112929-92-7Relevant academic research and scientific papers
Photochemistry of substituted 1-naphthylmethyl esters of phenylacetic and 3-phenylpropanoic acid: Radical pairs, ion pairs, and marcus electron transfer
DeCosta, Dayal P.,Pincock, James A.
, p. 2180 - 2190 (2007/10/02)
The ring-subtituted 1-naphthylmethyl esters of phenylacetic (3a-k) and 3-phenylpropanoic (5a-c) acid have been photolyzed in methanol solvent. The major products of these reactions are derived from two critical intermediates, the 1-naphthylmethyl radical/acyloxy radical pair and the 1-naphthylmethyl cation/carboxylate anion ion pair. The radical pair results in formation of the in-cage coupled products 8a-k and 10a-c after loss of carbon dioxide from the acyloxy radical. The ion pair leads to the methyl ethers 6a-k and the carboxylic acids 7 and 9. The competition between the radical and ionic pathways is very dependent upon the substituents on the naphthalene ring. Analysis of these substituent effects results in a proposed mechanism of initial homolytic cleavage of the carbon-oxygen bond of the ester from the excited singlet state. This radical pair then partitions between two pathways: decarboxylation of the acyloxy radical and electron transfer converting the radical pair to the ion pair. The rates of electron transfer are shown to fit Marcus theory in both the normal and the inverted region.
Intramolecular electron transfer in the photochemistry of substituted 1-naphthylmethyl esters of benzoic acids
DeCosta, D. P.,Pincock, J. A.
, p. 1879 - 1885 (2007/10/02)
Direct excitation of the esters 5 in methanol solvent leads to rapid intramolecular exciplex formation (kex = 1010 s-1 for X = CH3O, Y = CN) with electron transfer from the naphthalene to the benzoate ring.This process dominates the usual fluorescence and reaction of the excited singlet state.The rate of this process can be varied over 103 by suitable change in the substituents X and Y.The electron-transfer rates can be correlated with the two-parameter Hammett equation: log kex = 8.48 - 1.5?+ + 0.77?.For cases where the rate of exciplex formation is slow, the usual homolytic carbon-oxygen bond cleavage occurs from the excited singlet state.The eventual products result from the ion pair since the rate of electron transfer in the radical pair to form the ion pair is considerably faster than the rate of decarboxylation of the benzoyloxy radical.
