Haloacetic acids are carboxylic acids in which a halogen atom takes the place of a

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

atom in acetic acid. Thus, in a monohaloacetic acid, a single halogen would replace a hydrogen atom. For example,

chloroacetic acid Chloroacetic acid, industrially known as monochloroacetic acid (MCA), is the organochlorine compound with the formula ClCH2CO2H. This carboxylic acid is a useful building block in organic synthesis. It is a colorless solid. Related compounds a ...

would have the structural formula CH₂ClCO₂H. In the same manner, in

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 It is an acid, an analogue of acetic acid, in which 2 of the 3 hydrogen atoms of the methyl group have been replaced by chlorine atoms.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

two

chlorine Chlorine is a chemical element with the 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 them. Chlorine i ...

atoms would take the place of two hydrogen atoms (CHCl₂CO₂H). The

inductive effect In chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. It is present in a σ (sigma ...

caused by the electronegative halogens often result in the higher

acidity In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...

of these compounds by stabilising the negative charge of the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

Contaminants in drinking water

Haloacetic acids (HAAs) are a common undesirable by-product of

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...

chlorination Chlorination may refer to: * Chlorination reaction In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transform ...

. Exposure to such

disinfection by-product Disinfection by-products (DBPs) result from chemical reactions between organic and inorganic matter in water with chemical treatment agents during the water disinfection process. Chlorination disinfection byproducts Chlorinated disinfection agen ...

s in

, at high levels over many years, has been associated with a number of health outcomes by epidemiological studies. In water, HAAs are stable, with the five most common being: *

monochloroacetic acid Chloroacetic acid, industrially known as monochloroacetic acid (MCA), is the organochlorine compound with the formula ClCH2CO2H. This carboxylic acid is a useful building block in organic synthesis. It is a colorless solid. Related compounds a ...

(MCA) ClCH₂COOH *

(DCA) Cl₂CHCOOH *

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 calle ...

(TCA) Cl₃CCOOH *

monobromoacetic acid Bromoacetic acid is the chemical compound with the formula CH2BrCO2H. This colorless solid is a relatively strong alkylating agent. Bromoacetic acid and its esters are widely used building blocks in organic synthesis, for example, in pharmaceu ...

(MBA) BrCH₂COOH * dibromoacetic acid (DBA) Br₂CHCOOH Collectively, these are referred to as the HAA₅. HAAs can be formed by chlorination, ozonation or chloramination of water with formation promoted by slightly acidic water, high organic matter content and elevated temperature. Chlorine from the water disinfection process can react with organic matter and small amounts of bromide present in water to produce various HAAs. A study published in August 2006 found that total levels of HAAs in drinking water were not affected by storage or boiling, but that filtration was effective in decreasing levels.

References

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External links

Haloacetic Acids (For Private Water and Health Regulated Public Water Supplies)"Drinking Water Contaminants – Standards and Regulations"
US Environmental Protection Agency. Carboxylic acids Organohalides

Contaminants in drinking water

See also

References

Further reading

External links