The main application of benzophenone
The main application of benzophenone
1. Background and overview
Benzophenone white crystalline substance; elegant and lasting rose fragrance; melting point 48.5℃; boiling point 170℃/2kPa; freezing point>47.0℃; density D4951.0496; refractive index nD45.21.5893; insoluble in water, with 1:10 Soluble in 80% ethanol, soluble in ethanol, ether and acetic acid.
2. Production method
1) Phosgene method: The phosgene method is one of the important methods for synthesizing benzophenone series products, such as benzophenone, tetramethyl Michler's ketone, tetraethyl Michler's ketone, an important intermediate for basic dyes, etc. , The chemical reaction formula is as follows:
2) Benzoyl chloride method. From benzene and benzoyl chloride in the presence of aluminum trichloride Frett-Crafts condensation reaction to prepare benzophenone. Add benzene and zinc chloride solution into a glass-lined reaction pot, stir and heat to 70°C, add benzyl chloride dropwise, after the addition, stir and react at 70-75°C for 10 hours under reduced pressure (1.33×104Pa—2.66×104Pa) . Let stand for layering, wash the upper oily substance twice with clear water to remove zinc chloride and hydrochloric acid, and then wash it once with 1% dilute lye. The oil layer is evaporated to remove benzene and low-boiling substances below 150°C to obtain crude diphenylmethane. The yield is 95%. Add diphenylmethane and a few magnetic pieces into a glass-lined reaction pot, stir and heat to 100-115°C, and add nitric acid with a relative density of 1.4 dropwise. After the addition, keep it at 106-116°C for 8 hours. Separate the oil layer and wash it with hot water 3 times, and then wash it with 3% sodium carbonate solution 3 times. Under reduced pressure distillation, the yield is 145-180°C (666.5Pa-1199.7Pa) or 160-210°C (1333Pa-2399.4Pa) fractions to obtain benzophenone. The yield is 90%.
3. Application
There are many varieties of benzophenone series products, which have been widely used in the fields of medicine, pesticides, dyes, plastics, coatings, daily chemicals, electronic chemicals and so on. In many fields, it is mainly used as a photoinitiator, ultraviolet absorber, and pharmaceutical intermediates.
1. Photoinitiator
As an environmentally friendly green technology, light curing technology has developed vigorously in recent years and has been widely used in various industries such as coatings, inks, adhesives, electronic devices, and optical fiber materials. Photoinitiator is the main component of the light curing system, and it plays a decisive role in the sensitivity of the curing system. Photoinitiators are divided into three categories: homogeneous fragmentation type, hydrogen transfer type and cationic type. The benzophenone hydrogen transfer type photoinitiator has high quantum efficiency, fast curing speed, and the range of absorption spectrum is matched with the irradiation light source. It has good thermal stability and no dark reaction, and it is better than monomers and prepolymers. Good compatibility. The photo-cured film has no yellowing or discoloration, is low in price, and is safe to use. Therefore, it has become the photoinitiator with the largest output at present. In 2000, the domestic output of benzophenone was only 1,420t. The main benzophenone photoinitiators are benzophenone, 4-methylbenzophenone, 2-methylbenzophenone, 2,4,6-trimethylbenzophenone (EsacureTZT), etc. .
2. Ultraviolet absorber
Benzophenone UV absorbers are the most widely used and produced UV absorbers. In addition to absorbing 290-400nm ultraviolet light, it also absorbs part of visible light. Because of its good compatibility with other materials, it is widely used in plastics, inks, paints, cosmetics and other industries. There are many types of benzophenone ultraviolet absorbers, most of which are derivatives of 2,4-dihydroxybenzophenone (UV-0), such as 2-hydroxy-4-methylchlorobenzophenone ( UV-9), 2-hydroxy-4-n-octyloxybenzophenone (UV-531), 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone (UV-30), etc. . Foreign parabenzophenone series ultraviolet absorbers also have BP-X named series, such as UV-0 named BP-1, UV-531 named BP-17, UV-30 named BP-4, and so on. In recent years, people have achieved gratifying results in the research of reactive benzophenone ultraviolet absorbers, benzophenone Ni compounds and the development of new varieties. With the strengthening of people's awareness of UV protection and the rapid development of the polymer material industry, benzophenone series products as UV absorbers will also get greater development.
3. Pharmaceutical intermediates
The benzophenone series products are intermediates of many medicines. For example, benzophenone is an intermediate of anti-stun drug diphenhydramine, 2-amino-5-chlorobenzophenone is a stable pharmaceutical intermediate, 4- Chlorobenzophenone is used in the production of anti-allergic drugs such as Anqimin. For example, the high-efficiency anti-inflammatory and analgesic ketoprofen is produced by bromination, cyanidation, hydrolysis and methylation of m-methylbenzophenone.