organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, 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 Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

s: *

Chloroacetic acid Chloroacetic acid, industrially known as monochloroacetic acid (MCA), is the organochlorine compound with the formula . This carboxylic acid is a useful building block in organic synthesis. It is a colorless solid. Related compounds are dichlo ...

(chloroethanoic acid), CH₂ClCOOH *

Dichloroacetic acid Dichloroacetic acid (DCA), sometimes called bichloroacetic acid (BCA), is the organic compound with formula . It is an analogue of acetic acid, in which 2 of the 3 hydrogen atoms of the methyl group have been replaced by chlorine atoms. Like the ...

(dichloroethanoic acid; bichloroacetic acid, BCA), CHCl₂COOH *

Trichloroacetic acid Trichloroacetic acid (TCA; TCAA; also known as trichloroethanoic acid) is an analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms. Salts and esters of trichloroacetic acid are cal ...

(trichloroethanoic acid), CCl₃COOH

Properties

As the number of

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

atoms increases, the

electronegativity Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...

of that end of the molecule increases, and the molecule adopts a progressively more ionic character: its

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

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 envi ...

and acidity all increase. :

Production

* Chloroacetic acid is mainly made by hydrolysing

trichloroethylene Trichloroethylene (TCE) is an organochloride with the formula C2HCl3, commonly used as an industrial metal-degreasing solvent. It is a clear, colourless, non-flammable, volatile liquid with a chloroform-like pleasant mild smell and sweet taste.

in the presence of

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

: *: 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 Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

Uses

* Chloroacetic acid is chemical intermediate for production of various

pharmaceuticals Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, 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 ...

and

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

s. * Trichloroacetic acid is used for various analytic tests in

biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ...

. In sufficient concentration it will cause

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

and

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

out of

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solu ...

. * The

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

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 Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

. Even neutral salts however, tend to be significantly toxic, because the ions interfere in biological processes (such as the

citric acid cycle The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle, or TCA cycle (tricarboxylic acid cycle)—is a series of chemical reaction, biochemical reactions that release the energy stored in nutrients through acetyl-Co ...

) that normally process plain acetate ions. The chloroacetate

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

is the most toxic, with a rat, oral of about 0.5 g/kg.

References

{{Reflist Carboxylic acids Organochlorides