Chapter 8: 8.1 Physical Properties of Alcohols

Question 1

Alcohols contain what functional group?

Answer 1

Hydroxy (-OH)

Question 2

How can alcohols be classified?

Answer 2

1. Primary
2. Secondary
3. Tertiary

Question 3

True or False:

Alcohols are capable of H-bonding

Answer 3

True

Question 4

Compare:

Alcohol boiling point vs. Corresponding alkane boiling point

Answer 4

Alcohols have higher boiling points than their corresponding alkanes

Question 5

Why do alcohols have higher boiling points?

Answer 5

Increased intermolecular forces = Increased boiling point

Question 6

Define:

Phenols

Answer 6

Alcohols attached to an aromatic ring

Question 7

What factors affect the acidity of alcohols?

Answer 7

1. Resonance
2. Induction
3. Solvation Effects

Question 8

How does resonance affect acidity of alcohols?

Answer 8

Resonance-stabilized conjugate base is more stable and likely to form
* Corresponding conjugate acid is more acidic

Question 9

How does induction affect the acidity of alcohols?

Answer 9

Electron withdrawing groups (EWG) and Electron donating groups (EDG) nearby alcohols with inductively affect electron density

Question 10

Describe:

How EWG induction affects alcohol acidicity

Answer 10

• EWGs inductively pull electron density AWAY from negatively charged, deprotonated alcohol (alkoxide)
• Helps stabilize negative charge of the alkoxide conjugate base
• Stable, more likely to form conjugate base
• Conjugate acid is more acidic

Question 11

Describe:

How EDG induction affects alcohol acidity

Answer 11

• EDGs inductively pull electron density TO from negatively charged, deprotonated alcohol (alkoxide)
• Destabilizes negative charge of the alkoxide conjugate base
• Less stable, less more likely to form conjugate base
• Conjugate acid is less acidic

Question 12

Give examples of:

Inductively electron withdrawing groups

Answer 12

Electronegative atoms (O, N, F, Cl, etc.)

Question 13

Give examples of:

Inductively electron donating groups

Answer 13

Alkyl chains

Question 14

Why is the pKa of tertiary alcohols higher than that of secondary or primary alcohols?

Answer 14

Tertiary alcohols have more inductively electron donating alkyl chains

Question 15

How does solvation effects affect the acidity of alcohol?

Answer 15

Bulky/hindered groups are more poorly solvated than unhindered groups
* Less stable, as they interact less well with the solvent
* Less likely to become deprotonated
* Conjugate acid is less acidic