Sodium hyponitrite
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Properties | |
Na2N2O2 | |
Molar mass | 105.99 g/mol |
Appearance | colorless crystals |
Density | 2.466 g/cm3 |
Melting point | 100 °C (212 °F; 373 K) |
Boiling point | 335 °C (635 °F; 608 K) decomposes |
soluble | |
Solubility | insoluble in ethanol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium hyponitrite is a solid
There are cis and trans forms of the hyponitrite ion N
2O2−
2. The trans form is more common, but the cis form can be obtained too, and it is more reactive than the trans form.[1][2]
Trans isomer
The trans isomer is colorless and soluble in water and insoluble in ethanol and ether.[3][4]
Preparation
Sodium hyponitrite (trans) is conventionally prepared by
- 2 NaNO2 + 4 Na(Hg) + 2 H2O → Na2N2O2 + 4 NaOH + 4 Hg
Sodium hyponitrite (trans) was prepared in 1927 by
- RONO + NH2OH + 2 EtONa → Na2N2O2 + ROH + 2 EtOH
An earlier method, published by
Other methods included
Hydrates
A variety of
2N
2O
2(H
2O)x of the trans isomer have been reported, with x including 2, 3.5, 4, 5, 6, 7, 8, and 9;[11][3][12] but there is some dispute.[13]
The hydration water seems to be just trapped in the crystal lattice rather than coordinated to the ions.[13] The anhydrous substance can be obtained by drying the hydrates over phosphorus pentoxide and then heating them to 120 °C.[13]
Reactions
Sodium hyponitrite (trans) in solution is decomposed by carbon dioxide CO
2 from air to form sodium carbonate.[14]
Liquid N2O4 oxidises sodium hyponitrite (trans) to give sodium peroxohyponitrite Na2+
2[ON=NOO]2−).[15][1]
Cis isomer
The cis isomer of sodium hyponitrite is a white crystalline solid, insoluble in
Preparation
The cis isomer of can be prepared by passing nitric oxide (NO) through a solution of sodium metal in liquid ammonia at −50 °C.[1]
The cis isomer was also obtained in 1996 by
2O (laughing gas) in a sealed tube at 360 °C for 2 hours. The two reagents combined to yield the cis hyponitrite quantitatively as white microcrystals.[8][2]
Properties and reactions
The anhydrous cis salt is stable up to 325 °C, when it disproportionates to nitrogen and sodium orthonitrite:[2]
- 3 Na
2N
2O
2 → 2 Na
3O(NO
2) + 2 N
2
It is generally more reactive than the trans isomer.[1]
See also
References
- ^ ISBN 0-12-352651-5
- ^
- ^
- ^
- .
- doi:10.1021/ja00711a039.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ISBN 978-0-08-037941-8.
- ^ ISBN 978-0-13-175553-6.
- ^ Polydoropoulos, C. N. Chem. Ind. (London) 1963, 1686 and references therein.
- ^
- ^ M. N. Hughes and H. G. Nicklin (1969), "The action of dinitrogen tetroxide on sodium hyponitrite". Journal of the Chemical Society D: Chemical Communications, volume 1969, issue 2, page 80a.