Transcript Naming Carboxylic Acids

Chem 1152: Ch. 15
Carboxylic Acids and Esters
Carboxylic Acids
O
C
OH
COOH
CO2H
Produce sour tastes in foods
• Acetic Acid (vinegar)
• Citric acid (lemons)
• Malic acid (apples)
Esters are responsible for
fragrant odors in fruits and
flowers
• Used as flavoring agents and
scents (perfume, deodorant)
O
C
O
C
Esters
Naming Carboxylic Acids
• Identify the longest C chain including the carboxyl group.
• Number the parent chain so that carboxyl C has lowest number.
• So for monocarboxylic acids, this will be 1, and does not need to be
numbered in naming.
• Drop final –e (or –ene from benzene) from parent chain and replace
with –oic acid.
O
OH
Br
OH
H3C
H3C
O
OH
Br
propanoic acid
CH3
O
2,3-dibromobutanoic acid
3-methylbenzoic acid
O
OH
O
OH
H3C
O
CH3
3-methylpentanoic acid
CH3
Br
4-bromo-3-methoxypentanoic acid
Sweat!
Know common name and characteristics/uses of highlighted carboxylic acids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Physical Properties of Carboxylic Acids
Solubility
• Highly-soluble at low MW (H-bonds with HOH)
• Insoluble at high MW (7+ carbons)
General order of Solubility
Hydrocarbons < ethers < aldehydes and ketones < alcohols < carboxylic acids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Physical Properties of Carboxylic Acids
Boiling Points
• Higher BP than alcohols
due to formation of 2 Hbonds vs. 1 H-bond
between like molecules.
H
H3C
O
H
alcohol
O
CH3
Carboxylic acid
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Carboxylic Acids: Acidity
H+
Carboxylic acids weak acids: Only about 5% of acetic acid dissociates
compared to ~100% for mineral acid (e.g., HCl)
HCl + H2O  H3O+ + ClReaction is reversible for carboxylic acids (not HCl)
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Acidity/Basicity
H+
acidic
0
OHneutral
7
basic
14
pH
pH = -log[H+]
 The pH of solution determines form of carboxylic acid
 Ex. Carboxylate ion predominates at pH 7.4 (physiological pH)
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Carboxylic Acid Salts
Reaction with base produces salt and water
HCl + NaOH  H2O + NaCl
R
O
+
O
O
NaOH
R
-
H
+
+
H-OH
O Na
Sodium carboxylate
Naming carboxylic salts
 Name the metal first
 Change the –ic acid ending of the acid name to -ate
O
O
H3C
-
O
+
O Na
-
+
O K
sodium ethanoate
(sodium acetate)
potassium benzoate
CH3
O
-
Li
+
Lithium 2-methylbenzoate
Useful Carboxylic Acid Salts
O
Sodium stearate
-
 Important component of soap
 produced by hydrolysis of triglycerides (esters of fatty acids)
 How soap is made from animal fat
Sodium benzoate
 Food preservative
Zinc 10-undecylenate
 Used to treat athletes foot
http://chemicalland21.com/lifescience/phar/ZINC%20UNDECYLENATE.htm
+
O Na
H3C
O
-
+
O Na
Carboxylic Esters
 Esterification: Carboxylic acids can react with alcohols to form esters
 -OR’ group of alcohol forms ester linkage
Ester linkage
Ex. 1
H+ ,
heat
Ex. 2
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Ester Reaction Products
O
H3C
O
+
OH
O
H+, heat
CH3
H
HO
O
O
O
O
H3C
H3C
OH
OH
O
O
+
+
OH
+
+
CH3
CH3
H
H
H+, heat
H
O
CH3
Relatively Poor Yields
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
H2O
H2O
O
CH3
CH3
H2O
O
O
O
+
+
H+, heat
H+, heat
CH3
O
O
CH3
+
H2O
Important Esters
 Polyesters: Polymers of esters
 Formed by condensation polymerization (joining monomers, water
byproduct)
Symmetrical monomers
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Polyester Leisure Suits: Yeah…
http://en.wikipedia.org/wiki/File:LeisureSuitConvention4.jpg
Better Yield Reactions to Create Esters
 More reactive than carboxylic acids
 Non-reversible
 Still use alcohol
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Specific Reactions with Acid Chlorides/Anhydrides
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Naming Esters
 Esters may have common or IUPAC names
 The first word of the name of an ester is the name of alkyl or aromatic group (R)
 Change the –ic acid ending of the acid name to –ate (like naming carboxylic acid
salts)
 Parent contains the –COO group
O
O
O
CH3
O
O
O
CH3
CH3
CH3
methyl ethanoate
phenyl butanoate
ethyl benzoate
O
H
CH3
O
O
O
CH3
CH3
isopropyl
methanoate
methyl benzoate
Ester Products/Names
O
O
Cl
+
O
O
CH3
H
+
HCl
CH3
ethyl benzoate
Carboxylic acid chloride
O
O
O
+
O
CH3
O
OH
O
CH3
H
+
CH3
CH3
CH3
O
CH3
Carboxylic acid chloride
ethyl propanoate
O
O
O
O
+
O
O
H
O
CH3
CH3
+
O
H
methyl benzoate
O
O
+
H3C
O
H
CH3
CH3
H3C
Cl
CH3
O
CH3
isopropyl propanoate
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
+
HCl
Ester Reactions: Hydrolysis
 Reaction of ester with water to break ester linkage and produce alcohol and
carboxylic acid
 Reverse of esterification
 Catalyzed by strong acids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Ester Reactions: Saponification
 Reaction of ester with water to break ester linkage and produce alcohol and
carboxylic acid
 Reverse of esterification
 Done in solutions containing strong bases
 Carboxylic acid converted to salt
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Saponification Products
 Reaction of ester with water to break ester linkage and produce alcohol and
carboxylic acid
O
O
-
CH3
H3C
+
CH3
NaOH
H3C
HO
CH3
sodium propanoate
CH3
O
CH3
+
O
isopropyl propanoate
O
+
O Na
O
+
KOH
-
+
O K
CH3
+
HO
ethyl benzoate
potassium benzoate
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Esters of Inorganic Acids
 Alcohols can form esters by reaction with strong, inorganic acids (sulfuric, nitric
and phosphoric)
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011
Production of Phosphoric Anhydrides
 Alcohols can form esters by reaction with strong, inorganic acids (sulfuric, nitric
and phosphoric)
 Phosphoric most important
 Forms linkage for DNA/RNA, ATP/ADP
ADP
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7 th Edition, 2011