Chapter 6 Nucleophilic Reactions (Alkyl Halides)

Question 1

What is the differential solvation seen from Polar Aprotic Solvents?

Answer 1

• Polar aprotic solvents solubilize cations well using their unshared electrons
• Do not interact as strongly with anions because they cannot hydrogen bond with them
  
  • Positive regions of the solvent are shielded by steric effects from the anion

Question 2

How does the differential solvation of polar aprotic solvents contribute to increasing the rate of Sn2 rxns?

Answer 2

Cations are solubilized

Leaves anions free to act as nucleophiles - less encumbered by the cation and solvent

Question 3

What is a protic solvent?

Answer 3

solvent that has at least one hydrogen atom capable of participating in a hydrogen bond

Question 4

What effect do polar aprotic solvents have on the rates of Sn2 rxns

Answer 4

polar aprotic solvents increase SN2 rates

Question 5

How do protic solvents facilitate formation of carbocations?

Answer 5

Form hydrogen bonds with the leaving group as it departs = lowers the energy of the transition state = leads to a carbocation

Question 6

What is the dielectric constant?

Answer 6

measure of the solvent’s ability to insulate opposite charges (ie separate ions)