In organic chemistry, the chloroacetic acids (systematic name chloroethanoic acids) are three related chlorocarbon

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

s: * Chloroacetic acid (chloroethanoic acid), CH₂ClCOOH * Dichloroacetic acid (dichloroethanoic acid; bichloroacetic acid, BCA), CHCl₂COOH * Trichloroacetic acid (trichloroethanoic acid), CCl₃COOH

Properties

As the number of chlorine atoms increases, the electronegativity of that end of the molecule increases, and the molecule adopts a progressively more ionic character: its density,

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envir ...

and acidity all increase. :

Production

* Chloroacetic acid is mainly made by hydrolysing trichloroethylene in the presence of

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

: *: CCl₂=CHCl + 2 H₂O → CH₂ClCOOH + 2 HCl * Dichloroacetic acid is manufactured in small quantities by reducing trichloroacetic acid. * Trichloroacetic acid is made by directly reacting chlorine with acetic acid using a suitable catalyst.

Uses

* Chloroacetic acid is chemical intermediate for production of various

pharmaceuticals A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and rel ...

and

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

s. * Trichloroacetic acid is used for various analytic tests in biochemistry. In sufficient concentration it will cause protein, DNA and

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

to precipitate out of solution. * The sodium salt of trichloroacetic acid is used as a weedkiller.

Safety

All of these acids are unusually strong for organic acids, and should generally be treated with similar care as for strong mineral acids like hydrochloric acid. Even neutral salts however, tend to be significantly toxic, because the ions interfere in biological processes (such as the citric acid cycle) that normally process plain acetate ions. The chloroacetate anion is the most toxic, with a rat, oral of about 0.5 g/kg.

References

{{Reflist Carboxylic acids Organochlorides