Dichloroacetic acid preparation

Dichloroacetic acid is conveniently prepared by the action of calcium carbonate in the presence of a little sodium cyanide upon chloral hydrate, followed by acidification with concentrated hydrochloric acid ... 

Freshly opened bottles of diehloroacetyl chloride from Aldrich Chemical Company, Inc., were used. The acid chloride can also be prepared by the dropwiae addition of 1 volume of dichloroacetic acid to 2.5 volumes of phthaloyl chloride heated to 140°. After the addition is complete, the solution is vigorously heated and diehloroacetyl chloride, b.p. 106-108°, is distilled through a 30-cm. column packed with glass beads the yield is 85%. 

The aldehyde 38 was obtained from 35, by way of 36 and 37, by the carbodiimide—dimethyl sulfoxide oxidation procedure52 in the presence of 3-(3-dimethylaminopropyl)-l-ethylcarbodiimide hydrochloride (EDAC)53 and dichloroacetic acid. It was isolated in the form of its crystalline 1,3-diphenylimidazolidine derivative (39) by trapping the freshly prepared aldehyde 38 with N,N -diphen-ylethylenediamine. (This reagent was developed by Wanzlick and Lochel54 for the selective derivatization of aldehydes, and has been exploited for the isolation of nucleoside 5 -aldehydes55 and other aldehydo derivatives of carbohydrates by Moffatt and coworkers.52(b))... 

In addition to benzenoid diazo components, diazotised heterocyclic amines in which the amino group is attached to a nitrogen- or sulphur-containing ring figure prominently in the preparation of disperse dyes [87,88], since these can produce marked bathochromic shifts. The most commonly used of these are the 6-substituted 2-aminobenzothiazoles, prepared by the reaction of a suitable arylamine with bromine and potassium thiocyanate (Scheme 4.31). Intermediates of this type, such as the 6-nitro derivative (4.79), are the source of red dyes, as in Cl Disperse Red 145 (4.80). It has been found that dichloroacetic acid is an effective solvent for the diazotisation of 2-amino-6-nitrobenzothiazole [89]. Subsequent coupling reactions can be carried out in the same solvent system. Monoazo disperse dyes have also been synthesised from other isomeric nitro derivatives of 2-aminobenzothiazole [90]. Various dichloronitro derivatives of this amine can be used to generate reddish blue dyes for polyester [91]. 

O-linked polymer-bound Af-substituted hydroxylamines are prepared by reduction of resin-bound oximes with borane-pyridine complex in the presence of dichloroacetic acid (Scheme 94). Other reducing systems commonly used for imine or oxime reduction are ineffective, including borane-pyridine in the presence of acetic acid. Subsequently, the A-substituted products are acylated and cleaved from the resin to afford Af-substituted hydroxamic acids 220. ... 

Ethyl diethoxyacetate has been prepared from dichloroacetic acid by the action of sodium ethoxide followed by esterification of the intermediate diethoxyacetic acid. This esterification has been carried out with ethyl iodide on the sodium salt or on the silver salt.5 6 7 It has been more conveniently done with ethanol and acid.8 910 Poorer yields are reported when the dichloroacetic acid is first esterified and then treated with sodium ethoxide.11... 

Many chlorinated hydrocarbons are toxic to some degree. Thus the mixed solvent of dichloroacetic acid and ethylene dichloride should be handled with care. This solvent is also very corrosive. If it is necessary to prepare the PEG solutions, gloves should be worn. Use a pipette bulb do not pipette by mouth. Dispose of waste chemicals as instructed. 

The Step 1 product (111 mg) and the Step 2 product (302mg) were mixed in 2,2-dichloroacetic acid (22.2 g) and stirred until no further change was observed in the UV-Vis-NIR spectrum. Self-supported films were prepared by pouring about 1 ml onto a polypropylene substrate and removing the solvent by evaporation at 45°C. The film was detached from its substrate and dried under vacuum the film s thickness was on the order of 20 to 30 pM. 

Note All doping was conducted in 2,2-dichloroacetic acid with 20 to 30 pM films prepared on a polypropylene substrate. 

GlyoxyKc acid dithioethyl acetal, (C2HsS)2CHCOOH (1). Mol. wt. 180.29. This reagent is conveniently prepared in quantitative yield by addition of dichloroacetic acid to 3 equiv. of NaH in THF followed by reaction overnight with an excess of ethanethiol. ... 

The crystal structure of the hydroxyphosphorane (88) prepared by N2O4 oxidation of (87) showed an almost perfect tbp structure with the unit cell containing two molecules of the same helicity connected by H-bonds between the P-OH and carbonyl groups.The phosphorus ester (89), fashioned from two n-butyl tartrate moieties exists in solution due to intramolecular hydrogen bonds. On treatment with triethylamine, however, it forms the triethylammo-nium salt (90) of the corresponding hydroxyphosphorane. The pKa value of (89) was determined to be 7.7 in DMF and 4.4 in DMSO, similar to values for dichloroacetic acid in the same two solvents. ... 

A great advantage of electrochemical reactions compared with chemical conversions is the effective contribution to pollution control. The direct electron transfer from the electrode to the substrate avoids the problem of separation and waste treatment of the frequently toxic end products of the chemical oxidants or reductants. Furthermore, by electrodialysis, organic acids or bases can be regenerated from their salts without the use of sulfuric acid or sodium hydroxide, for example, which lead to the coproduction of sodium salts or sulfates as waste [79]. At the same time, inorganic acids and bases, necessary for chemical production, are provided by this process. An application of electrodialysis has been demonstrated in the preparation of methoxyacetic acid by oxidation of methoxyethanol at the nickel hydroxide electrode [80]. Finally, unwanted side products can be converted into the wanted product, which increases the economy of the process and reduces the problem of waste separation and treatment. This is accomplished in the manufacture of chloroacetic acid by chlorination of acetic acid. There the side product dichloroacetic acid, formed by overchlorination, is cathodically converted to chloroacetic acid [81]. 

The reagent (1) is prepared in 92% yield by the addition of 3-bromopropanol (Eastman) to ethyl vinyl ether catalyzed by dichloroacetic acid.1... 

Dichloroacetic acid has been prepared by the chlorination of acetic or chloroacetic acid, by hydrolysis of pentachloro-ethane, from trichloroacetic acid by electrolytic reduction or the action of copper, and by the action of alkali cyanides on chloral hydrate. The method described here is essentially that of Delepine. ... 

Prepared from chloral and urea by condensation catalysed with HCl, it is a crystalline compound insoluble in water and stable to acids. In alkaline medium it is decomposed into dichloroacetic acid and urea. In the soil it yields trichloroacetic acid by oxidative decomposition. According to Melnikov (1971a) these reactions... 

A method for preparing random point deletions in oligonucleotides has been described. Depending on the desired level of mutations, various concentrations of dichloroacetic acid replaces the conventional trichloroacetic acid and capping is omitted from the synthesis cycle. 

Dichloroacetic Acid, CHCI2.COOH, can be prepared by chlorinating acetic acid, but as the acid made in this way is mixed with chloroacetic acid, it is usually prepared by boiling chloral hydrate (329) with an aqueous solution of potassium cyanide —... 

The seminal work of Schulz and co-workers on anionic polymer initiators which contain protected hydroxyl functionality was reported in 1974." These researchers prepared 2-(6-lithio- -hexyloxy)tetrahydopyran by metal-halogen exchange in diethyl ether, see Figure 1. The lithium chloride co-product was removed by filtration. This initiator was successfully employed in the polymerization of 1,3-butadiene. The resultant functionalized living anion was subsequently functionalized with ethylene oxide or coupled with dimethyldichlorosilane. Mild acid hydrolysis with dichloroacetic acid liberated the telechelic dihydroxy polybutadiene. The polybutadienes produced with this initiator exhibited narrow molecular weight distributions = 1.05-1.08). 

From the viscosity measurements in dichloroacetic acid the molecular weights of polyglutamates were estimated. The solutions were prepared by weighing the polymer and solvent in a stoppered bottle. After shaking slowly on a magnetic stirrer for long time, the solutions were put carefully into the cell, which was having parallel sides 2mm apart. Then the top of the capillary of the cell was sealed to prevent the... 

Mullen and coworkers have also prepared the blue-emitting (A, iax = 450 nm) polyketal 149, films of which can be converted by exposure to dichloroacetic acid vapour to the orange-emitting (A,max = 580 nm) polyflu-orenone 150 (Scheme 71) [249]. The carbonyl groups enhance the electron-accepting properties of 150, and this polymer shows useful electrontransporting properties, though the acidic residues from the conversion are a potential source of problems for electronic applications [250]. 

High amylose starch, treated with formamide and dichloroacetic acid and a plasticizer yield homogenous, flowable quasi-solutions without formation of gels when they are heated, with stirring, to temperatures above 80°C. As plasticizers serve ethylene glycol, triethylene glycol, poly(vinyl alcohol), and glycerol (13). The properties of such prepared compositions are shown in Table 7.4. 

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