Phenoxyacetic acid, POA, is a white solid with the formula of C8H8O3.[1][2] Although not itself usefully active as an herbicide, it forms the part-structure of many phenoxy herbicide derivatives including MCPA and 2,4-D.
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| Names | |
|---|---|
| Preferred IUPAC name
Phenoxyacetic acid | |
| Identifiers | |
3D model (JSmol)
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| 907949 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.004.143 |
| EC Number |
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| 142730 | |
| KEGG | |
PubChem CID
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| UNII | |
| UN number | 3347 |
CompTox Dashboard (EPA)
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| Properties | |
| C8H8O3 | |
| Molar mass | 152.15 g/mol |
| Appearance | White solid or tan powder |
| Odor | Sweet and sour |
| Melting point | 98–99 °C (208–210 °F; 371–372 K) |
| log P | 1.48 |
| Acidity (pKa) | 3.7 |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H302, H315, H319, H335 | |
| P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure and synthesis
editPhenoxyacetic acid is an O-phenyl derivative of glycolic acid. It is both a monocarboxylic acid and an aryl ether. Its preparation from sodium phenolate and sodium chloroacetate in hot water was first reported in 1880.[3]
- 1) C6H5O−Na+ + ClCH2COO−Na+ → C6H5OCH2COO−Na+ + NaCl
- 2) C6H5OCH2COO−Na+ + HCl → C6H5OCH2COOH + NaCl
The phenolate anion reacts via nucleophilic attack on the methylene carbon of the chloroacetic acid, forming an ether bond.
Properties
editPhenoxyacetic acid is a white or clear crystalline compound at room temperature.[2] When impure, it can appear to be a light tan to brown. The compound has a solubility in water of 12 g/L and is highly soluble in organic solvents including ethanol, diethyl ether and benzene. Phenoxyacetic acid is a weak acid and weak base with a pKa of 3.7.[1][4]
Uses
editPhenoxyacetic acid has found minor uses as a food additive and perfume component and is categorised as "generally recognised as safe" in these applications.[5][6]
References
edit- ^ a b Wishart, David S.; Guo, An Chi; Oler, Eponine; Wang, Fel; Anjum, Afia; Peters, Harrison; Dizon, Raynard; Sayeeda, Zinat; Tian, Siyang; Lee, Brian L.; Berjanskii, Mark; Mah, Robert; Yamamoto, Mai; Jovel Castillo, Juan; Torres Calzada, Claudia; Hiebert Giesbrecht, Mickel; Lui, Vicki W.; Varshavi, Dorna; Varshavi, Dorsa; Allen, Dana; Arndt, David; Khetarpal, Nitya; Sivakumaran, Aadhavya; Harford, Karxena; Sanford, Selena; Yee, Kristen; Cao, Xuan; Budinsky, Zachary; Liigand, Jaanus; Zhang, Lun; Zheng, Jiamin; Mandal, Rupasri; Karu, Naama; Dambrova, Maija; Schiöth, Helgi B.; Gautam, Vasuk. "Showing metabocard for Phenoxyacetic acid (HMDB0031609)". Human Metabolome Database, HMDB. 5.0.
- ^ a b "Phenoxyacetic acid". Sigmaaldrich. 2021. Retrieved 2021-02-17.
- ^ "Phenoxyacetic Acid". Journal of the Chemical Society, Abstracts. 38: 318–319. 1880. doi:10.1039/CA8803800307.
- ^ Freed, V. H.; Chiou, C. T.; Schmedding, D.; Kohnert, R. (1979). "Some physical factors in toxicological assessment tests". Environmental Health Perspectives. 30: 75–80. doi:10.1289/ehp.793075. PMC 1637710. PMID 446460.
- ^ "Phenoxyacetic acid". The Good Scents Company. Retrieved 2021-02-17.
- ^ "Opinion of the Scientific Panel on food additives, flavourings, processing aids and materials in contact with food (AFC) related to Flavouring Group Evaluation 23 (FGE.23): Aliphatic, alicyclic and aromatic ethers including anisole derivatives from chemical groups 15, 16 and 26 (Commission Regulation (EC) No 1565/2000 of 18 July 2000". EFSA Journal. 5 (5). 2007. doi:10.2903/j.efsa.2007.417.