Phenolates
Phenolates (also called phenoxides) are anions, salts, and esters of phenols, containing the phenolate ion. They may be formed by reaction of phenols with strong base.[1]
Properties
[edit]Alkali metal phenolates, such as sodium phenolate hydrolyze in aqueous solution to form basic solutions.[2] At pH = 10, phenol and phenolate are in approximately 1:1 proportions.
The phenoxide anion (aka phenolate) is a strong nucleophile with a comparable to the one of carbanions or tertiary amines.[3] Generally, oxygen attack of phenoxide anions is kinetically favored, while carbon-attack is thermodynamically preferred (see Thermodynamic versus kinetic reaction control). Mixed oxygen/carbon attack and by this a loss of selectivity is usually observed if the reaction rate reaches diffusion control.[4]
Uses
[edit]Alkyl aryl ethers can be synthesized through the Williamson ether synthesis by treating sodium phenolate with an alkyl halide:[5]
- C6H5ONa + CH3I → C6H5OCH3 + NaI
- C6H5ONa + (CH3O)2SO2 → C6H5OCH3 + (CH3O)SO3Na
Production of salicylic acid
[edit]Salicylic acid is produced in the Kolbe–Schmitt reaction between carbon dioxide and sodium phenolate.
See also
[edit]References
[edit]- ^ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, p. 506, ISBN 978-0-471-72091-1
- ^ Jakubke, Hans-Dieter; Karcher, Ruth (1999). Lexikon der Chemie in drei Bänden, Band 3. Heidelberg: Spektrum Verlag. p. 14. ISBN 3-8274-0381-2.
- ^ [1]. Mayr’s Database of Reactivity Parameters. Retrieved July 10, 2019.
- ^ Mayer, Robert J.; Breugst, Martin; Hampel, Nathalie; Ofial, Armin R.; Mayr, Herbert (2019-06-26). "Ambident Reactivity of Phenolate Anions Revisited: A Quantitative Approach to Phenolate Reactivities". Journal of Organic Chemistry. 84 (14): 8837–8858. doi:10.1021/acs.joc.9b01485. PMID 31241938. S2CID 195696760.
- ^ Beyer, Hans; Walter, Wolfgang (1984). Organische Chemie. Stuttgart: S. Hirzel Verlag. pp. 463–464. ISBN 3-7776-0406-2.
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