1.14: Sn1 and Sn2 Reactions Answers

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1) I

3) H₂O < CH₃CO₂^- < HO^- < CH₃S^-

5) This is an Sn2 reaction. Rate \(= k[(CH_{3})_{3}CO^{-}][CH_{3}I]\). The rate increases as [CH₃I] increases.

6) D

The reaction is Sn2

8) 2-Chloropropane. The reaction is Sn2, and even though 1-chloro-2,2-dimethylpropane is a primary chloride, it is more sterically hindered than 2-chloropropane, which is secondary.

9) This is purely a solvent effect. The greater the percentage of water in this solvent mixture, the more polar the solvent. The more polar the solvent, the more easily solvated the developing carbocation and the more rapidly it is formed.

10)

2) carbocation rearrangement from secondary to tertiary by means of a hydride shift

11) A

12) 3-Iodo-3-methylpentane. This molecule forms the most stable cation (tertiary).

13) The intermediate carbocation is resonance stabilized (allylic). Can you draw the resonance structures?

14)

weak nucleophile and secondary substrate promote Sn1 mechanism

15)

The following combination might also work, but less effectively. The substrate is more sterically hindered than methyl iodide.

16) Sn1 - secondary substrate plus weak nucleophile.

17) B

18) A

19) E

20) A

21) 2-bromo-2-methylpentane < 1-chloro-2,2-dimethylpentane < 1-chloro-3,3-dimethylpentane < bromoethane

22) methyl iodide < isopropyl chloride < t-butyl bromide < t-butyl iodide

Again, solvolysis means ionization aided by the solvent. The substrate that can make the most stable cation will be most reactive. In this case there are two tertiary substrates. The one with the best leaving group (iodide) will be most reactive.