Generalized treatment of NMR spectra for rapid chemical reactions

✍ Scribed by Matthew D. Christianson; Clark R. Landis

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 265 KB
• Volume: 30A
• Category: Article
• ISSN: 1546-6086
• DOI: 10.1002/cmr.a.20090

✦ Synopsis

Abstract

Application of NMR spectroscopy to fast irreversible reactions (t~1/2~ < 0.7 s) has been hampered by limitations in instrumentation and general methods for modeling the complicated spectra that result. Analytical descriptions of nuclear spin dynamics during fast reactions, first solved by Ernst and coworkers, are limited to first‐order reaction kinetics. We demonstrate that numeric methods enable simulation of NMR spectra for fast reactions having any form of rate law. Simulated stopped‐flow NMR spectra are presented for a variety of common kinetic scenarios including reversible and irreversible reactions of first and second‐order, multistep reactions, and catalytic transformations. The simulations demonstrate that a wealth of mechanistic information, including reaction rates, rate laws, and the existence of intermediates, is imbedded in a single NMR spectrum. The sensitivity of modern NMR instrumentation along with robust methods for simulating and fitting kinetic parameters of fast reactions make stopped‐flow NMR an attractive method for kinetic studies of fast chemical reactions. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 165–183, 2007.