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1.
The values of activation parameters in uncured and cured epoxy resins, rubbers, and blends thereof are investigated. The dependences of activation energy and adhesion strength of epoxy-rubber compositions on rubber content are determined. The correlation of adhesion and activation energy values for polyurethane rubber and epoxy-rubber compositions is shown. 相似文献
2.
I. A. Bessonova Z. Sh. Faizutdinova Ya. V. Rashkes M. R. Yagudaev S. Yu. Yunusov 《Chemistry of Natural Compounds》1972,5(4):231-236
Conclusions The mass and NMR spectra of haplophyllidine, perforine, and their derivatives have been studied. The influence of the open and cyclic forms of the molecular ion on the nature of the fragmentation has been discussed. The main routes of fragmentation of the compounds considered are due to the presence of substituents at C8 and C4.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 4, pp. 273–279, 1969 相似文献
3.
Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB5型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。 相似文献
4.
I. A. Litvinov O. N. Kataeva L. V. Ermolaeva G. A. Vagina T. V. Troepol'skaya V. A. Naumov 《Russian Chemical Bulletin》1991,40(1):62-67
Aroyl- and acetylhydrazones of acet- (I) and benzaldehydes (IV) and benzoylhydrazones of acet- (II) and benzaldehydes (III) were studied by x-ray structural and quantum-chemical methods in order to establish their structures. Compund (I) was the EEZ structure in the crystal. Calculations and spectral data showed that the EEE form occurs in nonpolar solvents and in the gas phase. According to crystallographic data molecules (I)–(IV) are the E-isomers (relative to the N-N bond) and the hydrazone fragments are planar. Intermolecular N-H...O H-bonds from in the crystals. The data obtained suggest that the majority of acylhydrazones are conformationally rigid on dissolution although exceptions do occur. Apparently the reasons for the difference of acetyl- and benzoylhydrazones in electrocarboxylation reactions are electronic and not steric factors.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 75–81, January, 1991. 相似文献
5.
N. M. Bhatia P. A. Pathade H. N. More P. B. Choudhari S. D. Jadhav M. S. Bhatia 《Journal of Analytical Chemistry》2013,68(10):924-930
Verapamil is a calcium channel blocking agent which has found widespread use in the management of supraventricular tachyarrhythmias, angina pectoris, hypertrophic cardiomyopathy and hypertension. It is converted to its biologically active metabolite nor-verapamil in liver by cytochrome P450. In present communication, synthesis and characterization of nor-verapamil and development of reverse phase high performance liquid chromatographic method for the quantification of nor-verapamil along with verapamil in plasma has been carried out. The characterization of nor-verapamil was carried out using GC-MS, FT-IR and NMR spectroscopy. The separation was carried out with an isocratic JASCO RP-HPLC system using 5 μm KYA TECH HiQ Sil C18 HS column (250 mm × 4.6 mm internal diameter) as a stationary phase and methanol: water: 0.01 M orthophosphoric acid: triethylamine [70: 30: 2: 0.5, v/v/v/v] as mobile phase. The flow rate was maintained at 1.0 mL/min and UV detection at 222 nm. The calibration for verapamil and nor-verapamil were found to be linear over concentration range of 50–300 ng/mL with correlation coefficient (n = 6) of 0.9995 and 0.9997, respectively. This method was validated according to USFDA guidelines. The method was found to be simple, accuare, precise sensitive and selective for the determination of verapamil and nor-verapamil in plasma and thus useful in bioequivalence studies of verapamil. 相似文献
6.
Triazenide [M(eta2-1,3-ArNNNAr)P4]BPh4 [M = Ru, Os; Ar = Ph, p-tolyl; P = P(OMe)3, P(OEt)3, PPh(OEt)2] complexes were prepared by allowing triflate [M(kappa2-OTf)P4]OTf species to react first with 1,3-ArN=NN(H)Ar triazene and then with an excess of triethylamine. Alternatively, ruthenium triazenide [Ru(eta2-1,3-ArNNNAr)P4]BPh4 derivatives were obtained by reacting hydride [RuH(eta2-H2)P4]+ and RuH(kappa1-OTf)P4 compounds with 1,3-diaryltriazene. The complexes were characterized by spectroscopy and X-ray crystallography of the [Ru(eta2-1,3-PhNNNPh){P(OEt)3}4]BPh4 derivative. Hydride triazene [OsH(eta1-1,3-ArN=NN(H)Ar)P4]BPh4 [P = P(OEt)3, PPh(OEt)2; Ar = Ph, p-tolyl] and [RuH{eta1-1,3-p-tolyl-N=NN(H)-p-tolyl}{PPh(OEt)2}4]BPh4 derivatives were prepared by allowing kappa1-triflate MH(kappa1-OTf)P4 to react with 1,3-diaryltriazene. The [Os(kappa1-OTf){eta1-1,3-PhN=NN(H)Ph}{P(OEt)3}4]BPh4 intermediate was also obtained. Variable-temperature NMR studies were carried out using 15N-labeled triazene complexes prepared from the 1,3-Ph15N=N15N(H)Ph ligand. Osmium dihydrogen [OsH(eta2-H2)P4]BPh4 complexes [P = P(OEt)3, PPh(OEt)2] react with 1,3-ArN=NN(H)Ar triazene to give the hydride-diazene [OsH(ArN=NH)P4]BPh4 derivatives. The X-ray crystal structure determination of the [OsH(PhN=NH){PPh(OEt)2}4]BPh4 complex is reported. A reaction path to explain the formation of the diazene complexes is also reported. 相似文献
7.
Proton-NMR. spectra of amino- and hydroxypyrimidines including biologically important bases have been measured in four solvents: CF3COOH, CF3COOH? SO2, FSO3H and FSO3H? SbF5–SO2 at 27° and ?55°C. In CF3COOH mono-cations are formed, whereas in FSO3H and FSO3H? SbF5–SO2 double protonation occurs. In each case the structures of the protonated species are derived from the chemical shifts of CH, NH and OH protons and proton-proton spin coupling constants. A combination of the measurements described leads to a complete assignment of all proton resonances of the protonated pyrimidines. This approach is also recommended for the structural determination of heterocyclic compounds. 相似文献
8.
A method is reported for the extraction of molybdenum-phenylfluorone by chloroform. The extraction is complete whether perchlorate ions are present or not but the extractions in the presence of perchlorate ions gave a somewhat more sensitive procedure for the spectrophotometric determination of molybdenum in the solvent phase as the molybdenum-phenylfluorone complex.A procedure is reported for the simultaneous determination of molybdenum and selenium, and molybdenum and tellurium. The method involves first the formation and solvent extraction of the molybdenum-phenylfluorone complex by chloroform in the presence of perchlorate ions, followed by determination of selenium in the remaining aqueous phase as selenium-diethyldithiocarbamate complex after solvent extraction with 2-ethyl-1-hexanol in the presence of perchlorate ions. A similar procedure is reported for the simultaneous determination of molybdenum and tellurium except that in the determination of molybdenum, the phenylfluorone complex is extracted by chloroform in the absence of perchlorate ions. Tellurium is determined in the remaining aqueous phase as tellurium-diethyldithiocarbamate complex after solvent extraction by 2-ethyl-1-hexanol solvent extraction in the presence of perchlorate ions. 相似文献
9.
V. D. Ignatiev 《Journal of Structural Chemistry》2005,46(4):744-751
A new system of atomic radii for the elements up to barium inclusive is constructed. Values of the radii are chosen so as the dependence between the dissociation energy of diatomic homonuclear molecules and a depth of atom overlapping is monotonous, and the scatter of data is minimal. The depth of overlapping is calculated as a difference between the sum of atomic radii and an experimental interatomic distance. Conclusions are made that: the radii of free atoms and ions are determined by the value of the electron density equal to 0.01 au; they considerably change in molecules and crystals only as a result of the charge transfer from cation to anion; covalent bonding is well described by the overlapping of free atoms (ions), confined by the surface of the given radius, and its energy depends upon the depth of overlapping of valence electron densities of atoms. A method of overlapping atoms is proposed for the approximate estimation of ionic sizes and charges in bound systems. 相似文献
10.
Some strength-deformation and rheological properties of compositions of PE and SAN-copolymer obtained by three methods were studied. Light-microscopy analyses were made. It was established that the structural characteristics and the properties of the mixtures depend on the method of production rather than on composition. 相似文献
11.
Chlorine dioxide oxidation of cysteine (CSH) is investigated under pseudo-first-order conditions (with excess CSH) in buffered aqueous solutions, p[H+] 2.7-9.5 at 25.0 degrees C. The rates of chlorine dioxide decay are first order in both ClO2 and CSH concentrations and increase rapidly as the pH increases. The proposed mechanism is an electron transfer from CS- to ClO2 (1.03 x 10(8) M(-1) s(-1)) with a subsequent rapid reaction of the CS* radical and a second ClO2 to form a cysteinyl-ClO2 adduct (CSOClO). This highly reactive adduct decays via two pathways. In acidic solutions, it hydrolyzes to give CSO(2)H (sulfinic acid) and HOCl, which in turn rapidly react to form CSO3H (cysteic acid) and Cl-. As the pH increases, the (CSOClO) adduct reacts with CS- by a second pathway to form cystine (CSSC) and chlorite ion (ClO2-). The reaction stoichiometry changes from 6 ClO2:5 CSH at low pH to 2 ClO2:10 CSH at high pH. The ClO2 oxidation of glutathione anion (GS-) is also rapid with a second-order rate constant of 1.40 x 10(8) M(-1) s(-1). The reaction of ClO2 with CSSC is 7 orders of magnitude slower than the corresponding reaction with cysteinyl anion (CS-) at pH 6.7. Chlorite ion reacts with CSH; however, at p[H+] 6.7, the observed rate of this reaction is slower than the ClO2/CSH reaction by 6 orders of magnitude. Chlorite ion oxidizes CSH while being reduced to HOCl, which in turn reacts rapidly with CSH to form Cl-. The reaction products are CSSC and CSO3H with a pH-dependent distribution similar to the ClO2/CSH system. 相似文献
12.
Cowley AR Dilworth JR Nairn AK Robbie AJ 《Dalton transactions (Cambridge, England : 2003)》2005,(4):680-693
Reaction of the proligand Ph2PN(SiMe3)2 (L1) with WCl6 gives the oligomeric phosphazene complex [WCl4(NPPh2)]n, 1 and subsequent reaction with PMe2Ph or NBu4Cl gives [WCl4(NPPh2)(PMe2Ph)] (2) or [WCl5(NPPh2)][NBu4] (3), respectively. DF calculations on [WCl5(NPPh2)][NBu4] show a W=N double bond (1.756 A) and a P-N bond distance of 1.701 A, which combined with the geometry about the P atom suggests, there is no P-N multiple bonding. Reaction of L1 with [ReOX3(PPh3)2] in MeCN (X = Cl or Br) gives [ReX2(NC(CH3)P(O)Ph2)(MeCN)(PPh3)](X = Cl, 4, X = Br, 5) which contains the new phosphorylketimido ligand. It is bound to the rhenium centre with a virtually linear Re-N-C arrangement (Re-N-C angle = 176.6 degrees, when X = Cl) and there is multiple bonding between Re and N (Re-N = 1.809(7) A when X = Cl). The proligand Ph2PNHNMe2(L2H) reacts with [(C5H5)TiCl3] to give [(C5H5)TiCl2(Me2NNPPh2)] (6). An X-ray crystal structure of the complex shows the ligand (L2) is bound by both nitrogen atoms. Reaction of the proligands Ph2PNHNR2[R2 = Me2 (L2H), -(CH2CH2)2NCH3 (L3H), (CH2CH2)2CH2 (L4H)] with [{RuCl(mu-Cl)(eta6-p-MeC6H4iPr)}2] gave [RuCl2(eta6-p-MeC6H4iPr)L] {L = L2H (7), L3H (8), L4H (9)}. The X-ray crystal structures of 7-9 confirmed that the phosphinohydrazine ligand is neutral and bound via the phosphorus only. Reaction of complexes 7-9 with AgBF4 resulted in chloride ion abstraction and the formation of the cationic species [RuCl(6-p-MeC6H4iPr)(L)]+ BF4- {(L = L2H (10), L3H (11), L4H (12)}. Finally, reaction of complex 6 with [{RuCl(mu-Cl)(eta6-p-MeC6H4iPr)}2] gave the binuclear species [(eta6-p-MeC6H4iPr)Cl2Ru(mu2,eta3-Ph2PNNMe2)TiCl2(C5H5)], 13. 相似文献
13.
An efficient, transition-metal-free procedure for the N-arylation of amines, sulfonamides, and carbamates and O-arylation of phenols and carboxylic acids has been achieved by allowing these substrates to react with a variety of o-silylaryl triflates in the presence of CsF. Good to excellent yields of arylated products are obtained under very mild reaction conditions. This chemistry readily tolerates a variety of functional groups. 相似文献
14.
The recovery and preconcentration of Pb(II) and Bi(III) by coupling ion-exchange and precomplexation with 1,2-dihydroxy-3,5-benzenedisulphonic acid and 3,3',4'-trihydroxyfuchsone-2'-sulphonic acid has been investigated. Metal recoveries at 0.1-mg l . concentrations are better than 99% in the presence of cationic, anionic and non-ionic detergents, or an organic sequestering agent such as NTA, and at high ionic strength. Experiments with radiotracers show total recovery even at 15-ng l . concentrations. In the light of the results the procedure is proposed as a simple and rapid analytical method to preconcentrate Pb(II) and Bi(III). 相似文献
15.
Z. M. Enikeeva 《Chemistry of Natural Compounds》1999,35(5):556-563
New sulfur-containing derivatives of cholchicine and cholchamine with reduced toxicity and preserved pharmacological properties
(cytostatic activity for human cancer cells) are prepared. The ability of the new compounds to affect radiation treatment
is studied, enabling cholchicine derivatives with more significant radio-sensitizing properties to be found.
Institute of Oncology and Radiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya
Prirodnykh Soedinenii, No. 5, pp. 640–650, September–October, 1999. 相似文献
16.
红霉素9,11-亚胺醚和乙腈分子加合物的合成和晶体结构 总被引:1,自引:0,他引:1
通过控制红霉素A (E)肟的贝克曼重排反应条件合成了一种关键中间体红霉素9,11-亚胺醚, 该化合物可与乙腈形成稳定的分子加合物(摩尔比为1∶1), 未见文献报道. 阐述了该化合物的合成、晶体结构、晶体学数据和结构参数. 该化合物为无色透明晶体, 属单斜晶系, 空间群P21. 对该加合物和已知化合物红霉素6,9-亚胺醚晶体结构的对照解析, 有助于对重排反应机理、异构化机理和两异构体还原差异性的分析, 对重排反应和还原反应起到积极的指导作用. 相似文献
17.
Experiments have been made and an extensive thermodynamic discussion has taken place concerning the chemical transport of Mo, W, MoO2, WO2, MoS2 and WS2 in the presence of iodine. Efforts have been made to find the species via which Mo and W can migrate within the gas phase.Results: In each case the transport proceeds via the oxide iodides MoO2J2 and WO2J2 respectively, as already known for the dioxides. Thus the chemical transport of Mo, W, MoS2 and WS2 needs not only J2 but also H2O, usually liberated from the wall of the quartz ampoule.By means of J2 + H2O, the metals can be transported into the high temperature region of the ampoule (e.g., 1050 → 1150°C), whereas the transport of the sulfides proceeds in the opposite direction (e.g., 900 → 700°C).For the sulfide-transport the influence of the ratio of the transport agents has been discussed.The water content of the quartz glass out of which the ampoules are made is an important source for water, influencing the reactions.The addition of graphite which considerably lowers the H2O partial pressure prevents any transport of the metals or the sulfides, which proves that the use of J2 alone as a transport agent is insufficient in these cases.The gaseous iodides MoJx and WJz are without any importance under the experimental conditions used for the transport of the metals, their dioxides and sulfides.The partial pressures of MoO2(OH)2 and WO2(OH)2 under the experimental conditions chosen may usually be neglected. But in the system the transport via MoO2(OH)2 (1000 → 800°C) has been observed.The synthesis of MoO2 and WO2, starting with the elements or with powder of metal and trioxide is promoted by the addition of J2. The reaction steps involved are discussed. 相似文献
18.
Akira Miyashita Mayumi Ohyoshi Hiroaki Shitara Hiroyuki Nohira 《Journal of organometallic chemistry》1980,338(1):103-111
Bis(phosphine)-3,3-dimethylnickela- and palladacyclobutanes have been prepared by intramolecular C-H insertion reaction of the corresponding dineopentyl metal complexes. Nickelacyclobutane complexes decompose when heated thereby undergoing competitive carbon-carbon bond cleavage to give isobutene and ethylene, with reductive elimination affording 1,1-dimethylcyclopropane and skeletal isomeri-zation of the metallacyclic ring yielding 3-methyl-1-butene, whereas the palladium analog gave no significant amounts of CC bond cleavage products.Added phos-phine was seen to have an effect on CC bond scission of nickelacyclobutane complexes. Nickelacyclobutane complexes in solution are thought to be in equilibrium with olefin-coordinated nickel-carbene complex on the basis of available experimental evidence from hydrogenolysis, carbene-trap reactions with olefins and reaction with carbon monoxide 相似文献
19.
A. V. Borodavkin V. O. Chekhov Yu. S. Dolin Yu. V. Morozov F. A. Savin E. I. Budowsky D. Yu. Yakovlev 《International journal of quantum chemistry》1980,17(4):803-811
The individual absorption spectra of various ionic and tautomeric species of some derivatives of nucleic-acid components have been determined by computer handling of the summary spectra of these compounds measured at different pH values. These individual spectra have been decomposed into separate bands represented by log-normal curves and corresponding to different electronic transitions. Using the parameter system calculated earlier for the molecules of the vitamin B6 family, the calculation of the electronic spectra and electronic structure of various ionic and tautomeric species of the molecules studied have been carried out in the π-electron approximation. These properties have also been calculated by the all-valence electronic method CNDOS . The calculated results correlate well with both approximations and with our experimental spectral data. The localization of the molecular electronic excitation studied on the transition to the S1 and T1 states is considered in connection with the reactivity in these states. 相似文献
20.
T. Chad Willis John E. Sheats 《Journal of polymer science. Part A, Polymer chemistry》1984,22(5):1077-1084
Homopolymers of vinylruthenocene and its copolymers with methyl acrylate, styrene, and n-vinylpyrrolidinone have been prepared by free-radical polymerization. No evidence for the electron transfer termination mechanism postulated for polymerization of vinylferrocene was observed. Yields of soluble polymers were 40–90% with M w (4–25) × 103 and M w/M n = 3.0–13.2. TGA analysis showed little weight loss up to 300°C but rapid decomposition above 300°C. Polyvinylruthenocene is a highly brittle material with Tg above 250°C. Torsional braid analysis of the copolymer samples showed Tg in the range 90–130°C which in some samples increased upon cooling and reheating. Several samples showed weak thermal transitions occurring prior to or following Tg. The rise in Tg upon cooling and reheating is indicative of possible decomposition, crosslinking, or realignment of the polymer chains. 相似文献