Photochemical transformations and laser flash photolysis studies of dibenzobarrelenes containing 1,2-dibenzoylalkene moieties

Journal Article · Fri Dec 14 04:00:00 EST 1984 · J. Org. Chem.; (United States)

DOI:https://doi.org/10.1021/jo00199a035· OSTI ID:5837716

Kumar, C V; Murty, B A.R.C.; Lahiri, S; Chackachery, E; Scaiano, J C; George, M V

Phototransformations of the dibenzobarrelenes 10 = 11,12-dibenzoyl-9,10-dihydro-9,10-ethenoanthracene, 11 = 11,12-dibenzoyl-9,10-dihydro-9-methyl-9,10-ethenoanthracene, 23 = 11,12-dibenzoyl-9,10-dihydro-9,10-dimethyl-9,10-ethenoenthracene, prepared by the reaction of the appropriate anthracenes with dibenzoylacetylenes, are reported. Irradiation of 10 and 11 in solvents such as benzene, methanol, and acetone gave the corresponding dibenzosemibullvalenes, 17 = 8c, 8d-dibenzoyl-4b,8b,8c,8d-tetrahydrodibenzo(a,f)cyclopropa(c,d)- and 18, respectively, in good yields. These dibenzosemibullvalenes on catalytic hydrogenation using 5% Pd on charcoal gave the corresponding cyclopropane ring-opened products, 21 and 22, respectively. Irradiation of 23 in benzene gave a mixture of 2,3-dibenzoyl-2,3-dihydro-1,4-dimethyl-2,3-benzonaphthalene 27 (2%), 1,4-dibenzoyl-5,8-dimethyl-2,3:6,7-dibenzocyclo-octatetraene (24, 20%), the carbinol (45%), and benzoic acid (7%). Irradiation of 23 in methanol gave a mixture of 27 (25%), 24 (27%), and benzoic acid (8%). Laser flash photolysis (337.1 nm) of 10, 11, and 23 led to transient species, characterized by strong absorptions in the 300-650-nm region. These transients are due to the triplet states of the substrates, as established by quenching studies involving oxygen, di-tert-butylnitroxide, azulene, and ..beta..-carotene. Energy-transfer sensitization of 10, 11, and 23 by benzophenone in benzene also gave rise to the same transients, as formed under direct irradiation. The quantum yields of triplet formation (PHI/sub T/) were estimated to be high for 10 and 11 (approx. 1), whereas it is significantly lower for 23 (approx. 0.7). 24 references, 3 figures, 2 tables.

• Research Organization: Indian Institute of Technology, Kanpur
• OSTI ID: 5837716
• Journal Information: J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 49:25; ISSN JOCEA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
ACETONE
ALCOHOLS
ALKENES
AROMATICS
AZULENE
BENZENE
BENZOPHENONE
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CYCLOALKENES
DATA
DECOMPOSITION
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGENATION
HYDROXY COMPOUNDS
INFORMATION
KETONES
KINETICS
METALS
METHANOL
MONITORING
NITRO COMPOUNDS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SOLVENTS
OXYGEN
PALLADIUM
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLATINUM METALS
REACTION INTERMEDIATES
REACTION KINETICS
REAGENTS
SOLVENTS
SPECTROSCOPY
TRANSITION ELEMENTS