1. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.1 Naming a Carboxylic Acid For the systematic name of a carboxylic acid, first identify the longest chain containing the —COOH group and number it starting with the carboxylgroup carbon: Analysis Give the systematic and the common name for this compound: The IUPAC name of this molecule is 3-hydroxy-2-methylbutanoic acid; the common name of this acid is -hydroxy - -methylbutyric acid. Solution The parent compound is the 4-carbon acid, butanoic acid. It has a methyl group on carbon 2 and a hydroxyl group on carbon 3. From Table 17.1 we see that the common name for the 4-carbon acid is butyric acid. In the common nomenclature scheme, substituents are located by Greek letters rather than numbers:

2. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.2 Writing the Structure of an Ester from Its Name The two-word name consisting of an alkyl group name followed by an acid name with an -ate ending shows that the compound is an ester. The name “acetate” shows that the RCO— part of the molecule is from acetic acid (CH 3 COOH). The “butyl” part of the name indicates that a butyl group has replaced H in the carboxyl group. Analysis What is the structure of butyl acetate? The structure of butyl acetate is Solution

3. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.3 Naming an Ester from Its Structure The compound has the general formula RCOOR', so it is an ester. The acyl part of the molecule (RCO—) is from stearic acid (see Table 17.1). The R' group has 3 C atoms and is therefore a propyl group. Analysis What is the name of this compound? The compound is propyl stearate. Solution

4. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.4 Formation of Acid Anhydrides The reaction here fits the substitution-reaction pattern as follows: Analysis An important but often overlooked class of carboxylic acid derivatives is the acid anhydrides. (Anhydride means “without water.”) Acid anhydrides are formed when pairs of acid molecules react (dimerize) via a carbonyl-group substitution reaction to lose water. Relate the reactants below to the substitution reaction pattern (on p. 516) and complete the equation. The reaction is Solution with Z equal to

5. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Carboxylic acid anhydrides, although important in an organic chemistry lab, are of little importance in biochemistry. They easily react with water to give back the acids they came from (the reverse of the above reaction), so they are not found in biological systems. They are introduced here to prepare the way for the introduction of phosphoric acid anhydrides in Section 17.8, which do play a key role in biochemistry. Worked Example 17.4 Formation of Acid Anhydrides Continued

6. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.5 Effect of Structure on Carboxylic Acid Strength The structural difference is the replacement of 3 hydrogen atoms on the alpha carbon by 3 chlorine atoms. The chlorines are much more electronegative than the hydrogen and therefore draw electrons away from the rest of the molecule in trichloroacetic acid. The result is that the hydrogen atom of the —COOH group in trichloroacetic acid is held less strongly and is much more easily removed than the corresponding hydrogen atom in acetic acid. Analysis Write the structural formulas of trichloroacetic acid and acetic acid and explain why trichloroacetic acid is the much stronger acid of the two. Since the —COOH hydrogen atom in trichloroacetic acid is held less strongly, it is the stronger acid. Solution

7. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.6 Writing the Products of an Esterification Reaction First, write the two reaction partners so that the —COOH group of the acid and the —OH group of the alcohol face each other: Analysis The flavor ingredient in oil of wintergreen is an ester that is made by reaction of o-hydroxybenzoic acid (salicylic acid) with methanol. What is its structure? The product is the ester: Solution Next, remove —OH from the acid and —H from the alcohol to form water and then join the two resulting organic fragments with a single bond.

8. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.7 Writing the Products of Amide Formation First, rewrite the equation so that the —OH of the acid and the —H of the amine face each other: Analysis The mosquito and tick repellent DEET (diethyltoluamide) is prepared by reaction of diethylamine with m-methylbenzoic acid (m-toluic acid). What is the structure of DEET? The structure of DEET is Solution Next, remove the —OH from the acid and the —H from the nitrogen atom of the amine to form water, then join the two resulting fragments together to form the amide product.

9. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.8 Writing the Products of an Ester Hydrolysis The name of an ester gives a good indication of the names of the two products. Thus, ethyl formate yields ethyl alcohol and formic acid. To find the product structures in a more systematic way, write the structure of the ester and locate the bond between the carbonyl-group carbon and the —OR' group: Analysis What product would you obtain from acid-catalyzed hydrolysis of ethyl formate, a flavor constituent of rum? Carry out a hydrolysis reaction on paper. First form the carboxylic acid product by connecting an —OH to the carbonyl-group carbon. Then add an —H to the —OCH 2 CH 3 group to form the alcohol product. Solution

10. © 2013 Pearson Education, Inc. Fundamentals of General, Organic, and Biological Chemistry, 7e John McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson Worked Example 17.9 Writing the Products of an Amide Hydrolysis First, look at the name of the starting amide. Often, the amide’s name incorporates the names of the two products. Thus, N-ethylbutanamide yields ethylamine and butanoic acid. To find the product structures systematically, write the amide and locate the bond between the carbonyl-group carbon and the nitrogen. Then break this amide bond and write the two fragments: Analysis What carboxylic acid and amine are produced by the hydrolysis of N-ethylbutanamide? Carry out a hydrolysis reaction on paper and form the products by connecting an —OH to the carbonyl-group carbon and an —H to the nitrogen: Solution