Main applications of benzophenone_Kain Industrial Additives

Background and overview^[1]

Benzophenone is a white crystalline substance; elegant and long-lasting rose aroma; 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.

Preparation method^[2-3]

1) Phosgene method: The phosgene method is one of the important methods for synthesizing benzophenone series products, such as: benzophenone, important intermediates of basic dyes, tetramethylmysterol’s ketone, tetraethylbenzophenone The chemical reaction formula is as follows:

2) Benzoyl chloride method. Benzophenone is produced by the Freit-Crafts condensation reaction of benzene and benzoyl chloride in the presence of aluminum trichloride. Add the benzene and zinc chloride solution into the glass-lined reaction pot, stir and heat to 70°C, add benzyl chloride dropwise, complete the addition, stir and react at 70-75°C for 10 hours under reduced pressure (1.33×104Pa-2.66×104Pa) . Let stand and separate into layers. Wash the upper oily substance twice with clean water to remove zinc chloride and hydrochloric acid, and then wash it once with 1% dilute alkali solution. The oil layer is evaporated to remove benzene and low boiling matter below 150°C to obtain crude diphenylmethane. The yield is 95%. Add diphenylmethane and several magnetic pieces into the glass-lined reaction pot in sequence, stir and heat to 100-115°C, and dropwise add nitric acid with a relative density of 1.4. After adding, keep it at 106-116℃ for 8 hours. Separate the oil layer and wash it three times with hot water, and then wash it three times with 3% sodium carbonate solution. Distillation under reduced pressure yields 145-180°C (666.5Pa-1199.7Pa) or 160-210°C (1333Pa-2399.4Pa) fractions to obtain benzophenone. The yield is 90%.

Apply^[4]

There are many varieties of benzophenone series products, which have been widely used in medicine, pesticides, dyes, plastics, coatings, daily chemicals, electronic chemicals and other fields. In many fields, it is mainly used as photoinitiator, ultraviolet absorber and pharmaceutical intermediate.

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 photocuring system, and it plays a decisive role in the sensitivity of the curing system. Photoinitiators are divided into three categories: homolytic fragment type, hydrogen transfer type and cationic type. Benzophenone hydrogen transfer photoinitiators have high quantum efficiency, fast curing speed, absorption spectrum range matching the irradiation light source, good thermal stability, no dark reaction, and are better than monomers and prepolymers. Good compatibility. The light-cured film has no yellowing or discoloration, is cheap, and is safe to use. Therefore, it has become the photoinitiator with the largest output. In 2000, the domestic output of benzophenone alone reached 1420t. The main benzophenone photoinitiators include benzophenone, 4-methylbenzophenone, 2-methylbenzophenone, 2,4,6-trimethylbenzophenone (EsacureTZT), etc. .

2. UV absorber

Benzophenone UV absorbers are currently the most widely used and produced UV absorbers. In addition to absorbing ultraviolet light of 290 to 400nm, it also absorbs part of visible light. It is widely used in plastics, inks, paints, cosmetics and other industries because of its good compatibility with other materials. There are many types of benzophenone UV absorbers, most of which are derivatives of 2,4-dihydroxybenzophenone (UV-0), such as 2-hydroxy-4-methylchlorobenzophenone (UV-0). UV-9), 2-hydroxy-4-n-octoxybenzophenone (UV-531), 2-hydroxy-4-methoxy-5-sulfonate benzophenone (UV-30), etc. . Foreign p-benzophenone series UV absorbers are also named after BP-X, such as UV-0 named BP-1, UV-531 named BP-17, UV-30 named BP-4, etc. In recent years, research in the fields of reactive benzophenone UV absorbers, benzophenone Ni compounds and the development of new varieties has achieved gratifying results. With the strengthening of people’s awareness of ultraviolet protection and the rapid development of the polymer material industry, benzophenone series products as ultraviolet absorbers will also receive greater development.

3. Pharmaceutical intermediates

Benzophenone series products are intermediates for many pharmaceuticals. For example, benzophenone is an intermediate for the anti-suspension drug diphenhydramine, and 2-amino-5-chlorobenzophenone is an intermediate for diazepam pharmaceuticals. , 4-chlorobenzophenone is used in the production of anti-allergic drugs such as Anqilin. For example, the highly effective anti-inflammatory and analgesic drug ketoprofen is made from m-methylbenzophenone through bromination, cyanation, hydrolysis, and methylation.

Main reference materials

[1] Synthetic fragrance product technical manual

[2] Synthesis and application of benzophenone series products

[3] Synthetic fragrance product technical manual

[4] Greening the benzophenone synthesis process