2.4- Dichlorophenoxyacetic acid preparation

Step A Preparation of 2,3-Dichloro-4-Butyrylphenoxy Acid - The product is prepared using the following ingredients 22.1 grams (0.1 mol) 2,3-dichlorophenoxyacetic acid ... 

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... 

Dichloropropionyl chloridefiS was prepared by charging a two liter, 3-necked, roundbottom flask equipped with mechanical stirrer,thermometer, addition funnel, and condenser connected to a caustic scrubber with 250 g of 2,2-dichlorophenoxyacetic acid in 500 ml of chloroform and 10 ml of DMF. The mixture was refluxed for one hour, followed by the addition of 328 g of thionyl chloride over a period of one hour. The mixture was refluxed for two additional hours. After removal of excess thionyl chloride and solvent, the crude product was vacuum distilled yielding 210 g of the acid chloride (b.p. 75°C 20 mm). 

Because the metabolism of DEHP was relatively slow, the more readily hydrolyzed 2,4-dichlorophenoxyacetic acid-n-butyl ester was sometimes used for comparison. The hydrolysis of this compound, both by liver preparations and by serum also was inhibited by piperonyl butoxide. Liver homogenates from trout, which had been exposed to piperonyl butoxide in vivo, showed decreased capacity to metabolize DEHP (Table VIII). 

Surugiu et al. [67] have introduced an Enzyme Immuno-Like Assays (EzILA) for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The label was a 2,4-D conjugate with the tobacco peroxidase (TOP) enzyme, which allows for both colorimetric and chemiluminescent detection. In this case, the polymer imprinted with 2,4-D was synthesized in the form of microspheres. In contrast, despite its higher binding capacity for radiolabeled 2,4-D, a conventional MIP prepared by bulk polymerization showed only weak binding of the 2,4-D-TOP tracer. 

In addition to its use in making resins and adhesives, phenol is also the starting material for the synthesis of chlorinated phenols and the food preservatives BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole). Fenta-chlorophenol, a widely used wood preservative, is prepared by reaction of phenol with excess CI2. T he herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) is prepared from 2,4-dichlorophenol, and the hospital antiseptic agent hexa-chlorophene is prepared from 2,4,5-trichlorophenol. 

The principle of making depot preparations by esterification is widely applied not only to steroid hormones, but also to other drugs (e.g vitamin K, the tranquillizer fluphenazine, and the antimalarial amodiaquine (Fig. 35)158,159> and in the field of pesticides to the weedkiller dichlorophenoxyacetic acid. 

A herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D)-imprinted polymer particles were immobilized on a disposable three-electrode system prepared by screen printing [13]. The imprinted polymer particles were... 

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. 

Moreover, a magnetic molecularly imprinted polymer of 4-divinylpyridine and EGDMA particles was synthesized by inverse suspension polymerization [119]. The reaction was carried out in silicon oil as a dispersion phase, and in the presence of 2,4-dichlorophenoxyacetic acid and MPTS. The advantages of the silicon oil as a continuous phase are a low polarity and immiscibility with the monomer mixture. The prepared particle average size is 20 pm and the magnetic content is very low, at around 1 wt%. 

Dichlorophenoxyacetic acid (2,4-D) is a selective herbicide used for weed control, water hyacinth control, and various other uses. Several companies manufacture 2,4-D. 2,4,5-T, salts, and esters are used widely to control woody plants on industrial sites and range land. Amine formulations are used extensively for weed control on rice. The action and properties of these compounds are similar to those of 4,5-T preparations. 

Yongliang Liu, He Yonghuan, Jin Yulong, Huang Yanyan, Liu Guoquan, and Zhao Rui. Preparation of monodispersed macroporous core-shell molecularly imprinted particles and their application in the determination of 2,4-dichlorophenoxyacetic acid. J. Chromatogr. A. 1323 (2014) 11-17. 

Herbicides may be selective, as for broad-leaved weeds in cereal crops, or unselective, essentially for land clearance. 2,4-Dichlorophenoxyacetic acid (2,4-D), 24.6, was commercialized in the 1940s it is inexpensive, is easy to make, and kills broad-leaved weeds in cereal crops. Worldwide, it is the most widely used herbicide. It is a synthetic auxin, or plant hormone, acting only on dicots and not monocots. There is a whole family of related compounds, prepared from chloroacetic acid (or other halo acids) and various chlorinated phenols. Agent Orange, used as a defoliant in Vietnam in the 1970s, was a 1 1 mixture of 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The main concerns about its use relate to the possibility that dioxins are formed as contaminants in its manufacture. A few countries ban its use for control of weeds in domestic lawns. 

Organic anion based hydrazinium salts have also been prepared by neutralization of aqueous hydrazine hydrate with 2,4-dichlorophenyl-acetic acid, phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid. 

---