Res. Chem. Intermed.
, Vol. 31, No. 9, pp. 807–817 (2005)
Also available online - www.vsppub.com
Titanium-dioxide-mediated photocatalysed reaction
of selected organic systems
, M. MUNEER
and D. BAHNEMANN
Department of Chemistry, Aligarh Muslim University, Aligarh 202002, India
Institut für Technische Chemie, Universität Hannover, Callinstr. 3, D-30167 Hannover, Germany
Received 1 October 2004; accepted 28 January 2005
Abstract—The photocatalysed reaction of four selected organic systems, namely dichlone (1),
2-amino-5-chloropyridine (2), benzoyl peroxide (3) and 3-chloro perbenzoic acid (4), has been
investigated in an acetonitrile/water mixture in the presence of titanium dioxide and oxygen. An
attempt has been made to identify the products formed during the photo-oxidation process using the
GC/MS analysis technique. The photolysis of dichlone (1) leads to the formation of phthalic anhydride
(11) and 1H-indene-1,2,3-trione (10), whereas 2-amino-5-chloropyridine (2)gaveriseto2,2
bipyridyl (14), 2-pyridinamine (16), 2-hydroxy-5-chloropyridine (18), bipyridyl (19) and 2-amino
bipyridyl (21). The photolysis of benzoyl peroxide (3) yielded a mixture of products such as benzoic
acid (24), biphenyl (27), biphenyl-4-carboxylic acid (29) and benzoic acid phenyl ester (30). Two
intermediate products, as 3-chlorobenzaldehyde (35) and hydroxyl added 3-chlorobenzaldehyde (33),
have been identiﬁed in the case of 3-chloro perbenzoic acid (4). The products have been identiﬁed by
comparing the molecular ion and mass fragmentation peaks of the products with those reported in the
GC-MS library. A probable mechanism for the formation of the products has been proposed.
Keywords: Photocatalysis; titanium dioxide; dichlone; 2-amino-5-chloropyridine; benzoyl peroxide;
3-chloro perbenzoic acid.
The photocatalysed reaction of organic molecules in the presence of semiconduc-
tors such as TiO
has become a subject of serious study as it shows promise in
becoming a viable commercial technology for wastewater treatment [1–5]. This
process bears a close analogy to the charge separation developed in a photochem-
ical cell, containing semiconductor electrodes, and the principles governing photo-
electrochemistry apply equally well to reactions occurring on the surface of irradi-
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