Background and overview[1-2]
Phenol, also known as carbolic acid, is a basic organic chemical raw material and is widely used in the plastics industry, pharmaceutical industry, pesticide industry, and dye industry. Phenol can be directly chlorinated with chlorine or other chemical processes to produce p-chlorophenol, o-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol. Phenol and several other chlorinated derivatives of phenol. O-Chlorophenol is a colorless to yellowish-brown liquid with an unpleasant pungent odor. The relative density is 1.265 (15.5℃), the melting point is 7℃, and the boiling point is 175℃. Slightly soluble in water, soluble in ethanol, ether and sodium hydroxide solution. Can evaporate with water vapor. It is produced by chlorination and separation of phenol. For organic synthesis and dye preparation.
Apply[3]
O-Chlorophenol can be used to produce o-chlorobenzoyl chloroformate, the intermediate of the carbamate pesticide pyridoxine, and catechol, the pharmaceutical intermediate, as well as the acid-base indicator chlorophenol red.
(l) o-Chlorophenyl chloroformate is intended to obtain o-chlorophenyl chloroformate through phosgenation of o-chlorophenol. It is used as pesticide intermediates and other fine chemical intermediates.
(2) Catechol is obtained from o-chlorophenol by hydrolysis and esterification. This product is used in the pharmaceutical industry to manufacture berberine and isoproterenol. In the spice industry, it is used to synthesize vanillin, ethyl vanillin, piperonal, etc., and can also be used to produce dyes, etc. In 2002, my country’s total demand for catechol was approximately 900t. At present, all catechol production devices in my country are operating at full capacity, and their output is only 3,500t/a, which is far from meeting demand. Our country’s process for preparing catechol by basalization of phenol has been developed and mature, industrial production has also been realized, the development conditions are mature, and the raw materials hydrogen peroxide and phenol are sufficient, so it can be vigorously developed. my country’s pesticides are in a new era. A number of low-toxic and highly efficient carbamate varieties such as pyranol will continue to be developed. It is expected that my country’s production capacity of pyranol will reach 300t in 2002, and catechol will be consumed by then. About 500t. Propoxur is a non-systemic insecticide with a fumigation effect. Its efficacy is similar to that of dichlorvos, but its toxicity is extremely low. It is one of the excellent varieties of household pests and storage pest control agents recommended by the World Health Organization and has good development prospects. . It is estimated that my country’s propoxur production capacity will reach 1,000t in 2002, and approximately 650t of catechol will be consumed. tert-butylcatechol is widely used as polymerization inhibitor, antioxidant and light stabilizer. There are only a few manufacturers in my country, with an output of about 100t/a. With the localization of catechol, this product will definitely develop better in the future. my country is the main producer and exporter of vanillin in the world. The current total production capacity is about 10,000 t/a, and the annual export is nearly 200t. With the development of catechol production, vanillin production will gradually adopt new adjacent methods. Bencinol process. At present, Shanghai Xinhua Perfume Factory and Jilin Chemical Company Auxiliary Factory have adopted this method for production, with an annual consumption of catechol of about 100t. In the future, there will be greater room for development in the synthesis of vanillin via the catechol method. Piperonal is a traditional product. In recent years, it has been mainly exported. The annual output is about 300t and the consumption of catechol is about orot. The amount of catechol consumed in the production of piperonal is not expected to increase much in the near future.
(3) Chlorophenol red is obtained by mixing o-sulfobenzoic acid with o-chlorophenol and heating it at 130°C to obtain a crude product, which is then recrystallized with glacial ester acid. This product is mainly used as an acid-base indicator.
(4) Propyanophos is obtained from o-chlorophenol through substitution to o-chloro-para-phenol, and then reacts with 0-ethyl-S-propyl sulfide and phosphonium phthalide chloride under the action of acid coating agent. Propanophos is a non-systemic broad-spectrum insecticide with contact and stomach poisoning effects. It can control harmful insects and waxes in cotton and vegetable fields.
(5) Pestrocarb is obtained from the reaction of o-chlorophenol and CH3NCO. Paraprofen has a quick-acting effect and is effective against rice leafhoppers, rice planthoppers, etc. It has a short residual period of effect and cooling does not affect the effect.
(6) The synthesis method of 2,4-dichlorophenoxyacetic acid uses o-chlorophenol as raw material, first reacts with chloroacetic acid to generate o-chlorophenoxyacetic acid, and then o-chlorophenoxyacetic acid and chlorine are mixed in a mixed solvent The reaction is carried out to obtain 2,4-dichlorophenoxyacetic acid, and the mixed solvent is a mixture of DMF, water and dichloroethane. The invention uses o-chlorophenol as raw material, which not only provides an outlet for o-chlorophenol, but also provides a new idea for the synthesis of 2,4-D. The raw materials are easy to obtain and cheap, and the product production cost is low. The use of mixed solvents improves the selectivity of the reaction and avoids the use of catalysts. Through the coordination of other conditions, reaction temperature, etc., the product yield is increased, and the production of 2,6-dichlorophenoxyacetic acid and 2,4,6- For the generation of trichlorophenoxyacetic acid, the single-step yield of 2,4-dichlorophenoxyacetic acid can reach more than 95%.
Preparation[3]
(l) Sodium phenolate chloride acid precipitation method is prepared by chlorination and acid precipitation of sodium phenolate.
(2) Traditional phenol chlorination method: Phenol is distilled by passing chlorine in the solvent benzene. The chlorination reaction also produces p-chlorophenol and 2,4-dichlorophenol, which are used as high-pressure fractions during fractionation under reduced pressure. The boiling matter is collected and can be used as a by-product after separation. The yield of o-chlorophenol (mass fraction above 95%) is nearly 50%, and the yield of p-chlorophenol (mass fraction above 95%) is about 25.5%.
(3) The catalytic chlorination method of phenol uses phenol as raw material and performs selective chlorination in the solvent tetrachlorethylene under specific catalyst conditions. Obtained by distillation and purification. The Chemical Engineering Research Institute of Tianjin University successfully developed a process for the synthesis of o-chlorophenol through catalytic chlorination of phenol, and the Qingdao Jiaonan Chemical Plant Research InstituteIt has also been trial-produced based on European patents, with a phenol conversion rate of 75%, and has been used in industrial production.
Main reference materials
[1] Dictionary of Organic Compounds
[2] Degradation of o-chlorophenol in water by high-voltage pulse liquid-phase discharge
[3] Synthesis and Application of Series of Chlorinated Derivatives of Phenol
