Photochemical transformations of 1-pyrazolyl-cis-1,2-dibenzoylalkenes: a laser flash photolysis investigation
Photorearrangement of several pyrazolyl-cis-1,2-dibenzoylalkenes are reported. For some of the compounds, photolysis in benzene gave a mixture of butenoic acid and tetrahydroisoquinoline, whereas in methanol, a mixture of butenoic ester and tetrahydroisoquinoline is formed. Laser flash photolysis of some of the compounds in benzene and methanol led to (a) the formation of short-lived transients (less than or equal to 20ns), absorbing in the spectral region 400-500nm and assigned as the triplets of the photolyzed compounds, (b) pronounced end-or-pulse bleaching in the region of ground-state absorption (300-380nm), (c) formation of oxygen-insensitive transients, characterized by dual maxima at approx. 400 and approx. 600nm, and (d) growth (oxygen insensitive) of a methanol adduct with absorption maxima at 370-390nm in methanol and benzene plus methanol (0.5-5M) mixtures. Triplet sensitization studies using pulse-generated and ..gamma..-radiolytically generated biphenyl triplet photolysis suggest that the formation of the 400/600-nm species is triplet mediated while the methanol related reaction as well as the phototransformation leading to the butenoic acid ester derivatives occurs via intermediates from the triplet state. The 400/600-nm species is attributed to a zwitterion, and the methanol growth species is attributed to the reaction of a ketene with the alcohol.
- Research Organization:
- Univ. of Notre Dame, IN
- OSTI ID:
- 5939593
- Journal Information:
- J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 49:24; ISSN JOCEA
- Country of Publication:
- United States
- Language:
- English
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ALCOHOLS
ALKENES
AROMATICS
AZOLES
BENZENE
CHEMISTRY
CYCLOALKENES
DATA
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
GAMMA RADIATION
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
IONIZING RADIATIONS
LASER RADIATION
METHANOL
MULTIPLETS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMISTRY
RADIATIONS
TRIPLETS