Tellurols are analogues of alcohols and

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

s where

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionall ...

replaces oxygen. Tellurols,

selenol Selenols are organic compounds that contain the functional group with the connectivity C– Se–H. Selenols are sometimes also called selenomercaptans and selenothiols. Selenols are one of the principal classes of organoselenium compounds. The be ...

s, and

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

s have similar properties, but tellurols are the least stable. Although they are fundamental representatives of

organotellurium compound Organotellurium chemistry describes the synthesis and properties of chemical compounds containing a carbon-tellurium chemical bond. Organotellurium chemistry is a lightly studied area, in part because of the few applications. Functional groups The ...

s, tellurols are lightly studied because of their instability. Tellurol derivatives include telluroesters (RC(O)TeR') and tellurocyanates (RTeCN).

Properties

Alkyltellurols are colorless liquids with strong odors. Samples usually appear yellowish owing to the presence of dialkylditelluride impurities. Near room temperature, methanetellurol degrades with loss of elemental tellurium. It is reported to ignite in air. Aryltellurols are more robust and have been obtained as colorless crystals. Some of the most stable tellurols are the bulky silylated derivatives of tris(trimethylsilyl)methane and analogues. One series of readily isolable tellurols is , , and .

Acid–base properties

The acidity of tellurols can be inferred by the acidity and dissociation constant of

hydrogen telluride Hydrogen telluride is the inorganic compound with the formula H2 Te. A hydrogen chalcogenide and the simplest hydride of tellurium, it is a colorless gas. Although unstable in ambient air, the gas can exist at very low concentrations long enough ...

, , which has a (first) pK_a of 2.64 corresponding to a dissociation constant of 2.3 × 10^−3.5. has a lower pK_a and higher dissociation constant than and . The pKa is 9.3 for vs 10.8 for . The absence of hydrogen-bonding explains the low boiling temperature of tellurols.

Preparation

The first tellurol to be synthesized, ethanetellurol, was prepared in 1926 via the Grignard reagent. The most frequently used method involves reduction of the ditellurides ().

References

{{Functional Groups Organotellurium compounds Hydrides Functional groups