LECTURE 4

Question 1

Define Hammett’s 𝜎 values

Answer 1

Parameter describing the electronic effects of a functional group

– Determined by their effect on the pKa of benzoic acid

Question 2

What are the electronic effects of a substituent group with a positive 𝜎 value?

Answer 2

electron-withdrawing group
more acidic, lower pKa

Question 3

What are the electronic effects of a substituent group with a negative 𝜎 value?

Answer 3

electron-donating group
less acidic, higher pKa

Question 4

Define inductive effect

Answer 4

Electron density is withdrawn through the 𝜎 bond

Question 5

Define resonance effect

Answer 5

Lone pair electrons are shared through conjugated 𝜋 bonds

Question 6

What Hammett’s 𝜎 values indicates and electron-donating group?

Answer 6

negative 𝜎 value

Question 7

What Hammett’s 𝜎 values indicates and electron-withdrawing group?

Answer 7

positive 𝜎 value

Question 8

When electron-donating substituents are added, how is the acidity / basicity of the drug affected?

Answer 8

Decreased acidity
Increased basicity

Question 9

When electron-withdrawing substituents are added, how is the acidity / basicity of the drug affected?

Answer 9

Increased acidity
Decreased basicity