Studies on the reactions of polycyclic aromatic hydrocarbons with nitrogen dioxide in aprotic solvents

Thesis/Dissertation · Thu Dec 31 23:00:00 EST 1987

OSTI ID:6730315

Squadrito, G L

There is recent evidence that free radical nitration reactions occur in polluted urban air, and that the nitrated polycyclic aromatic hydrocarbon (NO{sub 2}-PAH) produced by this reaction pathway account for a substantial amount of the total NO{sub 2}-PAH found in ambient particulate organic matter. The nitration of PAH with nitrogen dioxide in solvents of low polarity has been studied as a model for the reaction occurring in the atmosphere (gas phase). While vast amounts of data available for the electrophilic ionic nitration and its mechanism of reaction is considered well-established, the literature documents relatively few reports on the mechanism of reaction of PAH with nitrogen dioxide. Our studies indicate that: (1) a free radical mechanism operates in solvents of low dielectric constant (e.g. CCl{sub 4}) and becomes less important as the dielectric constant is increased (CHCl{sub 3}, CH{sub 2}Cl{sub 2}, THF, CH{sub 3}CN, CH{sub 3}NO{sub 2}), (2) Bronsted and Lewis acids, and lower temperatures promote the electrophilic ionic reaction pathway, (3) the free radical mechanism involves metastable adducts of the PAH and two to four nitrogen dioxide equivalents, (4) the radical reaction yields nonconventional substitution patterns of dinitro-PAH even at low conversions (e.g. 1,2- and 1,3-dinitrofluoranthenes and, 1,3- and 2,3-dinitronaphthalenes), (5) the radical reaction of anthracene with nitrogen dioxide yields cis- and trans-9,10-dinitro,9,10-dihydroanthracene, which are isolable, (6) in radical nitration, the nitro-group does not have a strong deactivating effect towards further nitration as in electrophilic ionic nitration.

• Research Organization: Louisiana State Univ. and Agricultural and Mechanical Coll., Baton Rouge, LA (USA)
• OSTI ID: 6730315
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ADDUCTS
AIR POLLUTION
ANTHRACENE
AROMATICS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CONDENSED AROMATICS
HYDROCARBONS
KINETICS
NITRATION
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PARTICULATES
POLLUTION
POLYCYCLIC AROMATIC HYDROCARBONS
RADICALS
REACTION KINETICS
SOLVENTS