Question

How would you solve this question? confused about how SN1 and E1 reactions work

1) The following reactions have all the same electrophiles but different nucleophiles. Thus the rate of the following reactions is dependent upon the nucleophilicity of the nucleophile. In the following pairs of reactions determine which is faster x) or y) and choose the explanation and Potential Energy-Reaction Coordinate diagram given below to explain why. Use the bottom table below to answer the question. H EtOH + CH31 CH3 x) EtOH + CH3! Et CH3 2) 1) (CH3)3COH EtOH y) (CH3)3CO + CH31 (H3C)3C CH3 y) Eto + CH3! Et CH3 x) Eto Et + EtOH EtOH + CH3! Et CH3 *) Eto + CH31 Et CH3 + *) Eto 4) 3) EtOH y) Ets i CH3CO2H + CH3! Et y) CH3 + CH31 Explanations: a) Strong unhindered bases are good nucleophiles and in a group of nucleophiles in which the nucleophilic atom is the same, nucleophilicity follows basicity. b) A larger anion more polarizable than a small anion and is a better nucleophile. Also, the more basic smaller anion forms stronger hydrogen bonds with protic solvents than the larger, more polarizable anion. Thus, for anions the solvent hinders its movement and is not as "free" to move through the solvent. The ion must shed or displace the solvent as it attacks the electrophilic carbon. c) The unhindered nucleophile is a much better nucleophile than bulky nucleophile because it is less sterically hindered. The bulky nucleophile is sterically hindered from reaching the backside of the C-LG sigma bond because of electron-electron repulsion between the alkyl groups attached to the nucleophilic atom and the alky groups bonded to electrophilic carbon. d) A negatively charged nucleophile is always stronger than its conjugate acid.

Answer 1

1. y is faster than x because a negatively charged is nucleophile is always stronger than its conjugate acid.

3. y is faster than x because a large aniin more polarizable than a small anion and is beter nucleophile.

2. X is faster than y because strong unhindered bases are good nucleophile and in a groupof nucleophiles in which the nucleophilic atom is same, nucleophilicity follows basicity.

4. X is faster than y because of the explaination of option (c).