| High energy density cage compounds have attracted extensive attention for their high energy and low sensitivity owing to their symmetrical structures,particularly in combination with good thermal stability.Replacing the cabon atom of adamantine skeleton with one or more nitrogen atoms will make these moleculars have higher density,detonation velocity,detonation pressure and energy.It is expected that high energy density materials with excellent properties will be developed by futher study on azaadamantanes and their derivatives.Herein,recent reviews of the developments of polynitroazaadamantanes,the construction methods of azaadamantane skeletons were summarized.Then,some polynitroazaadamantanes and their derivatives were prepared,and several strategies for the construction of 2,6-diazaadamantane,2,4,6,8-tetraoxaadamantane and 2,4,6,8-tetraazaadamantane skeleton were attempted.3,5,7-Trinitro-l-azaadamantane was synthesized with overall yield of 27%from 1,3-dinitrobenzene via nitration,reduction,Henry reaction and condensation.The effects of molar ratio of HNO3 to H2SO4,mixed acid dosages and charging method on the nitration reaction were investigated.1,3,5-Trihydroxymethyl-1,3,5-trinitrocylohexane was synthesized by "stepwise" and "one-pot" process.The time of Henry reaction was shortened by increasing the reaction temperature.The effects of acids and bases on condensation of 1,3,5-trihydroxymethyl-1,3,5-trinitrocylohexane with ammonia were studied,and the reaction conditions and workup procedures were modified.The thermal stability of 3,5,7-trinitro-l-azaadamantane was studied by thermogravimetry(TG)and differential scanning calorimetry(DSC).2,4,4,8,8-Pentanitro-2-azaadamantane was prepared via Bamford-Stevens reaction,epoxidation,addition from bicyclo[3.3.1]nonane-2,6-dione in 8.8%overall yield of 11 steps.The key feature of this route is the replacement of N-acetyl by more soluble tert-butyloxycarbonyl group to afford the key intermediate 2-tert-butyloxycarbonyl-2-azaadamantane-4,8-dione.2,4,4,8,8-Pentanitro-2-azaadamantane has a crystal density of 1.813g·cm-3,calculated detonation pressure of 30.62 GPa and detonation velocity of 8250 m·s-1.TG-DSC curves show that 2,4,4,8,8-pentanitro-2-azaadamantane has good thermal stability,with an exothermic peak at 254?,which makes it possible to be used as high energetic materials.The construction of 2,6-diazaadamantane skeleton from 1,5-cyclooctadiene was attempted.In the process of one-step preparation of 9-azabicyclo[3.3.1]nona-2,6-diene from 1,2,5,6-tetrabromocyclooctane,several different ammonia sources were tried,but many byproducts were produced and no targert product was obtained,which might be attridbuted to the fact of various reactions.9-Azabicyclo[3.3.1]nonane-2,6-diol was prepared from 1,5-cyclooctadiene and 9-substituted-9-azabicyclo[3.3.1]nonane-2,6-diols,with substituent groups of acetyl,tert-butyloxycarbonyl and benzyl respectively,were prepared.The attemption to convert them to diene derivatives by bromination or esterification of hydroxyl followed by elimination but failed at all.2,4,9-Tribenzyl-2,4,9-triazaadamantane-7-ol was successfully constructed from ethyl chloroformate utilizing ozonization,reduction and condensation.Then,a novel high-performance energy compound 2,4,9-trinitro-2,4,9-triazaadamantane-7-yl nitrate was prepared from 2,4,9-tribenzyl-2,4,9-triazaadamantane-7-ol via one-pot debenzylation and acetylation followed by nitration.It has a density of 1.840g·cm-3 based on single crystal analysis.TG-DSC curves show that it has good thermal stability(198?),calculated detonation pressure of 32.03 GPa and detonation velocity of 8440 m·s-1,which are comparable to RDX.The construction of 2,4,6,8-tetraoxaadamantane skeleton was attempted by two routes.Because of the tendency of sodium 2-nitromalonaldehyde to take place Nef reaction under acidic condition,the first route was failed during the preparation of 2,2-nitromalonaldehyde.The oxidation of 2,2-dinitro-1,3-propanediol to prepare 2,2-nitromalonaldehyde gave no target product.Due to the labile property of 2,2-dibromomalonaldehyde,the bromination of sodium 2-bromomalonaldehyde failed as well.The oxidation of 2,2-ethylenedioxy-1,3-propanediol was still failed because the cycloketal moiety was deprotected and the the product couldn't be purified after oxidation.In the second route,during the course of the construction of 2,4,6,8-tetraoxaadamantane skeleton catalyzed by acid from 2,6,9-trioxa-4,8-diethoxycarbonylbicyclo-[3.3.1]nona-3,7-diene,the substrate didn't react in the weak acid and the ring of substrate was broken in both strong acid and reduction.The construction of 2,4,6,8-tetraoxaadamantane skeleton was attempted by two routes,in the first route,sodium 2-nitromalonaldehyde reacted with benzylamine and methylamine to afford N-(3-(benzylimino)-2-nitro-2-propylidene)benzylamine and 2,6,9-trimethyl-4,8-dinitro-2,6,9-triazabicyclo[3.3.1]nona-3,7-diene respectively.However,the two moleculars were found to hardly react with additional benzylamine and methylamine to construct tetraazaadamantane skeleton,the reason might be that the double bonds in both molecules connected with strong electron withdrawing nitro groups decrease dramatically the reaction activity.In the second route,the epoxidation of the double bonds and the reduction of nitro groups of 2,6,9-trimethyl-4,8-dinitro-2,6,9-triazabicyclo-[3.3.1]nona-3,7-diene were all failed.Two novel energetic compounds,2,4,4,6,6-pentaanitro-2-azaadamantane and 2,4,9-trinitro-2,4,9-triazaadamantane-7-yl nitrate,were prepared in this dissertation.A new method for the construction of 2,4,9-triazaadamantane skeleton was also developed,which provides a basic subtrate for the synthesis of 2,4,9-triazaadamantane derivatives.The construction of 2,6-diazaadamantane,2,4,6,8-tetraoxaadamantane and 2,4,6,8-tetraazaadamantane skeleton was attempted.The results establish the foundation of the synthesis of the adamantanes containing more nitro groups and nitrogen atoms. |
PDF Full Text Request