Title: Chapter Sixteen
1Chapter Sixteen
- Carboxylic Acids, Esters, and Other Acid
Derivatives
2- Carboxylic acid An organic compound with
carboxyl functional group - Carboxyl group A carbonyl group (CO) with a
hydroxyl group (OH) bonded to the carbonyl
carbon atom - A general structural representation for a
carboxyl group is shown below
Carbonyl group
Carboxylic acid
3Carboxylic Acids
- Fig. 16.1
- The three simplest carboxylic acids methanoic
acid, ethanoic acid, and propanoic acid.
4Carboxylic Acids
- Fig. 16.2
- Benzoic acid molecule
5Carboxylic Acids
- Carboxylic acids always contain the carboxyl
group on __________ ____. - A carboxyl group is a carbonyl attached to a
hydroxyl - Acts differently than an alcohol or a carbonyl
compound - O
- ??
- CH3 COH CH3COOH
-
- carboxyl group
6IUPAC Rules for Naming Monocarboxylic Acids
- Rule 1 Select the longest carbon chain that
includes the carbon atom of the carboxyl group as
the parent chain. - Rule 2 Name the parent chain by changing the
-e ending of the corresponding alkane to -oic
acid. - Rule 3 Number the parent chain by assigning the
1 to the carboxyl carbon atom. - Rule 4 Determine the identity and location of
any substituents in the usual manner, and append
this information to the front of the parent chain
name.
7Naming Rules
- Identify longest chain containing the ___________
group - (IUPAC) Number ____________ carbon as 1
- (Common) Assign ?, ?, g to carbon atoms adjacent
to ____________ carbon - CH3
-
- CH3 CHCH2 COOH
- IUPAC 3-methylbutanoic acid
- Common ?-methylbutryic acid
8Naming Carboxylic Acids
- Formula IUPAC Common
- alkan -oic acid prefix ic acid
- HCOOH methanoic acid formic acid
- CH3COOH ethanoic acid acetic
acid - CH3CH2COOH propanoic acid propionic
acid - CH3CH2CH2COOH butanoic acid
butyric acid -
9First Six Unbranched Monocarboxylic Acids
10First Six Unbranched Dicarboxylic Acids
11Aromatic Carboxylic Acids
- Benzoic Acid is the ______________ carboxylic
acid - Locates substituents by assigning 1 to the carbon
with the carboxyl group
3-chlorobenzoic acid
Benzoic acid
4-methylbenzoic acid
12Common Acids
- Acetic Acid CH3COOH
- Vinegar is 4-8 (v/v) acetic acid solution
- Colorless liquid with sharp odor
- Oxalic acid HOOC-COOH - found in spinach and
cabbage - Harmful at high concentrations
- Used to remove rust, bleach straw, and leather
and ink stains
13Polyfunctional Carboxylic Acids
- PCAs contain at least one or more functional
groups other than carboxyl group - PCAs are commonly found in living organisms an
play an important role in human body - Occur in many fruits
- Used in over the counter skin care products and
prescription drugs - Common types of PCAs
- Unsaturated acids
- Hydroxy acids
- Keto acids
14Unsaturated Acids
- Contain at least one carbon-carbon double bond
(CC) - Two types of monounsaturated carboxylic acids
- Trans - unsaturated carboxylic acids
- Cis unsaturated carboxylic acids
- Examples
- Propenoic acid (acrylic acid) used in the
manufacture of polymeric materials. - Futenedioic acid - has two forms
- Fumaric acid trans-form
- Maleic acid cis-form
15Hydroxy Acids
- Contain at least one hydroxyl group and are
naturally present in many foods - Examples
- Glycolic acid present in juice from sugar cane
and sugar beets - Lactic acid Present sour milk, sauerkraut, and
dill pickles - Malic acid and tartaric acid occur naturally in
fruits
16Keto Acids
- Contain a carbonyl (CO) group within a carbon
chain. - Example
- Pyruvic acid - simplest keto acid with odor
resembling that of vinegar (acetic acid) and it
is also a metabolic acid
17- Metabolic acids Polyfunctional acids formed as
intermediates of ________________ reactions in
the human body. - There are eight such acids that will appear
repeatedly in the biochemistry chapters - Metabolic acids are derived from
- Propionic acid, (C3 mono acids) lactic,
glyceric, and pyruvic acids - Succinic acid (C4 diacid) fumaric, oxaloacetic,
and malic acids - Glutaric acid (C5 diacid) a-ketoglutaric and
citric acids
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19At Room Temperature and Pressure
- Straight chain carboxylic acids with 1-9 carbon
atoms are liquids and strong odors - Straight chain carboxylic acids with gt10 C atoms
are waxy solids with no odor. - Aromatic and dicarboxylic acids Odorless solids
20Properties of Carboxylic Acids
- Like alcohols, carboxylic acids form ___________
intermolecular hydrogen bonds. - Most carboxylic acids exist as ___________.
- Boiling points higher than alkanes of similar MW.
- Small carboxylic acids (1-4 carbons) are soluble
in water
21Boiling Points
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23Synthesis of Carboxylic Acids
- Synthesized from aromatic rings, primary
alcohols and aldehydes. - Oxidizing Agents
- K2Cr2O7 / H2SO4
- or
- KMnO4
Carboxylic Acid
24Oxidation of Aromatic Compounds
- Benzene does not react with KMnO4.
- Alkyl groups on the ring (-R) are readily
oxidized though. - One product for all reactions.
25Oxidation of Aromatic Compoundswith KMnO4
26- Oxidation of primary alcohols and aldehydes
27- Oxidation of alcohols to carboxylic acids.
28Properties
- Carboxylic acids are ________ acids
- Stronger acids than alcohols
- In water they dissociate to release ___________
(H) and form carboxylate ion (RCOO-) --
equilibrium reactions and equilibrium lies
towards the left indicating that small amount of
acid is ionized - CH3COOH H2O CH3COO H3O
- Neutralized by a base
- CH3COOH NaOH CH3COO Na H2O
29- Monocarboxylic acids release ______ H to form
carboxylate ion with _______ negative charge - Dicarboxylic acids release ______ H ions to form
carboxylate ion with _____ negative charges and
so on
30- Carboxylic acids are obviously _________.
- Stronger acids than alcohols, but __________ than
mineral acids. - Will react with _________ to give metal
carboxylates. - There is a large range of acidities depending on
the substituents on a carboxylic acid.
31Carboxylate Ions
- The conjugate base of a carboxylic acid
- Formed when a carboxylic acid loses a proton
- Named by dropping the -ic acid ending and
replacing it with ate - CH3CH2COO- Propionate
- CH3COO- Ethanoate (Acetate)
- CH3CH2CH2COO- Butanoate
32Carboxylate Salts
- An ionic compound in which the negative ion is a
carboxylate ion - Naming the positive ion is named first,
followed by a separate word giving the name of
the negative ion - Converted back to a carboxylic acid by the
addition of a strong acid - CH3CH2COO-Na Sodium Propionate
- CH3COO-K Potassium Ethanoate
- CH3CH2CH2COO-Li Lithium Butanoate
33Uses of Carboxylic Acid Salts
- Good antimicrobial and antifungal agents
- Benzoate salts Effective (0.1, m/m) against
yeast and mold in beverages, jams and jellies,
etc. - Sodium sorbate Inhibits mold and yeast in dairy
products, dried fruits, some meat and fish
products - Propionate Used in preservation of baked goods
- Benzoate and sorbate cant be used in yeast
leavened baked goods as they inhibit mold and
yeast
34Carboxylic Acids
35Esters
- Fig. 16.12
- Methyl and ethyl esters of acetic acid.
36Ester
- In an ester, the _______ in the carboxyl group is
replaced with an ________ group - O
- ??
- CH3 CO CH3 CH3COO CH3
-
- ester group
- Sulfur analogs of esters are called thioesters
(sulfur replaces the hydroxyl oxygen)
37- The name for the alcohol part of the ester
appears _________ and is _____________ by a
separate word giving the name for the acid part
of the ester. - The name for the alcohol part of the ester is
simply the name of the R group (alkyl,
cycloalkyl, or aryl) present in the OR portion
of the ester. - The name for the acid part of the ester is
obtained by dropping the -ic acid ending for
the acids name and adding the suffix -ate.
38Naming Esters
- Name the alkyl from the alcohol O-
- Name the acid with the CO with ate
- acid alcohol
- O
- ?? methyl
- CH3 CO CH3
- Ethanoate methyl ethanoate (IUPAC)
- (acetate) methyl acetate (common)
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40Esters
41Esterification Preparation of Esters
- Reaction of a carboxylic acid and alcohol
- Acid catalyst
- O
- ?? H
- CH3 COH HOCH2CH3
-
- O
- ??
- CH3 COCH2CH3 H2O
42Hydrolysis Breaking Up Esters
- Esters react with water and acid catalyst
- Split into carboxylic acid and alcohol
- O
- ?? H
- H COCH2CH3 H2O
- O
- ??
- H COH HOCH2CH3
43Hydrolysis
44Saponification
- Esters react with bases
- Produce the salt of the carboxylic acid and
alcohol - O
- ?? H2O
- CH3COCH2CH3 NaOH
- O
- ??
- CH3CO Na HOCH2CH3
- salt of carboxylic acid
- Saponification reactions produce soaps
45Soaps
46- The following figure represents soap.
- Which end of the anion is hydrophobic?
47- How does soap interact with grease?
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51Dicarboxylic Acids
52The C2 dicarboxylic acid, oxalic acid,
contributes to the tart taste of rhubarb stalks.