Tung CH, Guan JQ. Regioselectivity in the Photocycloaddition of 9-Substituted Anthracenes Incorporated within Nafion Membranes.
J Org Chem 1998;
63:5857-5862. [PMID:
11672187 DOI:
10.1021/jo980412e]
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Abstract
The photocycloaddition of five 9-substituted anthracenes [AnCH(2)N(+)(CH(3))(3)Br(-) (1), AnCH(2)COO(-)Na(+) (2), AnCH(2)OH (3), AnCOCH(3) (4), and AnCH(3) (5), An = 9-anthryl] incorporated within Nafion membranes has been investigated. While irradiation of the above compounds in homogeneous solutions, and 5 in Nafion also, mainly gave rise to their head-to-tail (h-t) photocyclomers, photoirradiation of the samples of 1-4 incorporated within Nafion membranes almost exclusively resulted in the head-to-head (h-h) photocyclomers. Furthermore, the h-h photocyclomers are significantly more stable in Nafion membranes than in homogeneous solutions. These observations can be explained in terms of the preorientation of the substrate molecules in the inverse micelle-like clusters of Nafion.
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