Abstract
A series of TiO 2 particles of varying particle sizes from nano to micro scales was treated with three different oxidants (O 2 , TBHP, and aqueous H 2 O 2 ) under irradiation conditions to form activated TiO 2 particles bearing surface peroxo Ti(O 2 ) species. The resultant, heterogeneous catalysts were tested for photo-catalytic acetylation of 2-phenylethanol by acetic anhydride in 8 different solvents. The best scenario involves the use of 32 nm grade of TiO 2 nanoparticles and aqueous H 2 O 2 for pre-activation and the use of CH 2 Cl 2 as the reaction solvent. The 2-phenethyl acetate product can be completely formed in 10 h and isolated in essential quantitative yield. It was also found that catalysts derived from TiO 2 nanoparticles are superior to those from ZrO 2 , Y 2 O 3 and WO 3 nanoparticles by using the oxidative, photo-activation protocol. The newly developed heterogeneous catalytic system can be smoothly applied to photocatalytic acetylation of several representative primary aliphatic and aromatic alcohols. The intermediacy of Ti-OH or TiO surface groups was proposed in the photo-catalytic acetylation conditions. © 2011 The Royal Society of Chemistry.