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. 相似文献
Cookoff – the concept of heating explosives to ignition – is a useful tool for determining issues that may be related to safely using and storing explosives, and as such, cookoff experiments have been performed on many different materials. All explosive systems require a means of initiation, which is usually a detonator: a device that often contains a sensitive, primary explosive and a more powerful, secondary explosive. Even if the cookoff behaviors of all the individual explosives in an explosive system are known, the behavior of the combined system may be quite different. In this experiment, the cookoff behavior of non‐electric detonators is investigated. It was determined that there was no distinguishable difference between initiating detonators properly or heating them at a rate greater than 10 °C min−1. Heating detonators at rates less than 10 °C min−1 diminished their output. 相似文献
Two new highly stable energetic salts were synthesized in reasonable yield by using the high nitrogen‐content heterocycle 3,4,5‐triamino‐1,2,4‐triazole and resulting in its picrate and azotetrazolate salts. 3,4,5‐Triamino‐1,2,4‐triazolium picrate (1) and bis(3,4,5‐triamino‐1,2,4‐triazolium) 5,5′‐azotetrazolate (2) were characterized analytically and spectroscopically. X‐ray diffraction studies revealed that protonation takes place on the nitrogen N1 (crystallographically labelled as N2). The sensitivity of the compounds to shock and friction was also determined by standard BAM tests revealing a low sensitivity for both. B3LYP/6–31G(d, p) density functional (DFT) calculations were carried out to determine the enthalpy of combustion (ΔcH (1) =−3737.8 kJ mol−1, ΔcH (2) =−4577.8 kJ mol−1) and the standard enthalpy of formation (ΔfH° (1) =−498.3 kJ mol−1, (ΔfH° (2) =+524.2 kJ mol−1). The detonation pressures (P (1) =189×108 Pa, P (2) =199×108 Pa) and detonation velocities (D (1) =7015 m s−1, D (2) =7683 m s−1) were calculated using the program EXPLO5. 相似文献
A new enantioselective α‐alkylation of α‐tert‐butoxycarbonyllactams for the construction of β‐quaternary chiral pyrrolidine and piperidine core systems is reported. α‐Alkylations of N‐methyl‐α‐tert‐butoxycarbonylbutyrolactam and N‐diphenylmethyl‐α‐tert‐butoxycarbonylvalerolactam under phase‐transfer catalytic conditions (solid potassium hydroxide, toluene, −40 °C) in the presence of (S,S)‐3,4,5‐trifluorophenyl‐3,3′,5,5′‐tetrahydro‐2,6‐bis(3,4,5‐trifluorophenyl)‐4,4′‐spirobi[4H‐dinaphth[2,1‐c:1′,2′‐e]azepinium] bromide [(S,S)‐NAS Br] (5 mol%) afforded the corresponding α‐alkyl‐α‐tert‐butoxycarbonyllactams in very high chemical (up to 99%) and optical yields (up to 98% ee). Our new catalytic systems provide attractive synthetic methods for pyrrolidine‐ and piperidine‐based alkaloids and chiral intermediates with β‐quaternary carbon centers. 相似文献
N,N‐Dialkyl‐N′‐arylhydrazines have been prepared usually in high to excellent yields via the reaction of N,N‐dialkylhydrazines with aryl chlorides in the presence of Pd2(dba)3, Xphos and NaO‐t‐Bu in dioxane at 120 °C. With ortho‐substituted aryl chlorides best results have been obtained by using 2‐(2′,6′‐dimethoxybiphenyl)dicyclohexylphosphine (ligand d) as the ligand. 相似文献
The reaction of 2‐amino‐3‐carbomethoxythiophene ( 1a ) and 2‐amino‐3‐carboethoxy‐4,5‐dimethylthiophene ( 1b ) with methyl‐ or ethylmagnesium chloride leads to new 3‐(1‐aminoalkylidene)‐3H‐thiophen‐2‐ones 4a—d in good yields (60—87%). Treatment of the compounds 4a and 4c with catalytic amounts of p‐TsOH in boiling CHCl3 afforded the (±)‐4,4′‐bis‐(1‐aminoalkylidene)‐3′,4′‐4H,2′H‐[2,3′]bithiophenyl‐5,5′‐diones 9a and 9b as new interesting heterocycles in preparatively useful yields (60/mdash;65%). 相似文献
Ruthenium complexes with the formulae Ru(CO)2(PR3)2(O2CPh)2 [ 6a – h ; R=n‐Bu, p‐MeO‐C6H4, p‐Me‐C6H4, Ph, p‐Cl‐C6H4, m‐Cl‐C6H4, p‐CF3‐C6H4, m,m′‐(CF3)2C6H3] were prepared by treatment of triruthenium dodecacarbonyl [Ru3(CO)12] with the respective phosphine and benzoic acid or by the conversion of Ru(CO)3(PR3)2 ( 8e – h ) with benzoic acid. During the preparation of 8 , ruthenium hydride complexes of type Ru(CO)(PR3)3(H)2 ( 9g , h ) could be isolated as side products. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 6a – h were found to be highly effective catalysts in the addition of carboxylic acids to propargylic alcohols to give valuable β‐oxo esters. The catalyst screening revealed a considerably influence of the phosphine′s electronic nature on the resulting activities. The best performances were obtained with complexes 6g and 6h , featuring electron‐withdrawing phosphine ligands. Additionally, catalyst 6g is very active in the conversion of sterically demanding substrates, leading to a broad substrate scope. The catalytic preparation of simple as well as challenging substrates succeeds with catalyst 6g in yields that often exceed those of established literature systems. Furthermore, the reactions can be carried out with catalyst loadings down to 0.1 mol% and reaction temperatures down to 50 °C.
The formation of 4‐alkoxy‐2(5H)‐furanones was achieved via tandem alkoxylation/lactonization of γ‐hydroxy‐α,β‐acetylenic esters catalyzed by 2 mol% of [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold bis(trifluoromethanesulfonyl)imidate [Au(IPr)(NTf2)]. The economic and simple procedure was applied to a series of various secondary propargylic alcohols allowing for yields of desired product of up to 95%. In addition, tertiary propargylic alcohols bearing mostly cyclic substituents were converted into the corresponding spiro derivatives. Both primary and secondary alcohols reacted with propargylic alcohols at moderate temperatures (65–80 °C) in either neat reactions or using 1,2‐dichloroethane as a reaction medium allowing for yields of 23–95%. In contrast to [Au(IPr)(NTf2)], reactions with cationic complexes such as [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine](acetonitrile)gold tetrafluoroborate [Au(IPr)(CH3CN)][BF4] or (μ‐hydroxy)bis{[2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold} tetrafluoroborate or bis(trifluoromethanesulfonyl)imidate – [{Au(IPr)}2(μ‐OH)][X] (X=BF4, NTf2) – mostly stop after the alkoxylation. Analysis of the intermediate proved the exclusive formation of the E‐isomer which allows for the subsequent lactonization. 相似文献
The reaction of the Cu(II) bis N,O‐chelate‐complexes of L‐2,4‐diaminobutyric acid, L‐ornithine and L‐lysine {Cu[H2N–CH(COO)(CH2)nNH3]2}2+(Cl–)2 (n = 2–4) with terephthaloyl dichloride or isophthaloyl dichloride gives the polymeric complexes {‐OC–C6H4–CO–NH–(CH2)n–CH(nh2)(COO)Cu(OOC)(NH2)CH–CH2)n–NH‐}x 1 – 5 . From these the metal can be removed by precipitation of Cu(II) with H2S. The liberated ω,ω′‐N,N′‐diterephthaloyl (or iso‐phthaloyl)‐diaminoacids 6 – 10 react with [Ru(cymene)Cl2]2, [Ru(C6Me6)Cl2]2, [Cp*RhCl2]2 or [Cp*IrCl2]2 to the ligand bridged bis‐amino acidate complexes [Ln(Cl)M–(OOC)(NH2)CH–(CH2)nNH–CO]2–C6H4 11 – 14 . 相似文献