Carbocation Rearrangement - Hydride and Methanide Shifts

Professor Dave explains carbocation rearrangement, focusing on E1 and SN1 reactions. He discusses the formation of secondary carbocations and the mechanisms of hydride and methanide shifts, emphasizing the stability of more substituted carbocations. The video covers transition states and the role of thermodynamics in these rearrangements.

What is the role of a strong acid in the E1 and SN1 reactions?

• It stabilizes the carbocation.

• It increases the reaction temperature.

• It acts as a nucleophile.

• It provides a good leaving group.

What is a hydride shift?

• A shift of a water molecule.

• A shift of a methyl group with a negative charge.

• A shift of a hydrogen atom with a pair of electrons.

• A shift of a hydrogen atom with a positive charge.

Why does a hydride shift occur?

• To generate a more stable carbocation.

• To neutralize the solvent.

• To create a less stable carbocation.

• To increase the reaction rate.

What is the expected product when a hydride shift occurs in the presence of water?

• No reaction occurs.

• A single SN1 product.

• A racemic mixture of SN1 products.

• Only E1 products.

What is a methanide shift?

• A shift of a carbon atom with a positive charge.

• A shift of a water molecule.

• A shift of a methyl group with a negative charge.

• A shift of a hydrogen atom with a positive charge.

What drives the rearrangement in methanide shifts?

• Temperature

• Pressure

• Thermodynamics

• Kinetics

What happens to the carbocation after a methanide shift?

• It becomes more stable.

• It becomes less stable.

• It remains unchanged.

• It disappears.