Sodium ethoxide
Encyclopedia
Sodium ethoxide is an alkoxide
salt with the chemical formula C2H5ONa.
. It is easily prepared in the laboratory by reacting sodium
metal with ethanol
:
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.
Ethanolic solution gradually turns red on storage because of oxidation by air.
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.
, 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.
Alkoxide
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...
salt with the chemical formula C2H5ONa.
Preparation
It is commercially available as a white solid, or as a solution in ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
. It is easily prepared in the laboratory by reacting sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
metal with ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
:
- 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
Drying agent
The term drying agent has different meanings:* Desiccant for materials that absorb moisture and water* Oil drying agents for compounds that speed up the hardening of oils, often used in painting...
, driving the equilibrium to the right.
- C2H5OH + NaOH C2H5ONa + H2O
Ethanolic solution gradually turns red on storage because of oxidation by air.
Applications
Sodium ethoxide is commonly used in the Claisen condensationClaisen condensation
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone...
and malonic ester synthesis
Malonic ester synthesis
The malonic ester synthesis is a chemical reaction where diethyl malonate or another ester of malonic acid is alkylated at the carbon alpha to both carbonyl groups, and then converted to a substituted acetic acid. The major drawback of malonic ester synthesis is that the alkylation stage can also...
, 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
Nucleophilic substitution
In organic and inorganic chemistry, nucleophilic substitution is a fundamental class of reactions in which an electron nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms called the leaving group; the positive or partially positive...
. 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 ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, 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