Alcohols

Question 2

How do electon-withdrawing and electron-donating groups affect acidity?

Answer 2

Charges like to be spread out as much as possible. Acidity decreases as more alkyl groups are attached because they are electron-donating, which destabilizes the alkoxide anion (makes the oxygen have more electron density which it must share in order to become more stable). Resonance or electron-withdrawing groups stabilize the alkoxide anion, making the alcohol more acidic (oxygen more stable and does not have the electron density to react thus donates proton and prefers to stay that way).

Question 3

What will happen to a primary alcohol in the presence of a strong oxidizing agent?

Answer 3

Primary alcohols are completely oxidized into carboxylic acids in the presence of strong oxidizing agents.

Question 4

What will happen to a secondary alcohol in the presence of a stong oxidizing agent?

Answer 4

Secondary alcohols will be oxidized into ketones in the presence of strong oxidizing agents.

Question 5

What will happen to a primary alcohol (Ex: 1 - butanol) in the presence of Pryinidium Chlorochromate (PCC)?

Answer 5

Reacting a primary alcohol in the presence of PCC (an oxidizing agent) produces an aldehyde.

• Ex: 1 - butanol —> 1 - butanal

Question 6

What will happen to a primary alcohol (Ex: 1 - butanol) in the presence of chromate trioxide (CrO₃)?

Answer 6

Reacting a primary alcohol with chromate trioxide (a strong oxidizing agent) will produce a carboxylic acid.

• Ex: 1 - butanol —> butanoic acid

Question 7

What is the purpose of a mesylate or a tosylate?

Answer 7

• The purpose of a mesylate or a tosylate is to convert an alcohol into a better leaving group
  
  • Mesylates and tosylates are particularly useful in nucleophilic substitution reactions because it increases the stability of the product (makes -OH a better leaving group).
• Mesylates and tosylates can also be used as protecting groups because many reagents (especially oxidizing agents) that would react with an alcohol cannot react with these compounds.

Question 8

How can aldehydes or ketons be protected using alcohols?

Answer 8

Aldehydes and ketones can be proteccted by reacting them with two equivalents of an alcohol (or a diol) to form an acetal or ketal. Acetals and ketals are less reactive than aldehydes or ketones (especially to reducing agents), and can thus protect the functional group from reacting. The acetal or ketal can then be reverted back to the carbonyl by catalytic acid.

• The reversion step of adding a catalytic acid is known as deprotection.

Question 9

What are quinones and how are they produced?

Answer 9

Quinones are resonance-stabilized electrophiles that are synthesized by oxidation of phenols.

Question 10

How are hydroxyquinones produced?

Answer 10

Hydrozyquinones are produced by the oxidation of quinones, adding a variable number of additional hydroxyl groups.

Question 11

What is the difference between hydroquinones and hydroxyquinones?

Answer 11

A hydroquinone is a benzene ring with two hydroxyl groups. A hydroxyquinone contains two carbonyls and a variable number of hydroxyl groups.

Question 12

What chemical properties of ubiquinone allow it to carry out its biological functions?

Answer 12

Ubiquinone is a biologically active quinone that acts as an electron acceptor in complexes I, II, and III of the electron transport chain. Ubiquinone has conjugated rings that stavilize the molecule when accepting electrons converting it into its reduced form ubiquinol.

• Additionally, the long alkyl chain in the molecule allows for lipid solubility, which allows the molecule to function in the phospholipid bilayer.

Question 13

Tertiary alcohols are oxidized with difficulty because?

Answer 13

Tertiary alcohols are oxidized with difficulty because there isn’t a hydrogen attached to the carbon with the hydroxyl group.