Sodium phenoxide

Sodium phenoxide
Names
	Other names Sodium phenolate
Identifiers
CAS Number	139-02-6;
3D model (JSmol)	Interactive image;
ChemSpider	8420;
ECHA InfoCard	100.004.862
PubChem CID	4445035;
CompTox Dashboard (EPA)	DTXSID4027072 ;
	InChI InChI=1S/C6H6O.Na/c7-6-4-2-1-3-5-6;/h1-5,7H;/q;+1/p-1 Key: NESLWCLHZZISNB-UHFFFAOYSA-M; InChI=1/C6H6O.Na/c7-6-4-2-1-3-5-6;/h1-5,7H;/q;+1/p-1 Key: NESLWCLHZZISNB-REWHXWOFAP;
	SMILES c1ccc(cc1)[O-].[Na+];
Properties
Chemical formula	C6H5NaO
Molar mass	116.09 g/mol
Appearance	White solid
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Harmful, Corrosive
Flash point	Nonflammable
Autoignition; temperature	Nonflammable
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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.^[1] Anhydrous derivatives can be prepared by combining phenol and sodium:

Na + HOC₆H₅ → NaOC₆H₅ + 1/2 H₂

Like other sodium alkoxides, crystalline sodium phenolate 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.^[2]

Sodium phenoxide can be produced by the "alkaline fusion" of benzenesulfonic acid, whereby the sulfonate groups are displaced by hydroxide:

C₆H₅SO₃Na + 2 NaOH → C₆H₅ONa + Na₂SO₃

This route once was the principal industrial route to phenol.

Subunit of the structure of solvent-free sodium phenoxide, illustrating the binding of phenoxide to sodium through both the arene and the oxygen.

Reactions

Sodium phenoxide is a moderately strong base. Acidification gives phenol:^[3]

PhOH ⇌ PhO⁻ + H⁺ (K = 10⁻¹⁰)

Alkylation affords phenyl ethers:^[1]

NaOC₆H₅ + RBr → ROC₆H₅ + NaBr

The conversion is an extension of the Williamson ether synthesis. With acylating agents, one obtains esters:

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.

References

^ ^a ^b "γ-Phenoxypropyl Bromide". Org. Synth. 9: 72. 1929. doi:10.15227/orgsyn.009.0072. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
^ 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
^ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 978-0-471-72091-1

External links

Media related to Sodium phenoxide at Wikimedia Commons

[Speed-1] "γ-Phenoxypropyl Bromide". Org. Synth. 9: 72. 1929. doi:10.15227/orgsyn.009.0072. {{cite journal}}: Cite uses deprecated parameter |authors= (help)

[2] 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

[3] Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 978-0-471-72091-1

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