The production methods of o-phenylphenol mainly include separation methods and synthesis methods. The production method of o-phenylphenol (OPP) can be divided into two methods, a separation method and a synthesis method.
The separation method recovers from the distillation residue for producing phenol by sulfonation. The process is as follows: the distillation residue of phenol contains about 40% of phenylphenol, and the other components are phenol, inorganic salt, water and the like. After vacuum distillation, the mixed phenylphenol fraction is separated, the vacuum degree is 400-500 mmHg, and the temperature starts at 100-75 °C, but it does not exceed 135 °C. The mixture (mainly 2-hydroxybiphenyl and 4-hydroxybiphenyl) is heated and dissolved in trichloroethylene, and the 4-hydroxybiphenyl crystal is separated by cooling, centrifugally filtered and dried to obtain 4-hydroxybiphenyl. The mother liquor is washed with a sodium carbonate solution, and a dilute alkali solution is added to form a 2-hydroxybiphenyl salt. After static separation, the upper layer of 2-hydroxybiphenyl sodium salt is dehydrated under reduced pressure to obtain a finished sodium salt. Due to resource constraints, the production of o-phenylphenol by the separation process is very limited.
Synthetic method has developed a number of processes for the production of o-phenylphenol by organic synthesis technology at home and abroad. According to the different raw materials used, there are mainly the following: biphenyl oxygen method, 2-biphenyl oxygen (2-biphenylene oxide, Diphenylene oxide) is heated together with sodium metal at about 200 ° C, and then decomposed with acid to obtain OPP; aminobiphenyl diazotization hydrolysis method, diazotization of 2-aminobiphenyl, followed by hydrolysis; biphenyl Sulfonated hydrolysis method, sulfonating biphenyl with fuming sulfuric acid, caustic melting with caustic soda, and then acidifying the obtained product to obtain (in addition to the ortho product, there is a para-product), the unit consumption is 1.13t of biphenyl. /t, fuming sulfuric acid 0.77t / t, caustic soda 0.59t / t; cyclohexanone condensation dehydrogenation method, cyclohexanone liquid phase condensation synthesis of dimerketone, dimerketone gas phase catalytic dehydrogenation into OPP, and then distilled, Recrystallization from pure OPP; chlorobenzene, phenol coupling law, using chlorobenzene and phenol as raw materials, phase transfer catalysis synthesis of o-phenylphenol. This paper focuses on the production process of ortho-phenylphenol produced by the cyclohexanone condensation dehydrogenation process.
The production process and the description of the cyclohexanone condensation using a multi-tank series continuous technology, cyclohexanone and catalyst are continuously added to the first reaction kettle for reaction, and sequentially enter the second and third kettles, and the generated water is brought by the water-carrying agent. After the phase separation, the water-receiving agent is returned to each of the kettles, and the water generated by the reaction is combined and then sent to the water washing device for continuous water washing. The separated catalyst is recycled to the first reactor, and the washed reaction product continuously enters the continuous rectification unit, and the unreacted cyclohexanone is distilled off and recycled to the first reactor. After the fine dimer is metered into the dehydrogenation reactor, the crude OPP produced is subjected to rectification to remove the light component. After more than 99% of the OPP is added to the mixing tank, the stabilizer is added to the continuous sectioning and packaging, and the other part needs to be recrystallized. , centrifugation and drying to obtain more than 99.5% OPP products.