Green synthesis of UV absorber (E)-2-(((4-(benzyloxy)phenyl)imino)methyl)phenol by microwave method

Tóm tắt

In this work, a UV absorber compound (E)-2-(((4-(benzyloxy)phenyl)imino)methyl)phenol was synthesized by microwave method using a two steps protocol. In the first step, α-(4-hydroxyphenylimino)-o-cresol (1) was synthesized from 4-aminophenol and salicylaldehyde by circulating under microwave heating at 60 ^oC for 8 minutes, the reaction yield reached 82.91 %. In the second step (E)-2-(((4-(benzyloxy)phenyl)imino)methyl)phenol (2) was synthesized from precursor (1) and benzyl bromide by circulating under microwave heating at 80 ^oC for 3 minutes, the reaction yield reached 25.08 %. The overall yield for the synthesis of UV absorber 2 was 20.79 %. The molecular structures of precursor (1) and product (2) were analysed by high performance liquid chromatography - mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR) methods. The UV absorbance of precursor (1) and product (2) was investigated by UV absorption spectrometry. The obtained results show that product (2) has a higher UV absorption intensity than precursor (1), the UV absorption region extends from 240 nm to 390 nm, the maximum absorption peak is at the wavelength (λ_max) of 350 nm. The UV absorber (E)-2-(((4-(benzyloxy)phenyl)imino)methyl)phenol with cyclic structure, low molecular weight, and high UV absorbance has potential application as an UV absorber for greenhouse covering plastic, paint and ink systems.