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1.
M. Tasumi T. Shimanouchi H. Kenjo S. Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1966,4(5):1011-1021
Various samples of irregularly deuterated polyethylene were prepared and their infrared spectra were studied. The results support the previously proposed view that poly-trans-CHD?CHD or -cis-CHD?CHD obtained with Al(i-Bu)3–TiCl4 is an irregularly deuterated chain consisting of the CH2, CHD, and CD2 groups. A simplified calculation of the CHD scissors and CDH rocking vibration frequencies has been made for various model chains. The assignments of the CDH rocking vibration bands in the region of 700–500 cm.?1 have been given on this basis. 相似文献
2.
Z. Sharaby J. Jagur-Grodzinski M. Martan D. Vofsi 《Journal of polymer science. Part A, Polymer chemistry》1982,20(4):901-915
The anionic polymerization of 1.3-cyclohexadiene (1.3-CHD) was investigated in temperatures that ranged from 25 to ?77°C. Initiation by lithium naphthalene (N?·,Li+) in tetrahydrofuran at ?20°C yields polymers with fairly narrow molecular weight distribution. The M?w of these polymers so prepared is ca. 20,000. Polymerization of 1.3-CHD conducted at room temperature is accompanied by the dehydrogenation and disproportionation of the monomer, especially when N?·,K+ acts as initiator. Oligomers are formed when hexamethylphosphoramide is used as a solvent. The mechanism of the initiation of the polymerization of 1.3-CHD by N?·,Li+ was elucidated and the rate constants at ?20°C in tetrahydrofuran of the elementary reactions were determined. It was established that the dianions formed by disproportionation of N?·,Li+ act as effective initiators for 1.3-CHD. The adducts formed constitute the cyclohexanyl and naphthyl carbanionic groups. The former carbanions (λmax ~ 275 nm) propagate the polymerization. The initially formed dimeric adducts are stabilized by the separation of the carbanionic end groups by the additional monomer units. Chain transfer to the monomer limits the growth of the polymers. The isomerization of the cyclohexadienyl anions, formed as result of chain transfer, may be followed by the elimination of lithium hydride. The latter reaction represents a termination step. Addition of 1.4-CHD to the reaction mixture enhances the chain transfer and the termination. 相似文献
3.
Nobuhiro Kuwahara Shiro Higashida Mitsuo Nakata Motozo Kaneko 《Journal of Polymer Science.Polymer Physics》1969,7(2):285-295
Osmotic-pressure, viscosity, and light-scattering measurements have been carried out on dilute solutions of poly-N-vinylcarbazole fractions (4 < 10-4M < 230) in toluene, dioxane, and benzene. The theta temperature for poly-N-vinylcarbazole in toluene solutions has been found to be 37 ± 1°C. The intrinsic viscosity of poly-N-vinylcarbazole in toluene at 37°C is represented by [η]θ = 76.2 × 10?3M?n0.50. Values of the characteristic ratios (〈L2〉0/M)1/2 and σ = (〈L2〉0/〈L2〉0f)1/2 have been obtained as 633 × 10?11 and 2.85, respectively. It appears that the large σ value is due to the steric repulsion between large side groups. 相似文献
4.
Reikichi Iwamoto Bernhard Wunderlich 《Journal of Polymer Science.Polymer Physics》1973,11(12):2403-2411
The molecular conformation and the crystal structure of α-form poly-p-xylylene has been determined by x-ray diffraction. The polymer has a monoclinic unit cell with a = 5.92, b = 10.64, c (fiber axis) = 6.55 Å, and β = 134.7°. Two chains pass through the unit cell, and the space groups is C2/m. The packing fraction is 0.705. One monomer unit makes up the fiber identity period and the internal rotation angles are 0° and 90° for the ? CH2? CH2? and ? CH2? ?? bonds, respectively. All benzene rings are in parallel orientation, perpendicular to the ac plane. 相似文献
5.
Nobuhiro Kuwahara Kazuyoshi Ogino Makoto Konuma Noriko Iida Motozo Kaneko 《Journal of Polymer Science.Polymer Physics》1966,4(2):173-181
The relationship of intrinsic viscosity to the number-average molecular weight has been obtained for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene in a few solvents. Values of (〈L2〉0/M)1/2 have been estimated for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene through the use of the treatment of Stockmayer and Fixman. The values of (〈L〉0/M)1/2 have been obtained as 2.18 ± 0.08 and 2.52 ± 0.07 for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene, respectively. The σ value of a series of polystyrene derivatives has been found to increase with the bulk of side groups. This seems to indicate that the σ value is mainly determined by the steric repulsion between side groups. 相似文献
6.
J. Courtieu Y. Gounelle P. Gonord S. K. Kan 《Magnetic resonance in chemistry : MRC》1974,6(3):151-154
The NMR spectrum of acrolein and acroyl fluoride (CH2?CH? COX with X?H and F) oriented in a nematic phase has been measured and information about conformational equilibrium s-cis ? s-trans has been obtained. The barrier to internal rotation of the COX group has been studied with various hypotheses. Good agreement between experimental and calculated spectra has been obtained using the potential equation V(?) = ΣnVn(1 – cos n?)/2, with V1 = ?200 cal mol?1, V2 = 1500 cal mol?1 and V3 = 400 cal mol?1 for the fluorine compound, and V1 = 1200 cal mol?1, V2 = 3000 cal mol?1 and V3 = 2000 cal mol?1 for acrolein; this last compound is found to be mostly in the s-trans conformation. 相似文献
7.
《Journal of Coordination Chemistry》2012,65(17):2981-2991
[RuCl2(NCCH3)2(cod)], an alternative starting material to [RuCl2(cod)] n for the preparation of ruthenium(II) complexes, has been prepared from the polymer compound and isolated in yields up to 87% using a new work-up procedure. The compound has been obtained as a yellow solid without water of crystallization. The complexes [RuCl2(NCR)2(cod)] spontaneously transform into dimers [Ru2Cl(μ-Cl)3(cod)2(NCR)] (R?=?Me, Ph). 1H NMR kinetic experiments for these transformations evidenced first-order behavior. [RuCl2(NCPh)2(cod)] dimerizes slower by a factor of ten than [RuCl2(NCCH3)2(cod)]. The following activation parameters, ΔH #?=?114?±?3?kJ?mol?1 and ΔS #?=?66?±?9?J?K?1?mol?1 for R?=?CH3CN (ΔG #?=?94?±?5?kJ?mol?1, 298.15?K) and ΔH #?=?122?±?2?kJ?mol?1 and ΔS #?=?75?±?6?J?K?1?mol?1 for R?=?Ph (ΔG #?=?100?±?4?kJ?mol?1, 298.15?K), have been calculated from the first-order rate constants in the temperature range 294–323?K. The kinetic parameters are in agreement with a two-step mechanism with dissociation of acetonitrile as the rate-determining step. The molecular structures of [Ru2Cl(μ-Cl)3(cod)2(NCR)] (R?=?Me, Ph) have been determined by X-ray diffraction. 相似文献
8.
The gas-phase elimination of several polar substituents at the α carbon of ethyl acetates has been studied in a static system over the temperature range of 310–410°C and the pressure range of 39–313 torr. These reactions are homogeneous in both clean and seasoned vessels, follow a first-order rate law, and are unimolecular. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: 2-acetoxypropionitrile, log k1 (s?1) = (12.88 ± 0.29) – (203.3 ± 2.6) kJ/mol (2.303RT)?1; for 3-acetoxy-2-butanone, log ±1(s?1) = (13.40 ± 0.20) – (202.8 ± 2.4) kJ/mol (2.303RT)?1; for 1,1,1-trichloro-2-acetoxypropane, log ?1 (s?1) = (12.12 ± 0.50) – (193.7 ± 6.0) kJ/mol (2.303RT)?; for methyl 2-acetoxypropionate, log ?1 (s?1) = (13.45 ± 0.05) – (209.5 ± 0.5) kJ/mol (2.303RT)?1; for 1-chloro-2-acetoxypropane, log ?1 (s?1) = (12.95 ± 0.15) – (197.5 ± 1.8) kJ/mol (2.303RT)?1; for 1-fluoro-2-acetoxypropane, log ?1 (s?1) = (12.83 ± 0.15)– (197.8 ± 1.8) kJ/mol (2.303RT)?1; for 1-dimethylamino-2-acetoxypropane, log ?1 (s?1) = (12.66 ± 0.22) –(185.9 ± 2.5) kJ/mol (2.303RT)?1; for 1-phenyl-2-acetoxypropane, log ?1 (s?1) = (12.53 ± 0.20) – (180.1 ± 2.3) kJ/mol (2.303RT)?1; and for 1-phenyl?3?acetoxybutane, log ?1 (s?1) = (12.33 ± 0.25) – (179.8 ± 2.9) kJ/mol (2.303RT)?1. The Cα? O bond polarization appears to be the rate-determining process in the transmition state of these pyrolysis reactions. Linear correlations of electron-releasing and electron-withdrawing groups along strong σ bonds have been projected and discussed. The present work may provide a general view on the effect of alkyl and polar substituents at the Cα? O bond in the gas-phase elimination of secondary acetates. 相似文献
9.
Katsutoshi Nagai Shuji Machida Toshiaki Nonaka 《Journal of polymer science. Part A, Polymer chemistry》1981,19(3):773-784
In the reactions of 1,3-cyclohexadiene(1,3-CHD) with polar vinyl monomers, CH2?C(X)Y (X is -? CN and ? CO2CH3; Y is ? CI, ? H, and ? CH3), the two α-chlorosubstituted monomers underwent rapid spontaneous copolymerization, accompanied by the formation of a small amount of cycloadduct. Both polar monomers also gave predominantly copolymers in the reaction with 1,3-cycloheptadiene(1,3-CHpD) in lower yield. 1,3-Cyclooctadiene (1,3-COD) reacted only with α-chloroacrylonitrile (CAN) to give a copolymer, while only cycloaddition took place in systems involving cyclopentadiene(CPD) as diene. The charge–transfer (CT) complex formation of 1,3-CHD with CAN and methyl α-chloroacrylate(MCA) was confirmed by ultraviolet spectroscopic studies and the equilibrium constants estimated were 0.18 and 0.07 liter/mole, respectively, at 25°C in chloroform as solvent. The activation energies for the copolymerizations of 1,3-CHD with CAN and MCA in benzene were determined to be ca. 6.6 and 9.6 kcal/mole, respectively. In the system composed of 1,3-CHD and CAN, only the copolymerization was affected by solvents used and oxygen. Although addition of ZnCl2 to the system resulted in the acceleration of the both reactions, the variation in the product ratio of copolymer to cycloadduct with ZnCl2 concentration showed a maximum. Based on the results in the present and preceding studies for systems involving 1,3-cyclodienes and acceptor monomers, the relationship between the cycloaddition and the spontaneous copolymerization is discussed. 相似文献
10.
《Journal of Coordination Chemistry》2012,65(17):3051-3061
Substitution reactions of trans-[CoCl2(en)2]Cl (where en?=?ethylenediamine) with L-cystine has been studied in 1.0?×?10?1?mol?dm?3 aqueous perchlorate at various temperatures (303–323?K) and pH (4.45–3.30) using UV-Vis spectrophotometer on various [Cl?] from 0.05 to 0.01?mol?L?1. The products have been characterized by their physico-chemical and spectroscopic data. Trans-[CoCl(en)2(H2O)]2+, from the hydrolysis of trans-[CoCl2(en)2]+ in the presence of Cl?, formed a complex with L-cystine at all temperatures in 1?:?1 molar ratio. L-cystine is bidentate to Co(III) through Co–N and Co–S bonds. Product formation and reversible reaction rate constants have been evaluated. The rate constants for SNi mechanism have been evaluated and activation parameters E a, ΔH #, and ΔS # are determined. 相似文献
11.
Marcel Dekker 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1017-1020
Abstract Organic salts as initiators [A? +B?: Ph?3C+ClO? 4, Ph?3C+SbCl? 6, (?)Sp? +ClO? 4, and (?)(Sp)?2 3+(ClO4)? 3] and catalysts [A +B??: (+)CSA?; A? +B??: ph?3C+(+)CSA?? and (?)Sp?+(+)CSA??] are prepared and characterized by the dissociation constant (K d), fraction of free ions (α), and specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in the polymerization of N-vinylcarbazole is in the order A? +B?? > A +B?? > A? +B?. The specific rotations of the poly(N-vinylcarbazole) (PVCZ)s obtained are generally in this order. 相似文献
12.
Tatsuro Ouchi Masaharu Inamura Akinobu Kobayashi Minoru Imoto 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2561-2569
The polymerization of vinyl monomer initiated by poly-p-vinylphenol (PVPh) in NaOH aqueous solution was carried out at 85°C with shaking. Methyl methacrylate (MMA) was polymerized, whereas styrene and acrylonitrile were not. PVPh, which is dissociated into phenolate form (PVPh?Na+) in NaOH aqueous solution, was effective for the polymerization. The effects of the amounts of MMA, PVPh, NaOH, and H2O on the conversion of MMA were studied. The rate of polymerization of MMA increased with an increase in the molecular weight of PVPh-Na. The overall activation energy was estimated as 54 kJ mol?1. The polymerization proceeded through a radical mechanism. The addition of tetra-n-butylammonium bromide increased the rate of polymerization. 相似文献
13.
Determination of Dopamine Using 2-(4-Boronophenyl)quinoline-4-carboxylic Acids as Fluorescent Probes
The selective identification of dopamine is a significant issue because this compound is an important neurotransmitter closely related to Parkinson’s disease and other mental disorders. 2-(4-Boronophenyl)quinoline-4-carboxylic acid (PBAQA) has been previously reported as a water-soluble fluorescent probe for catechol. However, there are no significant differences in the binding constants between catechol and catecholamines, such as dopamine or levodopa. Here a series of bis-boronic acid compounds based on PBAQA were synthesized and the binding activities were characterized. As a representative compound, the binding constant of 4-(4-((3-(3-borono-4-chlorobenzamido)propyl)carbamoyl)quinolin-2-yl)boronic acid to dopamine is up to 104?L?mol?1 and much higher than previously reported boronic acid probes. Dopamine selectivity may be achieved by the variation of the substituents in the probe molecules. 4-(4-((3-(3-Borono-4-methoxybenzamido)propyl)carbamoyl)quinolin-2-yl)boronic acid has a stronger binding affinity to dopamine (Ka=5204?±?106?L?mol?1) than catechol (Ka=2588?±?273?L?mol?1) or levodopa (Ka=2383?±?273?L?mol?1). This fluorescence response was used for determining dopamine in a range from 5?×?10?5?mol?L?1 to 5?×?10?4?mol?L?1 with a detection limit of 7.7?×?10?6?mol?L?1. This compound has been successfully used for the assay of dopamine in rabbit plasma, exhibiting excellent specificity. It is believed that synthesized compounds hold great promise as practical platforms to monitor dopamine levels. 相似文献
14.
J. C. J. Thynne 《Journal of mass spectrometry : JMS》1973,7(7):899-901
The negative ion mass spectra of methanol, methanol-d and trideuteromethanol have been measured at 70 eV. Use of deuterated methanols has enabled the ion at m/e 31 to be identified as CH3O? and not CH2OH?. Isotope effects have been determined for H? and D? formation, and for OH? and OD? formation. It has been shown that OH? formation occurs as a rearrangement reaction as well as by simple C? O bond fission. 相似文献
15.
The (OH)? has been investigated ab initio for four different distances ROH taking all 10 electrons into account, using the Allgemeines Programmsystem/SCF ? MO ? LC (LCGO ) Method. The equilibrium distance ROH was estimated to be 1.82 a.u., the minimum of the total energy to be ?75.305 a.u. and the ionization energy of (OH)? (electron affinity of OH) to be 2.29 eV. The force constant was computed to be k = 7.47 mdyn/Å with a frequency of ω = 3655 cm?1. 相似文献
16.
Refat M. Hassan 《Journal of polymer science. Part A, Polymer chemistry》1993,31(5):1147-1151
The kinetics of decomposition of [Alg · Mn VIO42?] intermediate complex have been investigated spectrophotometrically at a constant ionic strength of 0.5 mol dm?3. The decomposition reaction was found to be first-order in the intermediate concentration. The results showed that the rate of reaction was base-catalyzed. The kinetic parameters have been evaluated and found to be ΔS? = ?103.88±6.18 J mol?1 K?1, ΔH? = 51.61 ± 1.02 kJ mol?1, and ΔG? = 82.57 ± 2.86 kJ mol?1, respectively. A reaction mechanism consistent with the results is discussed. © 1993 John Wiley & Sons, Inc. 相似文献
17.
The CH4 molecule has been investigated ab initio, for four different distances RC? H and one distortion of a triangle HCH about the equilibrium condition, taking all 10 electrons into account, using the Allgemeines Programmsystem/SCF ? MO ? LC (LCGO ) Methode. The equilibrium distance RC? H was estimated to 2.053 a.u., the minimum of the total energy to ?40.06 a.u., the heat of formation to 17.0 eV and the ionization energy to 14.8 eV. For the breathing force constant and the force constant of the twisting vibration a ω1 of 3139 cm?1 and a ω2 of 1865 cm?1 were found. 相似文献
18.
《Journal of Coordination Chemistry》2012,65(5):920-930
A new cobalt(II) complex, [Co(C3H4N2)(C8H8O5)(H2O)2]·2H2O, of demethylcantharate(7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C8H8O5) with imidazole has been synthesized from cobalt chloride, demethylcantharidin (NCTD) and imidazole. The complex was characterized by elemental analysis, IR, and X-ray single crystal diffraction. The complex crystallized in the monoclinic crystal system and P21/m space group with a?=?0.634790(10)?nm, b?=?0.963030(10)?nm, c?=?1.221770(10)?nm, α?=?90°, β?=?95.9700(10)°, γ?=?90°, V?=?0.742844(15)?nm3, Mr ?=?383.22, Dc ?=?1.713?g?cm?3, Z?=?2, F(0?0?0)?=?398, μ?=?1.206?mm?1, the final R?=?0.0291, and wR?=?0.0837 [I?>?2σ(I?)]. The interaction of the complex with deoxyribonucleic acid (DNA) was studied by electronic absorption spectra, fluorescence spectra, and viscosity measurements, which indicate that the complex binds to calf thymus DNA through a partially intercalative mode. The binding constant K b for the complex was 2.62?×?104?L?mol?1. The antiproliferation activity test showed that the complex has high antiproliferative ability against human hepatoma cells SMMC7721 (with IC50 being 42.8?±?0.9?µmol?L?1) and human lung cancer cells A549 (with IC50 being 65.1?±?3.2?µmol?L?1). The inhibition rates of the complex are much higher than those of NCTD. 相似文献
19.
Electrochemically active ruthenium oxide (RuOx?nH2O), ruthenium oxide/hexachloroiridate (RuOx?nH2O/IrCl62?), and ruthenium oxide/hexachloroiridate/platinum (RuOx?nH2O/IrCl62?/Pt) hybrid films have been prepared from the mixture of Ru3+, IrCl62?, and PtCl62? ions in an acidic aqueous solution. The repetitive cyclic voltammetry (CV) has been used for the film preparation process. The electrochemical properties and the growth mechanism of the above mentioned different kinds of hybrid films have been investigated using CV and electrochemical quartz crystal microbalance. The morphological and quantitative analyses have been carried out using scanning electron microscopy, atomic force microscopy and energy dispersive X‐ray. Among these above mentioned films, RuOx?nH2O/IrCl62?/Pt hybrid film exhibits promising electrocatalytic activity towards the oxidation of arsenic oxide, methanol and reduction of oxygen. Further, detailed study of electrocatalysis using rotating ring disk electrodes and amperometric methods have been carried out for arsenic oxide oxidation and oxygen reduction reactions at the hybrid films. From the results, the sensitivity of RuOx?nH2O/IrCl62?/Pt hybrid film has been calculated for arsenic oxide as 0.7 mA mM?1; and for oxygen as 1.8 mA mM?1. 相似文献
20.
The NMR spectra of monochloro-, monobromo- and monofluoroacetone (CH3? CO? CH2X with X = Cl, Br, F) oriented in a nematic phase have been measured and the direct dipolar coupling constants determined. The barrier to internal rotation for the CH2F group has been studied for fluorine compound using various hypotheses. The best agreement with IR data has been obtained using the potential equation V(θ) = Σn Vn × (1 – cos nθ)/2 and a Boltzmann distribution of the CH2F group (V1 = 250 ± 50 cal.mol?1, V2 = 1650 ± 100 cal.mol?1, V3 = ?1000 ± 100 cal.mol?1). 相似文献