NMR spectroscopic characterization of polyhalodisulfides via sulfenyl chloride inverse vulcanization with sulfur monochloride

Abstract

The preparation of sulfur containing polymers from inexpensive, commodity sulfur base chemicals is an emerging field of polymer chemistry as a route to consume elemental sulfur generated from fossil fuel refining. Recently a new process, termed, sulfenyl chloride inverse vulcanization has been developed that exploits the high reactivity and miscibility of sulfur monochloride, (S2Cl2) with a broad range of allylic monomers to prepare soluble, high molar mass linear polymers, segmented block copolymers and crosslinked thermosets with greater synthetic precision than achieved using classical inverse vulcanization with elemental sulfur. However, the ring-opening of episulfonium intermediates from this polymerization can proceed via Markovnikov, anti-Markovnikov, or alternative pathways resulting in complex regioisomeric microstructures, particularly when used with allylic ester monomers. Hence, to accelerate structural characterization of this new class of polyhalodisulfides prepared by the sulfenyl chloride inverse vulcanization process, we report on a detailed structural characterization to quantify the molar composition of regioisomeric units in these materials using NMR spectroscopy, focusing on sulfenyl chloride additions to allylic benzoate substrates. We report on a general methodology using one- and two-dimensional NMR spectroscopic techniques to enable direct integration of 2D NMR spectroscopic cross peaks to quantify the molar composition of regioisomeric units in 1,3-diallyl isophthalate (DAI) polymerized with S2Cl2, along with detailed studies on model compound reactions to detail the analytical methodology.