Para-aminobenzoic acid and two of its derivatives (4-dimethylaminobenzoic acid and 2-ethylhexyl, 4-dimethylaminobenzoate) are UV absorbers used in some UV-protective personal care products. They also degrade in the presence of UV light and can cause allergic reactions because of their acidic properties. The goal of this project is to assess the solvent-dependence of the light stability and to learn about the rate and mechanism of the degradation process. Solutions of p-aminobenzoic acid and two derivatives in various solvents were irradiated with UVB light and UV absorbance spectra of the solutions were measured as the molecules degraded. The rates of degradation were compared looking at molecule and solvent effects. The same method was repeated with each sample purged with N2 to test if oxidative processes are occurring. Further work includes manipulation of the substituent groups to enhance light stability and other properties favorable for use in personal care products.

Tracking ultraviolet degradation of p-aminobenzoic acid and two derivatives

253rd National Meeting (2017)

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