Density Functional Theory and X-ray Investigations of P- and M-Hexamethylene Triperoxide Diamine and Its Dialdehyde Derivative

Abstract

Recently, we carried out a density functional theory B3LYP/6-31+G(d) study of hexamethylene triperoxide diamine (HMTD) in order to elucidate the unusual, nearly planar, sp 2 hybridization of the two bridgehead nitrogen atoms, each bonded to the three CH 2 groups. We postulated that extended bonding orbitals between peroxide oxygens results in charge delocalization which decreases lone-pair repulsion and compensates the energy loss due to the sp 3 to sp 2 hybridization change on the nitrogen atoms. We have reexamined the crystal structure of HMTD by performing low-temperature, single-crystal X-ray studies, and we have determined that the unit cell contains a 50-50 racemic mixture of enantiomeric forms of HMTD, showing disorder about the mirror plane. At the low temperature, all hydrogen atoms were located and resolved, which was not previously possible. We have also crystallized and performed low-temperature X-ray analysis of a never previously reported dialdehyde form of HMTD, tetramethylene diperoxide diamine dialdehyde (TMDDD), which reveals enantiomers present in the unit cell without disorder. B3LYP density functional theory studies of HMTD and TMDDD are presented, as well as a transition state investigation of possible thermal interconversion of the HMTD enantiomers.

Humidity Effects on Fragmentation in Plasma-Based Ambient Ionization Sources

“…Also observed were two abundant adducts of a dialdehyde form of HMTD produced by peroxide bond cleavage [31], protonated for a net molecular formula of [M -H] + [32], and ammoniated for a net molecular formula of [M -H + NH 3 ]…”

Helical chirality in hexamethylene triperoxide diamine

“…2 Likely because it, like many peroxide explosives, is easily synthesized from commonly available materials, can be used as a primary explosive or detonator, and at the same time is somewhat more stable than most members of this class, it has been implicated in several recent terrorist incidents (Scheme 1). 3 The first deduction of the chemical structure of HMTD has been attributed 4 to Urbanski, and the compound has since been characterized by X-ray crystallography, 5 infrared, 6 Raman, and NMR spectroscopy, 7,8 and computational methods employing density functional theory (DFT). 4,6 Computation indicates the most stable conformation has D 3 symmetry and, remarkable for such a small molecule, is helically chiral ( Fig.…”

Synthesis and Degradation of Hexamethylene Triperoxide Diamine (HMTD)

“…The oxidation is catalyzed by acid,u sually citric acid. It was discovered in 1885 by Legler using formaldehyde, ammonium sulfate, and hydrogen peroxide [1].T he structure was proposed in 1900 by Baeyer and Villiger [2].V on Girsewald wast he first to use hexamine, citric acid, and hydrogen peroxide [3].X -ray diffraction showed exactly planar threefold coordination about the two bridgehead nitrogen atoms rather than pyramidal structure [4,5]. This ring strain in HMTD may account for its low thermal stability and high sensitivity to friction [6,7].B ecause there have beens everal unexpected violent reactions involving HMTD where counterterrorism personnel have beeni njured, we launched astudy to better understand its chemistry and, for the purposeso fd etection, to identify its signature under av ariety of conditions.…”

“…HMTD was synthesized according to the literature [5].T he yield of crude HMTD was ca. 50 %, assuming 1:1m olar ratio hexamine:HMTD.…”

“…The purified hexamine (397.6mg, 2.76 mmol) had am elting /sublimation point at 265-275 8C (by Mel-Temp apparatus). GC/MS( gas chromatography with mass spectrometricd etection) (144 m/z), infrared spectroscopy (IR), and 1 HN MR (CDCl 3 ): d = 4.73, showed good purity.S tirring formaldehyde and formamide at ambient conditions for ad ay yielded N-(hydroxymethyl)formamide (m/z 75, Ta ble 3e ntry 3.2) along with hexamine [9].T he synthesis of 1,3,5-triformylhexahydro-s-triazine( m/z 171, Ta ble 3e ntry 3.11) was accomplished by adding aceticformic anhydride to hexamethylenetetramine at room temperature, using the method of Gilbert [10].T etramethylene diperoxide diamine dialdehyde (TMDDD)w as synthesized by the route of Wierzbicki [5]. N,N'-methylenebisformamide (m/z 102, Ta ble 3entry 3.5) was purchased from Aldrich.…”