Additive-free, solvent-free chemical reactions are generally more environmentally benign than alternative processes that involve these reaction components. 2,4-Dinitroanisole (DNAN) is of interest to the military and to industry as a replacement for trinitrotoluene (TNT) in melt-cast explosives. As anisole is a widely used feedstock chemical, the development of an efficient, additive-free, solvent-free method for its dinitration could lead to adoption of a new “green” synthetic route for DNAN manufacture.
The project's goal was the scale‐up (from the previously demonstrated one gram scale to a 500 gram scale) of the additive‐free, solvent‐free dinitration of anisole using the equipment and facilities available at the Los Alamos National Laboratory.
Through a series of simple optimization processes, the project was successful at scaling demonstrating the development of a solvent-free process for the synthesis of 2,4-dinitroanisole using a batch process. The overall method involves the use of a mixture of propionic anhydride and 98% nitric acid to form the reactive nitrating species, proprionyl nitrate. This nitrating reagent is then added to a highly concentrated solution mixture of anisole and proprionic anhydride slowly over time to produce the desired 2,4-dinitroanisole product. This batch process could be scaled-up to the 270g scale. Flow-reaction methods should allow for larger scale production of DNAN.
This work has addressed environmentally benign methods for the synthesis of DNAN. Having achieved the goal, the next step will be to partner with a commercial manufacturer of explosive materials to scale the synthesis up to production levels.