Calculation of the Detonation Velocities and Detonation Pressures of Dinitrobiuret (DNB) and Diaminotetrazolium Nitrate (HDAT‐NO₃)

Abstract

The enthalpies of combustion (ΔcombH) of dinitrobiuret (DNB) and diaminotetrazolium nitrate (HDAT‐NO3) were determined experimentally using oxygen bomb calorimetry: ΔcombH(DNB)=5195±200 kJ kg−1, ΔcombH(HDAT‐NO3)=7900±300 kJ kg−1. The standard enthalpies of formation (ΔfH°) of DNB and HDAT‐NO3 were obtained on the basis of quantum chemical computations at the electron‐correlated ab initio MP2 (second order Møller‐Plesset perturbation theory) level of theory using a correlation consistent double‐zeta basis set (cc‐pVTZ): ΔfH°(DNB)=−353 kJ mol−1, −1 829 kJ kg−1; ΔfH°(HDAT‐NO3)=+254 kJ mol−1, +1 558 kJ kg−1. The detonation velocities (D) and detonation pressures (P) of DNB and HDAT‐NO3 were calculated using the empirical equations by Kamlet and Jacobs: D(DNB)=8.66 mm μs−1, P(DNB)=33.9 GPa, D(HDAT‐NO3)=8.77 mm μs−1, P(HDAT‐NO3)=33.3 GPa.

Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret

“…Biuret (trans), MNB (C 1 ), and DNB (C 2v ) have significantly smaller dipole moments than their corresponding conformers, which is consistent with the fact that stable biuret, MNB, and DNB exist, respectively, in the trans, C 1 , and C 2v forms in the solid state as is observed experimentally. 2,4 This reveals a simple way for evaluating reactivity of fuel conformers and suggests that, the planar MNB (trans), MNB (C s ), and MNB (cis), can be intermediates for a second NO 2 substitution to form DNB (C s ) and DNB (C 2v ). It is seen that DNB (C s ) has a much larger dipole moment than DNB (C 2v ), and its dipole moment vector points towards the H-atom which is not involved in hydrogen bonding; consequently, the DNB (C s ) can undergo a third NO 2 substitution.…”

“…They reported that the DNB molecule in the crystalline state had a planar structure with C 2v symmetry. 2 For MNB, the crystal structure was found to be non-planar, where the nitramine moiety was slightly rotated out of the biuret backbone plane, with a corresponding torsion angle, 4 As the backbone of MNB and DNB, the biuret geometry is crucial in understanding the molecular structures of its nitrosubstitutes. Biuret has been known to have two conformers, trans and cis, which refer to the two C==O groups that are either trans or cis to each other.…”

“…It was found that the trans-HNN(O)OH (trans) conformer dissociates via the following three reaction pathways: (1) a direct N-OH bond fission to produce OH + cis-HNNO, (2) × 10 5 Å 6 cm −1 for the long-range isotropic potential, and the high-pressure limit rate coefficient for decomposition of trans-HNN(O)OH (trans) to OH + cis-HNNO was determined to be 3.03 × 10 18 T −0.856 exp(−27 020.0/T) s −1 in the temperature range 500-2500 K. This rate coefficient is in good agreement with that derived from its reverse reaction coefficient by Klippenstein et al 32 The Direct isomerization of trans-HNN(O)OH (trans) via a four-member-ring transition state to form the nitramide which then dissociates to NH 2 + NO 2 is also possible. The PES for the reverse reaction, NH 2 + NO 2 , has been previously studied both theoretically and experimentally.…”

“…1,2 MNB was synthesized by nitration of biuret with HNO 3 /H 2 SO 4 , and DNB was obtained by the treatment of MNB with 100% HNO 3 using a modified procedure of Thiele, 3 with an overall yield of 46% from the starting biuret. 1,4 They observed that both MNB and DNB were white solids and MNB decomposed without melting at 153 • C, while DNB exploded when heated above 127 • C. In addition, DNB was observed to be impact and heat sensitive, had a density of 1.859 g/cm 3 , and detonated strongly without an oxidizer in a steel-sleeve test after 4 s. 2 Furthermore, they found that MNB and DNB showed distinctively different thermal behaviors, i.e., MNB had a significantly higher decomposition temperature than DNB and as such, was found to have better thermal stability. Using mass spectrometry and IR spectroscopy, they identified the gaseous products from the decomposition of MNB and DNB and proposed a reaction scheme to interpret their observations.…”

The preparation and characterization of guanylurea nitrate and perchlorate salts

“…Recently, we reported on energetic materials based on biuret (1) and found them to show interesting explosive properties [4,5]. Many reports have appeared in the literature mentioning about salts of the protonated parent guanylurea (2) with chloride [6], nitrate [7], or dinitramide [8] as the counteranion, the last one having shown prospective use as a new insensitive material with a high performance.…”