Photochemistry of polyhaloarenes. 5. Fragmentation pathways in polychlorobenzene radical anions

Journal Article · Wed Sep 03 04:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00278a027· OSTI ID:5264517

Freeman, P K; Srinivasa, R; Campbell, J A; Deinzer, M L

Negative chemical ionization mass spectroscopy of polychlorobenzenes reveals that parent radical anion undergoes fission by two pathways - (a) cleavage to aryl radical plus Cl/sup -/(k/sub Cl/sup -//) and (b) fission to aryl carbanion plus chlorine atom (k/sub Cl/) - and that there is a Hammett relationship between log (k/sub Cl//k/sub Cl/sup -//) and ..sigma..sigma. The dependence of the reciprocal of the quantum yield for photochemical dechlorination of trichlorobenzenes through pentachlorobenzene upon the reciprocal of the concentration of the electron donor, triethylamine, was analyzed in order to establish the optimum concentration for radical anion formation. The regiochemistries for the photodechlorination of trichlorobenzenes through pentachlorobenzene in the presence of triethylamine, with and without acetophenone sensitizer, were determined and found to be very similar and quite different from those observed for the direct photolysis in the absence of triethylamine for the comparison cases of 1,2,3,5-tetrachloro- and pentachlorobenzene. The regiochemistry of the fragmentation of polychlorobenzene radical anion to aryl radical plus chloride ion is rationalized in terms of a bent transition state.

• Research Organization: Oregon State Univ., Corvallis
• OSTI ID: 5264517
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:18; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
ANIONS
AROMATICS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
CHLORINATED AROMATIC HYDROCARBONS
DATA
EFFICIENCY
EXPERIMENTAL DATA
HALOGENATED AROMATIC HYDROCARBONS
INFORMATION
IONIZATION
IONS
MASS SPECTROSCOPY
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
QUANTUM EFFICIENCY
RADICALS
REACTION INTERMEDIATES
SPECTROSCOPY