35946-59-9Relevant articles and documents
Photocatalysis in an NMR tube: Carbon-carbon coupling ofphenoxyacetic acid with n-substituted maleimides
Mills, Andrew,O'rourke, Christopher
, p. 7 - 16 (2013)
The semiconductor-sensitised photocatalytic (SPC) carbon-carbon coupling of phenoxyacetic acid (PAA)and N-methylmaleimide (NMI) or maleimide (MI) has recently been reported and is studied in moredetail. Irradiations are performed on a much smaller scale than commonly used, i.e. 1 mL of reac-tion solution in a sol-gel titania coated NMR tube, and NMR is used to monitor the progress of thevarious photoreactions. Use of an NMR tube as the photoreactor allows much faster reaction times(ca. 10 times faster than the 40 mL scale reaction), and helps avoid the more usual need for sample-taking and pre-treatment, before analysis by NMR, HPLC etc. The photochemistries and photocatalyticprocesses associated with the individual reactants (i.e. PAA and NMI or MI) reveal the productionof significant products which are largely absent in the SPC-sensitised coupling reaction. Thus, whenboth PAA and NMI or MI are irradiated together, in the study of the coupling reaction the two mainproducts formed are: 1-methyl-3-(phenoxymethyl)pyrrolidine-2,5-dione (the adduct product), and 2-methyl-3a,4-dihydrochromeno[3,4-c]pyrrole-1,3(2H,9bH)-dione (the cyclic product), which are formedin reasonable yields up to 67% and 15% respectively after only 15 min (I = 3.5 mW cm-2per photoreac-tor hemisphere). Despite the well-known photochemical feature of NMI to form dimers efficiently, thiswork demonstrates that the background photochemistry and photocatalysis associated with the individ-ual reactants, PAA and NMI, in the photocatalysed coupling reaction are minimal due to the faster SPCkinetics for the coupling reaction, and the UV-filter effect of the sol-gel titania coating. The additionalformation of organic polymeric material in all the photocatalytic processes studied is discussed briefly.
