Tautomeric Equilibria Studies by UV-Vis Spectroscopy in β-diketones
محل انتشار: بیستمین کنگره شیمی ایران
سال انتشار: 1397
نوع سند: مقاله کنفرانسی
زبان: انگلیسی
مشاهده: 236
متن کامل این مقاله منتشر نشده است و فقط به صورت چکیده یا چکیده مبسوط در پایگاه موجود می باشد.
توضیح: معمولا کلیه مقالاتی که کمتر از ۵ صفحه باشند در پایگاه سیویلیکا اصل مقاله (فول تکست) محسوب نمی شوند و فقط کاربران عضو بدون کسر اعتبار می توانند فایل آنها را دریافت نمایند.
- صدور گواهی نمایه سازی
- من نویسنده این مقاله هستم
استخراج به نرم افزارهای پژوهشی:
شناسه ملی سند علمی:
IRANCC20_331
تاریخ نمایه سازی: 28 اردیبهشت 1398
چکیده مقاله:
In general, β-dicarbonyl compounds may exist in several tautomeric forms. It is well known that the cis-enol form of β-diketones is characterized by a strong intramolecular hydrogen bond. Benzoylacetone (BA) and trifluorobenzoylacetone (TFBA) can be considered as representative examples of chemically asymmetric β-diketone with different substitution at β positions. We study the theoretical and experimental UV absorption spectra to understand the absorption bands for tautomerism study in the absorption spectra to these molecules. The absorption spectrum are analyzed by (TD-DFT) at B3LYP/6-311++G(d,p) level of theory in normal hexane (ε =1.88) as solvent, using PCM method, where they are compared with regard to experimental Spectra. For both cis-enol-2 and cis-enol-4 forms of the target compounds, wavelength (l), oscillator strength (), major contributions of the calculated transitions and the theoretical and experimental enol-enol equilibrium constants with the experimental wavelength are given in Table 1. According to figure 1, three experimental bands are observed for these compounds, at about 325-330, 295-300, and 255-265 nm, as strong, shoulder, and weak band, respectively. According to the theoretical results, the strong and shoulder bands at about 325-330 and 295-300 nm (see Fig. 1) have been attributed to the cis-enol-4 and cis-enol-2 forms, respectively, the weak band at about 255-265 nm has been attributed to both cis-enol-2 and cis-enol-4 forms. These equilibrium constants have been obtained theoretically as ratio of oscillator strengths, and experimentally as ratio of absorbance as strong and shoulder bands. Therefore, consistent with the previous report [1-3], both cis-enol-2 and cis-enol-4 forms are present and coexist in the samples.
نویسندگان
Vahidreza Darugar
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
Mohammad Vakili
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
Sayyed Faramarz Tayyari
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran