2.4- Dichlorophenoxyacetic acid oxidation

Leavitt, D.D. and Abraham, M.A. Acid-catalyzed oxidation of 2,4-dichlorophenoxyacetic acid by ammonium nitrate in aqueous solution. Environ. Sci. Technol, 24(4) 566-571, 1990. 

These bacteria are induced for TCE oxidation by a wide variety of organic compounds including methane (Little et al., 1988 Oldenhuis et al., 1989 Moore, Vira Fogel, 1989 Uchiyama et al., 1992), ammonia (Arciero et al., 1989 Vannelli et al., 1990), isoprene (Ewers, Freier-Schroder Knackmuss, 1990), propane (Wackett et al., 1989), propylene (Ensign, Hyman Arp, 1992), phenol (Nelson et al., 1986 Montgomery et al., 1989 Harker Kim, 1990), 2,4-dichlorophenoxyacetic acid (Harker Kim, 1990), toluene (Nelson et al., 1986, 1987,1988 Wackett Gibson, 1988 Winter, Yen Ensley, 1989 Kaphammer, Kukor Olson, 1990) and isopropyl benzene (Dabrock et al., 1992). 

Photocatalytic oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) was investigated (Sun and Pignatello, 1995). In addition to the dominant hydroxyl radical mechanism, Sun and Pignatello found evidence that direct hole oxidation may be the mechanism for the photocatalytic degradation of some organic compounds. The assumed mechanism for this oxidation is H+ acting as an electron-transfer oxidant, while O behaves like a free OH and abstracts H or adds to C=C multiple bonds. Hole oxidation has been used to explain the oxidation of oxalate and trichloroacetate ions, which lack abstractable hydrogens or unsaturated C-C bonds. Whether the reaction... 

Sun, Y. and Pignatello, J., Evidence for a surface dual hole-radical mechanism in the Ti02 photocatalytic oxidation of 2,4-dichlorophenoxyacetic acid, Environ. Sci. Technol, 29, 2065, 1995. 

Despite the chemical diversity of the several hundred structures representing herbicidal activity, most reactions of herbicides fall within only a limited number of mechanistic types oxidation, reduction, nucleophilic displacements (such as hydrolysis), eliminations, and additions. "Herbicides", after all, are more-or-less ordinary chemicals, and their principal transformations in the environment are fundamentally no different from those in laboratory glassware. Figure 2 illustrates three typical examples which have received their share of classical laboratory study—the alkaline hydrolysis of a carboxylic ester (in this case, an ester of 2,4-dichlorophenoxyacetic acid, IX), the cycloaddition of an alcohol to an olefin (as in the acetylene, VI), and the 3-elimination of a dithiocarbamate which provides the usual synthetic route to an isothiocyanate (conversion of an N.N-dimethylcarbamic acid salt, XI, to methyl isothiocyanate). Allow the starting materials herbicidal action (which they have), give them names such as "2,4-D ester" or "pronamide" or "Vapam", and let soil form the walls of an outdoor reaction kettle the reactions and products remain the same. 

Boye, B., Brillas, E., Marselli, B., Michaud, P.A., Comninellis, Ch., Farnia, G. and Sandona, G. (2006) Electrochemical incineration of chloromethylphenoxy herbicides in acid medium by anodic oxidation with boron-doped diamond electrode. Electrochim. Acta 51, 2872-2880 Brillas, E., Calpe, J.C. and Cabot, P.L. (2003) Degradation of the herbicide 2,4-dichlorophenoxyacetic acid by ozonation catalyzed with Fe2+ and UVA light. Appl. Catal. B Environ. 46, 381-391. 

Badellino, C., Rodrigues, C. A. and Bertazzoli, R. (2006) Oxidation of pesticides by in situ electrogenerated hydrogen peroxide Study for the degradation of 2,4-dichlorophenoxyacetic acid. J. Hazard. Mater. B137, 856-864. 

Electrochemical immunosensors have been widely used for environmental analysis in amperometric, potentiometric, and conductimetric configurations. Amperometric immunosensors measure the current generated by oxidation or reduction of redox substances at the electrode surface, which is held at an appropriate electrical potential. Wilmer et al. measured concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in water by using an amperometric immunosensor with a limit of detection of 0.1 Jtg L-1 (Wilmer et al., 1997). Some examples of new developments are the disposable screen-printed electrodes for the detection of polycyclic aromatic hydrocarbons (PAHs)... 

AMOIL (131-18-0) see diamyl phthalate. AMONIACO ANHIDRO (Spanish) (7664-41-7) see ammonia, anhydrous. AMORPHOUS SILICA (68855-54-9 61790-53-2 112945-52-5, fumed 7631-86-9, hydrated) (60676-86-0, fused) SiOj Noncombustible solid. Contact with strong oxidizers chlorine trifluoride fluorine, oxygen difluoride, peroxides and hydroperoxides, or chlorine trifluoride may cause fire. Incompatible with strong acids metallic oxides at elevated temperatures. AMOXONE (94-75-7) see 2,4-dichlorophenoxyacetic acid. 

DICHLOROPHENOXYACETIC ACID, SALTS, AND ESTERS (94-75-7) CJH4CI2O3 Deconqjose in sunlight or heat above 356°F/180°C, forming hydrogen chloride fumes. Incompatible with strong oxidizers, alkahs. 

Finally, the substitution of Pt by BDD leads to a dramatic enhancement of the oxidation ability of the Fenton-based EAOPs, as observed for the pesticide 2,4-dichlorophenoxyacetic acid in Fig. 2. At present, BDD is the best anode material to oxidize organic pollutants, since it yields a high concentration of physisorbed hydroxyl radicals (BDD( OH)) at a very positive anode potential from reaction (7). Therefore, in the EF with BDD, the refractory organic molecules and their complexes with metal ions can be oxidized by the combined action of BDD( OH) formed at the anode and OH produced in the bulk. 

Rates of hydrolysis may be influenced by the presence of dissolved organic carbon or sediment and the effect is determined by the structure of the compound and by the kinetics of its association with these components. For example, whereas the neutral hydrolysis of chlorpyrifos was unaffected by sorption to sediments, the rate of alkaline hydrolysis was considerably slower (Macalady and Wolf 1985) humic acid also reduced the rate of alkaline hydrolysis of 1-octyl 2,4-dichlorophenoxyacetate (Perdue and Wolfe 1982). Conversely, sediment sorption had no effect on the neutral hydrolysis of 4-chlorostilbene oxide although the rate below pH 5 where add hydrolysis dominates was reduced (Metwally and Wolfe 1990). 

DICHLOROPHENOXYACETATE (94-11-1) Combustible liquid (flash point 175°F/ 79°C). Incompatible with strong oxidizers, strong acids, nitrates. Attacks some plastics, rubber, and coatings. 

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