This project aims to develop innovative scalable synthetic approaches leading to production of energetic materials that eliminate or dramatically reduce hazardous waste streams from nitration processes used in manufacturing. Specifically, the objective is to identify and optimize a protocol for performing nitrations electrochemically without the use of large excesses of nitric and sulfuric acids. The use of active nitrating agents electrolytically generated from species such as nitrogen tetroxide (N2O4), nitrite or nitrate salts has the potential to provide improved selectivity while reducing or eliminating acidic and/or toxic waste streams. Ideally, a process or set of complementary processes identified by this effort will be applicable to nitrations of a variety of substrates including aromatic hydrocarbons and polyols, maximizing impact across the portfolio of energetic materials currently in use by the United States Department of Defense (DoD).
Initial efforts will focus on identifying effective conditions for the nitration of toluene and anisole to form 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN), respectively, on small scale. These experiments will then inform further optimization efforts directed toward an analogous O-nitration protocol for glycerol and 1,2,4-butanetriol, targeting nitroglycerin and 1,2,4-butanetriol trinitrate (BTTN), respectively. Any promising reactivity discovered during this study will be demonstrated as a continuous process as a proof of concept to warrant further studies under a follow-on effort. A full assessment of the environmental and cost impacts of such processes will be performed as well.
A successful effort would deliver a scalable, chemoselective, low-cost protocol for the production of several high value energetic materials without the use of large excesses of acids or generation of environmentally problematic waste streams. Although some precedent for this type of reactivity exists, it has not been well explored, as electrochemical synthesis largely remains a nascent field at this time. As such, a successful campaign would benefit not only DoD manufacturing efforts but also the broader scientific community by providing a potentially widely applicable synthetic method.