Chapter 6: 6.9 Carbocation Rearrangements

Question 1

Define:

Carbocations

Answer 1

Carbon atoms that carry a positive charge

Question 2

When are carbocations formed?

Answer 2

1. Formed when a leaving group departs (see the SN1, SN2, E1, and E2 reaction)
2. Formed when an alkene acts as a nucleophile

Question 3

Carbocations that are more ———– are more stable

Answer 3

Substituted

Question 4

Compare:

Stable carbocations

Answer 4

Tertiary > Secondary > Primary&raquo_space;> Methyl

Question 5

Besides substitution, how else can carbocations be stabilized?

Answer 5

Resonance
* i.e. vinylic and allylic

Question 6

In some scenarios, what will carbocations do to produce a more stable form?

Answer 6

Rearrange

Question 7

What are the most common ways of carbocation rearrangements?

Answer 7

1. A 1,2-hydride shift
2. A 1,2-methyl shift

Question 8

Carbocation rearrangements leads to the production of…

Answer 8

Multiple products

Question 9

What is the rule behind carbocation rearrangements?

Answer 9

Ask if this is the best carbocation
* If it can be better, than keep going
* If not, draw the rearrangement and predict the products from both the rearranged and non-rearranged carbocation

Question 10

Why should you not draw too many rearrangements?

Answer 10

In any given reaction, there will only be one 1,2-hydride shift or 1,2-methyl shift