2-Amino-5-chlorobenzaldehyde

6628-86-0

20028-53-9

Example 3 The preparation of N-(4-chloro-2-formylphenyl)trifluoromethanesulfonamide (Formula 24) was carried out according to the reaction scheme shown in Figure 1. The specific steps were as follows: 6. a) To an aqueous solution (500 mL) containing Na2S2O4 (technical grade, 85%, 29.72 g, 145.09 mmol) and Na2CO3 (12.98 g, 122.46 mmol) was added dropwise over a period of 25 min at 45 °C 5-chloro-2-nitrobenzaldehyde (technical grade, 80%, 5.31 g, 22.89 mmol) to a methanol solution (100 mL). Subsequently, the reaction mixture was heated to 65 °C. After completion of the reaction, it was cooled to room temperature and extracted three times with CH2Cl2. The organic phases were combined, washed with water, dried and the solvent was concentrated under reduced pressure. The residue was filtered through a pad of silica gel (eluent was CH2Cl2/petroleum ether, 4:1) and after concentration of the solvent under reduced pressure, 2-amino-5-chlorobenzaldehyde 23 (2.12 g, 60% yield) was obtained as a yellow oil.