L.12 Carboxylic Acids derivatives

Question 1

What are the 3 Carboxylic Acid Derivatives

Answer 1

1. Anhydride
2. Esters
3. Amides

Question 2

What is a Fisher Esterification?

Answer 2

Esters are the condensation products of carboxylic acids with alcohols

Question 3

Triacylglycerols

Answer 3

• Fat storage
• Contain 3 ester bonds between glycerol and fatty acids

Question 4

How do you name Asymmetric Anhydrides?

Answer 4

• Symmetric anhydrides are named for the parent carboxylic acid, followed by anhydride.
• Asymmetrical anhydrides are named by listing the parent carboxylic acids in alphabetically, followed anhydride.

Question 5

In order of most to least, list the reactivity of all the carboxylic acid derivatives.

Answer 5

1. Anhydrides
2. Esters
3. Amides

Question 6

What is responsible for the increased rate of hydrolysis in a beta-lactam?

Answer 6

Ring Strain

Which is due to both torsional strain (eclipsing interactions)

and angle strain (deviation from 109.5 angles)

Question 7

What properties account for the differences in reactivity seen between anhydrides, esters, and amides with nucleophiles?

Answer 7

• Electron effects; like INDUCTION (uneven distribution of charge across a sigma bond because of the difference in electronegativity.)
• The difference in RESONANCE also explains the increase in the reactivity of anhydrides. Conjugation refers to the presence of alternating single and multiple bonds, which creates delocalized pi electrons clouds above and below the plane of the molecule; there is resonance through the unhybridized p-orbitals - stabilized transition states = more reactive!
• STERIC EFFECTS could also be significant, depending on the specific leaving group present. (Protecting groups like acetals can be used to hinder reaction of that specific region on the molecule)

Question 8

In a nucleophilic Acyl Substitution reaction, the addition of water to anhydride results in what?

Alcohol?

Amine or ammonia?

Answer 8

Addition of water results in Two Carboxylic Acids

Addition of alcohol results in an ESTER and a carboxylic acid

Addition of amine or ammonia results in an Amide and a carboxylic acid.

ANHYDRIDE CLEAVAGE

Question 9

What is Transesterification?

Answer 9

It is the exchange of one esterifying group for another on an ester.

The attacking nucleophile is an alcohol.

(the alcohol holds the oxygen bond that will complete the new ester group)

Question 10

What happens when an AMIDE is hydrolyzed?

Answer 10

Hydrolyzed = Addition of H₂O

Amides can be hydrolyzed under acidic conditions via nucleophilic substitution. The acidic conditions allow the carbonyl oxygen to become protonated, making the molecule more susceptible to nucleophilic attack by water.

Product = Carboxylic Acid + Ammonia

Reverse Reaction (Condensation) = AMIDES

Carboxylic acid + Ammonia = AMIDE