Chlorination and hydrolysis of o-chlorotoluene

It is obtained by chlorination and hydrolysis of o-chlorotoluene. ①Chlorination: heat o-chlorotoluene, phosphorus trichloride, and thionyl chloride to 150°C, and ventilate chlorine to the theoretical amount under ultraviolet irradiation to obtain o-chlorobenzylidene dichloride.

②Hydrolysis: Heat the mixture of o-chlorobenzylidene dichloride and zinc chloride at 120～130℃, add 1% ferric chloride aqueous solution dropwise with stirring, after the dropwise addition is completed, heat, bring water to reflux, and separate the oil layer. Refined o-chlorobenzaldehyde.

"In addition, the hydrolysis operation can also be carried out in the presence of sulfuric acid. Stir the o-chlorobenzylidene dichloride and industrial concentrated sulfuric acid together until the temperature automatically decreases and the evolution of hydrogen chloride slows down, and then slowly heat for 12 hours to keep the temperature at 30-40°C; after the reaction is complete, use a cold water layer, Separate the oily substance, wash and steam distillation to obtain the finished product.

Ortho-chlorotoluene chlorination and oxidation method

Chlorinated methyl in o-chlorotoluene and then oxidized with nitric acid. To

Add 380g (3.0mol) o-chlorotoluene to a 600mL photoreactor equipped with a thermometer, stirrer, chlorine gas blowing tube, reflux condenser and high-pressure mercury lamp illumination device, heat to 130℃, and blow 106g/chlorine gas under light. h (1.5 mol/h), pass time 3.6h. A total of 5.4 mol of chlorine gas was introduced. After the reaction is completed, dry nitrogen gas is introduced into the reaction solution to drive out hydrogen chloride and chlorine gas. A total of 558 g of the reaction solution is obtained, of which 0.5% (mol) of o-chlorotoluene, 28% of o-chlorobenzyl chloride, and 67% of o-chlorodichlorotoluene , O-chlorotrichlorotoluene 3%, the average chlorination degree of o-chloro-chlorotoluene is 1.8.

Add 64.7g (0.343mol) of the above-mentioned chlorinated mixture of o-chlorotoluene, 1440g of 3% (mass fraction) nitric acid and 2.0g of vanadium pentoxide into a 2 L three-necked flask equipped with a thermometer, stirrer and reflux condenser. , Heat to reflux for 6h under stirring. After the reaction is completed, cool, add 200 mL of toluene, separate the oil phase, and add 100 mL of toluene to the aqueous layer for extraction twice. The oil phase and the extract are combined, toluene is distilled out, and the remainder is distilled to collect 107～110°C (4.0kPa) fractions to obtain 36g of o-chlorobenzaldehyde. The yield is 73.5% based on o-chlorotoluene.