title: Tellurol
text: # Tellurol
  
  Tellurols are analogues of alcohols and phenols where tellurium replaces oxygen. Tellurols, selenols, and thiols have similar properties, but tellurols are the least stable. Although they are fundamental representatives of organotellurium compounds, 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 $(Me_3Si)_3CTeH,$ $(Me_3Si)_3SiTeH,$ and $(Me_3Si)_3GeTeH.$
  
  ### Acid–base properties
  
  The acidity of tellurols can be inferred by the acidity and dissociation constant of hydrogen telluride, $H_2Te,$ which has a (first) $pK_a$ of 2.64 corresponding to a dissociation constant of 2.3 × $10^{−3}.$ $H_2Te$ has a lower $pK_a$ and higher dissociation constant than $H_2S$ and $H_2Se.$ The pKa is 9.3 for $(Me_3Si)_3CTeH$ vs 10.8 for $(Me_3Si)_3CSeH.$
  
  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 $(R_2Te_2).$
  
  