and their oxy derivatives based on two-dimensional NMR techniques

Abstract

Two-dimensional homo- and heteronuclear NMR chemical shift correlation techniques were applied in the characterization of five tricyclic polychlorinated C10 hydrocarbons, chlordene (1), heptachlor (2), trans-nonachlor (3), α-chlordene (4) and γ-chlordene (5), which are spread globally in the environment owing to their use as insecticides. Approximate and partly contradictory 1H and 13C NMR chemical shifts reported in the literature were corrected in this work. The chemical shift assignments of 1–5 were based on DQF COSY, HMQC and HMBC experiments. In addition, an INADEQUATE experiment was needed to ascertain the 13C chemical shifts assignment of 2. The nJ(H,H)s of 1–5 were solved by computer-assisted spectral analyses. Further, complete 1H and 13C NMR parameter sets of three oxy derivatives, heptachlor exo-epoxide (6), 1-exo-hydroxychlordene (7) and its acetate (8), were also determined. Compounds 7 and 8 were synthesized to be used as model compounds, and their NMR parameters are reported for the first time. By using solvent susceptibility matched symmetrical micro-NMR tubes and HMQC and HMBC experiments, 1–5 can be reliably characterized at submilligram levels by their 1H and 13C NMR parameters with a 500 MHz (11.8 T) spectrometer and a 5 mm diameter standard probehead. Copyright © 1999 John Wiley & Sons, Ltd.