柴油十六烷值改进剂的理论研究

采用B3LYP/6-311++G**的方法对多种典型的柴油十六烷值(CN)改进剂进行了理论研究。求得硝基芳香族、硝酸酯和过氧化物3类改进剂的键裂解能。计算结果表明硝基萘、硝基苯、硝酸正丁酯和硝酸正戊酯的键裂解能太大,改进效果不明显。由相同实验条件获得的柴油CN改进值(ΔCN)结合键裂解能分析可知,随着柴油十六烷值改进剂的键裂解能的减小,ΔCN值会变大。因此,键裂解能可作为柴油十六烷值改进剂性能的重要判据。     

硝酸酯键断裂触发的含能增塑剂DNTN多阶热分解机理

采用反应分子动力学模拟、固相原位红外测试和同步热分析-红外-质谱联用技术相结合的方法对2,3-二羟甲基-2,3-二硝基-1,4-丁二醇四硝酸酯(DNTN)的热分解过程进行了研究,分析了其热分解气体产物和固相产物,阐明了其热分解机理.结果表明,DNTN的分解分为3个阶段:第一阶段为诱导分解阶段,温度区间为127～147℃,DNTN发生部分O—N键的断裂,释放少量的NO₂气体;第二阶段在147～220℃之间,DNTN快速分解,发生硝基基团脱去和季碳骨架的分解,并且伴随小环结构的生成和裂解,释放大量的NO₂和CO₂等气体,同时放出大量的热;第三阶段为240～350℃,DNTN剩余固态产物在高温下热解,释放少量的CO₂,并且在300℃后剩余的固相物质会进一步反应生成氰基.     

聚对苯二甲酸乙二醇酯二聚体模化物键离能的理论研究

采用密度泛函理论方法计算了聚对苯二甲酸乙二醇酯(PET)二聚体模化物的键离能,并设计PET热解的3条可能路径,分析PET热解机理.由于乙酸甲酯与PET具有相同的酯基官能团,因此以乙酸甲酯为简单模型参照物,采用M06-2X,B3P86,B3LYP以及BHandHLYP方法分别在基组LanL2DZ,6-31G(d),3-2...     

取代氯苯化合物的电子结构和键离解能的理论研究

利用密度泛函（DFT）三种交换／相关函数（B3LYP,B3PW91,B3P86）结合6—31G^＊＊和 6-311G^＊＊基组,计算了13个取代氯苯化合物的键离解能．结果表明B3PS6／6—311G^＊＊方法是计算取代氯苯化合物键离解能的可信方法,研究发现C—Cl键的键离解能与所使用的基组和计算方法密切相关,取代基对C—Cl键的键离解能的影响不明显．研究了目标化合物的前线轨道能级差,并对取代氯苯化合物的热稳定性做了评估．     

木质素模化物键离解能的理论研究

采用密度泛函理论B3P86方法,在6-31G(d,p)基组水平上,对木质素结构中的6种连接方式(β-O-4、α-O-4、4-O-5、β-1、α-1、5-5)的63个木质素模化物的醚键(C-O)和C-C键的键离解能E_B进行了理论计算研究。分析了不同取代基对键离解能的影响以及键长与键离解能的相关性。计算结果表明,C-O键的键离解能通常比C-C键的小,在各种醚键中C_α-O键的平均键离解能最小,为182.7 kJ/mol;其次是β-O-4连接中的C_β-O键,苯环和烷烃基上的取代基对醚键的键离解能有较强的弱化作用,C-O键的键长和键离解能的相关性较差。与C-O键相比,C-C键的键离解能受苯环上取代基的影响很小,而烷烃基上的取代基对C-C键的键离解能有较大的影响,C-C键的键离解能和键长之间存在较强的线性关系,C-C键的键长越长,其键离解能越小。     

薁X-H(X=CH2, NH, O)键离解能取代基效应的理论研究

本文利用UB3LYP/6-311++g(2df,2p)//UB3LYP/6-31+g(d)方法，首次就对位取代薁系列化合物(Y-C10H8X-H)的X-H(X=CH2, NH, O)键离解能进行了理论研究。结果发现，除了6-取代-2-甲基薁，取代基对薁X-H键离解能的效应与苯大致相同。然而，由于薁结构中固有偶极矩与不同取代基的电子效应相互作用，对位取代的羟基薁和氨基薁的反应常数( )变化非常显著。利用GE/RE和SIE理论方法，研究发现虽然基态效应在决定净取代基效应的大小中起了一定作用，但取代基效应主要来源于自由基效应的影响。     

硝酸甲酯分子间相互作用的DFT和ab initio比较

用密度泛函理论(DFT)和从头算(ab initio)方法,分别在B3LYP/6 31G和HF/6 31G水平上求得硝酸甲酯三种二聚体的全优化几何构型和电子结构,并用6 311G和6 311＋＋G基组进行总能量计算.对HF/6 31G计算结果进行MP4SDTQ电子相关校正.在各基组下均进行基组叠加误差(BSSE)和零点能(ZPE)校正求得结合能.对6 31G优化构型作振动分析并基于统计热力学求得200～600 K温度下单体和二聚体的热力学性质.详细比较两种方法的相应计算结果,发现DFT求得的分子间距离较短,分子内键长较长,所得结合能均小于相应ab initio计算值.     

反式-1,4,5,8-四硝基-1,4,5,8-四氮杂萘烷异构体热解机理与稳定性的理论研究

运用密度泛函理论和半经验分子轨道方法,对一系列高能杂环硝胺—反式-1,4,5,8-四硝基-1,4,5,8-四氮杂萘烷异构体的热解机理和稳定性进行了系统地计算研究。在B3LYP/6-31G**和PM3水平上,分别计算了标题物的化学键离解能(BDE)和热解反应活化能(Ea),并根据BDE和Ea数值考察了硝胺取代基对化合物稳定性和热解机理的影响;同时,还详细考察了BDE与Ea、化学键重叠布居数、前线轨道能级以及能隙之间的相关性。结果表明,由BDE、Ea和静态电子结构参数推断的标题物热稳定性和热解机理的结论基本是一致的,N-NO2键均裂是标题物的热解引发步骤,间位取代异构体较对位取代异构体稳定,而邻位取代的异构体稳定性最差。     

硝酸钕水合物热分解机理及脱水过程动力学的研究

本文采用TG-DTG法研究了Nd(NO)·nHO(n=6,5,4)的热分解行为,并通过IR对反应物、中间产物和最终产物进行了鉴别。发现中间产物有低水合物、无水盐和碱式盐,最终产物是氧化钕。另外,还进行了上述样品某些脱水过程的动力学研究,借助不同升温速率下的TG-DTG曲线,应用Kissinger法计算了它们脱水的表观活化能值,并利用DSC求出了它们的脱水焓值。     

5-硝基-1-氢-四唑分子热分解反应机理的密度泛函理论研究

利用密度泛函理论研究了5-硝基-1-氢-四唑分子热分解的反应机理。首先用 B3LYP/6-31G（d）方法优化反应中反应物、过渡态、中间体以及产物的几何构型， 通过振动分析得到零点能校正值并确认反应的过渡态。此外，对各个构型作了 CCSD（T）/6-31G（d,p）水平下的单点计算。报道了三条可能的反应途径，即直接 开环途径和质子转移途径；其中N（1）-N（2）键断裂直接开环的机理与文献报道 一致；而涉及质子转移的反应途径则是一个新的发现；另一条关于N（4）-C（5） 键断裂直接开环的途径由于能垒较高，因此发生的几率较小。     

Mechanism of Thermal Decomposition of d-metals Nitrates Hydrates

A series of six nitrates(V) hydrates of 4d-metals as well as mercury and cadmium thermal decomposition was examined by DTA, TG and EGA techniques. It was found that thermal decomposition of d-metals nitrate(V) hydrates proceeds in three stages: partial dehydration, oxo-nitrates and hydroxide nitrates formation and metal oxides formation. General chemical equations for all decomposition stages were proposed. It was found that dehydration of hydrated salts is accompanied by partial decomposition of nitrate(V) groups. This revised version was published online in August 2006 with corrections to the Cover Date.     

Theoretical studies on high energetic density nitramine explosives containing pyridine

The insensitive property of explosives containing pyridine is combined with the high energy of nitramine explosives,and the concept of new nitramine explosives containing pyridine is proposed,into which nitramine group with N N bonds is introduced as much as possible.Based on molecular structures of nitramine compounds containing pyridine,density functional theory(DFT) calculation method was applied to study designed molecules at B3LYP/6-31+G(d) level.The geometric and electronic structures,density,heats of formation(HOF),detonation performance and bond dissociation energies(BDE) were investigated and comparable to 1,3,5-trinitro-1,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).The simulation results reveal that molecules B and D perform similarly to traditionally used RDX.Molecule E outperform RDX,with performance that approach that of HMX and may be considered as potential candidate of high energy density compound(HEDC).These results provide basic information for molecular design of novel high energetic density compounds.     

Substituent effect on the molecular stability, group interaction, detonation performance, and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.     

Can Tetrylone Act in a Similar Fashion to Tetrylene in Ni(CO)2 Complexes? A Theoretical Study based on a Comparison using DFT Calculations

A comparison was made to investigate the structures and bonding of nickel complex that carry tetrylone and tetrylene ligands [(CO)₂Ni‐{E(PH₃)₂}] ( Ni1E ) and [(CO)₂Ni‐{NHE_Me}] ( Ni2E ) (E = C to Pb) using quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP, TZ2P+). The nature of the Ni–E bonds was analyzed with charge‐ and energy decomposition methods. The structures of tetrylone complexes Ni1E exhibit an interesting trend with the ligands E(PH₃)₂ are bonded in a tilted orientation relative to the fragment Ni(CO)₂. In contrast, the calculated equilibrium structures of complexes Ni2E exhibit the NHE_Me ligands (E = C to Sn) bonded in a head‐on way to the Ni(CO)₂ fragment, while the bending angle gives the strongest side‐on bonded ligand NHPb_Me when E = Pb. The interesting trend of the bond dissociation energy (BDE) is observed for the tetrylone, which has the same trend BDEs compared with tetrylene complexes. The EDA‐NOCV results indicate that the tetrylone ligands {E(PH₃)₂} in complexes are similar to the tetrylene ligands NHE_Me as strong σ‐donors and weak π‐acceptors. The BDEs calculated for the Ni–E bonds in Ni1E and Ni2E show that the effect of bulky ligands may obscure the intrinsic Ni–E bond strength. The bonding analysis shows that the tetrylone ligands in Ni1E may act in a similar fashion to the tetrylene ligands in Ni2E . All complexes Ni1E and Ni2E are suitable targets for synthesis.     

2，4，6-三硝基间苯二酚钡一水化合物的热分解动力学(英)

0IntroductionBarium2,4,6鄄trinitroresorecinatemonohydrate,Ba(TNR)·H2O,hasgooddetonatingpropertiesandissensitivetoflame.Itcanbeusedasinitiatingagent,igniterpowderordelaypowder.Itspreparation[1],pro鄄perties[1],crystalstructure[1]andthermalbehavior[2]haveb…     

Ab initio and DFT investigation of the structures and properties of chloromethyl and chlorofluoromethyl peroxyl radicals

Ab initio and Density Functional Theory (DFT) calculations were performed to determine the equilibrium geometries, charge distributions, spin density distributions, dipole moments, electron affinities (EAs), and C–O bond dissociation energies (BDEs) of CH₂ClO₂^? CHCl₂O₂^?, CCl₃O₂^?, CF₂ClO₂^?, CFCl₂O₂^?, and CHFClO₂^? peroxyl radicals. The C–H BDEs of the parent methanes were calculated using the same levels of theories. Both MP2(full) and B3LYP methods, using the 6‐31G(d,p) basis set, were found to be capable of accurately predicting the geometries of peroxyl radicals. The B3LYP/6‐31G(d,p) method was found to be comparable to high ab initio levels in predicting C–O BDEs of studied peroxyl radicals and C–H BDEs of the parent alkanes. The progressive chlorine substitution of hydrogen atoms in methyl peroxyl radicals results in an increase (decrease) of the spin density on the terminal (inner) oxygen, a decrease in dipole moments, and an increase in electron affinities. The substitution of fluorine by chlorine in the series CF₃O₂^? – CCl₃O₂^? was found to lengthen (destabilize) the C–O bonds. Both C–O BDEs and EAs of peroxyl radicals (RO₂^?) were found to correlate well with Taft σ* substituent constants for the R groups. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

水合硼酸锶的制备及脱水热分解动力学

以氯化锶和硼酸氢铵为原料,采用液相沉淀法制备了片状水合硼酸锶（SrB6O10•5H2O）粉体,并用XRD、FT-IR及SEM进行了表征。利用热重分析法对片状纳米硼酸锶粉体的脱水热分解动力学进行了研究,分别采用 Coats- Redfern 方程和 Flynn-Wall-Ozawa（FWO）法对热重分析数据进行了处理和拟合,初步确定了水合硼酸锶的四步脱水过程及相应的热分解反应机理,得到各步反应的表观活化能和指前因子。     

A theoretical study of five nitrates: Electronic structure and bond dissociation energies

Three density-functional methods (B3P86, B3PW91, and B3LYP) are employed to investigate the O–NO₂ bond lengths, frontier orbital energies, and O–NO₂ bond dissociation energies (BDEs) of n-propyl nitrate (NPN), isopropyl nitrate (IPN), 2-ethylhexyl nitrate (EHN), triethylene glycol dinitrate (Tri-EGDN), and tetraethylene glycol dinitrate (Tetra-EGDN). It is found that the O–NO₂ bond lengthens (destabilizes) in the order of IPN, NPN, EHN, Tetra-EGDN, and Tri-EGDN. From the data of frontier orbital energies (E_HOMO, E_LUMO), and energy gaps (ΔE), we estimate the relative thermal stability ordering of five nitrates and their corresponding radicals. The predicted BDEs of O–NO₂ bond in NPN, IPN, EHN, Tri-EGDN, and Tetra-EGDN, are 176.6, 174.5, 168.1, 156.1, and 159.3 kJ mol⁻¹, respectively. Based on the finding that the present results of BDEs are well coincident with the experimental results of apparent activation energies from the literature, we can draw a conclusion that the experimental thermolysis of five nitrates is only unimolecular homolytical cleavage of the O–NO₂ bonds.