Sodium phenoxide (sodium phenolate) is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...

with the formula NaOC₆H₅. It is a white crystalline solid. Its anion, phenoxide, also known as phenolate, is the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it requir ...

. It is used as a precursor to many other organic compounds, such as aryl

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again b ...

Synthesis and structure

Most commonly, solutions of sodium phenoxide are produced by treating phenol with sodium hydroxide. Anhydrous derivatives can be prepared by combining phenol and sodium. A related, updated procedure uses sodium methoxide instead of sodium hydroxide: :NaOCH₃ + HOC₆H₅ → NaOC₆H₅ + HOCH₃ Sodium phenoxide can also be produced by the "alkaline fusion" of

benzenesulfonic acid Benzenesulfonic acid (conjugate base benzenesulfonate) is an organosulfur compound with the formula C6 H6 O3 S. It is the simplest aromatic sulfonic acid. It forms white deliquescent sheet crystals or a white waxy solid that is soluble in water a ...

, whereby the sulfonate groups are displaced by hydroxide: :C₆H₅SO₃Na + 2 NaOH → C₆H₅ONa + Na₂SO₃ This route once was the principal industrial route to phenol.

Structure

Like other sodium

alkoxide In chemistry, an alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as , where R is the organic substituent. Alkoxides are strong bases and, wh ...

s, 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 A cubane-type cluster is an arrangement of atoms in a molecular structure that forms a cube. In the idealized case, the eight vertices are symmetry equivalent and the species has Oh symmetry. Such a structure is illustrated by the hydrocarbon cub ...

aOPhsub>4(

HMPA Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula This colorless liquid is a useful reagent in organic synthesis. Structure and reactivity HMPA is the oxide of the highly basic te ...

)₄.

Reactions

Sodium phenoxide is a moderately strong base. Acidification gives phenol: :PhOH ⇌ PhO⁻ + H⁺ (K = 10⁻¹⁰) The acid-base behavior is complicated by

homoassociation In acid–base chemistry, homoassociation (an IUPAC term) is an association between a base and its conjugate acid through a hydrogen bond. The alternate term ''homoconjugation'' also has wide usage, but is ambiguous because it has another meanin ...

, reflecting the association of phenol and phenoxide. 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 The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and a deprotonated alcohol (alkoxide). This reaction was developed by Alexander Williamson in 1850. Typically it involves the reaction of an alkoxide io ...

. With acylating agents, one obtains phenyl esters: :NaOC₆H₅ + RC(O)Cl → RCO₂C₆H₅ + NaCl Sodium phenoxide is susceptible to certain types of

electrophilic aromatic substitution Electrophilic aromatic substitution is an organic reaction in which an atom that is attached to an aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic n ...

s. For example, it reacts with carbon dioxide to form 2-hydroxybenzoate, the conjugate base of

salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substa ...

. In general however, electrophiles irreversibly attack the oxygen center in phenoxide. 500px, center, The Kolbe–Schmitt reaction.

References

External links

{{commons category inline Phenolates Organic sodium salts