排序方式: 共有2条查询结果,搜索用时 0 毫秒
1
1.
V. K. Rastogi M. A. Palafox Surabhi Singhal S. P. Ojha W. Kiefer 《International journal of quantum chemistry》2007,107(5):1099-1114
The geometry, vibrational wavenumbers, and thermodynamical parameters have been calculated using density functional methods (DFT) for benzonitrile (BN) and the six difluorobenzonitriles (DFBNs) of the series. The results were compared with the available experimental data, and correlations were established for the ? C?N and C? F moieties between the natural atomic charges and the geometrical parameters of the compounds. These relations were found as linear or slightly parabolic in most cases. Investigations were carried out to examine the effect of substituents on structural deformations and other properties. Correlations were also determined with the stretching vibrations. Other general conclusions have also been drawn. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
2.
Hans R. Kricheldorf Mazen Garaleh Gert Schwarz 《Journal of polymer science. Part A, Polymer chemistry》2003,41(23):3838-3846
Bisphenol A was polycondensed with 2,6‐dichlorobenzonitrile, 2,6‐difluorobenzonitrile, 2,4‐difluorobenzonitrile, and 3,5‐difluorobenzonitrile in sulfolane. With 2,6‐and 2,4‐difluorobenzonitrile, quantitative conversions were achieved, and matrix‐assisted laser desorption/time‐of‐flight mass spectra revealed a nearly quantitative formation of cyclic oligoethers and polyethers. Furthermore, O,O′‐bistrimethylsilyl bisphenol A was polycondensed with the aforementioned dihalobenzonitriles in dry N‐methylpyrrolidone (promoted by potassium carbonate). Both the temperature and time were optimized. Only with 2,6‐difluorobenzonitrile were nearly quantitative conversions achieved, and this resulted in high molecular weights and high cycle contents. Size exclusion chromatography elution curves exhibited a tendency toward a bimodal character when larger fractions of cycles were present. Calibration with polystyrene standards indicated number‐average molecular weights of up to 105 Da and weight‐average molecular weights of up to 2.3 × 105 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3838–3846, 2003 相似文献
1