Anisole nitration during gamma-irradiation of aqueous nitrite and nitrate solutions: Free radical versus ionic mechanisms

Journal Article · Thu Apr 01 04:00:00 EDT 2010 · Environmental Chemistry

DOI:https://doi.org/10.1071/EN09109· OSTI ID:978875

Elias, Gracy; Mincher, Bruce J; Martin, Leigh R; Mezyk, Stephen P; Cullen, Thomas

Radiolytic aromatic nitration mechanisms in the condensed phase are ubiquitous, and especially of interest in atmospheric aerosol chemistry, water treatment by advanced oxidation technologies, and nuclear fuel reprocessing. Here, the radiolytically-induced nitration reactions of anisole, the simplest aryl alkyl ether, were investigated in ?-irradiated acidic nitrate solution, and in neutral nitrate and nitrite solutions. The nitrated anisole product distribution was the same with and without radiation in acidic solution, although more products were formed as a result of irradiation. This suggests that the mechanism of nitration in acidic solution is nitronium ion- induced electrophilic aromatic substitution. The rate of production of nitrated products in neutral nitrate solution was much lower, although the distribution of isomers was similar to that expected for nitronium ion electrophilic nitration. In contrast, the product distribution in neutral nitrite solution approached a statistically random substitution pattern, suggesting a non-electrophilic free radical reaction involving •NO2 radical. When hydroxyl radical (•OH) was scavenged by varying the initial nitrite concentration, the concentration of nitrated products increased with increasing nitrite, indicating that the reaction was probably one of direct •NO2 radical addition. However, this latter mechanism will not be important in acidic solutions, such as those often encountered in atmospheric aerosols or ?-irradiated nuclear fuel reprocessing solutions, due to low amounts of produced •NO2 radical and the low reaction rate constants for the •NO2 radical with aromatic compounds.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 978875
• Report Number(s): INL/JOU-09-15270
• Journal Information: Environmental Chemistry, Journal Name: Environmental Chemistry Journal Issue: 2 Vol. 7; ISSN 1448-2517
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
AEROSOLS
ANISOLE
AROMATICS
Anisole
CHEMISTRY
DISTRIBUTION
HYDROXYL RADICALS
IRRADIATION
ISOMERS
NITRATES
NITRATION
NITRITES
NUCLEAR FUELS
Nitration
OXIDATION
PRODUCTION
RADIATIONS
RADICALS
REACTION KINETICS
REPROCESSING
WATER TREATMENT