Acids dichloroacetic

Fit a 1500 ml. bolt-head flask with a reflux condenser and a thermometer. Place a solution of 125 g. of chloral hydrate in 225 ml. of warm water (50-60°) in the flask, add successively 77 g. of precipitated calcium carbonate, 1 ml. of amyl alcohol (to decrease the amount of frothing), and a solution of 5 g. of commercial sodium cyanide in 12 ml. of water. An exothermic reaction occurs. Heat the warm reaction mixture with a small flame so that it reaches 75° in about 10 minutes and then remove the flame. The temperature will continue to rise to 80-85° during 5-10 minutes and then falls at this point heat the mixture to boiling and reflux for 20 minutes. Cool the mixture in ice to 0-5°, acidify with 107-5 ml. of concentrated hydrochloric acid. Extract the acid with five 50 ml. portions of ether. Dry the combined ethereal extracts with 10 g. of anhydrous sodium or magnesium sulphate, remove the ether on a water bath, and distil the residue under reduced pressure using a Claisen flask with fractionating side arm. Collect the dichloroacetic acid at 105—107°/26 mm. The yield is 85 g. 

Submitted by Arthur C. Cope, John R. Clark and Ralph Connor. 

A solution of 250 g. (1.51 moles) of chloral hydrate (Note 1) in 450 cc. of warm water (50-60°) is placed in a 3-I. round-bottomed flask bearing a reflux condenser and thermometer (Note 2). The condenser is temporarily removed and 152.5 g. (1.52 moles) of precipitated calcium carbonate added this is followed by 2 cc. of amyl alcohol (Note 3) and a solution of 10 g. of sodium cyanide (Note 4) in 25 cc. of water. Although the reaction is exothermic, the reaction mixture is heated with a low flame so that it reaches 75° in about ten minutes at this point heating is discontinued. The temperature continues to rise to 80-85° during five to ten minutes and then drops. As soon as the temperature begins to fall the solution is heated to boiling and refluxed for twenty minutes. The mixture is then cooled to 0-5° in an ice bath, acidified with 215 cc. of concentrated hydrochloric acid (sp. gr. 1.18) and extracted with five 100-cc. portions of ether (Note 5). The combined ether extracts are dried with 20 g. of anhydrous sodium sulfate, the ether is removed by distillation from a steam bath, and the residue distilled in vacuum from a Claisen flask with a fractionating side 

The amount of hydrogen cyanide evolved is small, and the reaction may be carried out in a hood without any special device for removing this gas. The use of mechanical stirring does not improve the results. 

Amyl alcohol is added to decrease the amount of foaming. 

The emulsion which often forms during the ether extraction may be broken by filtering through a fluted filter or with suction. 

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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 ... 

Gas chromatography or Hquid chromatography (23) are commonly used to measure impurities such as acetic, dichloroacetic, and trichloroacetic acids. High purity 99+% chloroacetic acid will contain less than 0.5% of either acetic acid or dichloroacetic acid. Other impurities that may be present in small amounts are water and hydrochloric acid. 

Dichloroacetic acid [79-43-6] (CI2CHCOOH), mol wt 128.94, C2H2CI2O2, is a reactive intermediate in organic synthesis. Physical properties are mp 13.9°C, bp 194°C, density 1.5634 g/mL, and refractive index 1.4658, both at 20°C. The Hquid is totally miscible in water, ethyl alcohol, and ether. Dichloroacetic acid K = 5.14 X 10 ) is a stronger acid than chloroacetic acid. Most chemical reactions are similar to those of chloroacetic acid, although both chlorine... 

Dichloroacetic acid is produced in the laboratory by the reaction of chloral hydrate [302-17-0] with sodium cyanide (31). It has been manufactured by the chlorination of acetic and chloroacetic acids (32), reduction of trichloroacetic acid (33), hydrolysis of pentachloroethane [76-01-7] (34), and hydrolysis of dichloroacetyl chloride. Due to similar boiling points, the separation of dichloroacetic acid from chloroacetic acid is not practical by conventional distillation. However, this separation has been accompHshed by the addition of a eotropeforming hydrocarbons such as bromoben2ene (35) or by distillation of the methyl or ethyl ester. 

Dichloroacetic acid is used in the synthesis of chloramphenicol [56-75-7] and aHantoin [97-59-6]. Dichloroacetic acid has vimcidal and fungicidal activity. It was found to be active against several staphylococci (36). The oral toxicity is low the LD q in rats is 4.48 g/kg. It can, however, cause caustic bums of the skin and eyes and the vapors are very irritating and injurious (28). 

Trichloroacetic acid K = 0.2159) is as strong an acid as hydrochloric acid. Esters and amides are readily formed. Trichloroacetic acid undergoes decarboxylation when heated with caustic or amines to yield chloroform. The decomposition of trichloroacetic acid in acetone with a variety of aUphatic and aromatic amines has been studied (37). As with dichloroacetic acid, trichloroacetic acid can be converted to chloroacetic acid by the action of hydrogen and palladium on carbon (17). 

Approximately 50% of an absorbed dose is transformed to fluoride ion, dichloroacetic acid, methoxydifluoroacetic acid, and oxaHc acid (50). 

Chloramphenicol. Only chloramphenicol and a few closely related analogues fall iato this group. Chloramphenicol, a nitro benzene derivative of dichloroacetic acid, inhibits proteia biosyathesis. 

Commercial monochloroacetic acid contains many other organic acids, particularly dichloroacetic acid [79 3-6] CI2CHCOOH, which has to be completely converted iato sulfur derivatives to avoid residual chlorine compounds which are harmful for cosmetic apphcations (8). Thioglycohc acid, which has to meet cosmetic specifications, must be free of metal impurities, and must be pure enough to avoid color and odor problems. 

Compound (1) decomposes to form dichloroacetyl chloride, which in the presence of water decomposes to dichloroacetic acid and hydrochloric acid (HCl) with consequent increases in the corrosive action of the solvent on metal surfaces. Compound (2) decomposes to yield phosgene, carbon monoxide, and hydrogen chloride with an increase in the corrosive action on metal surfaces. 

A. p-Methoxyphenyllead triaaetate. A 1-L Erlenmeyer flask, equipped with a magnetic stirring bar, is charged with 50 g (0.11 moll of lead tetraacetate (Note 1), chloroform (200 mL), and 140 g (1.09 moll of dichloroacetic acid (Note 21. To this solution is added 16 g (0.15 mol) of anisole (Note 3), and the mixture is stirred at 25°C until lead tetraacetate can no longer be detected (Note 41. The reaction mixture is washed with water (2 x 250 mil and the chloroform solution is treated with 1.5 L of hexane (Note 51. The yellow... 

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%. 

Acetic acid Acetic anhydride Acid mixtures Battery fluids Chloroacetic acid Chlorosulphonic acid Chromic acid Dichloroacetic acid Fluoroboric acid Fluorosilicic acid... 

D1CHLORO-5-PHENYL ISOCYANATE DICHLOROACETIC ACID DICHLOROACETYL CHLORIDE DICHLOROANILINE... 

Haloacetic acids dichloroacetic acid (zero) trichloroacetic acid (0.3 mg/L). Monochloroacetic acid, bromoacetic acid, and dibromoacetic acid are regulated with this group but have no MCLGs. 

The use of dichloroacetic acid instead of pyridinium trifluoroacetate increases the rate of oxidation considerably. This acid has been used in one case to obtain an optimum yield of the 11-ketoestrone (8) from the corresponding 1 la-hydroxy compound. ... 

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