Steric hinderance between the ortho hydrogens makes it impossible for the three phenyl rings to be coplanar. Instead the triphenylmethyl carbocation assumes a “ propeller ” conformation with the phenyl rings pitched at a 32° angle.

The triphenylmethyl cation can be prepared by reaction of a Grignard reagent with benzophenone to form triphenylmethyl alcohol. Treatment with fluoboric acid results in the trityl carbocation.

Safety Notes for Expt. 30 – Synthesis of Triphenylmethanol and the Trityl Carbocation

Physical Properties of the Reactants and Reagents in Expt. 30

IR Spectra of bromobenzene and benzophenone

Setup of the round-bottom flask, Claisen adapter, West condenser and addition funnel

A drying tube is added to the top of the condenser