CHEMISTRY · Single correct · A Level · Chemistry · Introduction to organic chemistry · Introduction to organic chemistry
Problem
The hydrolysis of tert-butyl chloride, (CH3)3CCl, in water is being studied. Two mechanisms have been suggested.
Mechanism I
(CH3)3CCl + H2O → (CH3)3COH + HCl (single concerted step)
Mechanism II
Step 1 (CH3)3CCl → (CH3)3C+ + Cl−
Step 2 (CH3)3C+ + H2O → (CH3)3COH + H+
Step 3 H+ + Cl− → HCl
Laser flash photolysis detects a transient absorption that is assigned to the tert-butyl cation, (CH3)3C+. Which statement is most strongly supported by this experimental evidence?
(a) Both mechanisms remain plausible because a concerted step can momentarily create a carbocation that can be detected.
(b) Only Mechanism II is supported because the detected tert-butyl cation is an intermediate explicitly proposed in that mechanism.
(c) Mechanism I is favored because the transient detection indicates that the cation is part of a single, fast step.
(d) Neither mechanism is supported because laser flash photolysis cannot distinguish between intermediates and unrelated side products.