The photolysis reactions of three compounds commonly used as a sunscreen agents, Parsol 1789 (1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-1,3- propanedione), Oxybenzone ((2-hydroxy-4-methoxyphenyl)phenyl-methanone) and Padimate O (2-ethylhexyl-4-(dimethylamino)benzoate), were investigated to provide a chemical background to aid in the understanding of the photosensitization of the sunscreen agents. Photolysis was carried out in cyclohexane for 70–140 h using a mercury vapor lamp (450W) without excluding oxygen.
Irradation of Parsol 1789 in cyclohexane yielded tert-butylbenzene, p-tert-butylbenzoic acid and p-methoxybenzoic acid; products obtained from the combination of the sunscreen with the solvent included the cyclohexyl esters of p-methoxybenzoic acid, p-tert-butylbenzoic acid and methanoic acid; products obtained from the solvent included cyclohexanol, cyclohexanone and dicyclohexyl ether.
Irradiation of Oxybenzone in the cyclohexane for 100 h produced no detectable products by either gas or liquid chromatographic analysis. Oxybenzone was recovered unchanged and no products were observed from the photoinitiated reaction of oxygen with the solvent.
Irradiation of Padimate O in cyclohexane yielded the ethylhexyl esters of p-aminobenzoic acid, p-monomethylaminobenzoic acid and p-dimethylamino (o/m)-methylbenzoic acid, as well as products from the photoinitiated reaction of oxygen with the solvent. 相似文献
The present paper covers three silabridged hafnocene dichlorides(1, 2 and 3) prepared by sequential reactions of α, ω-dichloropermethyl polysilane with cyclopentadienyl sodium, n-butyl lithium and hafnium tetrachloride. Their structures were characterized by elemental analyses, UV, 1H(13C) NMR and MS. Furthermore the crystal and molecular structures of 1 and 2 were determined by X-ray diffraction method. The crystal of 1 is monoclinic, space group C2/c with a=1. 3401(4), b=0. 9977(3), c = 1. 0922(4) nm; β=94. 07(1)° V=3. 6342 nm3, Z = 2, Dc = 2.155 g·cm-3. The final deviation factor R = 0. 064. The crystal of 2 is monoclinic, space group P21/c with a=0.0847(1), b=1.5181(1), c=2.9824(2) nm; β= 94. 07(1)°? V=3.634 nm3; Dc= l. 805 g·cm-3. The final deviation factor R = 0. 033. The relationship between the silabridged structure and spectral properties is also discussed. 相似文献