Ch 9 - Carboxylic Acid Derivatives Flashcards
What are amides and their nomenclature?
- the condensation products of carboxylic acids and ammonia or amines
- given the suffix -amide
- the alkyl groups on a substituted amide are written at the beginning of the name with the prefix N-
What are lactams and their nomenclature?
- cyclic amides
- named by the greek letter of the carbon forming the bond with nitrogen (beta-lactam, gamma-lactam, and so on)
What are esters and their nomenclature?
- the condensation products of carboxylic acids with alcohols (Fischer esterification)
- given the suffix -oate
- the esterifying group is written as a substituent, without a number
What are lactones and their nomenclature?
- cyclic esters
- named by the number of carbons in the ring and the Greek letter of the carbon forming the bond with the oxygen (alpha-acetolactone, beta-propiolactone, and so on)
What are triacylglycerols and how are they formed?
a form of fat storage
- include 3 ester bonds between glycerol and fatty acids
What is saponification?
the breakdown of fat using a strong base to form soap (salts of long-chain carboxylic acids)
What are anhydrides?
the condensation dimers of carboxylic acids
How are symmetric/asymmetric anhydrides named?
- symmetric: named for the parent carboxylic acid, followed by anhydride
- asymmetric: named by listing the parent carboxylic acids alphabetically, followed by anhydride
How can some cyclic anhydrides be synthesized and what form is most stable?
- by heating dioic acids
- 5- or 6-membered rings are generally stable
How does the reactivity of amides, anhydrides, and esters compare in nucleophilic substitution reactions?
anhydrides are more reactive than esters, which are more reactive than amides (need a strong acid/base to react)
What does steric hindrance describe?
when a reaction cannot proceed (or significantly slows) because of substituents crowding the reactive site
What are protecting groups?
- like acetals
- can be used to increase steric hindrance or otherwise decrease the reactivity of a particular portion of a molecule
What is induction?
- refers to uneven distribution of charge across a sigma bond because of differences in electronegativity
What is conjugation?
- refers to the presence of alternating single and multiple bonds, which creates delocalized pi electron clouds above and below the plane of the molecule
How does resonance affect stability?
electrons experience resonance through unhybridized p-orbitals, increasing stability
How does electronegativity of carbonyl-containing compounds affect reactivity?
- the more electronegative groups in a carbonyl-containing compound, the greater its reactivity
Why are conjugated carbonyl-containing compounds more reactive?
because they can stabilize their transition states
How does strain affect reactivity?
- increased strain in a molecule can make it more reactive
- beta-lactams are prone to hydrolysis because they have significant ring strain
What causes ring strain?
due to torsional strain from eclipsing interactions and angle strain from compressing bond angles below 109.5 degrees.
Which carboxylic derivatives undergo nucleophilic substitution reactions?
all can undergo these reactions, the rates at which they do are determined by their relative reactivities
How can anhydrides be cleaved?
by the addition of a nucleophile
- addition of ammonia/amine results in an amide and a carboxylic acid
- addition of an alcohol results in an ester and a carboxylic acid
- addition of water results in 2 carboxylic acids
What is transesterification?
the exchange of one esterifying groups for another on an ester
- the attacking nucleophile is an alcohol
How can amide be hydrolyzed to carboxylic acids?
under strong acidic or basic conditions
- the attacking nucleophile is water or the hydroxide anion
What happens in a condensation reaction?
- 2 molecules combine to form 1, with the loss of a small molecule (water)
- how carboxylic acid derivatives are formed
