Hypochlorous acid
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| Hypochlorous acid | |
|---|---|
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| General | |
| Systematic name | hypochlorous acid |
| Other names | ? |
| Molecular formula | HClO |
| SMILES | ? |
| Molar mass | 52.46 g/mol |
| Appearance | colorless aqueous solns |
| CAS number | [7790-92-3] |
| Properties | |
| Density and phase | ? g/cm3, ? |
| Solubility in water | soluble |
| Other solvents | Et2O, CH2Cl2 |
| Melting point | ? °C (? K) |
| Boiling point | ? °C (? K) |
| Acidity (pKa) | 7.497[1] |
| Structure | |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | oxidizer |
| NFPA 704 | |
| R/S statement | R: ? S: ? |
| RTECS number | ? |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | NaOCl |
| Other cations | HOBr, HOF |
| Related compounds | Cl2 Ca(OCl)2 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Hypochlorous acid is a weak acid with the chemical formula HOCl. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor (see below). HOCl is used as a bleach, an oxidizer, a deodorant, and a disinfectant.
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[edit] Formation
Addition of chlorine to water gives both hypochlorous acid and hydrochloric acid[2] (HCl):
- Cl2 + H2O → HClO + HCl
[edit] Chemical reactions
In aqueous solution, hypochlorous acid partially dissociates into the hypochlorite anion ClO- (also known as the chlorate(I) anion) and the proton H+. The salts of hypochlorous acid are also called hypochlorites. One of the best known hypochlorites is household bleach, sodium hypochlorite, NaClO.
In the presence of sunlight, hypochlorous acid decomposes into more hydrochloric acid and oxygen, so this reaction is sometimes seen as:
- 2Cl2 + 2H2O → 4HCl + O2
HClO is considered to be a stronger oxidant than chlorine.
[edit] Uses
In organic synthesis, HOCl converts alkenes to chlorohydrins.[3]
In biology, hypochlorous acid is produced by neutrophils to kill bacteria.[4][5][6]
Hypochlorous acid is the active sanitizer in chlorine-based swimming pool products.
[edit] Safety
HOCl is a strong oxidant and thus can form explosive mixtures, and it can give off toxic chlorine gas.
[edit] External links
[edit] References
- ^ Morris, J. C. 1966. The acid ionization constant of HOCl from 5 to 35 °. J. Phys. Chem. 70:3798-3805.
- ^ Fair, G. M., J. C. Morris, S. L. Chang, I. Weil, and R. P. Burden. 1948. The behavior of chlorine as a water disinfectant. J. Am. Water Works Assoc. 40:1051-1061.
- ^ Unangst, P. C. "Hypochlorous Acid" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
- ^ Harrison, J. E., and J. Schultz. 1976. Studies on the chlorinating activity of myeloperoxidase. J. Biol. Chem. 251:1371-1374.
- ^ Thomas, E. L. 1979. Myeloperoxidase, hydrogen peroxide, chloride antimicrobial system: Nitrogen-chlorine derivatives of bacterial components in bactericidal action against Escherichia coli. Infect. Immun. 23:522-531.
- ^ Winterbourne, C. C. 1985. Comparative reactivities of various biological compounds with myeloperoxidase-hydrogen peroxide-chloride, and similarity to the oxidant to hypochlorite. Biochim. Biophys. Acta 840:204-210.
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