Hypohalite
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Hypohalites are chemical compounds containing the hypohalite ion, with the general formula XO⁻, where X is a halogen element from Group 17 of the periodic table (fluorine, chlorine, bromine, or iodine). Hypohalites are the conjugate bases of hypohalous acids (HOX) and represent the lowest oxidation state (+1) of halogens in their oxoanions. The pseudohalogen analogues are hypopseudohalites.
Hypohalites, especially hypochlorite and hypobromite, are commonly used as disinfectants. In human bodies, the animal heme-dependent peroxidases of the immune system produce hypohalites (OCl⁻, OBr⁻, OI⁻) and hypothiocyanite as a weapon.[1][2] Hypohalites are also encountered in organic chemistry, often as acyl hypohalites (see the Hunsdiecker reaction). Sodium hypohalite is used in the haloform reaction as a test for methyl ketones.[3] In human bodies, the generate hypohalites and hypopseudohalites are generated by ]
Structure
The hypohalite ion consists of a halogen atom covalently bonded to an oxygen atom, carrying an overall negative charge. The halogen is in the +1 oxidation state, and the oxygen is in the usual −2 state. The general formula is:
- is the halogen atom, and
- is the oxygen atom
The Cl-O bond length in crystalline sodium hypochlorite pentahydrate, NaOCl·5H2O, is 1.686 Å, while in sodium hypobromite pentahydrate, NaOBr·5H2O, the Br–O bond length is 8% longer at 1.820 Å.[4]
