36707-29-6Relevant 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.
Photolysis of the 1-naphthylmethyl ester of substituted phenylacetic acids: intramolecular charge transfer and rates of decarboxylation of arylacyl radicals
Hilborn, James W.,Pincock, James A.
, p. 992 - 999 (2007/10/02)
The photolysis of esters 6 and 8 in methanol leads to products resulting from both naphthylmethyl cations and radicals.The product distribution is nearly independent of X for the esters 6 except when X equals methoxy.A mechanism involving initial homolytic cleavage of the carbon-oxygen bond in the excited singlet state of the ester is proposed.Competition between electron transfer in the radical pair to form the ion pair and decarboxylation of the arylacyloxy radical allows calculations of the rates of this decarboxylation process.The ρ values versus ? is close to zero.When X equals methoxy, intramolecular electron transfer occurs with the naphthalene ring serving as the acceptor and the methoxyaromatic as the donor.This exciplex fragments to carbon dioxide and 1-(1-naphthyl)-2-arylethane. Key words: acyloxy radical, decarboxylation, photolysis of benzylic esters.
Rates of decarboxylation of acyloxy radicals formed in the photocleavage of substituted 1-naphthylmethyl alkanoates
Hilborn, James W.,Pincock, James A.
, p. 2683 - 2686 (2007/10/02)
Rates of decarboxylation (kCO2R) have been estimated for the acyloxy racicals 7a-f formed in the photolysis of substituted 1-naphthylmethyl 6a-f. These rates are on a mechanism involving initial carbon-oxygen homolytic bond cleavage from the excited singlet state. The products are formed by two competing pathways: electron transfer in the radical pair to give an ion pair and decarboxylation. Measured product yields along with an of the electron-transfer rate (kET) allow calculation of kCO2R as a function of R. The values obtained are the following (R, k (109 s-1)): CH3, 3CH2, 2.0; (CH3)2CH, 6.5; (CH3)3C, 11; PhCH2, 5.0; PhCH2CH2, 2.3.
