Magnetic and micellar effects on photoreactions. Micellar cage and magnetic isotope effects on quantum yields. Correlation of /sup 13/C enrichment parameters with quantum yield measurements

Journal Article · Wed Nov 21 04:00:00 EST 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00518a066· OSTI ID:5528521

Turro, N J; Kraeutler, B; Anderson, D R

The photoinduced homolytic ..cap alpha..-cleavage reaction of dibenzyl ketone (DBK) produces a germinate triplet radical pair whose reactivity has been shown to be significantly influenced by micellar and magnetic effects (included in Scheme). The products derived from the initial PhCH/sub 2/COCH/sub 2/Ph triplet radical pair (/sup 3/D) may be classified as germinate (spin-correlated) products which form in a cage process or as free-radical (spin-uncorrelated) products which form after diffusional separation of the initially formed radical pair. The remarkable /sup 13/C enrichment discovered in recovered DBK after partial photolysis in micellar solution was interpreted in terms of an enhanced cage effect of radical pairs in a micellar and a magnetic isotope (/sup 13/C) effect. The enhanced cage effects of radical pairs in micelles predict (1) a decreased quantum yield for disappearance of DBK and appearance of 1,2-diphenylethane (DPE) in hexadecyltrimethylammonium chloride (HDTCl) micelles relative to the quantum yields in homogeneous benzene solution. The magnetic isotope effect concept allows these predictions: (2) the quantum yield for disappearance of DBK and appearance of DPE will be significantly less for a ketone enriched in /sup 13/C in the carbonyl carbon; (3) the quantum yield for disappearance of DBK and appearance of DPE will be influenced by the application of an external laboratory magnetic field on the sample during photolysis; (4) the quantum yields for cage reactions will be magnetic field dependent; (5) the magnitude of ..cap alpha.., predicted by Bernstein's formula is directly related to the value of ..cap alpha.. derived from quantum yield measurements. All five predictions were confirmed. 1 table. (DP)

• Research Organization: Columbia Univ., New York, NY
• OSTI ID: 5528521
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:24; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
400500 -- Photochemistry
AROMATICS
BENZENE
CARBON 13
CARBON ISOTOPES
CARBONYLS
CHEMICAL REACTIONS
DECOMPOSITION
EVEN-ODD NUCLEI
HYDROCARBONS
INTERACTIONS
ISOTOPE EFFECTS
ISOTOPES
KETONES
LIGHT NUCLEI
MAGNETIC FIELDS
MECHANICS
MICELLAR SYSTEMS
NUCLEI
ORGANIC COMPOUNDS
PAIR PRODUCTION
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
QUANTUM MECHANICS
RADICALS
STABLE ISOTOPES