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Sodium phenoxide

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Sodium phenoxide
Names
Other names
Sodium phenolate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.862 Edit this at Wikidata
  • 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
  • c1ccc(cc1)[O-].[Na+]
Properties
C6H5NaO
Molar mass 116.09 g/mol
Appearance White solid
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Harmful, Corrosive
Flash point Nonflammable
Nonflammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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 from 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 is 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.

Ball-and-stick model of the sodium coordination geometry in unsolvated sodium phenoxide Space-filling model of part of a chain in the crystal structure of unsolvated sodium phenoxide

Reactions

Basicity

Sodium phenoxide is a moderately strong base. At low pH's gives phenol:[3]

PhOH ⇌ PhO− + H+          (K = 10−10)

Nucleophilic substitution

Sodium phenoxide can be used to prepare phenyl ethers and metal phenolates:[1]

NaOC6H5 + RBr → ROC6H5 + NaBr

Electrophilic substitution reactions

Sodium phenoxide is susceptible to certain types of electrophilic aromatic substitution. For example, it reacts with carbon dioxide to form 2-hydroxybenzoate, the conjugate base of salicylic acid. In general however, electrophiles irreversibly attack oxygen.

The Kolbe–Schmitt reaction.
The Kolbe–Schmitt reaction.

References

  1. ^ a b C. S. Marvel and A. L. Tanenbaum "γ-Phenoxypropyl Bromide" Org. Synth. 1929, vol. 9, pp. 72.
  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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