Haloacetic acids
Encyclopedia
Haloacetic acids are carboxylic acid
s in which a halogen
atom takes the place of a hydrogen
atom in acetic acid
. Thus, in a monohaloacetic acid, a single halogen would replace a hydrogen atom. For example, chloroacetic acid
would have the structural formula CH2ClCO2H. In the same manner, in dichloroacetic acid
two chlorine
atoms would take the place of two hydrogen atoms (CHCl2CO2H). The inductive effect
caused by the electronegative halogens often result in the higher acidity of these compounds by stabilising the negative charge of the conjugate base.
chlorination
. Exposure to such disinfection by-product
s in drinking water
has been associated with a number of health outcomes by epidemiological studies, although the putative agent in such studies has not been identified. 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.
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s in which a halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...
atom takes the place of a hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
atom in acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
. Thus, in a monohaloacetic acid, a single halogen would replace a hydrogen atom. For example, chloroacetic acid
Chloroacetic acid
Chloroacetic acid, industrially known as monochloroacetic acid is the organochlorine compound with the formula ClCH2CO2H. This carboxylic acid is a useful building-block in organic synthesis.-Production:...
would have the structural formula CH2ClCO2H. In the same manner, in dichloroacetic acid
Dichloroacetic acid
Dichloroacetic acid, often abbreviated DCA, is the chemical compound with formula . It is an acid, an analogue of acetic acid, in which two of the three hydrogen atoms of the methyl group have been replaced by chlorine atoms. The salts and esters of dichloroacetic acid are called dichloroacetates...
two chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
atoms would take the place of two hydrogen atoms (CHCl2CO2H). The inductive effect
Inductive effect
In chemistry and physics, the inductive effect is an experimentally observable effect of the transmission of charge through a chain of atoms in a molecule by electrostatic induction...
caused by the electronegative halogens often result in the higher acidity of these compounds by stabilising the negative charge of the conjugate base.
Contaminants in drinking water
Haloacetic acids (HAAs) are a common undesirable by-product of drinking waterDrinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
chlorination
Chlorination
Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water...
. Exposure to such disinfection by-product
Disinfection by-product
Disinfection by-products result from reactions between organic and inorganic matter in water with chemical treatment agents during the water disinfection process.-Chlorination disinfection by-products:...
s in drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
has been associated with a number of health outcomes by epidemiological studies, although the putative agent in such studies has not been identified. 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.