The effect of deuteration on the keto–enol equilibrium and photostability of the sunscreen agent avobenzone

Abstract

Deuteration of avobenzone (sunscreen agent) at the keto–enol moiety increased the % diketone, altering photodegradation in sunlight (solution 1H NMR).

Determining the photostability of avobenzone in sunscreen formulation models using ultrafast spectroscopy

“…9,18 Deuteration of the diketo methylene/enol moiety affects the tautomerisation equilibrium, by shifting it towards the ketone form. 19 Many photofragments of avobenzone have also been identified, which in turn may induce cytotoxic and skin sensitization effects. [20][21][22] Transient electronic absorption spectroscopy (herein abbreviated as TEAS), is an ultrafast pump-probe technique that has been utilised previously to explore the photoprotection mechanisms of many individual UV filters in solution, including avobenzone; additional examples include benzophenone-3, ethylhexyl methoxycinnamate, homosalate, ethylhexyl salicylate, octocrylene and diethylamino hydroxybenzoyl hexyl benzoate.…”

Multistep Microwave-Assisted Synthesis of Avobenzone

“…The product was isolated exclusively in its enol form, as indicated by a singlet at 6.8 ppm. If the keto tautomer were to be observed, a signal would have shown up at 4.6 ppm . Purity determined by 1 H NMR showed small amounts of unreacted chalcone 3 with overall purity exceeding 90% (see Supporting Information).…”

Structural Studies of β-Diketones and Their Implications on Biological Effects

“…For avobenzone 1-(4-(tert-butyl)phenyl)-3-(4-methoxyphenyl)propane-1,3-dione, R 1 = 4-terbutylphenyl, and R 2 = 4-methoxyphenyl, as shown in Figure 1, and the amount of diketo-form can be increased in chloroform from 4 to 10% if the central carbon is dideuterated [31].…”