NMR characterization of functional groups: 9 ‐isomer ratios of available chloromethylstyrene mixtures

From the assignments of the 1 H and 13 C 11.7 tesla NMR spectra of available mixtures of m ‐ and p ‐chloromethylstyrene, the proportion of the meta and para compounds are easily determined. For these materials from two common commercial sources, proportions of 72 and 28% and 68 and 32% were found. These concentrations are substantially different from the often assumed 60 and 40% for the meta and para compounds, respectively. The influence of this difference on the desired properties of copolymers made from such mixtures is discussed. An alternative quantitative procedure for determining the chloromethyl group isomer ratios is also described which employs silver trifluoroacetate in acetone displacement of chloride and 19 F NMR examination of the resulting ester mixture with a 2.3 tesla spectrometer.