Nuclear magnetic resonance as a tool to determine chlorine percentage of chlorinated paraffin mixtures

Abstract

A new simple method for chlorine percentage calculations (method C), from proton nuclear magnetic resonance (¹H NMR) spectroscopy, has been established and applied to an industrial chlorinated paraffin (CP) mixture and 13 single-chain CPs of known carbon chain lengths. Two modified methods (method A and B), originating from the work of Sprengel et al., have been utilized on the same single-chain mixtures. All samples were analysed by ¹H NMR and two-dimensional heteronuclear quantum coherence (HSQC) for this purpose. All three methods worked well for medium chlorinated (45-55% Cl) single-chain mixtures of known carbon chain lengths. Method A yielded the best result for mixtures of lower chlorine content (<45% Cl), method C gave better estimations for higher chlorine contents (>55% Cl). Compared to Mohr's titration, method A showed a deviation of 0.7-7.8% (3.6% average), method B 4.1-11.3% (7.0% average) and method C 0.6-11.6% (5.2% average), for all 13 single-chain mixtures. The new method C is the only method that could be applied for determining the chlorine percentage of industrial mixtures of multiple, unknown chain lengths.

Keywords: Chlorinated paraffins; Chlorine percentage calculation; Industrial chlorinated paraffins; NMR spectroscopy; Reference standards.