2.4- Dichlorophenoxyacetic acid , function, 237

After these initial steps, TIQDT was tested for its capacity to screen environmentally relevant compounds. 2,4-Dichlorophenoxyacetic acid (2,4-D), l,l-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT), and 4-nonylphenol (4-NP) were selected as they are usually considered to be TGFDs [52-55]. Reports concerning the effect of methyhnercury (MeHg) on thyroid function are contradictory [56-58]. Two environmentally relevant compounds with no reported effects on the thyroid system, fenoxicarb and atrazine [59, 60], were included as negative controls to assess the specificity of the assay. Our data strongly suggest that TIQDT may be... 

Acrylic Acid Propenoic Acid Benzoic Acid Carboxylic Acids Carboxylic Acids and Derivatives Carboxylic Acids with Other Functional Groups Carboxylic Acids with Other Functional Groups Dichlorophenoxyacetic Acid 2,4-d Cesium... 

Fig. 5.19. Molecular imprinting of 2,4-dichlorophenoxyacetic acid using 4-VPY as functional monomer and methanol as diluent as described by Haupt et al. [33].

Fig. 3-8 Molecular imprinting of 2,4-dichlorophenoxyacetic acid (2,4-D) using 4-vinylpyridine as a functional monomer...

In another study by Dennis et al. [141], the DNA microarray technology was used to monitor the expression of catabolic genes related to 2,4-dichlorophenoxyacetic acid (2,4-D) degradation within pme and mixed cultures of the 2,4-D-degrading bacterium Ralstonia eutropha JMP134. With this technique, it was shown that two of five 2,4-D catabolic genes were induced upon addition of the pesticide. The study demonstrated the potential of DNA microarrays for the detection of functional genes in complex environmental systems. 

The molecular manipulation of nicotinic acid designed to obtain a compound with prolonged hypoHpidemic activity has led to a substance in which the carboxyl group of nicotinic acid has been exchanged for the tetrazole moiety [70]. Such an approach had been taken previously in the plant-hormone series, where the carboxyl functions of 3-indolylacetic acid and 2,4-dichlorophenoxyacetic acids had been replaced with the tetrazole group [71]. Parenthetically, the plant-growth regulator, 2,4-dichlorophenoxyacetic acid, has also been reported to possess hypocholesterolemic activity in experimental animals [72]. 

Other polychlorinated molecules function as herbicides 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid), diquat, paraquat, and Teklon. Many of these compounds are no longer used because their stability in the environment allows them to accumulate in the fat of fish, birds, and mammals. 

As early as 1989, Tomalia et al. [137] demonstrated with carbon-13, spin-lattice relaxation (Ti) techniques that small molecules such as acetylsalicyclic acid or 2,4-dichlorophenoxyacetic acid could be encapsulated within the interior of carboxymethyl ester terminated PAMAM dendrimers exhibiting guestihost stoichiometries of 4 1 by weight or 3 1 on a molar basis. These encapsulations appear to be driven by simple ion pairing of the acidic guest molecules with the tertiary amine sites located within the PAMAM dendrimer host. More recently, extensive work by Twyman et al. [138,139] and others [140] has shown that dendrimers may function as very versatile host molecules for drug delivery systems. Figure 18 illustrates the incorporation of benzoic acid within the interior of a hydroxyl terminated PAMAM dendrimer. 

Dichlorophenoxyacetic add 2,4-D under Carboxylic Acids with Other Functional Groups Dichloropropane, 1,2 under Saturated Alkyl Halides Dichlorotrifluoroethane HCFC-123 under Saturated Alkyl Halides Dieldrin under Dihalogenated and Polyhalogenated Ethers... 

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