奥克托金(HMX)的T-Jump/FTIR快速热裂解研究

采用T-Jump/FTIR快速热裂解原位红外光谱联用技术研究了奥克托金(HMX)在0.1,0.2,0.3和0.4MPa的Ar气条件下,以1000℃·s-1的升温速率快速升温至设定的反应温度,用快速扫描傅立叶变换红外光谱跟踪分析分解产物的种类和相对摩尔浓度的变化,研究了温度及压力对初始检测产物的影响.结果表明,HMX在快速热裂解5s过程中红外所检测到的主要气相产物为CO,CO2,NO,NO2,N2O,HCONH2,CH2O,H2O,HNCO及HCN,并给出了这些产物相对摩尔浓度随时间变化的曲线.根据气体产物相对摩尔浓度的比率N2O/HCN,研究了压力和反应温度对HMX的快速热裂解过程及机理的影响,认为在低温HMX分解的C—N键断裂在两竞争反应中占优,通过压力的变化证明了气相产物之间存在二次反应.     

3,4-二硝基呋咱基氧化呋咱的比热容、热力学性质、绝热至爆时间及热感度概率密度分布

应用Micro-DSCⅢ微热量仪对3,4-二硝基呋咱基氧化呋咱(DNTF)进行比热容测定, 得到了DNTF比热容随温度变化的线性方程定压cp=0.31064＋2.109×10-3T (285 K相似文献   

苦味酸碳酰肼、苦味酸氨基脲和苦味酸氨基胍的温度跃升傅里叶变换红外光谱

利用温度跃升傅里叶变换红外原位分析技术(T-jump/FTIR)对苦味酸碳酰肼,苦味酸氨基脲和苦味酸氨基胍的快速热分解过程进行了研究,利用快速扫描傅里叶变换红外光谱在线检测气相产物的种类及浓度变化趋势。研究发现,在0.1 MPa氩气气氛下,这3种化合物快速热分解过程的含氮气相产物主要有NO、NH3、HCN、NO2、HONO和HNCO,含碳气相产物主要有CO2、CO、HCN、HNCO和HONO,NH3可进一步氧化为NO2,N2O和H2O等产物;实验同时得到了快速热分解主要气相产物摩尔分数随时间的变化关系曲线。研究表明,苦味酸氨基脲作为新型、安全、环保起爆药剂和汽车安全气囊产气剂组分有很好的发展前景。     

氨基呋咱氧化为氨基硝基呋咱的合成研究

研究开发了将氨基呋咱转化为氨基硝基呋咱新的高收率氧化方法. 采用甲烷磺酸为介质, 以过氧化氢、碱或碱土金属和胺为基的氧化物(如钨酸钠或过硫酸铵)混合物的新氧化体系[H2O2/CH3SO3H/Na2WO4或(NH4)2S2O8]代替以硫酸为介质的过氧化氢和过硫酸铵混合物氧化体系, 分别对3,4-二氨基呋咱(DAF)、3,3’-二氨基-4,4’-氧化偶氮呋咱(DAAF)和3,3’-二氨基-4,4’-偶氮呋咱(DAAzF)进行氧化, 以高于65%的产率获得了3-氨基-4-硝基呋咱(ANF)和3-氨基-3’-硝 基-4,4’-氧化偶氮呋咱(ANAF), 并以15%的收率合成得到新化合物3-氨基-3’-硝基-4,4’-偶氮呋咱(ANAzF). 研究表明甲烷磺酸/过氧化氢/碱或碱土金属和胺为基的氧化物混合物是制备同时含有氨基和硝基基团的系列呋咱化合物非常有效的氧化体系.     

3,4-双（4＇-硝基呋咱-3＇-基）氧化呋咱合成、表征与性能研究

采用丙二腈为原料,经亚硝化、重排、肟化、脱水环化、分子间缩合环化以及氧化等反应合成含能化合物3,4-双（4＇-硝基呋咱-3＇-基）氧化呋咱（DNTF）,总收率为43%,并采用红外光谱、核磁共振光谱、INADEQUATE谱、质谱和元素分析等进行了结构表征.开展了DNTF物化与爆轰性能研究,其密度1.937 g/cm3,熔点109～110℃,爆速8930 m/s（ρ=1.870 g/cm3）,摩擦感度44%～60%（90°摆角）,撞击感度80%～96%（10 kg,25 cm）,特性落高H50为38.9 cm（5 kg）,爆发点315～340℃,爆热5789 J/g（ρ=1.83 g/cm3）,威力168.4%TNT当量,真空安定性（5 g样品,100℃,40 h）放气量1.09 mL.采用DSC法和TG-DTG法测定了DNTF的热稳定性,利用真空安定法研究了DNTF同1,3,5-三硝基-1,3,5-三氮杂环己烷（RDX）,1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷（HMX）,2,4,6-三硝基甲苯（TNT）及推进剂含能组分的相容性,结果表明：DNTF具有较好的热稳定性,其分解温度为253.56℃;良好的相容性,可与常用含能材料（RDX,HMX,TNT）相容.DNTF能量较高、熔点较低、机械感度适中,安定性好,可作为新一代熔铸混合炸药的液相载体.     

3-氨基-4-硝基呋咱和3,3’-二硝基-4,4’-偶氮呋咱的合成研究

3-氨基-4-硝基呋咱(ANF)及其衍生物是一类重要的含能材料. ANF的制备首先以乙二醛、盐酸羟胺和氢氧化钠为原料, 经过两步反应制得3,4-二氨基呋咱(DAF), 采用新的氧化体系过氧化氢/甲烷磺酸/钨酸钠混合物(H2O2/CH3SO3H/ Na2WO4)代替原氧化体系过氧化氢/硫酸/过硫酸铵混合物[H2O2/H2SO4/(NH4)2S2O8]氧化DAF以67%的产率获得了ANF. 然后在单电子氧化体系高锰酸钾/盐酸混合物作用下ANF发生氧化反应以54.7%的产率得到3,3’-二硝基- 4,4’-偶氮呋咱(DNAzF). 研究表明过氧化氢/甲烷磺酸/钨酸钠混合物是制备氨基硝基单/多呋咱非常有效的氧化体系.     

3-氨基-4-硝基氧化呋咱含能化合物的设计合成研究

在氧化呋咱环上引入氨基或硝基等功能基团,可提高含能化合物的能量密度和爆炸性能。为了获得更高能量密度的新型含能化合物,本文利用密度泛函理论（DFT）和单、双激发的耦合簇（CCSD）方法探索了以3-酰基叠氮基-4硝基氧化呋咱为起始材料,在二氧六环和水混合溶剂中合成3-氨基-4硝基氧化呋咱的反应机理,给出了反应的势能曲线。结果表明,该反应主要分为两个阶段：3-酰基叠氮基-4硝基氧化呋咱脱N₂后进行Curtious重排产生异氰酸酯;异氰酸酯经水解、羟基扭转、CO₂的脱离形成产物。反应的决速步为CO₂的脱离,能垒为44kcal/mol。因此,加热是实现该合成反应的必要条件。水既绿色环保,又参与反应,是该反应的最佳溶剂。这些结果为3-氨基-4-硝基氧化呋咱的实验合成提供了必要的理论依据。     

3,4-二氨基呋咱基氧化呋咱的合成及其晶体结构

通过3-氨基-4-氯肟基呋咱在稀碱作用下发生脱HC l,1,3-偶极反应制备了新型呋咱(氧化呋咱)类含能化合物3,4-二氨基呋咱基氧化呋咱(DAFF),产率70%。其结构经NMR,IR,四圆单晶X-射线衍射仪和元素分析表征。DAFF晶体属单斜晶系,空间群P21/c,a=0.8255(3)nm,b=0.9731(3)nm,c=1.1958(4)nm,β=91.93(3)°,Z=4,Dc=1.745 g.cm-3。DAFF分子不共面,三个环面扭曲。晶体中存在分子内和分子间氢键。     

3-氨基-4-硝基呋咱和3,3′-二硝基-4，4′-偶氮呋咱的合成研究

3-氨基-4-硝基呋咱（ANF）及其衍生物是一类重要的含能材料．ANF的制备首先以乙二醛、盐酸羟胺和氢氧化钠为原料,经过两步反应制得3,4-二氨基呋咱（DAF）,采用新的氧化体系过氧化氢,甲烷磺酸,钨酸钠混合物（H2O2／CH3SO3H,Na2WO4）代替原氧化体系过氧化氢／硫酸,过硫酸铵混合物[H2O2／H2SO4/（NH4）2S2O8]氧化DAF以67％的产率获得了ANF．然后在单电子氧化体系高锰酸钾,盐酸混合物作用下ANF发生氧化反应以54．7％的产率得到3,3′-二硝基,4,4′-偶氮呋咱（DNAzF）．研究表明过氧化氢,甲烷磺酸,钨酸钠混合物是制备氨基硝基单／多呋咱非常有效的氧化体系．     

用分子子图法计算硝基呋咱化合物的生成热

用新的分子子图法计算硝基呋咱类化合物的生成热,将呋咱基团视为母体,即基子图项;硝基、叠氮基、甲基、氰基拆分为一个个原子,从原子的角度来分分子子图,将碳、氢、氧、氮原子视为取代基,即亚子图项.同时考虑呋咱基团的个数,考虑1位、 2位、 3位、 4位上碳、氢、氧、氮原子及双键、叁键对生成热的影响,还考虑不饱和度、总硝基个数、环的个数(除呋咱环)、氮氮及氮氧双键的个数对生成热的影响.用这种新的分子子图编码方法,对硝基呋咱化合物的生成热进行了拟合和预估,取得了满意的结果,其回归方程的相关系数达到了0.9954.     

在束-气装置上研究Sr(1S),Sr(3P)+Cl2的化学发光反应动力学

本文在束-气条件下研究了Sr(~1S), Sr(~3P)+Cl_2的化学发光反应。实验压力为10~(-5)～10~(-4)Torr, 金属束炉温1000 K左右。同时, 观测和分析了Sr, Sr~*+Cl_2反应产物Sr(A,B)、SrCl_2~*的发光光谱。发现Cl_2压力(pcl_2)较低时, 主要生成SrCl~*; 而pcl_2增高时(>2×10~(-4)Torr), SrCl_2~*的发射光谱逐渐增强。实验结果表明, SrCl~*是单次碰撞的直接产物, 其发光强度(I_(SrCl)~*)与pcl_2、Sr的原子密度均为直线关系, 而I_(SrCl_2)~*与pCl_2成二次关系, 表明SrCl_2~*是SrCl~*和Cl_2碰撞的产物, 与BaCl_2~*的生成机理相同。由实验结果计算而得到的亚稳态Sr~*原子及基态Sr原子在Cl_2中的总消除截面分别为9.7±5 nm~2及5.8±5 nm~2。由此估计由亚稳态Sr~*及基态Sr与Cl_2反应生成SrCl(A)的相对光子产率为Φ~*/Φ~0=115。     

2,4-二硝基咪唑铅配合物Pb(DNI)2(H2O)4的热分解

应用TG, TG-DSC-FTIR-MS联用技术和热裂解原位RSFT-IR技术研究了2,4-二硝基咪唑铅(PDNI)的热分解机理. 结果表明, PDNI在102 ℃附近脱除分子内配位水, 生成Pb(DNI)2; 在284 ℃附近C—NO2断裂, 生成NO2, 咪唑环开环, 伴随发生强烈的氧化放热反应, 生成CO2, N2O和铅盐与咪唑残余基团形成的复杂混合物或多聚烃类化合物; 在300～400 ℃范围内, PDNI继续缓慢分解, 生成CO2, N2O和Pb[NCO]2; 升温至410 ℃以上, PDNI分解生成CO和Pb[CN]2.     

Structure-activity relationship of cyclic nitroxides as SOD mimics and scavengers of nitrogen dioxide and carbonate radicals

Synthetic nitroxide antioxidants attenuate oxidative damage in various experimental models. Their protective effect reportedly depends on ring size and ring substituents and is greater for nitroxides having lower oxidation potential. The present study focuses on the kinetics and mechanisms of the reactions of piperidine, pyrrolidine and oxazolidine nitroxides with HO2*/O2*-, *NO2 and CO3*- radicals, which are key intermediates in many inflammatory and degenerative diseases. It is demonstrated that nitroxides are the most efficient scavengers of *NO2 at physiological pH (k = (3-9) x 10(8) M(-1) s(-1)) and among the most effective metal-independent scavengers of CO3*- radicals (k = (2 - 6) x 10(8) M(-1) s(-1)). Their reactivity toward HO2*, though not toward *NO2 and CO3*-, depends on the nature of the ring side-chain and particularly on the ring-size. All nitroxide derivatives react slowly with O2*- and are relatively inefficient SOD mimics at physiological pH. Even piperidine nitroxides, having the highest SOD-like activity, demonstrate a catalytic activity of about 1000-fold lower than that of native SOD at pH 7.4. The present results do not indicate any correlation between the kinetics of HO2*/O2*-, *NO2 and CO3*- removal by nitroxides and their protective activity against biological oxidative stress and emphasize the importance of target-oriented nitroxides, i.e., interaction between the biological target and specific nitroxides.     

苯甲醛缩氨基脲铜（II）配合物为载体的高选择性硫氰酸根离子电极的研究

首次研究以苯甲醛缩氨基脲铜（II）[Cu(II)-BASA]为中性载体的PVC膜电极， 该电极对硫氰酸根离子（SCN~-）具有优良的电位响应特性并呈现出反Hofmeister 选择性行为，其选择性次序为：SCN~- > ClO_4~- > I~- > Sal~- > Br~- > NO_3~- > Cl~- > NO_2~- > SO_3~(2-) > SO_4~(2-) > H_2PO_4~-。电极在pH 6. 0的磷酸盐缓冲体系中，对SCN~-在1.0 * 10~(-1)～8.0 * 10~(-6) mol/L浓度范围 内呈近能斯特响应，斜率为56.0 mV/sSCN~- (28 ℃)，检测下限为3.0 * 10~(-6) mol/L。采用交流阻抗技术和紫外可见光谱技术初步研究了阴离子与载体的作用机 理，结果表明配合物中心金属原子的结构以及载体本身的结构与电极的响应行为之 间有非常密切的构效关系。该电极具有响应快、重现性好、检测限低、制备简单等 优点。将电极初步应用于实际样品废水分析，结果与HPLC法一致。     

六硝基六氮杂异伍兹烷及其残余物的热分解

在(2.0±0.1) MPa氩气氛围下六硝基六氮杂异伍兹烷(HNIW)在(204.0±0.5)、(208.0±0.5)、(212.0±0.5)和(216.0±0.5) ℃下分别加热10、20、30、40、50 和60 min. 采用元素分析、扫描电子显微镜(SEM)、傅立叶变换红外(FTIR)光谱仪、差示扫描量热(DSC)仪、热重-差示扫描量热仪-质谱(TG-DSC-MS)仪和热重-红外(TG-FTIR)仪对(208.0±0.5) ℃下得到的残余物进行研究. 结果表明, HNIW离子在210.0 ℃左右恒温热解60 min 后, 残余物的组成为C2H2N2O. 残余物中未分解的HNIW比初始HNIW稳定性差. 在等温条件下, HNIW是逐步分解的. HNIW残余物的热分解分为三个阶段, 第一个分解阶段主要为未分解的HNIW的热分解, 第二阶段主要为五员环硝铵和碳氮杂环化合物的分解反应, 第三阶段主要为五员环硝铵的分解反应和NO2的二次反应, 并获得了每一个阶段的热分解产物.     

Synthesis of Ozone at Atmospheric Pressure by a Quenched Induction-Coupled Plasma Torch

The technical feasibility of using an induction-coupled plasma (ICP) torch to synthesize ozone at atmospheric pressure is explored. Ozone concentrations up to ~250 ppm were achieved using a thermal plasma reactor system based on an ICP torch operating at 2.5 MHz and ~11 kVA with an argon/oxygen mixture as the plasma-forming gas. The corresponding production rate and yield were ~20 g ozone/hr and ~2g ozone/kWh, respectively. A gaseous oxygen quench formed ozone by rapid mixing of molecular oxygen with atomic oxygen produced by the torch. The ozone concentration in the reaction chamber was measured by Fourier Transform infrared (FTIR) spectroscopy over a wide range of experimental conditions and configurations. The geometry of the quench gas flow, the quench flow velocity, and the quench flow rate played important roles in determining the ozone concentration. The ozone concentration was sensitive to the torch RF power, but was insensitive to the torch gas flow rates. These observations are interpreted within the framework of a simple model of ozone synthesis.     

Kinetic and thermodynamic properties of the aminoxyl (NH2O*) radical

The product of one-electron oxidation of (or H-atom abstraction from) hydroxylamine is the H2NO* radical. H2NO* is a weak acid and deprotonates to form HNO-*; the pKa(H2NO*) value is 12.6+/-0.3. Irrespective of the protonation state, the second-order recombination of the aminoxyl radical yields N2 as the sole nitrogen-containing product. The following rate constants were determined: kr(2H2NO*)=1.4x10(8) M-1 s-1, kr(H2NO*+HNO-*)=2.5x10(9) M-1 s-1, and kr(2HNO-*)=4.5x10(8) M-1 s-1. The HNO-* radical reacts with O2 in an electron-transfer reaction to yield nitroxyl (HNO) and superoxide (O2-*), with a rate constant of ke(HNO-*+O2-->HNO+O2-*)=2.2x10(8) M-1 s-1. Both O2 and O2-* seem to react with deprotonated hydroxylamine (H2NO-) to set up an autoxidative chain reaction. However, closer analysis indicates that these reactions might not occur directly but are probably mediated by transition-metal ions, even in the presence of chelators, such as ethylenediamine tetraacetic acid (EDTA) or diethylenetriamine pentaacetic acid (DTPA). The following standard aqueous reduction potentials were derived: E degrees (H2NO*,2H+/H3NOH+)=1.25+/-0.01 V; E degrees (H2NO*,H+/H2NOH)=0.90+/-0.01 V; and E degrees (H2NO*/H2NO-)=0.09+/-0.01 V. In addition, we estimate the following: E degrees (H2NOH+*/H2NOH)=1.3+/-0.1 V, E degrees (HNO, H+/H2NO*)=0.52+/-0.05 V, and E degrees (HNO/HNO-*)=-0.22+/-0.05 V. From the data, we also estimate the gaseous O-H and N-H bond dissociation enthalpy (BDE) values in H2NOH, with BDE(H2NO-H)=75-77 kcal/mol and BDE(H-NHOH)=81-82 kcal/mol. These values are in good agreement with quantum chemical computations.     

Enhanced surface photochemistry in chloride-nitrate ion mixtures

Heterogeneous reactions of sea salt aerosol with various oxides of nitrogen lead to replacement of chloride ion by nitrate ion. Studies of the photochemistry of a model system were carried out using deliquesced mixtures of NaCl and NaNO3 on a Teflon substrate. Varying molar ratios of NaCl to NaNO3 (1 : 9 Cl- : NO3-, 1 : 1 Cl- : NO3-, 3 : 1 Cl- : NO3-, 9 : 1 Cl- : NO3-) and NaNO3 at the same total concentration were irradiated in air at 299 +/- 3 K and at a relative humidity of 75 +/- 8% using broadband UVB light (270-380 nm). Gaseous NO2 production was measured as a function of time using a chemiluminescence NO(y) detector. Surprisingly, an enhanced yield of NO2 was observed as the chloride to nitrate ratio increased. Molecular dynamics (MD) simulations show that as the Cl- : NO3- ratio increases, the nitrate ions are drawn closer to the interface due to the existence of a double layer of interfacial Cl- and subsurface Na+. This leads to a decreased solvent cage effect when the nitrate ion photodissociates to NO2+O*-, increasing the effective quantum yield and hence the production of gaseous NO2. The implications of enhanced NO2 and likely OH production as sea salt aerosols become processed in the atmosphere are discussed.     

Inhibition of peroxynitrite-induced nitration of tyrosine by glutathione in the presence of carbon dioxide through both radical repair and peroxynitrate formation

Peroxynitrite (ONOO-/ONOOH) is assumed to react preferentially with carbon dioxide in vivo to produce nitrogen dioxide (NO2*) and trioxocarbonate(1-) (CO3*-) radicals. We have studied the mechanism by which glutathione (GSH) inhibits the NO2*/CO3*--mediated formation of 3-nitrotyrosine. We found that even low concentrations of GSH strongly inhibit peroxynitrite-dependent tyrosine consumption (IC50 = 660 microM) as well as 3-nitrotyrosine formation (IC50) = 265 microM). From the determination of the level of oxygen produced or consumed under various initial conditions, it is inferred that GSH inhibits peroxynitrite-induced tyrosine consumption by re-reducing (repairing) the intermediate tyrosyl radicals. An additional protective pathway is mediated by the glutathiyl radical (GS*) through reduction of dioxygen to superoxide (O2*-) and reaction with NO2* to form peroxynitrate (O2NOOH/O2NOO-), which is largely unreactive towards tyrosine. Thus, GSH is highly effective in protecting tyrosine against an attack by peroxynitrite in the presence of CO2. Consequently, formation of 3-nitrotyrosine by freely diffusing NO2* radicals is highly unlikely at physiological levels of GSH.