Molecular structure and vibrational assignment of benzylacetoacetate
- سال انتشار: 1388
- محل انتشار: دوازدهمین سمینار شیمی فیزیک ایران
- کد COI اختصاصی: ISPTC12_160
- زبان مقاله: انگلیسی
- تعداد مشاهده: 853
نویسندگان
Department of Chemistry, Islamic Azad university, Shahroud Branch, Shahroud, Iran
Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Chemistry, Islamic Azad university, Shahroud Branch, Shahroud, Iran
Department of Chemistry, Islamic Azad university, Shahroud Branch, Shahroud, Iran
چکیده
The cis-enol form of β-dicarbonyl compounds are stabilized by a strong intramolecular hydrogen bond with a double minimum character [1,2]. The vibrational spectra of these compounds have been the subject of numerous investigations, which support the existence of a strong intramolecular hydrogen bond of chelating nature in the enol form of β-dicarbonyl compounds [3-5]. The hydrogen bond formation leads to an enhancement of the resonance conjugation of the π-electrons, which causes a marked tendency for equalization of the bond order of the valance bonds in the resulting six-member chelated ring. Therefore, it seems that any parameter that affects the electron density of the chelated ring will change the hydrogen bond strength. It is well known that substitution in the α or β-positions drastically changes the hydrogen bond strength and the equilibrium between enol and keto tautomers [6]. BAA is an interesting compound among the -substituted derivatives so far investigated, since this compound has two - substituted groups with different effects. Comparison of this compound with AA, which has a symmetrical structure, may give an understanding of the substitution effect that the O-CH2-ph has as an electron donating group on structure and hydrogen bond strength of the system. In contrast to the regular asymmetric -diketones, BAA seems to accept the enolated proton solely on one of its two oxygen atoms (i.e. posses an asymmetric single minimum potential). Experimental Section BAA was obtained from Aldrich Chemical Co. Deuterated BAA was prepared according to the method described in the literature. The infrared and Raman spectra were taken on a Bomem MB-154 Fourier Transform spectrometer. The Raman spectrometer was equipped with a ZnSe beam splitter and a TE cooled InGaAs detector. Rayleigh filtering was afforded by a set of two Holographic technology filters. Laser power at the samples was 30 mw.کلیدواژه ها
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