Diphenyl ketone, benzoyl benzene, phenyl ketone, diphenylmethanone, alpha-oxodiphenylmethane, alpha-oxoditane
White crystals with a rose or geranium-like odor.
Benzophenone is used to prevent ultraviolet light from damaging scents and colors in products such as perfumes and soaps.
This allows the manufacturer to package the product in clear glass or plastic. Without it, opaque or dark packaging would be used.
It can also be added to the plastic packaging as a UV blocker.
It is also sometimes used as a flavoring agent.
Ultraviolet light is often divided into two types, UV-A, which has a longer wavelength (320-360nm) and UV-B, which has a shorter wavelength (280-320nm). Shorter wavelengths mean higher energies. UV-B is more damaging than UV-A. Some UV blockers are optimized to block the shorter wavelengths, while letting the longer wavelengths get through.
There are many variants of benzophenone in use. You may see numbers after the name, as a shorthand indication of which variant is in use. The variations change features like the solubility, or how well it bonds with plastics use in packaging. For example, benzophenone-2 is used in alcohol-based products, while benzophenone-5 is used in water-based products. Benzophenone-6 is used in nail polish, and benzophenone-9 is used in bath products and skin care products.
Some examples are shown below:
Can be added to plastic packaging as a UV blocker.
Water-soluble form used in cosmetics, hair sprays, and hair dyes.
This form is also added to plastic packaging as a UV blocker. It bonds with the plastic and will not migrate out.
benzophenone-1: 2,4-dihydroxy benzophenone
benzophenone-2: 2,2',4,4'-tetrahydroxy benzophenone
benzophenone-5: 2-hydroxy-4-methoxy-5-sulfonyl benzophenone sodium salt
benzophenone-6: 2,2'-dihydroxy-4,4'-dimethoxy benzophenone
benzophenone-9: 2,2'-dihydroxy-4,4'-dimethoxy benzophenone-5,5'-disulfonate sodium
benzophenone-12: 2-hydroxy-4-N-octoxy benzophenone
Other UV blockers:
amyl p-methoxy cinnamate
octyl p-methoxy cinnamate