Until now, it has been assumed that the primary decomposition
pathway
for the liquid plasticizer bis(2,2-dinitropropyl)acetal and bis(2,2-dinitropropyl)formal
(BDNPA/F) was nitrous acid elimination (NAE). An ultrahigh-performance
liquid chromatography (UHPLC) coupled to quadrupole time-of-flight
mass spectrometry (QTOF) methodology was developed to discover and
identify the degradation products of BDNPA/F. No evidence of NAE was
found. However, two other degradation pathways were found: (1) hydrolysis
of the acetal/formal functional group and (2) radical-based homolysis
of the C–N bond, followed by hydrogen atom abstraction. Hydrolysis
of BDNPA/F proceeds by the formation of 2,2-dinitropropanol (DNPOH)
and 2,2-dinitropropyl hemiacetal/hemiformal, which further decompose
into DNPOH and ethanal/methanal, respectively. Hydrolysis is the dominant
decomposition pathway in all samples; however, at higher temperatures,
C–N homolysis becomes more significant. Also, the solid PBX
9501 has different ratios of decomposition products than the liquid
BDNPA/F due to the slower rate of diffusion through solids than liquids.