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CH2210 Carboxylic Acids
and Their Derivatives
Families Containing the Carbonyl Group
O
CZY
O
CCO
Family Y Z
aldehyde H or C H
ketone C C
carboxylic acid H or C -O-H
ester H or C -O-C
acid halide H or C -F,-Cl,-Br,-I
acid anhydride H or C
amide H or C -N
Carboxylic Acid Functional Group
Carbonyl + hydroxyl = “Carboxyl”
General Formula: R-COOH R C O O H =
The carbonyl carbon and oxygen are sp2 hybridized. The hydroxyl oxygen is sp3 hybridized.
Sources of Carboxylic Acids
Oxidation of Primary Alcohols and Aldehydes
R C O HH
HR C O H
OR C
OH
primary alcohol aldehyde carboxylic acid
[O][O]
Substituted Benzenes as a Source of Substituted Benzoic Acids
CO O
H
Benzoic Acid
MnO4-
Cr2O72-
CompoundSystematic
NameCommon Name
HCOOH Methanoic Acid Formic Acid
CH3COOH Ethanoic Acid Acetic Acid
CH3CH2COOH Propanoic Acid Propionic Acid
CH3CH2CH2COOH Butanoic Acid Butyric Acid
CH3CH2CH2CH2COOH Pentanoic Acid Valeric Acid
CH3CH2CH2CH2CH2COOH Hexanoic Acid Caproic Acid
CH3CH2CH2CH2CH2CH2COOH Heptanoic Acid Enanthic Acid
Names of Simple Carboxylic Acids
Systematic Nomenclature
Names of the Simplest Carboxylic Acids
Compound Systematic Name Trivial (Common) Name
HCOOH Methanoic Acid Formic Acid
CH3COOH Ethanoic Acid Acetic Acid
CH3CH2COOH Propanoic Acid Propionic Acid
CH3CH2CH2COOH Butanoic Acid Butyric Acid
CH3CH2CH2CH2COOH Pentanoic Acid Valeric Acid
CH3CH2CH2CH2CH2COOH Hexanoic Acid Caproic Acid
CH3CH2CH2CH2CH2CH2COOH Heptanoic Acid Enanthic Acid
Systematic Nomeclature
CH3CH2CH2CHCH2COOH
CH33-methyl hexanoic acid
β-methyl caproic acid
CH2CHCOOH
NH22-amino-3-phenylpropanoic acid
phenylalanine
Names of the Simplest Carboxylic Acids
Compound Systematic Name Trivial (Common) Name
HCOOH Methanoic Acid Formic Acid
CH3COOH Ethanoic Acid Acetic Acid
CH3CH2COOH Propanoic Acid Propionic Acid
CH3CH2CH2COOH Butanoic Acid Butyric Acid
CH3CH2CH2CH2COOH Pentanoic Acid Valeric Acid
CH3CH2CH2CH2CH2COOH Hexanoic Acid Caproic Acid
CH3CH2CH2CH2CH2CH2COOH Heptanoic Acid Enanthic Acid
Systematic Nomeclature
CH3CH2CH2CHCH2COOH
CH33-methyl hexanoic acid
β-methyl caproic acid
CH2CHCOOH
NH22-amino-3-phenylpropanoic acid
phenylalanine
Physical Properties of Carboxylic Acids
Boiling Points - Higher than alcohols of similar molecular weight
Carboxylic acids “self associate” through hydrogen bonds.
Water Solubility- More water soluble than ethers,
aldehydes, ketones and alcohols of similar molecular weight
Carboxylic acids have three opportunities for hydrogen
bonding.
CH3 CH2 CO
O HCH3CH2C
O
OH
CH3 CH2 C
O
O H OH
H
OH
H
O H
H
Structure Common Name Melting Point (ºC) Boiling Point (ºC)
HCOOH Formic Acid 8 101CH3COOH Acetic Acid 17 118
CH3CH2COOH Propionic Acid -22 141CH3CH2CH2COOH Butyric Acid -4 163
CH3CH2CH2CH2COOH Valeric Acid -34 185CH3CH2)16COOH Stearic Acid 70 383
HOOCCOOH Oxalic Acid 190 DecomposesHOOCCH2COOH Malonic Acid 134 Decomposes
HOOCCH2CH2COOH Succinic Acid 188 DecomposesHOOCCH2CH2CH2COOH Glutaric Acid 98 Decomposes
Physical Properties of Some Carboxylic Acids
COOH COOH
OH
Benzoic Acid, m.p. 122 ºC
Salicylic Acid, m.p. 159 ºC
H3CCH2
C
O
O HO
H
H
H3CCH2
C
O
O
OH
HH
propanoic acidwater
“propanoate” ion
“hydronium” ion
Acidity of Carboxylic Acids
Acidity of Carboxylic AcidsCarboxylic acids are generally stronger acids than
phenols but weaker than mineral acids.
Acidity of Carboxylic AcidsCarboxylic acids are generally stronger acids than
phenols but weaker than mineral acids.
CH3C
O
O H
CH3C
O
O
OH
H
+ NaOH
Na+
Chemical and Physical Properties of Carboxylic AcidsCarboxylic acids react with strong bases quantitatively.
acetic acid
sodium acetate
Carboxylate salts are ionic and possess much higher boiling and melting points than those of the corresponding carboxylic acids (Ionic
forces are much stronger than secondary forces).
Sodium acetate: a solid at room temperature Acetic acid: a liquid at room temperature
MP 324°C
MP 17°C
+ -
Worksheet
CH3CH2 C
O
CH CH
CH3
CH3
OHa.
b.
CO
O H
Cl
H3C
H3C
2,3-dimethyl pentanoic acid
2-chloro-4,5-dimethyl benzoic acid
1. Give an appropriate name for each compound.
α,β-dimethyl valeric acid
1
245
3
2. Give structure(s) and name(s) for the major organic product(s) of the following reactions
a. _____________________________________ b. _____________________________________
CH3CH2 C
O
CH CH
CH3
CH3
OH NaOH, H2O
CO
O H
Cl
H3C
H3C KOH, H2O
OCCHCHCH2H3C
ONa
CH3
CH3
H3C
H3C
Cl
C
O
O
K
sodium 2,3-dimethyl pentanoate
potassium 2-chloro-4,5-dimethyl benzoate
Families Containing the Carbonyl Group
O
CZY
O
CCO
Family Y Z
aldehyde H or C H
ketone C C
carboxylic acid H or C -O-H
ester H or C -O-C
acid halide H or C -F,-Cl,-Br,-I
acid anhydride H or C
amide H or C -N
Carboxylic Acid Esters
R C
O
OH R’HO R C
O
R’O+ + H2OH+
Synthesized from a carboxylic acid and an alcohol:
carboxylic acid alcohol or
phenol
ester
Nomenclature base on parent alcohol and carboxylic acid:
CH3 C
O
OH CH3HO CH3 C
O
CH3OCH2CH2 + + H2O
methanolpropanoic acid methyl propanoate
hydrolysis
condensation
H3CC
O
O
H
H3CC
O
O
CH3
H3CC
O
O
Na+
acetic acid
sodium acetate
methyl acetate
Notice the similarities and differences !!
Worksheet
Carboxylic Acid Esters3.
CH3
CH OH
CH3
C
O
CH3CH2CH2HO
isopropyl alcohol
butanoic acid isopropyl butanoate
CH3CH2HOC
O
CH3CH2CHCH2CH3
OH
3-methyl pentanoic acid
ethyl alcohol ethyl 3-methyl pentanoate
CH3 C
O
OH
CH3
CH2HO
CH3
CH
acetic acid isobutyl alcohol isobutyl acetate
4. Give an appropriate name for each compound. a.
b.
c.
CO
O CH2F
F
CH3
COCH2 CH
CH3
CH3
O
OC
O
CH2 CHCH3
CH3
`
phenyl-3-methyl butanoate
isobutyl benzoate
ethyl 2,4-difluoro benzoate
OC
O
CH2 CHCH3
CH3
H
3-methylbutanoic acid
C
O
O Hbenzoic acid
C
O
O H
2,4-difluorobenzoic acid
F
F
C
O
OHC
O
HO CH3HO + excess
terephthalic acidH+
methyl alcohol
C
O
OCH3
dimethyl terephthalate
C
O
CH3O + 2 H2O
A Diester Synthesis
Physical Properties of Esters
Ester molecules cannot hydrogen bond to each other.
Therefore, esters have much lower boiling and melting points than those of carboxylic acids.
Propanoic acid, bp 141°C Methyl acetate , bp 57°C
Esters are less soluble in water than are carboxylic acids because esters cannot form as many hydrogen bonds to
water molecules as can carboxylic acids.
CH3 C
O
OHCH2 CH3 C
O
CH3O
Physical Properties of Esters
The secondary forces in esters are weaker than those in aldehydes and ketones, and thus esters have lower melting
and boiling points.
Methyl acetate, bp 57°C Butanal, bp 76°C
Esters have about the same water solubilities as aldehydes and ketones because all three hydrogen bond to water equally well.
CH3 C
O
CH3O C
O
CH3CH2CH2 H
Esters Have Characteristic Odors
C
O
O C
O
OCH3C
O
OCH2CH3
Pear ApplePineapple
C
O
OHC
O
O
Raspberry Rum
C
O
O
Banana
C
O
O
C
O
OOrangePeach
Amides - Structure and Classification
Subclassification
C
O
NH
H
R1C
O
N
H
R1R2 C
O
NR1R2
R3
1º 2º 3º
Can amides engage in hydrogen bonding??
Amides - Structure and Classification
The amide is better represented as a dipolar ion:
C
O
N C
O
N
Because the bond between the carbonyl carbon atom and the nitrogen atom has a partial double bond character, the bond angles about the carbonyl carbon atom and nitrogen atom are both close to 120° (sp2 hybridization).
The dipolar ion nature of the amide bond is very important in determining the structure and function of protein molecules.
Amides - Synthesis
At low temperatures a carboxylic acid and an amine will take part in a simple acid-base reaction to form an ammonium salt.
R1 C
O
OH R2H N R1 C
O
O+R3
R2H N
R3
H
20-50o C
carboxylic amine ammonium acid carboxylate
:
H3CCH2
C
O
OHN
H3C CH3
H
H3CCH2
C
O
ON
H3C CH3
HH
propanoic dimethyl dimethylammonium acid amine propanoate
:
Amides - Synthesis
At a higher temperature, a condensation reaction takes place between the carboxylic acid and the amine.
carboxylic ammonia primary acid amide
carboxylic 1º amine secondary acid amide
R1 C OH HH N+H
R1 C
O
H N
H>100o C
+ H2O
O
R1 C
O
OH R2H N+H
R1 C
O
R2 N
H>100o C
+ H2O
carboxylic 2º amine tertiary acid amide
R1 C
O
OH R2H N+R3
R1 C
O
R2 N
R3>100o C
+ H2O
Amides - Nomenclature
CH3C C
O
H N
HCH3
CH3
2,2-dimethyl propanamide
HN CH2CH2CH3C
O
N-propyl benzamide
R1C
O
N
R2
R3
Acyl part
Amino part
123
Amides - Synthesis and Nomenclature
OHC
H3C
O
CH3
H2N+
CH3
HN
C
O
H3C
+ H2O
NH2
HOC
CH3
O
+
HN
C
O
CH3
+ H2O
acetic acid methylamine N-methylacetamide
aniline acetic acid N-phenyl acetamide
Δ
Δ
H CH2CH3CO
NCH2CH2CH3
NO2
CH2CH3CO
NH
formamideN-ethyl- N-propyl-
HC
O
OH
formic acid
benzamideN-ethyl- 2-nitro-
C
O
OH
benzoic acid
Amides - Physical Properties
Amides have the strongest secondary attractive forces and the highest melting and boiling points of any covalent organic compounds.
Potential Hydrogen Bonds:
R CO
N H
H
RCO
NH
H
Amides - Physical Properties
CH3 C
O
OHacetic acid
CH3 C
O
N
H
N-methylacetamide
CH3
CH3 C
O
N
H
acetamide
H
CH3 C
O
NN,N-dimethylacetamide
CH3
CH3
Amides - Physical PropertiesThe resonance structure of the amide functional group results in a
large charge separation in an amide molecule resulting in large polarity and secondary attractive forces.
RC
O
NR"
R'
RC
O
NR"
R'
[ ]
RC
O
NH
R'
RC
O
NH
R'
RC
O
NH R'
R
CON
R"
R'
R
CO N
R"
R'hydrogen bonding
intermolecular attraction
Boiling Point Comparison for Classes of Straight-Chain Organic Compounds
Boilin
g Po
int (
ºC)
-200
-100
0
100
200
300
400
Molar Mass0 50 100 150 200
AlkanesAlcoholsCarboxylic Acids
Primary Amides
