Amino acids 2 4-dichlorophenoxyacetates

Dichlorophenoxyacetates. Amino acids react with 2 chlorophenoxyacetyl chloride to give crystalline derivatives ... 

Optical isomerism of phenoxycarboxylic acids also plays a decisive role in their activity. Of the amino acid derivatives of 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenoxypropionic acid only the derivatives of the dl- and L-amino acids are active, while the respective D-amino acid derivatives are completely inactive. This can be attributed to the fact that plants are unable to hydrolyse the peptide bond of the D-derivatives (Wood and Fontaine, 1952 Krewson et al., 1956). 

The major natural auxin is indole-3-acetic acid (lAA) [42]. A number of related compounds exist in plants, including indolebutyric acid and indoleacetonitrile (Fig. la). These related compounds are active primarily when first converted to lAA [42]. In addition, there are a series of LAA conjugates with sugars and amino acids [43]. Some of these may be detoxification products, but others may be reservoirs of releasable lAA, especially in seeds. Phenylacetic acid (Fig. la) has auxin activity, and exists in sizable amounts in a few plants such as tobacco [42], but it is unclear that this compound actually moves from one part of a plant to another. In addition to the natural auxins, a whole host of synthetic auxins are known. The most widely used are a-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) (Fig. la). 

Differences of 2,4-D (2,4-dichlorophenoxyacetic acid) conjugation in wheat (tolerant) versus some broadleaf weeds (susceptible) exemplifies how Phase II metabolism imparts herbicide selectivity. Many susceptible broadleaf weeds produce glucose ester metabolites, which are readily susceptible to hydrolysis, yielding phytotoxic 2,4-D. Conversely, 2,4-D-tolerant wheat rapidly produces amino acid conjugates and 0-glucosides, which are stable, nonphytotoxic metabolites that are not easily hydrolyzed 11,12),... 

The scientists from Hong Kong reported83 on a sol-gel derived molecular imprinted polymers (MIPs) based luminescent sensing material that made use of a photoinduced electron transfer (PET) mechanism for a sensing of a non-fluorescent herbicide - 2,4-dichlorophenoxyacetic acid. A new organosilane, 3 - [N,V-bis(9-anthrylmethyl)amino]propyltriethoxysilane, was synthesized and use as the PET sensor monomer. The sensing MIPs material was fabricated by a conventional sol-gel process. 

There is qualified support for the weak-acid hypothesis, particularly for compounds such as 2,4-dichlorophenoxyacetic acid. Crisp and Look (.5) compared the phloem mobility of several synthetic 4-chlorophenoxy derivatives. The carboxyl derivative was loaded and transported in the phloem, whereas derivatives in which the COOH group was replaced by an ethyl ester, amide, ketone, alcohol, or amino group were not translocated. 

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. 

The indiscriminate use of such agricultural chemicals as pesticides, herbicides, and fertilizers is an important source of environmental pollution. A novel application of polymer-bound materials has been made in the controlled release of agricultural chemicals (Allan et al., 1973 Beasley and Collins, 1970 Shambu et al., 1976 Schacht et al., 1977, 1978 reviews of Neogi and Allan, 1974 Scher, 1977). When these chemicals are covalently bound to a polymer from which they can be slowly released into the environment, they not only check pollution but their duration of action is prolonged. The same effect can be obtained by encapsulation of the chemicals in polymeric beads from which they can be released slowly, e.g., 2,4-dichlorophenoxyacetic acid and 4-amino-3,5,6-trichloropicolinic acid have been used in polymer-bound form. 

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