Trityl alcohol (also known as trityl alcohol and TrOH) is an organic compound. It is a white crystalline solid, insoluble in water and petroleum ether, but easily soluble in ethanol, ether and benzene. In strongly acidic solutions, it produces a deep yellow color due to the formation of a stable "trityl" carbocation. Many derivatives of trityl alcohol are important dyes.
history
Following the first synthesis of triphenylmethanol in 1872 by German chemist August Kekulé and his Belgian student Antoine Paul Nicolas Franchimont (1844-1919),[2] Russian doctoral student Walerius Hemilian (1851-1914) passed triphenylmethane in 1874 Trityl alcohol was synthesized for the first time by the reaction of bromide with water and by the oxidation of trityl methane.
Structure and properties[edit]
Trityl alcohol has three phenyl (Ph) rings and an alcohol group attached to a central tetrahedral carbon atom. All three C-Ph bonds are typical sp3-sp2 carbon-carbon bonds with a length of about 1.47 Å, while the C-O bond is about 1.42 Å in length. [4]
The presence of three adjacent phenyl groups confers the special properties embodied in the reactivity of alcohols. For example, it reacts with acetyl chloride to form triphenylmethyl chloride instead of an ester:[5]
Ph3COH + MeCOCl → Ph3CCl + MeCO2H
The three phenyl groups also provide steric protection. Reacts with hydrogen peroxide to form the unusually stable hydroperoxide Ph3COOH. [6]
Acid-base properties
As a methanol derivative, trityl alcohol is expected to have a pKa in the range of 16-19. For alcohols, the resonance does not provide the stability of the conjugate base due to bonding to a saturated carbon atom. Due to the steric influence of the three phenyl groups, stabilization of the anion by solvation forces is largely ineffective.
The basicity of trityl alcohol is enhanced due to the formation of resonance-stabilized carbocations upon C–O bond cleavage. After oxygen protonation under strongly acidic conditions, trityl alcohol loses water to form a trityl (“trityl”) cation:
Ph3COH + H+ → Ph3C+ + H2O
The trityl cation is one of the easiest carbocations to isolate, although it reacts rapidly with water.