Chapter 5 - Alcohols

Question 1

Describe the nomenclature of Alcohols

Answer 1

Have the general form ROH and are named with the suffix -ol. If they are not the highest priority, they are given the prefix hydroxy-

Question 2

Describe the nomenclature of Phenols

Answer 2

Benzene rings with hydroxyl groups. They are named for the relative positions of the hydroxyl groups:

1. Ortho- adjacent to carbons
2. Meta- separated by one carbon
3. Para- on opposite sides of the ring

Question 3

What are the most prominent physical properties of Phenols?

Answer 3

Aromatic alcohols (the H of the hydroxy group is more acidic due to the ring its attached to) higher Ka and lower pKa = more acidic.

Question 4

What are the most prominent physical properties of Alcohols?

Answer 4

They’re capable of intermolecular hydrogen bonding, resulting in significantly higher melting and boiling points.

Question 5

What does hydrogen bonding do to physical properties?

Answer 5

It causes increased melting points, boiling points, and solubility in water.

Question 6

How do Electron-Donating groups affect acidity?

Answer 6

Electron-donating groups like alkyl groups decrease acidity because they destabilize the charge of the conjugate base.

Question 7

How do Electron-Withdrawing groups affect acidity?

Answer 7

Electron-Withdrawing groups like electronegative atoms, resonance, and aromatic rings increase acidity because they stabilize negative charges.

Question 8

What are the main reactions seen for alcohols on the MCAT?

Answer 8

1. Oxidation
2. Preparation of mesylates and tosylates
3. Protection of carbonyls by alcohols

Question 9

What happens when primary alcohols are oxidized by Pyridinium Chlorochromate (PCC)?

Answer 9

They form Aldehyde. PCC is the only way

Question 10

What happens when secondary alcohols are oxidized by PCC (or any stronger oxidizing agent)?

Answer 10

They form Ketones. (Jones Oxidation)

Question 11

What happens when a primary alcohol gets oxidized by a strong oxidizing agent that ISN’T PCC?

Answer 11

Forms carboxylic acid.

Strong oxidizing agents include Na2Cr2O7 or K2Cr2O7.

Question 12

What is the purpose of converting Alcohols to Mesylates and Tosylates?

Answer 12

Hydroxyl (OH) groups are poor leaving groups so they can turn into these to become better leaving groups for nucleophilic substitution reactions.

Question 13

What are Mesylates?

Answer 13

Contain the functional group -SO3CH3 (derived from methanesulfonic acid).

Prepared in presence of base

Question 14

What are Tosylates?

Answer 14

Contain the functional group -SO3C6H4CH3 (derived from toluenesulfonic acid).

Question 15

How can Aldehydes or Ketones be protected?

Answer 15

By converting them into Acetals or Ketals.

Question 16

How is an Acetal formed? What about Ketals?

Answer 16

Two equivalents of alcohol or di-alcohol are reacted with the carbonyl to form an acetal or ketal.

Question 17

What is an Acetal?

Answer 17

A primary carbon with two -OR groups and a hydrogen atom.

Question 18

What is a Ketal?

Answer 18

A secondary carbon with two -OR groups.

Question 19

How can the Acetal or Ketal be converted back to a Carbonyl?

Answer 19

By catalytic acid, which is called deprotection.

Question 20

What is a Quinone and what can it be oxidized to?

Answer 20

Quionone forms when a phenol is oxidized. They are resonance-stabilized electrophiles.

Question 21

What are some examples of biochemically relevant Quinones?

Answer 21

1. Vitamin K (phylloquinone)

2. Vitamin K2 (menaquinone)

Question 22

What are Hydroxyquinones?

Answer 22

Produced by oxidation of quinones, adding a variable number of hydroxyl groups.

Question 23

What is Ubiquinone?

Answer 23

Aka. coenzyme Q. one example of a biologically active quinone. vital electron acceptor in complexes I, II, III of the electron transport chain.

Question 24

What is Ubiquinone reduced by?

Answer 24

Ubiquiol