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Triphenylmethanol: Wikis

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Triphenylmethanol
Triphenylmethanol
Triphenylmethanol ball and stick.png
IUPAC name
Other names Triphenylcarbinol
Tritanol
Identifiers
CAS number 76-84-6 Yes check.svgY
SMILES
Properties
Molecular formula C19H16O
Molar mass 260.33 g/mol
Density 1.199 g/cm3
Melting point

162 °C

Boiling point

360-380 °C

Hazards
MSDS External MSDS
Related compounds
Related compounds Triphenylmethane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Triphenylmethanol (also known as triphenylcarbinol) is an aromatic organic compound. It is a white crystalline solid that is insoluble in water and petroleum ether, but well soluble in ethanol, diethyl ether and benzene. In strongly acidic solutions, it produces an intensely yellow color, due to the formation of a stable carbocation.

Contents

Structure and Properties

Triphenylmethanol contains three phenyl rings and a hydroxyl group bound to a central tetrahedral carbon atom. All three C-Ph bonds are typical of sp3-sp2 carbon-carbon bonds with lengths of approximately 1.47 Å, while the C-O bond length is approximately 1.42 Å.[1]

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Acidity and basicity

As triphenylmethanol is simply an alkyl-substituted derivative of methanol, its pKa will be expected to lie somewhere in the range of 16-19. Typical of alcohols, resonance offers no stabilization of the conjugate base due to its being bonded to a saturated carbon atom. Furthermore, stabilization of the anion by solvation forces is largely ineffective due to the three bulky phenyl groups.

On the other hand, the basicity of triphenylmethanol is enhanced due to the formation of a stable carbocation upon breaking of the C-O bond. In a highly acid solution, the protonated form of triphenylmethanol will lose the equivalent of a water molecule to form the highly stable triphenylmethylium carbocation.

Synthesis

The preparation of triphenylmethanol from methyl benzoate or benzophenone and bromobenzene is a common laboratory experiment for teaching the Grignard reaction.[2] An alternative starting material is diethyl carbonate.[3]

Synthesis of triphenylmethanol

References

  1. ^ Guidebook to Mechanism in Organic Chemistry, Sixth Edition, 1996, Peter Sykes, ISBN 0-58-244695-3
  2. ^ W. E. Bachmann and H. P. Hetzner, "Triphenylcarbinol", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0839  ; Coll. Vol. 3: 839  
  3. ^ Latimer, Devin (2007). "The GC–MS Observation of Intermediates in a Stepwise Grignard Addition Reaction". J. Chem. Educ. 84: 699. http://jchemed.chem.wisc.edu/Journal/Issues/2007/Apr/abs699.html.  

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