Chapter 20 The Chemistry of Carboxylic Acids. Carboxylic Acids General structure: Characteristic...
-
Upload
scot-parks -
Category
Documents
-
view
235 -
download
4
Transcript of Chapter 20 The Chemistry of Carboxylic Acids. Carboxylic Acids General structure: Characteristic...
Chapter 20The Chemistry of Carboxylic Acids
Carboxylic Acids
• General structure:
• Characteristic functional group is called the carboxy group
220.1 Nomenclature of Carboxylic Acids
3
Acetic acid Butyric acid Caproic acid
Palmitic acid
4
Common Nomenclature
• Change the “-yl” (or “-oyl”) of the acyl group to “ic acid”
5
Acetyl group
6
More Complicated Common Nomenclature
• Dicarboxylic acids
7
β-chlorovaleric acid
8
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”
9
• When a carboxyl group is bonded to a ring:1) The ring carbon bonded to the –CO2H group is
considered C12) The ending is “-carboxylic acid”
10
Problems
1) Name the following molecules using common nomenclature
2) Name the following molecules using IUPAC nomenclature
11
3) Draw 1,2,4-benzenetricarboxylic acid
12
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
13
Structure and Physical Properties
• Carboxylic acids have relatively high boiling points– Polarity– Hydrogen bonding
• Many are water soluble14
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)
15
NMR Spectroscopy
• O-H: 9-13 (broad)
1620.3 Spectroscopy of Carboxylic Acids
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.
17