Sodium telluride
# Sodium telluride

Sodium telluride is the chemical compound with the formula $Na_2Te.$ This salt is the conjugate base of the thermally unstable acid hydrogen telluride, but it is usually prepared by reduction of tellurium with sodium. $Na_2Te$ is a challenging material to handle because it is very sensitive to air. Air oxidizes it initially to polytellurides, which have the formula $Na_2Te_x$ (x > 1), and ultimately Te metal. Samples of $Na_2Te,$ which are colourless when absolutely pure, generally appear purple or dark gray due to the effects of air oxidation.

## Synthesis, structure, and solution properties

The synthesis is typically conducted using ammonia as the solvent.

$Na_2Te,$ like many related compounds with the formula $M_2X,$ adopts the antifluorite structure. Thus, in solid $Na_2Te$ each $Te^{2−}$ ion is surrounded by eight $Na^+$ ions and each $Na^+$ ion is surrounded by four $Te^{2−}$ ions.

Simple salts of the type $M_2X,$ where X is a monatomic 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, $Te^{2−}$ protonates:

    $Na_2Te$ + $H_2O$ → NaHTe + NaOH

Because of this reaction, many processes attributed to $Na_2Te$ may involve NaHTe (CAS # 65312-92-7), which is more soluble and formed readily.

## Applications in organic chemistry

$Na_2Te$ finds use in organic synthesis, both as a reagent for reductions and as a source of Te in the synthesis of organotellurium compounds. Aryl halides are substituted to diaryl tellurides, as illustrated by the synthesis of dinaphthyltelluride:

    $Na_2Te$ + 2 $C_{10}H_7I$ → $(C_{10}H_7)_2Te$ + 2 NaI

$Na_2Te$ reacts with 1,3-diynes to give the corresponding tellurophene, which are structurally analogous to thiophenes:

    $Na_2Te$ + RC≡C-C≡CR + 2 $H_2O$ → $TeC_4R_2H_2$ + 2 NaOH

As a reducing agent, $Na_2Te$ converts nitro groups to amines and will cleave certain C-X bonds.

