Cocrystallization Improves Explosives

Cocrystallizing pairs of explosive organic compounds is a viable route to improving the compounds’ chemical stability, shock sensitivity, and other properties that determine an explosive’s usefulness in applications, according to a study (J. Am. Chem. Soc. 2015, DOI: 10.1021/jacs.5b00661). Acetone peroxides are easy to prepare and inexpensive, but they tend to be unstable—exploding unpredictably—and low in density, a property associated with low explosive power. Those factors limit their usefulness as commercial explosives. The University of Michigan’s Adam J. Matzger and coworkers may have a way to bypass those limitations. The team formed cocrystals in one-to-one ratios between diacetone diperoxide (DADP) and three trihalotrinitrobenzenes—the trichloro (TCTNB), tribromo (TBTNB), and triiodo (TITNB) analogs. They found that cocrystallization increased DADP’s density and stability. They also found that, compared with DADP, the cocrystal DADP-TCTNB was just as sensitive to impact yet less volatile and higher in density. In contrast, DADP-TITNB exhibited much lower impact sensitivity than either DADP or TITNB, showing for the first time that an energetic cocrystal can be less sensitive to impact than its pure components.