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温度

0 °C

To a cooled (0° C.) solution of 2-methoxymethyl-benzothiazole (2.4 g, 13.4 mmol) in concentrated sulfuric acid (8 mL) was added a mixture of 90% fuming nitric acid (2 mL) and concentrated sulfuric acid (1.3 mL) at a rate to keep the internal temperature below 5° C. After the addition was completed, the reaction mixture was stirred for 15 min at 0° C. and then at RT for 2 h. The mixture was poured into ice cold water. Collection of the precipitated solid by filtration, washing with cold water until the pH of the eluent was neutral, afforded 2.6 g (79%) of the title compound. 1H NMR (300 MHz, CDCl3): δ 8.8 (d, J=2.1 Hz, 1H), 8.36 (dd, J=9, 2.1 Hz, 1H), 8.08 (d, J=9 Hz, 1H), 4.90 (s, 2H), 3.59 (s, 3H).

1. additionwas added
2. customthe internal temperature below 5° C
3. additionAfter the addition
4. waitat RT for 2 h
5. additionThe mixture was poured into ice cold water
6. customCollection of the precipitated solid
7. filtrationby filtration
8. washwashing with cold water until the pH of the eluent