Carboxylic Acid Derivatives - Part 1 | Organic Chemistry 2
Properties and Relative Reactivities
H on an α-carbon of the carbonyl bond is acidic. The pKa depends on the electronegativity of L ⇒ the lower the electronegativity, the higher the pKa
Acyl halides: pKa ~ 16; Carboxylic anhydrides: pKa ~ 20; Esters: pKa ~ 25; Amides: pKa ~ 30
Chemistry of Acyl Halides
Nomenclature:
The -oic acid ending of the corresponding carboxylic acid is replace by -oyl halide (halide = fluoride, chloride, bromide, iodide)
Reactivity of acyl halides:
- Formation of carboxylic acids, carboxylic anhydrides, esters and amides:
NuH = HOH ⇒ carboxylic acid formation
NuH = R'COOH ⇒ carboxylic anhydride formation
NuH = R'OH ⇒ ester formation
NuH = R'HNH ⇒ amide formation
Mechanism: addition-elimination
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Formation of ketones:
Mechanism: addition-elimination
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Formation of aldehydes:
Mechanism: addition-elimination
Chemistry of Esters
Nomenclature:
The alkyl chain R' is named as a substituent. This is followed by the name of the parent chain (RC) where the -ane ending of the corresponding alkane is replaced by -oate
Reactivity of esters:
- Formation of carboxylic acids, esters and amides:
- NuH = HOH ⇒ carboxylic acid formation
- NuH = R''OH ⇒ new ester formation (Transesterification)
- NuH = R''HNH ⇒ amide formationMechanism: addition-elimination
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Formation of alcohols:
- Formation of aldehydes:
Chemistry of Carboxylic Anhydrides
Nomenclature:
Add the term anhydride to the name of the corresponding carboxylic acid
Reactivity of carboxylic anhydrides:
- Formation of carboxylic acids, esters and amides:
- NuH = HOH ⇒ carboxylic acid formation
- NuH = R'OH ⇒ ester formation
- NuH = R'HNH ⇒ amide formationMechanism: addition-elimination
Chemistry of Amides
Nomenclature:
The -ane ending of the corresponding alkane is replace by -amide. Substituents on nitrogen are indicated as prefixes preceded by N- or N,N- (if 2 similar groups)
Reactivity of amides:
- Formation of carboxylique acids:
Mechanism: addition-elimination
- Formation of amines:
- Formation of aldehydes: