(a) Triphenylmethane [structure in part (b)] has a pK_a of 31.5 and, although an alkane, it is almost as acidic as a 1-alkyne. (Most alkanes have pK_a ≽ 55.) By considering the structure of its conjugate base, suggest a reason why triphenylmethane is such a strong hydrocarbon acid.

(b) Fluoradene is structurally very similar to triphenylmethane, except that the three aromatic rings are “tied together” with single bonds. Fluoradene has a pK_a of 11. Suggest a reason why fluoradene is much more acidic than triphenylmethane.

Transcribed Image Text:

H triphenylmethane pk = 31.5 HIO Η fluoradene pk = 11