Reactions of singlet oxygen. Part V. Dye sensitized photooxidation of m-hydroxydiphenylamine

Abstract

Methylene blue sensitized photooxidation of m-hydroxydiphenylamine gives N-(3-hydroxyphenyl)-p-benzoquinoneimine as the primary product in acetonitrile–water medium. The experimental results are in good agreement with the theoretical plots calculated on the basis of the reaction undergoing through the participation of [Formula: see text] as well as the excited dye interacting with the substrate. β-Value and rate constant of reactivity of m-hydroxydiphenylamine with singlet oxygen have been calculated. The effects of β-carotene, 1,4-diazabicyclo[2,2,2]octane, triethylamine, allyl thiourea, 2,5-diphenylfuran, and dielectric of different solvents show the participation of singlet oxygen at low substrate concentration and interaction of the excited dye with the substrate at its high concentrations. The data on oxygen concentration effect fit into the derived rate expressions. No complexation between methylene blue and m-hydroxydiphenylamine is observed.

Stereoselective Bromocyclization of Allylated Aldoxime Ethers

“…During our ongoing studies we were surprised to find that the related bromoamination of O ‐allyl aldoxime ethers 3 afforded the corresponding bromo‐5,6‐dihydro‐4 H ‐1,3‐oxazines 4 in high yields and diastereoselectivities. 1,3‐Oxazines can be found as a core motif in some natural products5 and are highly desirable target structures due to their antibiotic,6 antitumor,7 hepatoprotective,8 and analgesic9 properties. Several synthetic methods have been developed that allow for the preparation of 5,6‐dihydro‐4 H ‐1,3‐oxazines 10.…”

Prediction of photofading of N‐β‐hydroxyethylamino‐o‐nitrophenyl derivatives: a theoretical study

“…The nitro group of the molecule acts as a strong acceptor to manipulate colour by creating large bathochromic shifts, while N ‐β‐hydroxyethyl increases the hydrophilicity. The products of amine photooxidation are nitroso‐ and nitro‐derivatives and quinones 26–33 …”

Thionine sensitized areobic photooxidation of thiourea in acidic medium

“…Recent studies on simple chemicals have led to rapid advances in the understanding of photosensitized oxidation. Not only one pathway but a number of different pathways have been shown to occur [1,2]. Photosensitized oxidation of amines and other compounds showed that dyes act as a sensitizer in a large number of these reactions [3].…”