Sodium ethoxide

Sodium ethoxide
IUPAC name Sodium ethoxide
Identifiers
CAS number	141-52-6 Y
ChemSpider	8516 Y
Jmol-3D images	Image 1
SMILES [Na+].[O-]CC
InChI InChI=1S/C2H5O.Na/c1-2-3;/h2H2,1H3;/q-1;+1 Y Key: QDRKDTQENPPHOJ-UHFFFAOYSA-N Y InChI=1/C2H5O.Na/c1-2-3;/h2H2,1H3;/q-1;+1 Key: QDRKDTQENPPHOJ-UHFFFAOYAQ
Properties
Molecular formula	C2H5ONa
Molar mass	68.05 g/mol
Appearance	white powder hygroscopic
Density	0.868 g/cm^3
Melting point	260 °C, 533 K, 500 °F
Solubility in water	Reacts violently with water (miscible with ethanol and methanol)
Acidity (pKa)	15.5[1]
Hazards
MSDS	Oxford MSDS
EU classification	F+ Xn C
NFPA 704	2 2 1 W
Y ethoxide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium ethoxide is an alkoxide salt with the chemical formula C₂H₅ONa.

Preparation

It is commercially available as a white solid, or as a solution in ethanol. It is easily prepared in the laboratory by reacting sodium metal with ethanol:

2 C₂H₅OH + 2 Na → 2 C₂H₅ONa + H₂

An alternative, cheaper route is to react sodium hydroxide with anhydrous ethanol. This converts most of the hydroxide to ethoxide, and a higher purity can be reached by removing water, for example by refluxing under a column packed with a drying agent, driving the equilibrium to the right.

C₂H₅OH + NaOH ⇌ C₂H₅ONa + H₂O

Ethanolic solution gradually turns red on storage because of oxidation by air.^[2]

Applications

Sodium ethoxide is commonly used in the Claisen condensation and malonic ester synthesis, if an ethyl ester is one of the reactants. Sodium ethoxide may either deprotonate the α-position of the ester, or the ester may undergo nucleophilic substitution. If the starting material is an ethyl ester, no scrambling may occur since the product is identical to the starting material.

Safety

Sodium ethoxide is a strong base. It reacts with water vigorously to give ethanol, which is flammable, and sodium hydroxide, which is corrosive. Sodium ethoxide also oxidises quite easily which can be harmful when mixed with other electrophilic substances.

C₂H₅ONa + H₂O → C₂H₅OH + NaOH

References

1. ^ disassociation constant of Ethanol, referenced in the CRC Handbook of Chemistry and Physics 87th edition.
2. ^ M. Eagleson "Concise encyclopedia chemistry" p.997.

See also

• Alkoxide