title: Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.
abstract: Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds.
authors: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane QLD 4001, Australia. fathimasifani.zavahir@hdr.qut.edu.au.
authors: Sifani
authors: S
authors: Zavahir
authors: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane QLD 4001, Australia. hy.zhu@qut.edu.au.
authors: Huaiyong
authors: H
authors: Zhu
mesh_terms: D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D055772:Green Chemistry Technology; D007097:Imines / Q000138:chemical synthesis*; D008027:Light; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D017640:Silicates / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D000588:Amines; D007097:Imines; D017640:Silicates; C009495:titanium dioxide; D014025:Titanium
references: Chemistry. 2012 Jun 25;18(26):8048-56
references: 22674851
references: Chem Commun (Camb). 2010 Oct 14;46(38):7074-89
references: 20820526
references: Chem Soc Rev. 2012 Mar 21;41(6):2003-24
references: 22310886
references: Angew Chem Int Ed Engl. 2003 Apr 4;42(13):1479-83
references: 12698478
references: Chemistry. 2011 Aug 22;17(35):9816-24
references: 21735494
references: Chem Commun (Camb). 2013 Jun 4;49(44):5034-6
references: 23615815
references: Chem Rev. 2011 Apr 13;111(4):2626-704
references: 21405021
references: Angew Chem Int Ed Engl. 2010 Dec 10;49(50):9657-61
references: 21053223
references: Angew Chem Int Ed Engl. 2011 Jan 17;50(3):657-60
references: 21226146
references: Chem Commun (Camb). 2007 Sep 7;(33):3425-37
references: 17700873
references: ChemSusChem. 2010 Oct 25;3(10):1135-8
references: 20830724
references: Chem Rev. 2002 Oct;102(10):3811-36
references: 12371903
references: J Org Chem. 2009 Apr 3;74(7):2877-9
references: 19265414
references: Chemistry. 2003 Sep 22;9(18):4353-61
references: 14502621
references: Chemistry. 2010 Sep 10;16(34):10502-6
references: 20652912
references: Angew Chem Int Ed Engl. 2010 Jul 26;49(32):5515-8
references: 20607786
references: J Am Chem Soc. 2008 Feb 6;130(5):1568-9
references: 18189405
references: Chemistry. 2012 Feb 27;18(9):2624-31
references: 22271403