Laser flash photolysis study of photodehydroxylation phenomena of 9-phenylxanthen-9-ol and photobehavior of related intermediates. Enhanced electrophilicity of 9-phenylxanthenium cation singlet

In the course of 248-nm laser flash photolysis, solutions of 9-phenylxanthen-9-ol (1) undergo homolytic and heterolytic photodehydroxylation, the relative efficiency of which depends strongly on the solvent nature. Polar/hydroxylic solvents, particularly aqueous mixtures, cause copious formation of...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the American Chemical Society 1989-11, Vol.111 (24), p.8858-8866
Main Authors: Minto, Robert E, Das, Paritosh K
Format: Article
Language:English
Subjects:
360100 - Metals & Alloys
400500 - Photochemistry
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA ANALYSIS
DECOMPOSITION
Exact sciences and technology
EXPERIMENTAL DATA
General and physical chemistry
INFORMATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
KINETICS
MATERIALS SCIENCE
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
PHENOLATES
PHENOXY RADICALS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
Physical chemistry of induced reactions (with radiations, particles and ultrasonics)
RADICALS
REACTION KINETICS
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In the course of 248-nm laser flash photolysis, solutions of 9-phenylxanthen-9-ol (1) undergo homolytic and heterolytic photodehydroxylation, the relative efficiency of which depends strongly on the solvent nature. Polar/hydroxylic solvents, particularly aqueous mixtures, cause copious formation of 9-phenylxanthenium cation (2), the ground, and excited-state properties of which are conveniently studied by single- and double-laser flash photolysis. In 1:1 H{sub 2}O/MeCN, the quantum yield of carbenium ion generation is 0.4 {plus minus} 0.1; only 1 % of photoheterolysis occurs through an adiabatic route. Surprisingly, in polar but nonhydroxylic solvents (e.g., acetonitrile and 1,2-dichloroethane) also, the cation is photogenerated in small but sufficient yields to allow time-resolved spectroscopic detection and study in these relatively neutral and inert media. In relatively nonpolar solvents, e.g., n-heptane and benzene, the photolysis of 1 is dominated by homolytic cleavage to 9-phenxylxanthenyl radical (3). The short-lived triplets of 1 ({tau}{sub T} {
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00206a014