Chem 1152: Ch. 15 Carboxylic Acids and Esters
Chem 1152: Ch. 15
Jan 19, 2016
Chem 1152: Ch. 15. Carboxylic Acids and Esters. Carboxylic Acids. O. C. COOH. CO 2 H. OH. Produce sour tastes in foods Acetic Acid (vinegar) Citric acid (lemons) Malic acid (apples). Esters are responsible for fragrant odors in fruits and flowers - PowerPoint PPT Presentation
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Chem 1152: Ch. 15
Carboxylic Acids and Esters
Carboxylic AcidsCarboxylic Acids
Produce sour tastes in foods•Acetic Acid (vinegar)•Citric acid (lemons)•Malic acid (apples)
C
O
OH COOH CO2H
C
O
O C
EstersEsters
Esters are responsible for fragrant odors in fruits and flowers•Used as flavoring agents and scents (perfume, deodorant)
Naming Carboxylic AcidsNaming 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
CH3
OH
Br
Br
CH3
O
OH
CH3
O OH
propanoic acid 2,3-dibromobutanoic acid 3-methylbenzoic acid
CH3
CH3
O
OH
3-methylpentanoic acid
CH3
Br
O
O OH
4-bromo-3-methoxypentanoic acid
Know common name and characteristics/uses of highlighted carboxylic acids
Sweat!
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Physical Properties of Carboxylic AcidsPhysical Properties of Carboxylic Acids
Solubility•Highly-soluble at low MW (H-bonds with HOH)•Insoluble at high MW (7+ carbons)
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
General order of SolubilityHydrocarbons < ethers < aldehydes and ketones < alcohols < carboxylic acids
Physical Properties of Carboxylic AcidsPhysical Properties of Carboxylic Acids
Boiling Points•Higher BP than alcohols due to formation of 2 H-bonds vs. 1 H-bond between like molecules.
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
H
CH3 O H
CH3
O
alcohol
Carboxylic acid
Carboxylic Acids: AcidityCarboxylic Acids: Acidity
Carboxylic acids weak acids: Only about 5% of acetic acid dissociates compared to ~100% for mineral acid (e.g., HCl)
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
H+
HCl + H2O H3O+ + Cl-
Reaction is reversible for carboxylic acids (not HCl)
Acidity/BasicityAcidity/Basicity
0 7 14
pH
basicneutralacidic
pH = -log[H+]
H+ OH-
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, 7th Edition, 2011
Carboxylic Acid SaltsCarboxylic Acid SaltsReaction with base produces salt and water
H
R
O
O
+ NaOH + H-OHR
O
O-
Na+
HCl + NaOH H2O + NaCl
Sodium carboxylate
Naming carboxylic saltsName the metal firstChange the –ic acid ending of the acid name to -ate
CH3
O
O-
Na+
O
O-
K+
sodium ethanoate(sodium acetate)
Li+
CH3
O
O-
potassium benzoate Lithium 2-methylbenzoate
Useful Carboxylic Acid SaltsUseful Carboxylic Acid Salts
Sodium stearate
http://chemicalland21.com/lifescience/phar/ZINC%20UNDECYLENATE.htm
O
O-
CH3 Na+
Important component of soap produced by hydrolysis of triglycerides (esters of fatty acids) How soap is made from animal fat
Sodium benzoate
Food preservative
O
O-
Na+
Zinc 10-undecylenate
Used to treat athletes foot
Carboxylic EstersCarboxylic Esters Esterification: Carboxylic acids can react with alcohols to form esters -OR’ group of alcohol forms ester linkage
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Ester linkage
H+, heat
Ex. 1
Ex. 2
Ester Reaction ProductsEster Reaction Products
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
+O
OHCH3
H+, heatCH3
O
OOH + OH2H
O CH3
+H+, heat
H
O
CH3
O
OH+ OH2
CH3
O O
+H+, heat
+ OH2
OH
O
H
CH3
O
CH3
CH3
CH3
O
O
Relatively Poor Yields
+O
OHCH3
H+, heatCH3
O
OOH + OH2H
O CH3
+H+, heat
H
O
CH3
O
OH+ OH2
CH3
O O
+H+, heat
+ OH2
OH
O
H
CH3
O
CH3
CH3
CH3
O
O
Important EstersImportant Esters
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Polyesters: Polymers of esters Formed by condensation polymerization (joining monomers, water
byproduct)
Symmetrical monomers
Polyester Leisure Suits: Yeah…Polyester Leisure Suits: Yeah…
http://en.wikipedia.org/wiki/File:LeisureSuitConvention4.jpg
Better Yield Reactions to Create EstersBetter Yield Reactions to Create Esters
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
More reactive than carboxylic acids Non-reversible Still use alcohol
Specific Reactions with Acid Chlorides/AnhydridesSpecific Reactions with Acid Chlorides/Anhydrides
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Naming EstersNaming 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
methyl ethanoate phenyl butanoate ethyl benzoate
isopropyl methanoate
methyl benzoate
O
CH3
OCH3
CH3
O O O
O CH3
CH3
CH3O
H
O
O
OCH3
Ester Products/NamesEster Products/Names
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
O
Cl + CH3H
O
O
CH3
O + HCl
CH3
O
O
CH3
O
+ CH3H
O +CH3
CH3
O
OOH
CH3O
+ HO
CH3
OO
OCH3
O
O
H
O
O+
+CH3
O
ClCH3
CH3H
OCH3
CH3
CH3
O
O
+ HCl
ethyl benzoate
ethyl propanoate
methyl benzoate
isopropyl propanoate
Carboxylic acid chloride
Carboxylic acid chloride
Ester Reactions: HydrolysisEster Reactions: Hydrolysis
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Reaction of ester with water to break ester linkage and produce alcohol and carboxylic acid
Reverse of esterification Catalyzed by strong acids
Ester Reactions: SaponificationEster Reactions: Saponification
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
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
Saponification ProductsSaponification Products
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Reaction of ester with water to break ester linkage and produce alcohol and carboxylic acid
O
CH3
O CH3
CH3
+ NaOH
O
CH3
O-
Na+
+OH CH3
CH3
O
O
CH3
+ KOH +O
O-
OH
CH3K+
isopropyl propanoate sodium propanoate
ethyl benzoate potassium benzoate
Esters of Inorganic AcidsEsters of Inorganic Acids
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Alcohols can form esters by reaction with strong, inorganic acids (sulfuric, nitric and phosphoric)
Production of Phosphoric AnhydridesProduction of Phosphoric Anhydrides
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
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
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