2,4-Dichlorophenoxyacetic acid, solution

Fig. 19.7 TOC decay with total charge passed during the mineralization of 125 cm3 of an 02-saturated 220 mg dm 3 2,4-D (2,4-dichlorophenoxyacetic acid) solution with ImM Fe3+ in H2SO4 of pH 2 at room temperature in the cathodic compartment of a divided Pt/carbon felt cell at Ecm = —0.5V vs. SCE giving a current of 60 mA [adapted from Oturan (2000)]...

J. Horacek and P. Skladal, Improved direct piezoelectric biosensors operating in liquid solution for the competitive label-free immunoassay of 2,4-dichlorophenoxyacetic acid. Anal. Chim. Acta 347, 43-50 (1997). 

Dichlorophenoxyacetyl chloride i4)was prepared by addition of 110.0 g (0.498 moles) of 2,4-dichlorophenoxyacetic acid in 250 ml of benzene and 7 ml of N,N-dimethylformamide (DMF) into a one liter, 3-necked roundbottomed flask equipped with mechanical stirrer, addition funnel, thermometer and condenser connected to a caustic scrubber. After heating to reflux, a solution of... 

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. 

For a given pesticide which undergoes hydrolysis, any or all of these hydrolytic pathways may be relevant at various pH s. Organophosphorothioates, for example, have measurable neutral and alkaline hydrolysis rate constants (7). Esters of 2,4-dichlorophenoxyacetic acid (2,4-D), on the other hand, hydrolyze by acid and alkaline catalyzed reactions, but have extremely small neutral hydrolysis rate constants ( ). Thus, any study of the hydrolysis of sorbed pesticides must be prefaced by an understanding of the hydrolytic behavior of individual pesticides in aqueous solution. 

Tsyganok, A.I., Yamanaka, I. and Otsuka, K. (1998) Pd-loaded carbon felt as the cathode for selective dechlorination of 2,4-dichlorophenoxyacetic acid in aqueous solution. J. Electrochem. Soc. 145, 3844-3850. 

An approach similar to the amperometric morphine sensor has very recently been described by Kroger et al. [81]. Particles of poly(EDMA-co-4-vinylpyridine) imprinted with 2,4-dichlorophenoxyacetic acid were trapped in agarose on a screen-printed carbon electrode. The sensor was equilibrated in a solution of the template analyte species with a fixed amount of the electroactive competitor homogentisic acid, then the free homogentisic acid was quantified by differential pulse voltammetry. This approach has the advantage of being applicable to non-redox-active species, provided a suitable redox-active competitive probe can be found. 

A mixture of 2,4-dichlorophenoxyacetic acid (2,4-D 1 mmol), 4-vinylpyridine (4 mmol), ethylene glycol dimethacrylate (20 mmol), and ADVN (0.31 mmol) in a methanol/water mixture (4 mL/1 mL) was sonicated and purged with nitrogen for 2 min. The solution was polymerized at 45 °C for 4 h, and then at 60 °C for 2 h. The polymer was ground and sieved in acetone. The particles were washed by methanol/acetic acid (7/3, v/v twice), acetonitrile/acetic acid (9/1, v/v twice), acetonitrile (once), and methanol (twice) for 2 h each time, followed by centrifugation. The particles were then suspended in acetone for 4 h. The particles in suspension were collected and the procedure was repeated four times. The solvent was removed by centrifugation and the particles were dried in vacuo [8],... 

Solution Examination of 2,4-Dichlorophenoxyacetic acid (2,4-D), the compound we wish to synthesize, shows that it... 

Sorption of 2,4-dichlorophenoxyacetic acid (2,4-D) by Bentone 24 was rapid and occurred in considerable quantities, as shown in Figure 1. Although uncoated Wyoming bentonite had no sorption of 2,4-D within the detectable limits (less than about 0.3 mg/liter) of the analysis, the Bentone 24 sorbed about 13 mg of 2,4-D per gram of organo-clay when the equivalent of 20 mg of 2,4-D per 200 ml of aqueous solution was available. This sorption was nearly complete within 30 minutes and remained constant after 3 hours. Longer periods were used for equilibration because they were convenient. These longer periods also assured equilibrium at other temperatures used. 

Cabrera M.I., Martin C.A., Alfano O.M. and Cassano A.E. 1997a. Photochemical decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution. I. Kinetic study. Water Sci. Technol., 35(4), 31-39. 

Amylopectins. — The effects of acrylamide graft copolymerization on the solution properties of amylopectin have been discussed. Amylopectin has been dyed with DyAmyl-L and used in this form as a substrate for the assay of a-amylase. Amylopectin has been treated with isocyanate derivatives of 4-amino-( 1,1-dimethyl ethyl)-3-(methylthio)-l,2,4-triazin-5(4/f)-one ( metribuzin ) or acid chloride derivatives of 2,4-dichlorophenoxyacetic acid ( 2,4-D ) and 2,2-dichloropropionic acid ( dalapon ), to produce controlled-release polymeric pesticide systems. The solvent system utilized for these reactions, a lithium chloride or bromide salt in AW-dimethylacetamide, allows dissolution of the reactant salt and facilitates analysis of the polymer product by such techniques as i.r., U.V., and n.m.r. spectroscopies and gel permeation chromatography. Derivatives of other naturally occurring polysaccharides, including amylopectin, cellulose, chitin, and dextran, were also prepared. 

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