2.4- Dichlorophenoxyacetic acid methyl ester

The detection limit was 0.1 pM 2,4-D, comparable to that of the radioassay, and the response range was 0.1-50 pM in buffer. Cross-reactivity of the polymer towards 2,4-dichlorophenoxyacetic acid methyl ester (2,4-D-OMe) was lower than that reported for immunoassays. 

Gas Chromatography. Dichlorophenoxyacetic acid methyl ester system GA—RI 1605 system GK—retention time 0.65 relative to caffeine. Dichlorophenoxyacetic acid iso-octyl ester system GK—retention times 1.12, 1.18 relative to caffeine. 

Dichlorophenoxyacetic Acid. Isopropyl Ester 2,4-D Esters 0,0-Diethyl-0-(3-Chloro-4- Methyl-2-Oxo-(2H)-l- Couinaphos... 

In additional in vitro studies with a number of methylene-dioxyphenyl compounds, only tropital, in addition to piperonyl butoxide, had similar inhibitory effects on the metabolism of DEHP by trout liver homogenates and serum (16). Of the methyl-enedioxyphenyl compounds studied, only tropital had a long side chain like that of piperonyl butoxide. This suggests that similarities in the side chains of these two compounds and the side chains of DEHP and 2,4-dichlorophenoxyacetic acid-n-butyl ester may be responsible for this inhibition. 

Alkaline Hydrolysis Studies. Alkaline catalyzed hydrolysis kinetics in sediment/water systems have been investigated for chlorpyrifos and the methyl and n-octyl esters of 2,4-dichlorophenoxyacetic acid (2,4-D). 

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. 

RELATIVE DETECTION LIMITS OF HALOETHYL ESTERS OF 4-CHLORO-2-METHYL-PHENOXYACETIC ACID (MCPA) AND 2,4-DICHLOROPHENOXYACETIC ACID (2,4-D) WITH THE USE OF ECD [500]... 

Fig. 8. Gas chromatograms of the methyl esters of some chlorinated phenoxy acids. A, methylchlorophenoxyacetic acid B, dichlorophenoxyacetic acid C, trichlorophenoxyacetic acid ...

The esters of the common herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) also illustrate how the rate of hydrolysis is influenced by the size of the alcohol moiety, Table 8.3. It is clear that the steric effect is amplified by the number of substituents located near the reaction site compare methyl and 2-propyl and 1- and 2-octyl esters. The inductive effect of an oxygen substituent is also apparent. A discussion... 

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