Table 1.
1H NMR chemical shifts of lac dye (LD) and methylated lac dye (MLD)
| No. | Lac dye (LD) | Methylated lac dye (MLD) |
|---|---|---|
| 1 | 13.197 (1H, s)Ar-COOH | 4.121 (1H, s)Ar-COOCH3 |
| 2 | 13.638 (1H, s)Ar-COOH | 4.095 (1H, s)Ar-COOCH3 |
| 3 | 3.559 (1H, br s)Ar-OH | 3. 691 (1H, br s)Ar-OH |
| 4 | 7.670 (1H, s)Ar-H | 7.884 (1H, s)Ar-H |
| 5 | 3.421 (1H, br s)Ar-OH | 3. 691 (1H, br s)Ar-OH |
| 6 | 3.540 (1H, br s)Ar-OH | 3.958 (1H, br s)Ar-OH |
| 7 | – | – |
| 8 | 3.215 (1H, br s)Ar-OH | 3.517 (1H, br s)Ar-OH |
| 9 | – | – |
| 10 | – | – |
| 1′ | – | – |
| 2′ | 3.540 (1H, br s)Ar-OH | 3.958 (1H, br s)Ar-OH |
| 3′ | 6.884 (1H, q J = 1.9 Hz)Ar-H | 6.995 (1H, q J = 1.9 Hz)Ar-H |
| 4′ | 6.814 (1H, d J = 1.4 Hz)Ar-H | 7.163 (1H, d J = 1.4 Hz)Ar-H |
| 5′ | – | – |
| 6′ | 6.835 (1H, s)Ar-H | 7.280 (1H, s)Ar-H |
Solvent DMSO-d6, s singlet, br s broad singlet, d doublet, q quartet