Synthetic method of o-chlorobenzaldehyde
(1) Obtained from the chlorination and hydrolysis of p-chlorotoluene: add p-chlorotoluene and phosphorus trichloride to the reaction pot, heat up to 155°C under light, and introduce chlorine gas. Control the temperature at 160-170℃, and pass chlorine to the calculated amount to obtain the chlorinated liquid. Add it to concentrated sulfuric acid while stirring, and stir at room temperature for 5 hours. Let stand for layering, take the lower layer liquid into ice water to crystallize, cool to below 5°C and filter. The filter cake is washed with ice water to obtain a crude product, and then distilled under reduced pressure, and the fraction at 108-111°C (3.33kPa) is collected to obtain the finished product.
(2) p-chlorotoluene manganese dioxide oxidation method: first add p-chlorotoluene to the reaction pot, then add 70% sulfuric acid, and slowly add manganese dioxide below 70°C. After the addition, react for 0.5h, and then steam distillation. In addition, p-chlorotoluene can be oxidized with air to obtain p-chlorobenzaldehyde.