Transcript Chapter 1 Chemical Bonding and Chemical Structure

Chapter 20
The Chemistry of Carboxylic Acids
Carboxylic Acids
• General structure:
• Characteristic functional group is called the
carboxy group
20.1 Nomenclature of Carboxylic Acids
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Acetic acid
Butyric acid
Caproic acid
Palmitic acid
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Common Nomenclature
• Change the “-yl” (or “-oyl”) of the acyl group to “ic acid”
Acetyl group
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More Complicated Common Nomenclature
β-chlorovaleric acid
• Dicarboxylic acids
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IUPAC Nomenclature
• Replace the “-e” of the alkane name with “-oic acid”
• The carbonyl carbon is numbered as C1
• For multiple carboxyl groups, retain the “-e” in the alkane
name and insert a Greek prefix (di, tri etc.) between the “e”
and “oic acid”
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• When a carboxyl group is bonded to a ring:
1) The ring carbon bonded to the –CO2H group is
considered C1
2) The ending is “-carboxylic acid”
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Problems
1) Name the following molecules using common nomenclature
2) Name the following molecules using IUPAC nomenclature
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3) Draw 1,2,4-benzenetricarboxylic acid
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Structure and Physical Properties
• The carbonyl oxygen is the oxygen involved with the
C=O double bond
• The carboxylate oxygen is the oxygen involved with
the C-O single bond
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Structure and Physical Properties
• Carboxylic acids have relatively high boiling points
– Polarity
– Hydrogen bonding
• Many are water soluble
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IR Spectroscopy
• Carboxylic acids have two characteristics in IR spectroscopy that
make them easy to identify
– C=O stretch: 1710 cm-1 (as the dimer)
– O-H stretch: 2400-3600 cm-1 (very broad)
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NMR Spectroscopy
• O-H: d 9-13 (broad)
20.3 Spectroscopy of Carboxylic Acids
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Problem
• Compound X, C4H8O3, has infrared absorptions at
1710 and 2500-3100 cm-1 and has the 1H NMR
spectrum shown below. Propose a structure for X.
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