title: Photochemistry of aryl tert-butyl ethers in methanol: the effect of substituents on an excited state cleavage reaction
abstract: The photolysis of a set of 10 substituted aryl tert-butyl ethers, 8a-j, in methanol gave, as the major product, the corresponding phenol along with tert-butyl-substituted phenols resulting from photo-Fries reaction. The corresponding 4-cyanophenyl 1-adamantyl ether, 9, also gave 1-methoxyadamantane 16 (16%), indicating that, at least for this ether, some of the products were ion-derived. Quenching studies with 2,3-dimethylbutadiene for the tert-butyl ethers indicated that these reactions were occurring from the singlet excited state. Rate constants for the reaction, obtained from quantum yields and singlet lifetimes, were found to correlate reasonably well with sigma(h)()(nu) values, rho = -0.77 (r = 0.975), a result that is unexpected for a reaction where the polarity of the bond breaking in the transition state is expected to be -O(delta-). C(delta+).
authors.affiliation: Departments of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J3, and University of Colombo, Colombo, Sri Lanka.
authors.initials: DP
authors.lastname: DeCosta
authors.initials: A
authors.lastname: Bennett
authors.initials: AL
authors.lastname: Pincock
authors.initials: JA
authors.lastname: Pincock
authors.initials: R
authors.lastname: Stefanova