:Sodium phenoxide
{{Short description|Chemical Compound}}
{{Chembox
| ImageFile = Structural formula of sodium phenoxide.svg
| ImageSize = 130px
| ImageAlt =
| ImageFile1 = File:Sodium-phenoxide-3D-balls.png
| ImageAlt1 =
| PIN = Sodium phenoxide{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=1071, 1129 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}
| OtherNames = Sodium phenolate
|Section1={{Chembox Identifiers
| CASNo = 139-02-6
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII = 4NC0T56V35
| UNII_Ref = {{fdacite|correct|FDA}}
| PubChem = 4445035
| ChemSpiderID = 8420
| SMILES = [Na+].[O-]c1ccccc1
| InChI = 1/C6H6O.Na/c7-6-4-2-1-3-5-6;/h1-5,7H;/q;+1/p-1
| InChIKey = NESLWCLHZZISNB-REWHXWOFAP
| StdInChI = 1S/C6H6O.Na/c7-6-4-2-1-3-5-6;/h1-5,7H;/q;+1/p-1
| StdInChIKey = NESLWCLHZZISNB-UHFFFAOYSA-M }}
|Section2={{Chembox Properties
| Formula = C6H5NaO
| MolarMass = 116.09 g/mol
| Appearance = White solid
| Density =
| MeltingPt =
| BoilingPt =
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|Section3={{Chembox Hazards
| MainHazards = Harmful, Corrosive
| FlashPt = Non-flammable
| AutoignitionPt = Non-flammable }}
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Sodium phenoxide (sodium phenolate) is an organic compound with the formula NaOC6H5. It is a white crystalline solid. Its anion, phenoxide, also known as phenolate, is the conjugate base of phenol. It is used as a precursor to many other organic compounds, such as aryl ethers.
Synthesis and structure
Most commonly, solutions of sodium phenoxide are produced by treating phenol with sodium hydroxide.{{cite journal|author=C. S. Marvel |author2=A. L. Tanenbaum |title=γ-Phenoxypropyl Bromide|journal=Org. Synth.|year=1929|volume= 9|page=72|doi=10.15227/orgsyn.009.0072}} Anhydrous derivatives can be prepared by combining phenol and sodium. A related, updated procedure uses sodium methoxide instead of sodium hydroxide:{{cite journal |doi=10.1021/ja01520a030|title=Heterogeneity as a Factor in the Alkylation of Ambident Anions: Phenoxide Ions1,2|year=1959|last1=Kornblum|first1=Nathan|last2=Lurie|first2=Arnold P.|journal=Journal of the American Chemical Society|volume=81|issue=11|pages=2705–2715}}
:NaOCH3 + HOC6H5 → NaOC6H5 + HOCH3
Sodium phenoxide can also be produced by the "alkaline fusion" of benzenesulfonic acid, whereby the sulfonate groups are displaced by hydroxide:
:C6H5SO3Na + 2 NaOH → C6H5OH + Na2SO3
This route once was the principal industrial route to phenol.{{Citation needed|date=September 2022}}
Structure
Like other sodium alkoxides, solid sodium phenoxide adopts a complex structure involving multiple Na-O bonds. Solvent-free material is polymeric, each Na center being bound to three oxygen ligands as well as the phenyl ring. Adducts of sodium phenoxide are molecular, such as the cubane-type cluster [NaOPh]4(HMPA)4.Michael Kunert, Eckhard Dinjus, Maria Nauck, Joachim Sieler "Structure and Reactivity of Sodium Phenoxide - Following the Course of the Kolbe-Schmitt Reaction" Chemische Berichte 1997 Volume 130, Issue 10, pages 1461–1465. {{doi|10.1002/cber.19971301017}}
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Reactions
Sodium phenoxide is a moderately strong base. Acidification gives phenol:{{March6th}}
:PhOH ⇌ PhO− + H+ (K = 10−10)
The acid-base behavior is complicated by homoassociation, reflecting the association of phenol and phenoxide.{{cite book|title=Acid-Base Dissociation Constants in Dipolar Aprotic Solvents|author=K. Izutsu |publisher=Blackwell Scientific Publications|year=1990|volume=35}}
Sodium phenoxide reacts with alkylating agents to afford alkyl phenyl ethers:
:NaOC6H5 + RBr → ROC6H5 + NaBr
The conversion is an extension of the Williamson ether synthesis. With acylating agents, one obtains phenyl esters:{{citation needed|date=May 2024}}
:NaOC6H5 + RC(O)Cl → RCO2C6H5 + NaCl
Sodium phenoxide is susceptible to certain types of electrophilic aromatic substitutions. For example, it reacts with carbon dioxide to form 2-hydroxybenzoate, the conjugate base of salicylic acid. In general however, electrophiles irreversibly attack the oxygen center in phenoxide.{{citation needed|date=May 2024}}
:image:Kolbe-Schmitt.png.]]{{clear-left}}
