1H and 13C NMR spectra of betaines, >N+(CH2)nCOO−, and their hydrogen halides. Additivity rules for carbon-13 chemical shifts
✍ Scribed by Zofia Dega-Szafran; Ewa Dulewicz; Mirosław Szafran
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 86 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0749-1581
No coin nor oath required. For personal study only.
✦ Synopsis
The 1 H and 13 C chemical shifts of N-methylpiperidine betaines (1), C 5 H 10 N C CH 3 CH 2 n COO , and their derivatives C 5 H 10 N C CH 3 CH 2 n COOHÐX (2) and C 5 H 10 N C CH 3 CH 2 n COOC 2 H 5 ÐX (3) with n D 1-5 were identified using two-dimensional homonuclear ( 1 H) chemical shift correlation (COSY) and heteronuclear ( 1 H, 13 C) chemical shift correlation spectroscopy (H,C-COSY). The effects of the positively charged nitrogen and COO , COOH, COOEt groups on the methylene protons in the tether groups [N C CH 2 n COO] and the ring protons in 1, N-methylpyrrolidine betaines (4), pyridine betaines (6) and their hydrogen halides, were analysed. Empirical additivity rules for the 13 C chemical shifts of tether C-1, C-2, C-3, C-4 and C-5 atoms for 1, 4 and 6 and their hydrogen halides were derived from the experimental results. The effect of N C on the ˇcarbon vary with the ring type.