chapter 20 carboxylic acids and derivativesb-myers/organic/2521_files/chapter20_notes.pdfchapter 20...
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Chapter 20 Carboxylic Acids and Derivatives
Also: look at naming of acid derivatives (esters, acid chlorides, nitriles, anhydrides, amides)
Carboxylic Acids and Derivatives
O O O
H
O
OH
O
O MeO
Cl
carbonyl ketone aldehyde carboxylicacid
ester acid chloride
O
R
O
ROanhydride
acid anhydride
O
Me
O
MeO
acetic anhydride
O
NR'2
amide
O
NH
H1° amide
O
NPr
H2° amide
N-propylacetamide
O
NPr
Me3° amide
N-methyl,N-propylacetamide
O
NR'2R'2N
urea
O
NR'2RO
carbamateor urethane
O
ORRO
carbonate
Some other Specially Named Acids
Dicarboxylic Acids
Diabolic Acids:
A class of compounds where the m and n chains can have different lengths and unsaturation. Named after the Greek diabollo, meaning to mislead–since they were particularly difficult to isolate. Also, one of the inventors thought that they had 'horns like the devil’.
• Carboxylic acids form hydrogen bonds.• Carboxylic acids of 6 carbons or less are typically quite water soluble.• Carboxylic acids are considerably more acidic than alcohols due to the
resonance stabilization of the carboxylate.
Carboxylic Acid Properties
Synthesis of Carboxylic Acids
[1] Oxidation of 1° alcohols
[2] Oxidation of alkyl benzenes
R OH
HH
R OH
OH2CrO4
or1) KMnO4, NaOH2) H3O+
H2CrO4
or1) KMnO4, NaOH2) H3O+
R’
R’ HO
OH
Synthesis of Carboxylic Acids
[3] Oxidative cleavage of alkynes
[4] Oxidative cleavage of alkenesAlso: KMnO4, OH–
Synthesis of Carboxylic Acids
[5] Hydrolysis of nitriles
CN
heptanenitrile
H3CCN
acetonitrile
N
benzonitrile
Nitriles: although they don't have a carbonyl, the nitrile carbon has the same oxidation state as a carboxylic acid.
[6] Nucleophilic Addition to CO2
1) Mg°, Et2O2) CO23) H2OBr
O
OH
RC
N H3O+
R CO
OH or1. NaOH,H2O2. H+
Extraction
Compound Solubility in g/100 mL H2O
Amino Acids
Amino Acids
18
• An amino acid can exist in three different forms depending on pH.
pH and Amino Acid Structure
Amino Acids and the Isoelectric Point
The Isoelectric Point of Tyrosine
Nucleophilic Acyl Substitution
R Z
O
NucR Nuc
O+ Z
OH
O
Cl
O
O
O
OCH3
O
NH2
OO
MoreReactive Less
Reactive
Acid Halides(acetyl chloride)
Acid Anhydrides(acetic anhydride)
Esters(methyl acetate)
Amides(acetamide)
CarboxylicAcids
Relative Reactivity
Acid Derivatives Interconversion Map
OH
O
Cl
O
OR
O
Ester
Acid Chloride
Acid
NH2
O
Amide
O
O O
Acid Anhydride
H3CC
N
NitrileH
O
Aldehyde