One-pot imine synthesis from benzylic alcohols and nitrobenzene on CdS-sensitized TiO2 photocatalysts: Effects of the electric nature of the substituent and solvents on the photocatalytic activity

• Published in: Molecular catalysis Vol. 443; pp. 203 - 208
• Main Authors: Nakai, Yuta, Azuma, Masashi, Muraoka, Masahiro, Kobayashi, Hisayoshi, Higashimoto, Shinya
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2017
• Subjects: CdS-TiO2 photocatalyst; Imine; One-pot synthesis; Visible-light; One-pot synthesis; CdS-TiO2 photocatalyst; Imine; Visible-light
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2017.09.018

[Display omitted] •One-pot synthesis of imines from benzylic alcohols and nitrobenzene were studied.•The CdS-TiO2 was utilized as visible-light responsible photocatalyst.•The activity depends on the electric nature of benzylic alcohol following Hammett rule.•Solvent effects were investigated in the non-polar and polar solvents. A new strategy for the one-pot synthesis of imines from several benzylic alcohols with such substituted groups as CF3, Cl, CH3, OCH3 and nitrobenzene were studied on the CdS-sensitized TiO2 (CdS-TiO2) photocatalyst under visible-light irradiation (λ>420nm) at room temperature. It was observed that the photocatalytic activities strongly depended on the electric nature of the substituted groups in the benzylic alcohols, following the Hammett rules. The photocatalytic activities can be explained by the photocurrent efficiency and a shift of the flatband potentials of the CdS photoelectrode depending on the degree of electron-donacity of the substituted groups. Moreover, the solvent effects on the yields of imines were also investigated in non-polar solvents (toluene, cyclohexane) and polar solvents (ethanol, acetonitrile). It was observed that the non-polar solvents caused higher photocatalytic activities for the synthesis of several imines than polar solvents due to the efficient condensation of photo-formed benzaldehyde and aniline.