TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The 3-methyl catechol is obtained by mixing 3-methyl salicylaldehyde with polar solvent, adding into alkali, dripping into hydrogen peroxide aqueous solution, preserving the heat and reacting for 2-5 hours. The oxidation reaction is performed using sodium peroxydisulfate as oxidizing agent. The oxidation is performed by mixing a solution of water and lower fatty alcohol, injecting 4-methyl-2,2-difluorobenzodioxole, soluble diatomic iron salt and copper salt into the reaction mixture, dripping into sodium peroxydisulfate aqueous solution or mixed solution of water and lower fatty alcohol, preserving heat, reacting at 50-100 degrees C for 1-5 hours, extracting with water-immiscible organic solvent, drying and evaporating the solvent. The molar ratio of 4-methyl-2,2-difluorobenzodioxole, soluble diatomic iron salt, copper salt and sodium peroxydisulfate is 1:0.005-0.1:0.005-0.1:2-4. The chloridization reaction is performed using phosphorus pentachloride as chloridizing agent in solvent. The fluorination reaction is performed using trihydrofluoride triethylamine. Preferred Composition: The molar ratio of 3-methyl salicylaldehyde, alkali and hydrogen peroxide aqueous solution is 1:0.5-2.0:1-2. The polar solvent is chosen from water, methanol, ethanol, lower fatty alcohol, dimethylformamide, dimethylsulfoxide, tetrahydrofuran and other water-soluble polar solvents. The alkali is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or other alkaline substance. The lower fatty alcohol is methanol or ethanol. The soluble diatomic iron salt is iron sulfate. The copper salt is copper acetate. The water-immiscible organic solvent is toluene or dimethylbenzene. The molar ratio of 4-methyl benzodioxole and phosphorus pentachloride is 1:1-1.5. The solvent is toluene, dimethylbenzene, dichloromethane, trichloromethane, carbon tetrachloride or carbon disulfide. The molar ratio of 4-methyl-2,2-difluorobenzodioxole and trihydrofluoride triethylamine is 1:1-4.