Identification of 2,2‐dinitropropanol, a Hydrolyzed Product of Aged Eutectic Bis(2,2‐dinitropropyl) Acetal – Bis(2,2‐dinitropropyl) Formal Mixture

Abstract

Eutectic bis(2,2‐dinitropropyl) acetal ‐ bis(2,2‐dinitropropyl) formal mixture, nitroplasticizer (herein called NP) has historically been produced by either the ter Meer or oxidative nitration synthesis process, wherein 2,2‐dinitropropanol (DNPOH) is produced as an intermediate step in both processes. Therefore that DNPOH, could be present in NP either as a production or hydrolysis degradation product is worth investigation. Here, we synthesized DNPOH, validated the synthesis using NMR, and identified DNPOH in aged NP using liquid chromatography tandem time of flight – quadrupole mass spectrometry (LC‐QTOF). Using these results, for the first time we positively identify that DNPOH is absent from NP after its production, but is present as a degradation product through hydrolysis from a thermo‐chemical aging profile of NP. To hydrolyze NP, prerequisite is the presence of both water and acid. Despite the presence of water in NP, DNPOH is only generated in the late stage of the aging process, when acid concentration is sufficiently high. It has been previously shown both theoretically and experimentally that a primary step of NP degradation is HONO elimination followed by decomposition, wherein nitric acid, nitrous acid, and water are produced (NP→NP’+2HONO and 2HONO→NO+NO2+H2O). It is shown from this reaction series that water slows HONO decomposition and therefore in small quantities, 100 s of ppm, water actually stabilizes NP against hydrolysis by equilibrium and reducing acidity.

Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry: A Strategy for Optimization, Characterization, and Quantification of Antioxidant Nitro Derivatives

“…DNPOH was synthesized by David Langlois at Los Alamos National Laboratory. 30 The PBNA standard was purchased from Sigma-Aldrich. N -(4-nitrophenyl) naphthalen-2-amine, the reference standard of the mononitro-PBNA derivative, was purchased from Aurora Fine Chemicals (San Diego, CA).…”

“…DNPOH was synthesized by David Langlois at Los Alamos National Laboratory . The PBNA standard was purchased from Sigma-Aldrich.…”

Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Analysis of Eutectic Bis(2,2-dinitropropyl) Acetal/Formal Degradation Profile: Nontargeted Identification of Antioxidant Derivatives

“…The peak intensities of PBNA derivatives, hydrolyzed phenols, and DNPOH were examined as functions of aging time. Due to in-source fragmentation, m / z 119.0098 was used as the primary identifier for DNPOH 20 and its identity was verified through the T R and fragmentation pattern of the DNPOH reference standard (2.886 min; Table S1 ).…”

“…When the dinitro-PBNA derivative is depleted, which is also indicated by the maximum peak intensities of the trinitro derivative (e.g., 28 months of aging at 55 °C or 16 months of aging at 64 °C), the antioxidant activity is effectively nullified. As a result, NP decomposition proceeds at a faster pace and the accumulation of HNO x , NO x , and water likely dissociates into charged components, which not only create reactive electrophiles (e.g., NO + , NO 2 + NO 3 – , H 2 NO 2 + , and HN 2 O 4 + ) , but also increase the acidity in the aged samples in the later stage of thermal aging. − These conditions can catalyze the nitration reaction of polycyclic aromatic hydrocarbons. , Hence, the fourth and the fifth NO 2 additions are achievable, especially at elevated temperatures and in the presence of HNO 3 (Figure S18). Accordingly, tetra- and penta-nitro-PBNA derivatives can be deemed less relevant during the early stage of NP aging.…”

“…BDNPA and BDNPF reference standards were provided by the Pantex Plant. Deuterated BDNPA-d8, BDNPF-d6, and 2,2-dinitropropanol (DNPOH) were synthesized by David Langlois at Los Alamos National Laboratory. , PBNA standard was purchased from Sigma-Aldrich. n -(2,4-Dinitrophenyl) naphthalen-2-amine, a structural isomer of dinitro-PBNA, was purchased from Chemspace (Monmouth Junction, NJ).…”