Abstract

An essential feature of chemical research is advancing new laboratory findings to a form useful to industry. Dimethyl sulfoxide (DMSO) is an important dipolar, aprotic solvent for conducting chemical reactions. Unfortunately, separation of the products of reaction from the solvent is difficult and expensive. We have proposed the use of piperylene sulfone (PS) as a substitute for DMSO, and herein, we establish a roadmap to its sustainable and scalable synthesis. PS is a potentially important new dipolar aprotic solvent that has solvent properties similar to those of DMSO; in contrast to DMSO, PS is fully recyclable and undergoes a reversible retrocheletropic reaction at 110 °C, permitting facile solvent removal and recycle. PS is synthesized by the reaction of trans-piperylene with sulfur dioxide. Because PS is not commercially available, we synthesized laboratory quantities using a method not sustainable on a large scale because of expensive chemicals and considerable waste generation. To develop and optimize a scalable process, we (1) determined the kinetic parameters associated with the reaction by employing in situ proton NMR measurements and (2) studied the effects of radical inhibitors in reducing unwanted side reactions. In addition, we recovered PS from the reaction mixture through a sustainable CO2 separation method, which resulted in a substantial waste reduction. Our development of a more efficient, safe, and sustainable scaleup method for PS thus illustrates an important aspect of chemical research: the need to render the results usable and useful to industry.