Answer
¹H NMR Spectrum Interpretation of Berberine
Overview
Berberine is a protoberberine alkaloid with a complex aromatic structure. Its ¹H NMR spectrum, typically recorded in methanol-d₄ (CD₃OD) at 600 MHz, exhibits characteristic signals corresponding to its unique hydrogen environments.
Major Peaks and Assignments
| δ (ppm) | Multiplicity | Integration | Assignment | Description |
|---|---|---|---|---|
| 9.59 | Singlet | 1H | H-8 | Aromatic proton adjacent to nitrogen atom |
| 8.56 | Singlet | 1H | H-13 | Aromatic proton in the isoquinoline moiety |
| 8.26 | Singlet | 1H | H-11 | Aromatic proton in the isoquinoline moiety |
| 8.10 | Singlet | 1H | H-1 | Aromatic proton in the isoquinoline moiety |
| 7.83 | Singlet | 1H | H-4 | Aromatic proton in the isoquinoline moiety |
| 6.98 | Singlet | 1H | H-10 | Aromatic proton in the isoquinoline moiety |
| 5.97 | Singlet | 2H | H-6 | Methylene bridge protons connecting aromatic rings |
| 4.12 | Singlet | 3H | OCH₃ | Methoxy group attached to aromatic ring |
| 4.02 | Singlet | 3H | OCH₃ | Methoxy group attached to aromatic ring |
Note: The chemical shifts and assignments provided are based on literature values and may vary slightly depending on solvent, concentration, and temperature.