Synthesis and Application of Benzophenone

 Benzophenone is an organic compound with the molecular formula (C6H5)2C=O, which can be abbreviated as Ph2CO. Diphenyl ketone, as the nucleus of diaryl ketone, is an important synthetic intermediate in organic chemistry.

use

Benzophenone can be used as a photoinitiator for UV curing of varnishes in the ink, imaging and printing industries. Diphenyl ketone prevents the damaging effects of UV light on fragrances or colorants in products such as perfumes and soaps. It can also be added to plastic bags as a UV shielding agent. By using benzophenone, manufacturers can dispense the product into clear glass bottles or plastic. If benzophenone is not available, opaque or black outer packaging is required.

synthesis

Diphenyl ketone can be prepared by reacting benzene with carbon tetrachloride to obtain diphenyl dichloromethane, and then continue to undergo hydrolysis reaction. [1] Or prepared by Friedel-Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid catalyst such as aluminum trichloride. Industrial synthesis is based on the oxidation of diphenylmethane with oxygen under copper-catalyzed conditions.

organic chemistry

Benzophenone is a commonly used photosensitizer in photochemistry. It can cross from the S1 state to the triplet state in nearly 100% yield. The resulting diradical can take a proton from a suitable hydrogen donor to form a carbonyl radical.

diphenyl ketone free radical

Benzophenone is often used as an anhydrous indicator in organic synthesis. Sodium can reduce diphenyl ketone to the dark free radical anion, diphenyl carbonyl radical:

Na + Ph2CO → Na+Ph2CO·−

Carbonyl radicals can react with water and oxygen to give non-volatile products, so they are often used to purify hydrocarbon solvents. Carbonyl radicals are soluble in the dried organic solvent, and thus react rapidly with moisture and oxygen remaining in the solvent. Carbonyl radicals can appear blue or purple, depending on how dry and oxygen-free the solvent is. The bluer the color of the solution after the addition of benzophenone, the less oxygen and water in the solution. It is best to treat with a common desiccant (such as sodium sulfate) before drying a large amount of aqueous solvent to shorten the drying time. In contrast, if sodium is used as a drying agent, sodium has a relatively low solubility in organic solvents, forms a heterogeneous mixture with the solvent, and the drying rate is relatively slow.

commercial application

At present, the general sunscreen substances contain the core structure of benzophenone. Some examples are 2-hydroxy-4-methoxybenzophenone and 2,2'-hydroxy-4-methoxybenzophenone. Due to the photosensitive benzophenone as the parent nucleus, the safety of these substances is highly controversial.

p,p'-bis(N,N-dimethylamino)benzyl ketone, or Michler's ketone, has a dimethylamino substituent at each para position.

The high strength polymer polyetheretherketone can be prepared from benzophenone derivatives.