Photo-degradation of 2,4-dinitroanisole (DNAN): An emerging munitions compound

- 2,4-dinitroanisole (DNAN) changes color from white to red when exposed to sunlight.
- 2-methoxy-5-nitroaniline and 4-methoxy-3-nitrophenol are the main transformation products.
- Degradation products identified had concentrations <1% of that of DNAN.
- Concentration of 2-methoxy-5-nitroaniline was high when ammonium perchlorate present.
- Unknown A (possibly a nitrosobenzene) was present in most samples.

The US military is developing insensitive munitions (IM) that are less sensitive to shock and high temperatures to minimize unintentional detonations. DNAN (2,4-dinitroanisole) is one of the main ingredients of these IM formulations. During live-fire training, chunks of IM formulations are scattered by partial detonations and, once on the soil, they weather and dissolve. DNAN changes color when exposed to sunlight suggesting that it photodegrades into other compounds. We investigated the photo-degradation of DNAN both as a pure solid and as part of solid IM formulations, IMX101, IMX104 and PAX21. The concentrations of degradation products found were small, <1%, relative to DNAN concentrations. We saw transient peaks in the chromatograms indicating intermediate, unstable products but we consistently found methoxy nitrophenols and methoxy nitroanilines. We also found one unknown in most of the samples and other unknowns less frequently.

(A) Image showing sunlight-induced color changes on a DNAN-containing explosive particle (IMX101); (B) possible formation pathways for some known degradation products of DNAN.150