Nuclear Magnetic Resonance. Part-1. Dynamic 1H nmr Spectral Studies on lndole-l-carboxaldehydes
| Main Authors: | K. M. BISWAS, R N. DHARA, (Mrs) HAl MANTI MALLIK, (Miss) SUMITA ROY |
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| Format: | Article Journal |
| Bahasa: | eng |
| Terbitan: |
, 1986
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/6254928 |
Daftar Isi:
- Department of Chemistry, University College of Science, Univeisity of Calcutta, 92 A. P. C. Road, Calcutta-700 009 Manuscript received 7 May 1984, revised 27 March 1985, accepted 2 December 1985 3-Ethyhndole-1-carboxaldebyde (1) and 3-phenylmdole-1-carboxaldehyde (2) are shown to exist in (\(E\)) and (\( Z\)) conformations by dynamic 1H nmr spectral studies The coalescence temperature of the two rotamers of 2 is 230 and that in the case of 1 is 50°. This difference is probably due to the effect of the electron withdrawing phenyl group of the former and the electron donating ethyl group of the latter. The spectrum of the weighted average of the two rotamers of each of 1 and 2 is observed at elevated temperature (90°). The aldehyde proton of the (\(E\)) rotamers and H-7 of the (\( Z\)) rotamers resonate at higher frequencies than the corresponding protons of the other rotamers because of the deshielding effect of the benzene ring on the former and of the magnetic anisotlopy of the carbonyl group on the latter. The barriers to internal rotation about:the N—C bond of the (\(E\)) and (\( Z\)) onligurations of 1 have been determined and discussed in terms of electronic effect.