|Jmol-3D images||Image 1|
|Molar mass||39.01 g mol-1|
|Density||1.39 g cm-3|
|Melting point||210 °C (410 °F; 483 K)|
|Boiling point||400 °C (752 °F; 673 K)|
|Solubility in water||reacts|
|Solubility||0.004 g/100 mL (liquid ammonia), reacts in ethanol|
|Acidity (pKa)||38 (conjugate acid) |
heat capacity C
|66.15 J/mol K|
|76.9 J/mol K|
|Std enthalpy of
|Gibbs free energy ΔG||-59 kJ/mol|
|EU Index||Not listed|
|Flash point||4.44 °C (39.99 °F; 277.59 K)|
|Other anions||Sodium bis(trimethylsilyl)amide|
|Other cations||Potassium amide|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Sodium amide, commonly called sodamide, is the inorganic compound with the formula NaNH2. This solid, which is dangerously reactive toward water, is white, but commercial samples are typically gray due to the presence of small quantities of metallic iron from the manufacturing process. Such impurities do not usually affect the utility of the reagent. NaNH2 conducts electricity in the fused state, its conductance being similar to that of NaOH in a similar state. NaNH2 has been widely employed as a strong base in organic synthesis.
Preparation and structure
Sodium amide can be prepared by the reaction of sodium with ammonia gas, but it is usually prepared by the reaction in liquid ammonia using iron(III) nitrate as a catalyst. The reaction is fastest at the boiling point of the ammonia, c. −33 °C. An electride, [Na(NH3)6]+e-, is formed as an intermediate.
- 2 Na + 2 NH3 → 2 NaNH2 + H2
NaNH2 is a salt-like material and as such, crystallizes as an infinite polymer. The geometry about sodium is tetrahedral. In ammonia, NaNH2 forms conductive solutions, consistent with the presence of Na(NH3)6+ and NH2- anions.
Sodium amide is mainly used as a strong base in organic chemistry, often in liquid ammonia solution. It is the reagent of choice for the drying of ammonia (liquid or gaseous). One of the main advantages to the use of sodamide is that it is rarely functions as a nucleophile. In the industrial production of indigo, sodium amide is a component of the highly basic mixture that induces cyclisation of N-phenylglycine. The reaction produces ammonia, which is recycled typically.
Sodium amide induces the loss of two equivalents of hydrogen bromide from a vicinal dibromoalkane to give a carbon-carbon triple bond, as in a preparation of phenylacetylene. Usually two equivalents of sodium amide yields the desired alkyne. Three equivalents are necessary in the preparation of a terminal alkynes because the terminal CH of the resulting alkyne protonates an equivalent amount of base.
Deprotonation of carbon and nitrogen acids
Carbon acids which can be deprotonated by sodium amide in liquid ammonia include terminal alkynes, methyl ketones, cyclohexanone, phenylacetic acid and its derivatives and diphenylmethane. Acetylacetone loses two protons to form a dianion. Sodium amide will also deprotonate indole and piperidine.
Related nonnucleophilic bases
It is however poorly soluble in solvents other than ammonia. Its use has been superseded by the related reagents sodium hydride, sodium bis(trimethylsilyl)amide (NaHMDS), and lithium diisopropylamide (LDA).
- Rearrangement with orthodeprotonation
- Oxirane synthesis
- Indole synthesis
- Chichibabin reaction
- NaNH2 + H2O → NH3 + NaOH
- 2 NaNH2 + 4 O2 → Na2O + 2 NO2 + 2 H2O
In the presence of limited quantities of air and moisture, such as in a poorly closed container, explosive mixtures of peroxides may form. This is accompanied by a yellowing or browning of the solid. As such, sodium amide is be stored in a tightly closed container, under an atmosphere of inrty gas. Sodium amide samples which are yellow or brown in color represent explosion risks.
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- ; Coll. Vol. 5: 526
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- "Sodium Amide". Princeton, NJ: Princeton University. 2011-03-16. Retrieved 2011-07-20.