Sodium telluride
5297038
192882710
2008-02-20T21:01:26Z
V8rik
195918
/* Applications in organic chemistry */ organotellurium
{{Chembox new
| Name = Sodium telluride
| ImageFile = Sodium telluride.jpg
<!-- | ImageSize = 200px -->
| ImageName = Sodium telluride
| OtherNames = Disodium telluride
| Section1 = {{Chembox Identifiers
| CASNo = 12034-41-2
}}
| Section2 = {{Chembox Properties
| Formula = Na<sub>2</sub>Te
| MolarMass = 173.58 g/mol
| Appearance = white powder,<br /> [[hygroscopic]]
| Density = 2.90 g/cm<sup>3</sup>, solid
| Solubility = very soluble
| MeltingPt = 953°C
| BoilingPt =
}}
| Section7 = {{Chembox Hazards
| EUClass = not listed
| NFPA-H = 2
| NFPA-R = 1
| NFPA-F = 0
}}
}}
Sodium telluride is the [[chemical compound]] with the [[chemical formula|formula]] Na<sub>2</sub>Te. This [[salt]] is the [[conjugate base]] of the thermally unstable [[acid]] [[hydrogen telluride]], but it is usually prepared by reduction of [[tellurium]] with [[sodium]]. Na<sub>2</sub>Te is a challenging material to handle because it is very [[Air sensitive|sensitive to air]]. Air oxidizes it initially to polytellurides, which have the formula Na<sub>2</sub>Te<sub>x</sub> (x > 1), and ultimately Te metal. Samples of Na<sub>2</sub>Te, which are colourless when absolutely pure, generally appear purple or gray due to the effects of air oxidation.
==Synthesis, structure, and solution properties==
The synthesis is typically conducted using [[ammonia]] as the solvent.
Na<sub>2</sub>Te, like many related compounds with the formula M<sub>2</sub>X, adopts the anti[[fluorite]] structure. Thus, in solid Na<sub>2</sub>Te each Te<sup>2-</sup> ion is surrounded by eight Na<sup>+</sup> ions and each Na<sup>+</sup> ion is surrounded by four Te<sup>2-</sup> ions.<ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.</ref>
Simple salts of the type M<sub>2</sub>X, where X is a monoatomic anion, are not typically soluble in any solvent because they have a high [[lattice energy]]. Upon addition of water - even moist air - or treatment with alcohols, Te<sup>2-</sup> protonates:
:Na<sub>2</sub>Te + H<sub>2</sub>O → NaHTe + [[Sodium hydroxide|NaOH]]
Because of this reaction, many processes attributed to Na<sub>2</sub>Te may involve NaHTe (CAS# 65312-92-7), which is more soluble and formed readily.
==Applications in organic chemistry==
Na<sub>2</sub>Te finds use in [[organic synthesis]], both as a [[reagent]] for reductions and as a source of Te in the synthesis of [[organotellurium]] compounds.<ref name=ditt>”Sodium Telluride” Dittmer, D. C. in Encyclopedia of Reagents for Organic Synthesis © 2001. DOI: 10.1002/047084289X.rs103.</ref> [[Arene|aryl]] halides are substituted to diaryl tellurides, as illustrated by the synthesis of dinaphthyltelluride:
:Na<sub>2</sub>Te + 2 C<sub>10</sub>H<sub>7</sub>I → (C<sub>10</sub>H<sub>7</sub>)<sub>2</sub>Te + 2 NaI
Na<sub>2</sub>Te reacts with 1,3-[[Diacetylene|diyne]]s to give the corresponding tellurophene, which are structurally analogous to [[thiophene]]s:
:Na<sub>2</sub>Te + RC≡C-C≡CR + 2 H<sub>2</sub>O → TeC<sub>4</sub>R<sub>2</sub>H<sub>2</sub> + 2 NaOH
As a reducing agent, Na<sub>2</sub>Te converts nitro groups to amines and will cleave certain C-X bonds.<ref name=ditt/>
==References==
{{reflist}}
[[Category:Tellurides]]
[[Category:Sodium compounds]]
[[Category:Inorganic compound stubs]]
{{inorganic-compound-stub}}
[[ar:تيلوريد صوديوم]]