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Sodium amide

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Sodium amide

General
Other names Sodamide
Molecular formula NaNH2
Molar mass 39.01 g/mol
Appearance gray powder
CAS number [7782-92-5]
Properties
Density and phase ? g/cm3, ?
Solubility in water reacts
Melting point 210°C
Boiling point 400°C
Basicity (pKb) ≈-19
Structure
Coordination
geometry 		?
Crystal structure ?
Hazards
MSDS External MSDS
EU classification not listed
NFPA 704
Flash point Non-flammable.
RTECS number ?
Supplementary data page
Structure and
properties 		n, εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Sodium hydroxide
Other cations Potassium amide
Related compounds Ammonia
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
[Chemical infoboxInfobox disclaimer and references]

Sodium amide, also called sodamide, is NaNH2. This solid is highly reactive, dangerously so in the presence of moisture or air. It hydrolyzes readily to ammonia. The pure solid is white, but commercial samples are often grey in colour due to the presence of small quantities of metallic iron from the manufacturing process: this does not usually affect the use of the product. Sodium amide samples which are yellow or brown in colour should be destroyed immediately (see Safety below).

Contents

Preparation

Sodium amide can be prepared by the reaction of sodium with ammonia gas,[#endnote_PrepnOS] but it is usually prepared by the reaction in liquid ammonia using iron(III) nitrate as a catalyst.[#endnote_PrepnIS]
2Na + 2NH3 → 2NaNH2 + H2

Uses

Sodium amide is used in the industrial production of indigo, hydrazine, and sodium cyanide.[#endnote_Merck] It is the reagent of choice for the drying of ammonia (liquid or gaseous) and is also widely used as a strong base in organic chemistry, often in liquid ammonia solution. Its use has been superseded by the popularlization of related reagents such as NaH, NaN[Si(CH3)3]2, and LiN[CH(CH3)2]2.

Preparation of alkynes

Sodium amide induces the loss of two molecules of hydrogen bromide from a vicinal dibromoalkane to give a carbon-carbon triple bond, as in the preparation of phenylacetylene below.[#endnote_Campbell]

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Hydrogen chloride and/or ethanol can also be eliminated in this way,[#endnote_Jones][#endnote_Bou][#endnote_Magriotis][#endnote_Ashworth] as in the preparation of 1-ethoxy-1-butyne.[#endnote_Newman]

800px

Cyclization reactions

Where there is no β-hydrogen to be eliminated, cyclic compounds may be formed, as in the preparation of methylenecyclopropane below.[#endnote_Salaun]

500px

Cyclopropenes,[#endnote_Nakamura] aziridines[#endnote_Bottini] and cyclobutanes[#endnote_Skorcz] may be formed in a similar manner.

Deprotonation of carbon and nitrogen acids

Carbon acids which can be deprotonated by sodium amide in liquid ammonia include terminal alkynes,[#endnote_Saunders][#endnote_Peterson][#endnote_Kauer] methyl ketones,[#endnote_Coffman][#endnote_Hauser2] cyclohexanone,[#endnote_Vanderwerf] phenylacetic acid and its derivatives[#endnote_Hauser1][#endnote_Kaiser][#endnote_Wawzonek] and diphenylmethane.[#endnote_Murphy] Acetylacetone loses two protons to form a dianion.[#endnote_Hampton]

750px

Sodium amide will also deprotonate indole[#endnote_Potts] and piperidine.[#endnote_Bunnett]

Other reactions

Safety

Sodium amide reacts violently with water to produce ammonia and sodium hydroxide: and will burn in air to give oxides of sodium and nitrogen.
NaNH2 + H2O → NH3 + NaOH
2NaNH2 + 4O2 → Na2O2 + 2NO2 + 2H2O
In the presence of limited quantities of air and moisture, such as in a poorly closed container, explosive mixtures of oxidation products can form. This is accompanied by a yellowing or browning of the solid. As such, sodium amide should always be stored in a tightly closed container, if possible under an atmosphere of nitrogen gas. Sodium amide samples which are yellow or brown in colour should be destroyed immediately: one method for destruction is the careful addition of ethanol to a suspension of sodium amide in a hydrocarbon solvent.

Sodium amide may be expected to be corrosive to the skin, eyes and mucous membranes. Care should be taken to avoid dispersal of the dust.

References

  1. ↑  Bergstrom, F. W. (1955). "[Sodium amide]". Org. Synth. Coll. Vol. 3:778.
  2. ↑  Greenlee, K. W.; Henne, A. L. (1946). "Sodium Amide". Inorg. Synth. 2:128–35.
  3. ↑  Merck Index (12th Edn.)
  4. ↑  Campbell, Kenneth N.; Campbell, Barbara K. (1950). "[Phenylacetylene]". Org. Synth. 30:72; Coll. Vol. 4:763.
  5. ↑  Jones, E. R. H.; Eglinton, Geoffrey; Whiting, M. C.; Shaw, B. L. (1954). "[Ethoxyacetylene]". Org. Synth. 34:46; Coll. Vol. 4:404.
  6. ↑  Bou, Anna; Pericàs, Miquel A.; Riera, Antoni; Serratosa, Fèlix (1987). "[Dialkoxyacetylenes: di-tert-butoxyethyne, a valuable synthetic intermediate]". Org. Synth. 65:68; Coll. Vol. 8:161.
  7. ↑  Magriotis, Plato A.; Brown, John T. (1995). "[Phenylthioacetylene]". Org. Synth. 72:252; Coll. Vol. 9:656.
  8. ↑  Ashworth, P. J.; Mansfield, G. H.; Whiting, M. C. (1955). "[2-Butyn-1-ol]". Org. Synth. 35:20; Coll. Vol. 4:128.
  9. ↑  Newman, Melvin S.; Stalick, W. M. (1977). "[1-Ethoxy-1-butyne]". Org. Synth. 57:65; 6:564.
  10. ↑  Salaun, J. R.; Champion, J.; Conia, J. M. (1977). "[Cyclobutanone from methylenecyclopropane via oxaspiropentane]". Org. Synth. 57:36; Coll. Vol. 6:320.
  11. ↑  Nakamura, Masuharu; Wang, Xio Qun; Isaka, Masahiko; Yamago, Shigeru; Nakamura, Eiichi (2003). "[Synthesis and (3+2)-cycloaddition of a 2,2-dialkoxy-1-methylenecyclopropane: 6,6-dimethyl-1-methylene-4,8-dioxaspiro(2.5)octane and cis-5-(5,5-dimethyl-1,3-dioxan-2-ylidene)hexahydro-1(2H)-pentalen-2-one]". Org. Synth. 80:144.
  12. ↑  Bottini, Albert T.; Olsen, Robert E. (1964). "[N-Ethylallenimine]". Org. Synth. 44:53; Coll. Vol. 5:541.
  13. ↑  Skorcz, J. A.; Kaminski, F. E. (1968). "[1-Cyanobenzocyclobutene]". Org. Synth. 48:55; Coll. Vol. 5:263.
  14. ↑  Saunders, J. H. (1949). "[1-Ethynylcyclohexanol]". Org. Synth. 29:47; Coll. Vol. 3:416.
  15. ↑  Peterson, P. E.; Dunham, M. (1977). "[(Z)-4-Chloro-4-hexenyl trifluoroacetate]". Org. Synth. 57:26; Coll. Vol. 6:273.
  16. ↑  Kauer, J. C.; Brown, M. (1962). "[Tetrolic acid]". Org. Synth. 42:97; Coll. Vol. 5:1043.
  17. ↑  Coffman, Donald D. (1940). "[Dimethylethynylcarbinol]". Org. Synth. 20:40; Coll. Vol. 3:320.
  18. ↑  Hauser, C. R.; Adams, J. T.; Levine, R. (1948). "[Diisovalerylmethane]". Org. Synth. 28:44; Coll. Vol. 3:291.
  19. ↑  Vanderwerf, Calvin A.; Lemmerman, Leo V. (1948). "[2-Allylcyclohexanone]". Org. Synth. 28:8; Coll. Vol. 3:44.
  20. ↑  Hauser, Charles R.; Dunnavant, W. R. (1960). "[α,β-Diphenylpropionic acid]". Org. Synth. 40:38; Coll. Vol. 5:526.
  21. ↑  Kaiser, Edwin M.; Kenyon, William G.; Hauser, Charles R. (1967). "[Ethyl 2,4-diphenylbutanoate]". Org. Synth. 47:72; Coll. Vol. 5:559.
  22. ↑  Wawzonek, Stanley; Smolin, Edwin M. (1951). "[α,β-Diphenylcinnamonitrile]". Org. Synth. 31:52; Coll. Vol. 4:387.
  23. ↑  Murphy, William S.; Hamrick, Phillip J.; Hauser, Charles R. (1968). "[1,1-Diphenylpentane]". Org. Synth. 48:80; Coll. Vol. 5:523.
  24. ↑  Hampton, K. Gerald; Harris, Thomas M.; Hauser, Charles R. (1971). "[Phenylation of diphenyliodonium chloride: 1-phenyl-2,4-pentanedione]". Org. Synth. 51:128; Coll. Vol. 6:928. Hampton, K. Gerald; Harris, Thomas M.; Hauser, Charles R. (1967). "[2,4-Nonanedione]". Org. Synth. 47:92; Coll. Vol. 5:848.
  25. ↑  Potts, K. T.; Saxton, J. E. (1960). "[1-Methylindole]". Org. Synth. 40:68; Coll. Vol. 5:769.
  26. ↑  Bunnett, J. F.; Brotherton, T. K.; Williamson, S. M. (1960). "[N-β-Naphthylpiperidine]". Org. Synth. 40:74; Coll. Vol. 5:816.
  27. ↑  Brazen, W. R.; Hauser, C. R. (1954). "[2-Methylbenzyldimethylamine]". Org. Synth. 34:61; Coll. Vol. 4:585.
  28. ↑  Allen, C. F. H.; VanAllen, J. (1944). "[Phenylmethylglycidic ester]". Org. Synth. 24:82; Coll. Vol. 3:727.
  29. ↑  Allen, C. F. H.; VanAllen, James (1942). "[2-Methylindole]". Org. Synth. 22:94; Coll. Vol. 3:597.

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