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991.
Structural Characterization and Thermal Properties of 1-Amino-1-ethylamino-2,2-dinitroethylene 下载免费PDF全文
1-amino-1-ethylamino-2,2-dinitroethylene (AEFOX-7) was synthesized by the reaction of 1,1-diamino-2,2-dinitroethylene (FOX-7) and ethylamine aqueous solution at 92 oC. The the-oretical investigation on AEFOX-7 was carried out by B3LYP/6-311++G**method. The IR frequencies and NMR chemical shifts were performed and compared with the experi-mental results. The thermal behavior of AEFOX-7 was studied with differential scanning calorimetry and thermal gravity-derivative thermogravimetry methods, and can be divided into a melting process and an exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential factor of the exothermic decomposition reaction were obtained as 374.88 kJ/mol, 169.7 kJ/mol, and 1019.24 s-1, respectively. The critical temper-ature of thermal explosion of AEFOX-7 is 145.2 oC. The specific heat capacity of AEFOX-7 was determined with micro-DSC method and theoretical calculation method, and the molar heat capacity is 214.50 J/(mol K) at 298.15 K. The adiabatic time-to-explosion of AEFOX-7 was calculated to be a certain value between 1.38-1.40 s. The thermal stability of AEFOX-7 is much lower than that of FOX-7. 相似文献
992.
该文以2种不同立构聚丙烯(iPP和sPP)为讨论对象,首先研究了量化计算方法在预测高分子13C 各向同性和各向异性化学位移(CSA)中的应用,然后讨论了近年来发展的测定13C CSA粉末线形的2种重要固体NMR实验技术(SUPER和RAI)的特点和实验优化问题. 最后,利用可获得接近无扭曲线形的SUPER技术测定了等规立构聚丙烯样品的13C CSA粉末线形,并与量化计算理论结果比较. 结果表明:13C 各向同性化学位移及CSA粉末线形的理论计算结果均与固体NMR实验结果有很好的符合,预示通过13C CSA量化计算结合固体NMR实验是阐明高分子微观结构的有力工具. 相似文献
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Carboxyltransferase domain(CT) of acetyl-coenzyme A carboxylase(ACCase, EC 6.4.1.2) from a family of Poaceae is an important target of commercial herbicide APPs for controlling grass weed growth. As the abuse of APPs herbicides, the resistant ACCase due to the mutation of a single residue(Ile→Leu), which is lo-cated in CT active site, is emergent in many populations and species of Poaceae. So it is urgent to understand the re-sistant mecha-nism so as to design new effect herbicides. Herein lies the complex of CT dimmer from Lolium rigi-dum and herbicide haloxyfop successfully constructed for wild type enzyme and Ile/Leu mutant, respectively, pro-viding a basis for explaining the resistance from microscopic structure. Moreover, the binding free energy difference between wild type and mutant enzymes was predicted in good agreement with the known observation, and the various contributions to it were analyzed, by Molecular mechanics-Poisson-Boltzmann surface area(MM-PBSA) method. The results indicate the van der Waals interaction difference between the protein and inhibitor, –22.94 kJ/mol of CT wild type lower than that of mutant, is the major reason for resistance. Structure analysis further suggests that van der Waals interaction difference is originated from the steric hindrance between the side chain of mutated residue Leu and the chiral methyl group of haloxyfop. All these findings enhance the understanding of resistant mechanism of ACCase to herbicide by Ile/Leu mutation and provide an important clue for the rational design of high effective herbicides. 相似文献
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设P(n,k)为整数n分为k部的无序分拆的个数,每个分部≥1;P(n)为n的全分拆的个数.P(n,k)是用途广泛的、且又十分难予计算的数.本文证明了下述定理:当n<k,P(n,k)=0;当k≤n≤2k,P(n,k)=P(n-k);当k=1,4≤n≤5,或者当k≥2,2k+1≤n≤3k+2,P(n,k)=P(n-k)-(?)P(t)还定义了P(n,k)的良城,因面可借助若干个P(n)的值,迅速地计算大量的P(n,k)的值. 相似文献
996.
用密度泛函理论(DFT)B3LYP方法,取6-31G基组,求得环四甲撑四硝胺分子的几何构型、电子结构、 IR谱和298~1200 K的热力学性质.全优化几何构型和电子结构均具有Ci对称性.在相邻原子之间以N-NO2键的Mulliken集居数最小,表明其间电子分布较少,预示其为热解和起爆的引发键.IR谱与实验结果良好相符. 相似文献
997.
用密度泛函理论(DFT)B3LYP方法,在6-31G*基组水平下,全优化计算了环五甲撑五硝胺(CRX)的分子几何和优化构型下的电子结构.环C-N键长为0.144~0.148 nm, N-NO2键长为0.139~0.142 nm; CRX的最高占有MO(HOMO)能级和最低未占MO(LUMO)能级之间的差值ΔEg(5.2054 eV)较大,预示CRX较稳定.基于简谐振动分析求得IR谱频率和强度.运用统计热力学方法,求得在200~1200 K的热力学性质C0p,m、 S0m和H0m.还运用Kamlet公式预示了它的爆速和爆压分别为9169 m/s和37.88 GPa. 相似文献
998.
Naoki Yasuda Shigeyuki Yamamoto Yuji Wada Shozo Yanagida 《Journal of polymer science. Part A, Polymer chemistry》2001,39(24):4196-4205
Photochemical reactions of aromatic azide groups were applied for a novel photosensitive silicone ladder polymer, that is, partially vinyl‐substituted polyphenylsilsesquioxane sensitized with aromatic bisazide compounds as a photocrosslinker. The photocrosslinking reaction in this system was investigated from the viewpoint of the efficiency of the photocrosslinker, that is, the ratio of the photocrosslinker consumed for crosslinking. The numbers of photodecomposed azide groups and crosslinks in the polymer were determined by Fourier transform infrared measurements. At a higher bisazide concentration, the predominant reaction of nitrenes formed as the intermediary radical by the photolysis of azide was a coupling reaction that could not contribute to the gelation of the polymer. The ratio of the bisazide compound consumed for crosslinking showed the highest value at its concentration of 3 wt % and decreased with the addition of a larger amount. The semiempirical molecular orbital calculations were applied to the theoretical analysis of the photoreaction of nitrenes using phenylnitrene as a model structure. The calculation results indicated that the coupling reaction of nitrenes should proceed more easily than the photocrosslinking reaction in N2 atmosphere, and the fact that the oxidation of nitrenes should proceed exclusively in the atmosphere including O2 agreed with the experimental results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4196–4205, 2001 相似文献
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