Nitrogen dioxide and carbonate radical anion: two emerging radicals in biology.

Oxidation of sulfamethoxazole and related antimicrobial agents by TiO2 photocatalysis

This review summarizes direct and indirect analytical methods for the detection and quantification of the reactive oxygen species (ROS): 1O2, O2·−/HOO·, H2O2, HO·, and CO3·− in aqueous solution. Each section briefly describes the chemical properties of a specific ROS followed by a table (organized alphabetically by detection method, i.e., absorbance, chemiluminescence, etc.) summarizing the nature of the observable (associated analytical signal) for each method, limit of detection, application notes, and reaction of the probe molecule with the particular ROS.

Methods for reactive oxygen species (ROS) detection in aqueous environments

Significant role of UV and carbonate radical on the degradation of oxytetracycline in UV-AOPs: Kinetics and mechanism.

The presence of amino acids in atmospheric precipitation and aerosols has been noted for many years, yet relatively little is known about these or other nitrogen containing organic compounds in the atmosphere. Marine and continental rainwater analyses indicate that atmospheric aerosols, and subsequently atmospheric precipitation, may contain substantial levels of free and combined amino acids. The most likely source of amino N in the remote marine atmosphere appears to be the injection of proteinaceous material through the action of bursting bubbles at the sea-air interface or the long range transport from terrestrial sources. The capacity of these substrates to undergo photooxidation and photodegradation in the atmosphere to simpler species, such as ammonium ions, carboxylic acids, and for the S containing amino acids, oxidized forms of sulfur, has received little attention from atmospheric chemists. The photochemistry of covalently bound amino groups, particularly as found in peptides and amino acids, is discussed here with the purpose of summarizing what is known of their occurrence and their possible importance to atmospheric chemistry.

Amino acid nitrogen in atmospheric aerosols: Occurrence, sources and photochemical modification

Reactions of the carbonate radical with aliphatic amines

Rate constants for the reaction of carbonate radical with aniline and some parasubstituted anilines have been determined by the flash photolysis technique. Using σ+ para values the rate constants at pH 8.5 correlate very well with the Hammett equation yielding ρ= − 1. The carbonate radical oxidises aniline giving the anilino radical. The products so formed have been identified through studies under conditions of continuous irradiation.

Reaction of the carbonate radical with substituted anilines

Flash photolysis of an aqueous solution of sodium metaborate and potassium peroxydisulphate at pH 115 gives rise to a new transient species with an absorption maxima at 590 nm (Iµ= 80 m2 mol–1) and 650 nm (Iµ= 90 m2 mol–1) The laser-Raman and 11B nmr spectra of metaborate solutions at pH 115 are consistent with the presence of the tetrahydroxyborate ion, B(OH)–4 The pKa and reduction potential of the radical B(OH)˙4, produced on flashing a mixture of B(OH)–4 and S2O2–8 are found to be 1075 ± 002 and + 14 V, respectively The rate constants for the oxidation of several amines and phenols by this one-electron oxidant have been determined Salt-effect studies are consistent with the reactive species being B(OH)3O˙–

Redox and acidic properties of the borate radical B(OH)˙4. A flash photolysis study

Rate constants for the reaction of phosphate radical with some aromatic and aliphatic amines have been determined by the flash photolysis technique. The products formed under conditions of continuous irradiation have been identified. In the case of an aromatic amine the major product is the azo compound while in the case of an aliphatic amine a carbonyl compound is formed.

Reaction of the phosphate radical with amines — A flash photolysis study

Carbonate radical shows moderate reactivity (k2=1.8·106 M−1 s−1) with nickelglycine complex. As an oxidizing free radical, it may attack the ligand to form Ni(II) coordinated glycine radical or oxidize the metal center to form a Ni(III) glycine transient. Continuous γ-irradiation of the complex-bicarbonate mixture yields glyoxalic acid (G=1.7) as the major product. The reaction involves an attack of the ligand and precludes the oxidation of metal center.

V. Ramakrishnan

Papers

Reactions of the carbonate radical with aliphatic amines

Reaction of the carbonate radical with substituted anilines

Redox and acidic properties of the borate radical B(OH)˙4. A flash photolysis study

Reaction of the phosphate radical with amines — A flash photolysis study

Radiation chemical studies of nickel-glycine reaction with carbonate radical