Following are the four molecules "P", "Q", "R" and "S". Which one among the four molecules will react with H-Br(aq) at the fastest rate? [figure]
- Q
- S
- P
- R
Answer
(1) Q
Solution
Rate-determining step: protonation carbocation; the more stable cation forms fastest.
[figure]
[figure]
Oxocarbenium > tertiary > secondary with -I (P).
Answer: (1)