In the trial scale-up of the sulfonation of phenylchloroformate and subsequent formation of sulfonated phenyl carbonates, samples from the batch process showed a number of unexpected by-products. Because they were suspected to have an unusual ring substitution pattern, phenylchloroformate sulfonation was studied by <sup>1</sup>H and two-dimensional nuclear magnetic resonance (NMR) techniques. Distance geometry was used to compute internuclear distances, which were used to substantiate the observation of the nuclear Overhauser effect. The reaction mechanism leading to these by-products is proposed.
David Kwoh, Judith L. Kerschner, Arnold Jensen, and Anthony Cece, "NMR Characterization of Sulfonation Products of Phenylchloroformate with Verification of NOE Effects by Molecular Modeling," Appl. Spectrosc. 49, 407-412 (1995)