Sodium ethoxide

Last updated
Sodium ethoxide
Sodium ethoxide.svg
Sodium-ethoxide-xtal-layer-view-1-Mercury-3D-bs.png
Names
Other names
Sodium ethanolate, sodium ethylate (obsolete)
Identifiers
3D model (JSmol)
3593646
ChEBI
ChemSpider
ECHA InfoCard 100.004.989 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 205-487-5
PubChem CID
UNII
  • InChI=1S/C2H5O.Na/c1-2-3;/h2H2,1H3;/q-1;+1 Yes check.svgY
    Key: QDRKDTQENPPHOJ-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C2H5O.Na/c1-2-3;/h2H2,1H3;/q-1;+1
    Key: QDRKDTQENPPHOJ-UHFFFAOYAQ
  • [Na+].[O-]CC
Properties
CH3CH2ONa
Molar mass 68.051 g·mol−1
AppearanceWhite hygroscopic powder
Density 0.868 g/cm3 (of a 21 wt% solution in ethanol)
Melting point 260 °C (500 °F; 533 K)
Reacts
Solubility ethanol and methanol
Acidity (pKa)15.5 [1]
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
Danger
H228, H251, H302, H314
P210, P235+P410, P240, P241, P260, P264, P270, P280, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P363, P370+P378, P405, P407, P413, P420, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
2
2
1
W
Safety data sheet (SDS) Oxford MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium ethoxide, also referred to as sodium ethanolate, is the ionic, organic compound with the formula CH3CH2ONa, C 2 H 5 O Na , or NaOEt (Et = ethyl). It is a white solid, although impure samples appear yellow or brown. It dissolves in polar solvents such as ethanol. It is commonly used as a strong base. [2]

Contents

Preparation

Few procedures have been reported to prepare the anhydrous solid. Instead the material is typically prepared in a solution with ethanol. It is commercially available and as a solution in ethanol. It is easily prepared in the laboratory by treating sodium metal with absolute ethanol: [3]

2 CH3CH2OH + 2 Na → 2 CH3CH2ONa + H2

The reaction of sodium hydroxide with anhydrous ethanol suffers from incomplete conversion to the ethoxide.

Structure

The crystal structure of sodium ethoxide has been determined by X-ray crystallography. It consists of layers of alternating Na+ and O centres with disordered ethyl groups covering the top and bottom of each layer. The ethyl layers pack back-to-back resulting in a lamellar structure. The reaction of sodium and ethanol sometimes forms other products such as the disolvate CH3CH2ONa·2CH3CH2OH . Its crystal structure has been determined, although the structure of other phases in the CH3CH2ONa/CH3CH2OH system remain unknown. [4]

Sodium-ethoxide-xtal-layer-stacking-Mercury-3D-bs.png Sodium-ethoxide-xtal-Na-coordination-Mercury-3D-bs.png Sodium-ethoxide-xtal-O-coordination-Mercury-3D-bs.png
ball-and-stick model of layer stacking
in the crystal structure of CH3CH2ONa
coordination geometry at Nacoordination geometry at O

Reactions

Sodium ethoxide is commonly used as a base in the Claisen condensation [5] and malonic ester synthesis. [6] Sodium ethoxide may either deprotonate the α-position of an ester molecule, forming an enolate, or the ester molecule may undergo a nucleophilic substitution called transesterification. If the starting material is an ethyl ester, trans-esterification is irrelevant since the product is identical to the starting material. In practice, the alcohol/alkoxide solvating mixture must match the alkoxy components of the reacting esters to minimize the number of different products.

Many alkoxides are prepared by salt metathesis from sodium ethoxide.

Stability

Sodium ethoxide is prone to reaction with both water and carbon dioxide in the air. [7] This leads to degradation of stored samples over time, even in solid form. The physical appearance of degraded samples may not be obvious, but samples of sodium ethoxide gradually turn dark on storage. It has been reported that even newly-obtained commercial batches of sodium ethoxide show variable levels of degradation, and responsible as a major source of irreproducibility when used in Suzuki reactions. [7]

In moist air, CH3CH2ONa hydrolyses rapidly to sodium hydroxide (NaOH). The conversion is not obvious and typical samples of CH3CH2ONa are contaminated with NaOH.

In moisture-free air, solid sodium ethoxide can form sodium ethyl carbonate from fixation of carbon dioxide from the air. Further reactions lead to degradation into a variety of other sodium salts and diethyl ether. [7]

This instability can be prevented by storing sodium ethoxide under an inert atmosphere (e.g., N2).

Safety

Sodium ethoxide is a strong base, and is therefore corrosive.

See also

Related Research Articles

<span class="mw-page-title-main">Hydroxide</span> Chemical compound

Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.

<span class="mw-page-title-main">Sodium hydroxide</span> Chemical compound with formula NaOH

Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH.

<span class="mw-page-title-main">Potassium hydroxide</span> Inorganic compound (KOH)

Potassium hydroxide is an inorganic compound with the formula KOH, and is commonly called caustic potash.

<span class="mw-page-title-main">Alkoxy group</span> Chemical group (R–O)

In chemistry, the alkoxy group is an alkyl group which is singularly bonded to oxygen; thus R−O. The range of alkoxy groups is vast, the simplest being methoxy. An ethoxy group is found in the organic compound ethyl phenyl ether.

<span class="mw-page-title-main">Aldol condensation</span> Type of chemical reaction

An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties react to form a β-hydroxyaldehyde or β-hydroxyketone, and this is then followed by dehydration to give a conjugated enone.

<span class="mw-page-title-main">Diethyl malonate</span> Chemical compound

Diethyl malonate, also known as DEM, is the diethyl ester of malonic acid. It occurs naturally in grapes and strawberries as a colourless liquid with an apple-like odour, and is used in perfumes. It is also used to synthesize other compounds such as barbiturates, artificial flavourings, vitamin B1, and vitamin B6.

<span class="mw-page-title-main">Sodium acetate</span> Chemical compound

Sodium acetate, CH3COONa, also abbreviated NaOAc, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses.

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. The reaction produces a β-keto ester or a β-diketone. It is named after Rainer Ludwig Claisen, who first published his work on the reaction in 1887. The reaction has often been displaced by diketene-based chemistry, which affords acetoacetic esters.

<span class="mw-page-title-main">Xanthate</span> Salt that is a metal-thioate/O-esters of dithiocarbonate

A xanthate is a salt or ester of a xanthic acid. The formula of the salt of xanthic acid is [R−O−CS2]M+ ,. Xanthate also refers to the anion [R−O−CS2]. The formula of a xanthic acid is R−O−C(=S)−S−H, such as ethyl xanthic acid, while the formula of an ester of a xanthic acid is R−O−C(=S)−S−R', where R and R' are organyl groups. The salts of xanthates are also called O-organyl dithioates. The esters of xanthic acid are also called O,S-diorganyl esters of dithiocarbonic acid. The name xanthate is derived from Ancient Greek ξανθός xanthos, meaning “yellowish, golden”, and indeed most xanthate salts are yellow. They were discovered and named in 1823 by Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas: the production of cellophane and related polymers from cellulose and for extraction of certain sulphide bearing ores. They are also versatile intermediates in organic synthesis.

<span class="mw-page-title-main">Triethyl orthoformate</span> Chemical compound

Triethyl orthoformate is an organic compound with the formula HC(OC2H5)3. This colorless volatile liquid, the orthoester of formic acid, is commercially available. The industrial synthesis is from hydrogen cyanide and ethanol.

<span class="mw-page-title-main">Sodium hydrosulfide</span> Chemical compound

Sodium hydrosulfide is the chemical compound with the formula NaSH. This compound is the product of the half-neutralization of hydrogen sulfide with sodium hydroxide (NaOH). NaSH and sodium sulfide are used industrially, often for similar purposes. Solid NaSH is colorless. The solid has an odor of H2S owing to hydrolysis by atmospheric moisture. In contrast with sodium sulfide, which is insoluble in organic solvents, NaSH, being a 1:1 electrolyte, is more soluble.

<span class="mw-page-title-main">Sodium methoxide</span> Ionic organic compound (CH3ONa)

Sodium methoxide is the simplest sodium alkoxide. With the formula CH3ONa, it is a white solid, which is formed by the deprotonation of methanol. It is a widely used reagent in industry and the laboratory. It is also a dangerously caustic base.

In organic chemistry, the acetoxy group, is a functional group with the formula −OCOCH3 and the structure −O−C(=O)−CH3. As the -oxy suffix implies, it differs from the acetyl group by the presence of an additional oxygen atom. The name acetoxy is the short form of acetyl-oxy.

<span class="mw-page-title-main">Sodium phenoxide</span> Chemical Compound

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.

Organosodium chemistry is the chemistry of organometallic compounds containing a carbon to sodium chemical bond. The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds, which are commercially available and exhibit more convenient reactivity.

<span class="mw-page-title-main">Potassium ethyl xanthate</span> Chemical compound

Potassium ethyl xanthate (KEX) is an organosulfur compound with the chemical formula CH3CH2OCS2K. It is a pale yellow powder that is used in the mining industry for the separation of ores. It is a potassium salt of ethyl xanthic acid.

Potassium methoxide is the alkoxide of methanol with the counterion potassium and is used as a strong base and as a catalyst for transesterification, in particular for the production of biodiesel.

Potassium ethoxide, also known as potassium ethanolate, is an off-white or yellow powder with the chemical formula of C2H5KO. Potassium ethoxide contains an ethoxide ion, the conjugate base of ethanol, which makes this compounds strongly basic. It hydrolyzes to yield ethanol and potassium hydroxide.

<span class="mw-page-title-main">Etabonate</span> Class of chemical compounds

Etabonate or ethyl carbonate is the chemical group with formula –CO
3
–C
2
H
5
, or H
3
C–CH
2
–O–C(=O)–O
–. The names are also used for esters R–OCO
2
C
2
H
5
, for the anion [C
2
H
5
OCO
2
], and for salts of the latter.

<span class="mw-page-title-main">Alkoxide</span> Conjugate base of an alcohol

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 RO, where R is the organyl substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands. Alkoxides, although generally not stable in protic solvents such as water, occur widely as intermediates in various reactions, including the Williamson ether synthesis. Transition metal alkoxides are widely used for coatings and as catalysts.

References

  1. disassociation constant of ethanol, referenced in the CRC Handbook of Chemistry and Physics 87th edition.
  2. K. Sinclair Whitaker; D. Todd Whitaker (2001). "Sodium Ethoxide". In Charette, André B. (ed.). Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rs070. ISBN   978-0-470-84289-8.
  3. C. S. Marvel, E. E. Dreger (1926). "Ethyl Acetopyruvate". Organic Syntheses . 6: 40. doi:10.15227/orgsyn.006.0040.
  4. M. Beske; L. Tapmeyer; M. U. Schmidt (2020). "Crystal structure of sodium ethoxide (C2H5ONa), unravelled after 180 years". Chem. Commun. 56 (24): 3520–3523. doi:10.1039/C9CC08907A. PMID   32101200. S2CID   211523921.
  5. Clayden, Jonathan; Greeves, Nick; Warren, Stuart (2012). Organic chemistry (2nd ed.). New York: Oxford University Press. p. 645. ISBN   978-0-19-927029-3.
  6. Wang, Zerong (15 September 2010). Comprehensive organic name reactions and reagents. John Wiley. pp. 1811–1815. ISBN   978-0-471-70450-8.
  7. 1 2 3 Wethman, Robert; Derosa, Joseph; Tran, Van; Kang, Taeho; Apolinar, Omar; Abraham, Anuji; Kleinmans, Roman; Wisniewski, Steven; Coombs, John; Engle, Keary (2020-08-19), An Under-Appreciated Source of Reproducibility Issues in Cross-Coupling: Solid-State Decomposition of Primary Sodium Alkoxides in Air, American Chemical Society (ACS), doi:10.26434/chemrxiv.12818234.v1, S2CID   242420220