**5. Organic synthesis mediated by heterogeneous photocatalysis**

Despite the widespread use of titanium dioxide, modified or not, or even other semiconductors with photocatalytic activity in photodegradation and mineralization of organic matter (Agostiano et al., 2003; Mrowetz et al.,2004; Machado et al.,2008; Hoffmann et al.,2010; Gupta et al.,2011), and its other capabilities (Mrowetz et. al.,2004; Zaleska, 2008a, 2008b), these semiconductors have been little explored in the synthesis of compounds of interest, although it is recognized that the photocatalytic synthesis should enable the efficient production of chemicals through combined fotoredox reactions with significant advantages compared to other methods (Swaminathan & Krishnakumar, 2011).

Synthetic methods based on photocatalytic processes have been reported for the preparation of different organic substrates (Amano et al., 2006; Palmisano et al., 2007b; Denmark & Venkatraman, 2006; Hakki et al.,2009; Swaminathan & Selvam, 2011; Swaminathan & Krishnakumar, 2011). Although the production of chemicals of industrial interest using heterogeneous photocatalysis has been shown to be a viable process, there is still little research on the use of photocatalysis for this purpose, and about the performance of these photocatalytic processes (Kanai et al., 2001; Murata et al., 2003; Amano et al., 2006; Denmark & Venkatraman, 2006; Hakki et al.,2009; Swaminathan & Selvam, 2011;Swaminathan & Krishnakumar, 2011). Apparently, the reason for this is that, in general, these methods are not yet fully satisfactory with regard to operational simplicity, cost of reagents and performance.

The stimulus for research in this field is necessary so that new and viable methodologies can be established.
