Sodium telluride
Encyclopedia
Sodium telluride is the chemical compound
with the formula
Na2Te. This salt
is the conjugate base of the thermally unstable acid
hydrogen telluride
, but it is usually prepared by reduction of tellurium with sodium
. Na2Te is a challenging material to handle because it is very sensitive to air
. Air oxidizes it initially to polytellurides, which have the formula Na2Tex (x > 1), and ultimately Te metal. Samples of Na2Te, which are colourless when absolutely pure, generally appear purple or gray due to the effects of air oxidation.
as the solvent.
Na2Te, like many related compounds with the formula M2X, adopts the antifluorite
structure. Thus, in solid Na2Te each Te2− ion is surrounded by eight Na+ ions and each Na+ ion is surrounded by four Te2− ions.
Simple salts of the type M2X, 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, Te2− protonates:
Because of this reaction, many processes attributed to Na2Te may involve NaHTe (CAS #
65312-92-7), which is more soluble and formed readily.
, 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:
Na2Te reacts with 1,3-diyne
s to give the corresponding tellurophene, which are structurally analogous to thiophene
s:
As a reducing agent, Na2Te converts nitro groups to amines and will cleave certain C-X bonds.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Na2Te. This salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
is the conjugate base of the thermally unstable acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
hydrogen telluride
Hydrogen telluride
Hydrogen telluride is the inorganic compound with the formula H2Te. The simplest hydride of tellurium, it is rarely encountered because of it decomposes rapidly to the constituent elements. Most compounds with Te-H bonds are unstable with respect to loss of H2. H2Te is chemically and structurally...
, but it is usually prepared by reduction of tellurium with sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
. Na2Te is a challenging material to handle because it is very sensitive to air
Air sensitive
Air sensitivity is a term used, in particular in chemistry, to denote the reactivity of chemical compounds with some constituent of air. Most often, reactions occur with atmospheric oxygen or water vapor , although reactions with the other constituents of air such as carbon monoxide , carbon...
. Air oxidizes it initially to polytellurides, which have the formula Na2Tex (x > 1), and ultimately Te metal. Samples of Na2Te, 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 ammoniaAmmonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
as the solvent.
Na2Te, like many related compounds with the formula M2X, adopts the antifluorite
Fluorite
Fluorite is a halide mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon...
structure. Thus, in solid Na2Te each Te2− ion is surrounded by eight Na+ ions and each Na+ ion is surrounded by four Te2− ions.
Simple salts of the type M2X, where X is a monoatomic anion, are not typically soluble in any solvent because they have a high lattice energy
Lattice energy
The lattice energy of an ionic solid is a measure of the strength of bonds in that ionic compound. It is usually defined as the enthalpy of formation of the ionic compound from gaseous ions and as such is invariably exothermic. Lattice energy may also be defined as the energy required to completely...
. Upon addition of water - even moist air - or treatment with alcohols, Te2− protonates:
- Na2Te + H2O → NaHTe + NaOH
Because of this reaction, many processes attributed to Na2Te may involve NaHTe (CAS #
CAS registry number
CAS Registry Numbersare unique numerical identifiers assigned by the "Chemical Abstracts Service" toevery chemical described in the...
65312-92-7), which is more soluble and formed readily.
Applications in organic chemistry
Na2Te finds use in organic synthesisOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
, both as a reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
for reductions and as a source of Te in the synthesis of organotellurium compounds. Aryl
Arene
Arene or Arênê or Arène may refer to:*an aromatic hydrocarbon*Arene , a genus of marine snails in the family Areneidae*Arene , the wife of Aphareus and mother of Idas and Lynceus in Greek mythology...
halides are substituted to diaryl tellurides, as illustrated by the synthesis of dinaphthyltelluride:
- Na2Te + 2 C10H7I → (C10H7)2Te + 2 NaI
Na2Te reacts with 1,3-diyne
Diacetylene
Diacetylene , with the formula C4H2, is a highly unsaturated hydrocarbon that contains three single bonds and two triple bonds. It is the first in the series of polyynes.-Occurrence:...
s to give the corresponding tellurophene, which are structurally analogous to thiophene
Thiophene
Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a flat five-membered ring, it is aromatic as indicated by its extensive substitution reactions. Related to thiophene are benzothiophene and dibenzothiophene, containing the thiophene ring fused with one and two benzene...
s:
- Na2Te + RC≡C-C≡CR + 2 H2O → TeC4R2H2 + 2 NaOH
As a reducing agent, Na2Te converts nitro groups to amines and will cleave certain C-X bonds.