The safe preparation and characterization (XRD, NMR and vibrational spectroscopy, DSC, mass spectrometry, sensitivities) of a new explosive dihydroxylammonium 5,5 0 bistetrazole 1,1 0 diolate (TKX 50) that outperforms all other commonly used explosive materials is detailed. While much publicized high performing explosives, such as octanitrocubane and CL 20, have been at the forefront of public awareness, this compound differs in that it is simple and cheap to prepare from commonly available chemicals. TKX 50 expands upon the newly exploited field of tetrazole oxide chemistry to produce a material that not only is easily prepared and exceedingly powerful, but also possesses the required thermal insensitivity, low toxicity, and safety of handling to replace the most commonly used military explosive, RDX (1,3,5 trinitro 1,3,5 triazacyclohexane). In addition, the crystal structures of the intermediates 5,5 0 bistetrazole 1,1 0 diol dihydrate, 5,5 0 bistetrazole 1,1 0 diol dimethanolate and dimethylammonium 5,5 0 bistetrazole 1,1 0 diolate were determined and presented.
A large variety of twice-deprotonated nitrogen-rich 5,5'-bistetrazolates, that is, the ammonium (1), hydrazinium (2), hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6), triaminoguanidinium (7), and diaminouronium (8) salts, have been synthesized. Energetic compounds 1-8 were fully characterized by single-crystal X-ray diffraction (except 8), NMR spectroscopy, IR and Raman spectroscopy, and differential scanning calorimetry (DSC) measurements. With respect to their potential use in propellant applications, the sensitivity towards impact, friction, and electrical discharge were determined. Several propulsion and detonation parameters (e.g., heat of explosion, detonation velocity) were computed by using the EXPLO5 computer code based on calculated (CBS-4M) heats of formation and X-ray densities. Additionally, the performance of 1-8 in various formulations was investigated by calculating the specific energy and specific impulse of the compounds under isochoric conditions.
Two-photon photoemission spectroscopy was employed for an investigation of the image states on Pd(111) with various coverages of Ag. Image states from areas with different thicknesses of the Ag layer can be observed simultaneously. This proves the applicability of the concept of a local work function. The decay length of the wave function of the image state on Ag(l 11) into the metal was determined experimentally to be 7.6 ± 1.2 A, and the probability to find the electron in the metal is estimated as 10%.PACS numbers: 73.61. At, 79.20.Ds, The most fundamental property of the surface of a metal is the work function, which is generally defined as the minimum energy needed (at T=0 K) to remove an electron from the metal and to bring it far away from the surface. Despite this simple definition work functions are difficult to calculate theoretically and to determine experimentally [1]. One of the experimental problems lies in the nature of real surfaces, which are not infinitely extended and homogeneous, but contain defects. These can be inherent or introduced deliberately by putting adsorbate atoms on the surface. Most methods to measure the work function determine a value averaged over a macroscopic area of the surface, which may contain terraces of the ideal surface and patches covered by defects or adsorbate atoms. It is, therefore, plausible to ascribe a local work function to each of the homogeneous areas of the surface. This local work function can be measured through the photoemission of adsorbed Xe atoms, which is able to resolve the work function locally up to the size of a Xe atom [2].In this Letter we investigate the question of what work function and potential an electron feels if it is trapped in front of a metal surface. This situation can occur if the electron cannot penetrate deep into the metal, as is the case in a gap of the projected bulk band structure, and if it cannot leave the surface, because its energy is below the vacuum energy. The electron is attracted to the surface through the image force. The resulting bound states are, therefore, called image states. The important feature in our context is that these states form a series converging towards the vacuum energy [3], which differs from the Fermi energy by the work function. The energy of the image states yields, therefore, information about the surface potential and the work function. For an inhomogeneous surface this raises the following question: Does an electron in an image state feel the macroscopic or a local work function? This addresses also the problem of the lateral extent of the wave function of the image state.We studied the image states on a Pd(lll) surface covered with various amounts of Ag. This system exhibits an epitaxial layer-by-layer growth [4], shows a large work function change, and image states have been observed for Pd(lll) [5] as well as for Ag(lll) [6]. Besides the question raised above, it is interesting to see at which thickness of the Ag film the image-state series of the Ag(lll) surface is reached. This gives di...
Abstract1H,1′H‐5,5′‐Bitetrazole‐1,1′‐diol was synthesized starting from glyoxal, which is converted to glyoxime after treatment with hydroxylamine. Chlorination of glyoxime with Cl2 gas in ethanol and following chloro/azido exchange yields diazidoglyoxime, which is cyclized under acidic conditions (HCl gas in diethyl ether) to give 1H,1′H‐5,5′‐bitetrazole‐1,1′‐diol dihydrate (1). A large variety of nitrogen‐rich salts of 1 such as the diammonium (2), the dihydrazinium (3), the bis‐guanidinium (4), the bis(aminoguanidinium) (5), the diaminoguanidinium salt monohydrate (6), the triaminoguanidinium salt monohydrate (7), the 1‐amino‐3‐nitroguanidinium salt dihydrate (8), the diaminouronium salt monohydrate (9), the bis(oxalyldihydrazidinium) (10), the oxalyldihydrazidinium salt dihydrate (11), the 3,6‐dihydrazino‐1,2,4,5‐tetrazinium (12), the 5‐aminotetrazolium (13), the bis(5‐amino‐1‐methyl‐1H‐tetrazolium) salt (14), the bis(5‐amino‐2‐methyl‐2H‐tetrazole) adduct (15), and the 1,5‐diaminotetrazolium salt (16) were synthesized by means of Brønsted acid–base or metathesis reactions. All compounds were fully characterized by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The crystal structures of 1–16 could be determined by using single‐crystal X‐ray diffraction. The heats of formation of 1–16 were calculated by using the atomization method on the basis of CBS‐4M enthalpies. With regard to their potential use as cyclotrimethylene trinitramine (RDX) or hexanitrostilbene (HNS) replacements, several detonation parameters such as the detonation pressure, detonation velocity, explosion energy, and explosion temperature were computed using the EXPLO5 code on the basis of the experimental (X‐ray) densities and calculated heats of formation. In addition, the sensitivities towards impact, friction, and electrical discharge were tested using the BAM drop hammer, a friction tester, as well as a small‐scale electrical discharge device.
Imidazole-1-sulfonyl azide hydrochloride, an inexpensive and effective diazotransfer reagent, was recently found to be impact sensitive. To identify safer-to-handle forms of this reagent, several different salts of imidazole-1-sulfonyl azide were prepared, and their sensitivity to heat, impact, friction, and electrostatic discharge was quantitatively determined. A number of these salts exhibited improved properties and can be considered safer than the aforementioned hydrochloride. The solid-state structures of the chloride and less sensitive hydrogen sulfate were determined by single-crystal X-ray diffraction in an effort to provide some insight into the different properties of the materials.
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