- Sila-Substitution of Alkyl Nitrates: Synthesis, Structural Characterization, and Sensitivity Studies of Highly Explosive (Nitratomethyl)-, Bis(nitratomethyl)-, and Tris(nitratomethyl)silanes and Their Corresponding Carbon Analogues
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A series of analogous nitratomethyl compounds of carbon and silicon of the formula types Me3ElCH2ONO2 (1a/1b), Me 2El(CH2ONO2)2 (2a/2b), MeEl(CH 2ONO2)3 (3a/3b), (CH2) 4El(CH2ONO2)2 (4a/4b), and (CH 2)5El(CH2ONO2)2 (5a/5b) were synthesized [El = C (a), Si (b); (CH2)4El = (sila)cyclopentane-1,1-diyl; (CH2)5El = (sila)cyclohexane-1,1-diyl]. All compounds were characterized by using NMR, IR, and Raman spectroscopy and mass spectrometry. In addition, the crystal structures of Me2C(CH2ONO2)2 (2a), (CH2)4C(CH2ONO2)2 (4a), Me2Si(CH2ONO2)2 (2b), and (CH 2)5Si(CH2ONO2)2 (5b) were determined by single-crystal X-ray diffraction. The gas-phase structures of the C/Si analogues 1a and 1b were determined by electron diffraction and compared with the results of quantum chemical calculations at different levels of theory. The thermal stabilities of the C/Si pairs 1a/1b-5a/5b were investigated by using DSC. In addition, their friction and impact sensitivities were measured with standard BAM methods. The extreme sensitivities of the silicon compounds 1b-5b compared to those of the corresponding carbon analogues 1a-5a were discussed in terms of the structures of the C/Si analogues and possible geminal Si???O interactions.
- Evangelisti, Camilla,Klapoetke, Thomas M.,Krumm, Burkhard,Nieder, Anian,Berger, Raphael J.F.,Hayes, Stuart A.,Mitzel, Norbert W.,Troegel, Dennis,Tacke, Reinhold
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experimental part
p. 4865 - 4880
(2010/08/06)
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- Clean nitrations: Novel syntheses of nitramines and nitrate esters by nitrodesilylation reactions using dinitrogen pentoxide (N2O5)
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In this novel nitration method dinitrogen pentoxide (N2O5) in an inert solvent is used as the nitrating agent, thereby removing the need for strong acids as the reaction medium. The N2O5 cleaves heteroatom-silicon bonds, in silylamines and silyl ethers respectively, to yield the desired energetic groupings (nitramines or nitrate esters respectively) without liberation of acids which would occur with conventional substrates (amines or alcohols). These nitrodesilylation reactions proceed cleanly and in good yield, and the scope of the reaction is illustrated by 29 examples, some of which produce high energy compounds, notably plasticisers and an energetic polymer precursor. These reactions are therefore potentially clean nitrations for the manufacture of energetic compounds which will minimise the impact of this activity on the environment in the future.
- Millar, Ross W.,Philbin, Simon P.
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p. 4371 - 4386
(2007/10/03)
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- Preparation of di- and polynitrates by ring-opening nitration of oxetanes by dinitrogen pentoxide (N2O5)
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Ten oxetanes bearing various substituents were reacted with N2O5 in chlorinated hydrocarbon solvents to yield 1,3-dinitrate esters (I) by ring-opening nitration. The yields ranged from 73 to 88% for di-/trinitrates derived from oxetanes unsubstituted in the 2-position, to only 15 to 21% for oxetanes bearing such substituents. Although selective ring cleavage of oxetanes bearing non-hydroxylic substituents (epoxy (oxiranyl), spiro-oxetane and alkene) was not, in general, possible, selective nitration of hydroxyalkyloxetanes was achievable under the conditions employed to yield nitrato-methyloxetanes useful as precursors for energetic polyethers. A semi-quantitative reactivity comparison with representative epoxides indicated that the reactivity of oxetanes towards N2O5 was lower, as expected on account of their lower ring strain.
- Golding,Millar,Paul,Richards
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p. 7051 - 7062
(2007/10/02)
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- NITRATION BY OXIDES OF NITROGEN, PART 1: PREPARATION OF NITRATE ESTERS BY REACTION OF STRAINED-RING OXYGEN HETEROCYCLES WITH DINITROGEN PENTOXIDE
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Epoxides and oxetanes react with dinitrogen pentoxide to give the corresponding dinitrates in high to near quantitative yields.The scope and limitations of the method are briefly discussed.
- Golding, P.,Millar, R. W.,Paul, N. C.,Richards, D. H.
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p. 2731 - 2734
(2007/10/02)
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