ORGN 242 |
| Chang Kiu Lee, Kyu Ok Jeon, and Ji Sook Yu. Department of Chemistry, Kangweon National University, Chuncheon, 200-701, South Korea |
| A possibility of determining the indices of aromaticity of five-membered monoheterocyclic compounds (thiophene, pyrrole, furan) was investigated by correlating the chemical shifts of protons and carbons of a series of carbonyl derivatives. The NMR spectra of 2-formyl, 2-acetyl, 2-benzoyl, and 2-methoxycarbonyl derivatives of the heterocycles as well as their benzene counterparts were obtained in 0.1 M solution of deuteriated chloroform, dimethyl sulfoxide, and methanol. The signals of the heterocycles are linearly shifted to downfield as the polarity of the solvents are increased. But the effect of the solvent is almost negligible in the benzene derivatives. From the chemical shift values of the ortho-H a set of a new indices of aromaticity has been calculated as benzene 1.00, thiophene 0.83, pyrrole 0.72, and furan 0.63. |
|
Heterocycles and Aromatics
8:00 AM-12:00 PM, Monday, September 8, 2003 Sheraton New York -- Royal Ballroom B, Oral
Division of Organic Chemistry |