排序方式: 共有37条查询结果,搜索用时 7 毫秒
1.
Wadysaw Charmas Wawrzyniec Podkocielny Joachim Brunn 《Journal of polymer science. Part A, Polymer chemistry》1989,27(7):2397-2415
The process of oxirane ring opening of thioether glycidyl resins under various temperatures has been described. Reaction rate constants (k) and the activaton parameters (Eα, ΔH*, ΔS*) for epoxy group loss of 1,2-epoxy-3-(phenylthio)propane, 1,2-epoxy-3-(p-tolythio)propane, and 1,2-epoxy-3-(p-chloro-phenylthio)propane using classical kinetic methods were determined. The reaction products were separated and analyzed by means of chromatography and the structure of the compounds was determined by means of the spectral analyses: IR, 1H-NMR, and 13C-NMR 相似文献
2.
Wawrzyniec Podkocielny Danuta Wdowicka 《Journal of polymer science. Part A, Polymer chemistry》1983,21(10):2961-2972
New polythioesters by interfacial polycondensation of bis/4-mercaptophenyl/ether with oxalyl, succinyl, adipoyl, suberoyl, or sebacoyl chlorides were obtained. To define the optimal conditions of the process, the polythioesters of dithiol and adipoyl or sebacoyl chlorides were chosen as a model system. Yield for all reaction products and reduced viscosity were found. The following factors were studied: organic phase, contribution of catalyst, concentration and molar ratio of reagents, rate of addition of acid chloride, temperature of reaction, contribution of emulsifier, and concentration of hydrochloride acceptor. The structure of all polythioesters was determined by elementary analysis, infrared spectra, and x-ray. Initial decomposition and initial intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Some mechanical and electrical properties of polythioesters from dithiol and adipoyl or sebacoyl chlorides were studied. The molecular weights for these polymers were also determined by gel-chromatography. 相似文献
3.
Marcin Śnieżek Sebastian Stecko Irma Panfil Bartłomiej Furman Zofia Urbańczyk-Lipkowska Marek Chmielewski 《Tetrahedron: Asymmetry》2013,24(2-3):89-103
The stereoselectivity of 1,3-dipolar cycloaddition reactions of C-phenyl open-chain nitrones and α,β-unsaturated γ- and δ-lactones was investigated under thermal and catalytic conditions. It was found that under thermal conditions, the endo approach of the reactants was preferred leading to the thermodynamic product. In the presence of Sc(OTf)3 the exo adduct was obtained in high yield and selectivity. The energies of the cycloaddition reactions were investigated by means of molecular orbital calculations at the B3LYP/6-31+G(d,p) and MP3/6-31+G(d,p) theory level. Different reaction channels and reactant approaches, fitting the individual regio- and stereochemical preferences, are discussed. The computational results were compared with the corresponding experimental data and found to be in good agreement. 相似文献
4.
Irma Panfil CzesLaw Belzecki Marek Chmielewski 《Journal of carbohydrate chemistry》2013,32(3):463-470
Abstract Saturated lactone 8, easily available by 1,3-dipolar cycloaddition of nitrone 4 to unsaturated lactone 7 was transformed into the β-lactam 22having a polyol side chain at the C-3 position of the azetidinone ring. The same sequence of reactions, when applied to 9 and 10 failed to give the respective β-lactams owing to the removal of the nitrogen atoms from those molecules. 相似文献
5.
Dr. Wawrzyniec Kaszub Andrea Marino Dr. Maciej Lorenc Prof. Eric Collet Prof. Elena G. Bagryanskaya Prof. Evgeny V. Tretyakov Prof. Victor I. Ovcharenko Prof. Matvey V. Fedin 《Angewandte Chemie (International ed. in English)》2014,53(40):10636-10640
Molecular compounds with photoswitchable magnetic properties have been intensively investigated over the last decades due to their prospective applications in nanoelectronics, sensing and magnetic data storage. The family of copper‐nitroxide‐based molecular magnets represents a new promising type of photoswitchable compounds. We report the first study of these appealing systems using femtosecond optical spectroscopy. We unveil the mechanism of ultrafast (<50 fs) spin state photoswitching and establish its principal differences compared to other photoswitchable magnets. On this basis, we propose potential advantages of copper‐nitroxide‐based molecular magnets for the future design of ultrafast magnetic materials. 相似文献
6.
It is shown that Lyuksyutov's conclusion [1] about the fluctuation-induced ordering in the system of two interacting fields has no basis. 相似文献
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8.
Anna Kultys Wawrzyniec Podkocielny Stanisaw Pikus 《Journal of polymer science. Part A, Polymer chemistry》1998,36(13):2359-2369
Two series of new linear polyesters containing sulfur in the main chain were obtained by melt polycondensation of naphthalene-1,4-bis(methylthioacetic acid) (N-1,4-BMTAA) or naphthalene-1,5-bis(methylthioacetic acid) (N-1,5-BMTAA) with some aliphatic diols using a 0.05 molar excess of diol. Softening temperatures ranging from 55 to 130°C, reduced viscosities in the range of 0.15–0.39 dL/g, and low-molecular weights were their characteristic. The structure and thermal properties of all polyesters were examined by using elemental analysis, FT-IR and 1H-NMR spectroscopy, X-ray diffraction analysis, differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorymetry (DSC). The kinetics of polyester formation by uncatalyzed melt polycondensation was studied in a model system: N-1,4-BMTAA or N-1,5-BMTAA and 2,2′-oxydiethanol (ODE) at 150, 160, and 170°C. Reaction rate constants (k3) and activation parameters (ΔG‡, ΔH‡, ΔS‡) from carboxyl group loss were determined using classical kinetic methods. Hydroxyl-terminated polyesters derived from 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol were used for preparation of the polyurethanes by melt polyaddition with hexamethylene diisocyanate (HDI). They were characterized by reduced viscosity, FT-IR spectroscopy, X-ray diffraction analysis, TGA, DSC, polarizing microscope observation, and hardness and tensile properties. The resulting polyurethanes behave like high-elasticity thermoplastic elastomers, except the one derived from N-1,5-BMTAA and 1,6-hexanediol-based polyester. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2359–2369, 1998 相似文献
9.
Wawrzyniec Podkoscielny Anna Kultys 《Journal of polymer science. Part A, Polymer chemistry》1981,19(9):2167-2174
New polythioesters by interfacial polycondensation of 4,4′-di(mercaptomethyl) benzophenone with oxalyl, succinyl, adipoyl, suberoyl, and sebacoyl chlorides were obtained. To determine the optimal conditions for interfacial polycondensation the influence of the following factors on yield and value of reduced viscosity were studied: type of organic phase, the quantitative ratio of aqueous and organic phase, concentration of hydrogen chloride acceptor, molar ratio of reagents, temperature of reaction, rate of acid chloride addition, and contribution of catalyst and emulsifier. A thorough examination was carried out only for polycondensation of dithiol with adipoly and sebacoyl chlorides. The structure of all polythioesters obtained under the model conditions was determined by elementary analysis and infrared spectra. Initial decomposition and initial intensive decomposition temperature were defined from the curves of thermogravimetric analysis. Some mechanical and electrical properties of the polythioesters obtained from 4,4′-di(mercaptomethyl)benzophenone and adipoyl and sebacoyl chlorides were determined. The molecular weight was not measured because of the low solubility of the obtained polythioesters. 相似文献
10.
Irma Panfil Wojciech Abramski Marek Chmielewski 《Journal of carbohydrate chemistry》2013,32(9):1395-1403
Abstract 4-Substituted-butenolides treated with free hydroxylamine at pH=5 undergo conjugate addition - rearrangement to afford isoxazolidin-5-ones. This is in contrast to N-substituted hydroxylamines which under the same conditions produce Michael adducts only. In the presence of base, butenolides undergo racemization via flat tautomeric forms. 相似文献