In Section 17.7B, we suggested that the mechanism of

Which is the stronger acid in each pair? COOH O COOH (a) CH or 3COOH Acetic acid CH3SO3H Methanesulfonic acid (b) or 2-Oxopropanoic acid (Pyruvic acid) Propanoic acid

Account for the observation that the following b-ketoacid can be heated for extended periods at temperatures above its melting point without noticeable decarboxylation. O OH O

Write the IUPAC name of each compound, showing stereochemistry where relevant: COOH COOH COO2NH4 1 HO COOH COOH COOH OH (a) (b) (c) COOH (d) (e) (f)

Draw a structural formula for each compound. (a) Phenylacetic acid (b) 4-Aminobutanoic acid (c) 3- Chloro-4-phenylbutanoic acid (d) Propenoic acid (acrylic acid) (e) (Z)-3-Hexenedioic acid (f) 2- Pentynoic acid (g) Potassium phenylacetate (h) Sodium oxalate (i) 2-Oxocyclohexanecarboxylic acid ( j) 2,2-Dimethylpropanoic acid

Megatomoic acid, the sex attractant of the female black carpet beetle, has the following structure. COOH (a) What is its IUPAC name? (b) State the number of stereoisomers possible for this compound.

Draw a structural formula for each salt. (a) Sodium benzoate (b) Lithium acetate (c) Ammonium acetate (d) Disodium adipate (e) Sodium salicylate (f) Calcium butanoate

The monopotassium salt of oxalic acid is present in certain leafy vegetables, including rhubarb. Both oxalic acid and its salts are poisonous in high concentrations. Draw the structural formula of monopotassium oxalate.

Potassium sorbate is added as a preservative to certain foods to prevent bacteria and molds from causing food spoilage and to extend the foods shelf life. The IUPAC name of potassium sorbate is potassium (2E,4E)-2,4-hexadienoate. Draw a structural formula for potassium sorbate.

Zinc 10-undecenoate, the zinc salt of 10-undecenoic acid, is used to treat certain fungal infections, particularly Tinea pedis (athletes foot). Draw a structural formula for this zinc salt.

On a cyclohexane ring, an axial carboxyl group has a conformational energy of 5.9 kJ (1.4 kcal)/mol relative to an equatorial carboxyl group. Consider the equilibrium for the alternative chair conformations of trans-1,4-cyclohexanedicarboxylic acid. Draw the less stable chair conformation on the left of the equilibrium arrows and the more stable chair on the right. Calculate DG0 for the equilibrium as written, and calculate the ratio of the more stable chair to the less stable chair at 25C.

Arrange the compounds in each set in order of increasing boiling point. (a) CH3(CH2)5COOH CH3(CH2)6CHO CH3(CH2)6CH2OH OH O (b) OH O

Acetic acid has a boiling point of 118C, whereas its methyl ester has a boiling point of 57C. Account for the fact that the boiling point of acetic acid is higher than that of its methyl ester, even though acetic acid has a lower molecular weight.

Given here are 1 H-NMR and 13C-NMR spectral data for nine compounds. Each compound shows strong absorption between 1720 and 1700 cm21 , and strong, broad absorption over the region 25003300 cm21 . Propose a structural formula for each compound. Refer to Appendices 4, 5, and 6 for spectral correlation tables. (a) C5H10O2 (b) C6H12O2 1 H-NMR 13C-NMR 0.94 (t, 3H) 180.71 1.39 (m, 2H) 33.89 1.62 (m, 2H) 26.76 2.35 (t, 2H) 22.21 12.0 (s, 1H) 13.69 1 H-NMR 13C-NMR 1.08 (s, 9H) 179.29 2.23 (s, 2H) 47.82 12.1 (s, 1H) 30.62 29.57 (c) C5H8O4 (d) C5H8O4 1 H-NMR 13C- NMR 0.93 (t, 3H) 170.94 1.80 (m, 2H) 53.28 3.10 (t, 1H) 21.90 12.7 (s, 2H) 11.81 1 H-NMR 13C- NMR 1.29 (s, 6H) 174.01 12.8 (s, 2H) 48.77 22.56 (e) C4H6O2 (f) C3H4Cl2O2 1 H-NMR 13C-NMR 1.91 (d, 3H) 172.26 5.86 (d, 1H) 147.53 7.10 (m, 1H) 122.24 12.4 (s, 1H) 18.11 1 H-NMR 13C-NMR 2.34 (s, 3H) 171.82 11.3 (s, 1H) 79.36 34.02

Given here are 1 H-NMR and 13C-NMR spectral data for nine compounds. Each compound shows strong absorption between 1720 and 1700 cm21 , and strong, broad absorption over the region 25003300 cm21 . Propose a structural formula for each compound. Refer to Appendices 4, 5, and 6 for spectral correlation tables. (a) C5H10O2 (b) C6H12O2 1 H-NMR 13C-NMR 0.94 (t, 3H) 180.71 1.39 (m, 2H) 33.89 1.62 (m, 2H) 26.76 2.35 (t, 2H) 22.21 12.0 (s, 1H) 13.69 1 H-NMR 13C-NMR 1.08 (s, 9H) 179.29 2.23 (s, 2H) 47.82 12.1 (s, 1H) 30.62 29.57 (c) C5H8O4 (d) C5H8O4 1 H-NMR 13C- NMR 0.93 (t, 3H) 170.94 1.80 (m, 2H) 53.28 3.10 (t, 1H) 21.90 12.7 (s, 2H) 11.81 1 H-NMR 13C- NMR 1.29 (s, 6H) 174.01 12.8 (s, 2H) 48.77 22.56 (e) C4H6O2 (f) C3H4Cl2O2 1 H-NMR 13C-NMR 1.91 (d, 3H) 172.26 5.86 (d, 1H) 147.53 7.10 (m, 1H) 122.24 12.4 (s, 1H) 18.11 1 H-NMR 13C-NMR 2.34 (s, 3H) 171.82 11.3 (s, 1H) 79.36 34.02 5498X_17_ch17_p649-679.indd 672 12/13/10 3:48:58 PM . Problems 673 (g) C5H8Cl2O2 (h) C5H9BrO2 1 H-NMR 13C-NMR 1.42 (s, 6H) 180.15 6.10 (s, 1H) 77.78 12.4 (s, 1H) 51.88 20.71 1 H-NMR 13C-NMR 0.97 (t, 3H) 176.36 1.50 (m, 2H) 45.08 2.05 (m, 2H) 36.49 4.25 (t, 1H) 20.48 12.1 (s, 1H) 13.24 (i) C4H8O3 1 H-NMR 13C-NMR 2.62 (t, 2H) 177.33 3.38 (s, 3H) 67.55 3.68 (s, 2H) 58.72 11.5 (s, 1H) 34.75

Complete each reaction. (a) CH2OH (b) (c) (d) CHO OH HO 1.Cl2, KOH in water/dioxane 2.HCl, H2O K2Cr2O7, H2SO4 H2O, acetone 2.CO2 1.Mg, ether 3.HCl, H2O 1.Ag(NH3)2 1 2.H2O, HCl O Br OCH3

Show how to bring about each conversion in good yield. OH (a) (c) (b) OH CH2OH COOH Cl COOH O C6H5 C6H5 COOH

Show how to prepare pentanoic acid from each compound. (a) 1-Pentanol (b) Pentanal (c) 1-Pentene (d) 1-Butanol (e) 1-Bromopropane (f) 1-Hexene

Draw the structural formula of a compound with the given molecular formula that, on oxidation by potassium dichromate in aqueous sulfuric acid, gives the carboxylic acid or dicarboxylic acid shown. C6H14O OH O oxidation (a) OH HO C6H14O2 O O oxidation (c) C6H12O OH O oxidation

Show the reagents and experimental conditions necessary to bring about each conversion in good yield. CH3CH"CHCH3 CH3CH"CHCH2COOH (a) (b) CH3COH CH3CCOOH OH COOH CH3 CH3 CH3 CH3 (d) CH3COH CH3CHCH2COOH CH3 CH3 CH3 (c) CH3COH CH3CHCOOH (e) CH3 CH3 CH3

Succinic acid can be synthesized by the following series of reactions from acetylene. Show the reagents and experiential conditions necessary to carry out this synthesis. OH HO OH HO HO OH Acetylene 2-Butyne-1,4-diol 1,4-Butanediol Butanedioic acid (Succinic acid) O O H99999H

The reaction of an a-diketone with concentrated sodium or potassium hydroxide to give the salt of an a-hydroxyacid is given the general name benzil-benzilic acid rearrangement. It is illustrated by the conversion of benzil to sodium benzilate and then to benzilic acid. Propose a mechanism for this rearrangement. Benzil (an -diketone) Sodium benzilate Ph9C9C9Ph Ph9C9C9O2Na 1 NaOH 1 O O O H2O HCl H2O Ph HO Benzilic acid Ph9C9C9OH O Ph HO

Select the stronger acid in each set. (a) Phenol (pKa 9.95) and benzoic acid (pKa 4.19) (b) Lactic acid (Ka 8.4 3 1024 ) and ascorbic acid (Ka 7.9 3 1025 )

In each set, assign the acid its appropriate pKa. O (a) (b) (pKa 3.58 and 2.49) (c) CH3CH2COOH and N#CCH2COOH (pKa 4.78 and 2.45) COOH SO3H and and (pKa 4.19 and 0.70) COOH COOH O

Low-molecular-weight dicarboxylic acids normally exhibit two different pKa values. Ionization of the fi rst carboxyl group is easier than the second. This effect diminishes with molecular size, and, for adipic acid and longer chain dicarboxylic acids, the two acid ionization constants differ by about one pK unit. 5498X_17_ch17_p649-679.indd 674 12/13/10 3:48:58 PM . Problems 675 Why do the two pKa values differ more for the shorter chain dicarboxylic acids than for the longer chain dicarboxylic acids?

Complete the following acid-base reactions. (a) CH2COOH 1 (b) CH3CH"CHCH2COOH 1 NaHCO3 NaOH OCH3 1 NaHCO3 COOH (c) (d) CH3CHCOOH 1 H2NCH2CH2OH OH (e) CH3CH"CHCH2COO2 Na1 1 HCl h (f) CH3CH2CH2CH2Li 1 CH3COOH h (g) CH3CH2CH2CH2MgBr 1 CH3CH2OH

The normal pH range for blood plasma is 7.357.45. Under these conditions, would you expect the carboxyl group of lactic acid (pKa 3.08) to exist primarily as a carboxyl group or as a carboxylic anion? Explain.

The Ka1 of ascorbic acid is 7.94 3 1025 . Would you expect ascorbic acid dissolved in blood plasma (pH 7.357.45) to exist primarily as ascorbic acid or as ascorbate anion? Explain.

Excess ascorbic acid is excreted in the urine, the pH of which is normally in the range 4.88.4. What form of ascorbic acid would you expect to be present in urine of pH 8.4, free ascorbic acid or ascorbate anion? Explain.

Give the expected organic product when phenylacetic acid, PhCH2COOH, is treated with each reagent. (a) SOCl2 (b) NaHCO3, H2O (c) NaOH, H2O (d) CH3MgBr (one equivalent) (e) LiAlH4 followed by H2O (f) CH2N2 (g) CH3OH 1 H2SO4 (catalyst)

Show how to convert trans-3-phenyl-2-propenoic acid (cinnamic acid) to each compound. (a) (b) (c) O C6H5 OH C6H5 OH C6H5 OH

Show how to convert 3-oxobutanoic acid (acetoacetic acid) to each compound. (a) OH (b) (c) (racemic) (racemic) O O OH OH OH OH

Complete these examples of Fischer esterifi cation. Assume that the alcohol is present in excess. (a) (c) (b) OH 1 1 O OH HO H1 H1 H1 COOH 1 COOH CH3OH OH O HO O

Benzocaine, a topical anesthetic, is prepared by treatment of 4-aminobenzoic acid with ethanol in the presence of an acid catalyst followed by neutralization. Draw a structural formula for benzocaine.

Name the carboxylic acid and alcohol from which each ester is derived. (a) (c) (d) (b) OMe O O O O O O EtO O O OEt O

When 4-hydroxybutanoic acid is treated with an acid catalyst, it forms a lactone (a cyclic ester). Draw the structural formula of this lactone, and propose a mechanism for its formation

Fischer esterifi cation cannot be used to prepare tert-butyl esters. Instead, carboxylic acids are treated with 2-methylpropene in the presence of an acid catalyst to generate them. O 2- Methylpropene A tert-butyl ester (Isobutylene) R OH O R O 1 H1 (a) Why does the Fischer esterifi cation fail for the synthesis of tert-butyl esters? (b) Propose a mechanism for the 2-methylpropene method.

Draw the product formed on thermal decarboxylation of each compound. C6H5CCH2COOH C6H5CH2CHCOOH CCH3 COOH (a) (b) (c) O O COOH

When heated, carboxylic salts in which there is a good leaving group on the carbon beta to the carboxylate group undergo decarboxylation/elimination to give an alkene. O Br O2Na1 1 CO2 1 Na1Br2 (a) heat Br O2Na1 1 CO2 1 Na1Br2 Br (b) heat Br O 5498X_17_ch17_p649-679.indd 676 12/13/10 3:48:59 PM. Problems 677 Propose a mechanism for this type of decarboxylation/elimination. Compare the mechanism of these decarboxylations with the mechanism for decarboxylation of b-ketoacids; in what way(s) are the mechanisms similar?

Show how cyclohexanecarboxylic acid could be synthesized from cyclohexane in good yield. COOH

In Section 17.7B, we suggested that the mechanism of Fischer esterifi cation of carboxylic acids is a model for the reactions of functional derivatives of carboxylic acids. One of these reactions is that of an acid chloride with water (Section 18.4A). Suggest a mechanism for this reaction. R9C9Cl 1 H2O O R9C9OH 1 HCl O

We have studied Fischer esterifi cation, in which a carboxylic acid is reacted with an alcohol in the presence of an acid catalyst to form an ester. Suppose that you start instead with a dicarboxylic acid such as terephthalic acid and a diol such as ethylene glycol. Show how Fischer esterifi cation in this case can lead to a macromolecule with a molecular weight several thousands of times that of the starting materials. HO OH OH poly(ethylene terephthalate) (PET) 1 HO O O 1,4-Benzenedicarboxylic acid (Terephthalic acid) 1,2-Ethanediol (Ethylene glycol) As we shall see in Section 29.5B, the material produced in this reaction is a highmolecular-weight polymer, which can be fabricated into Mylar fi lms, and into the textile fi ber known as Dacron polyester

Use the roadmap you made for problems 15.19 and 16.72 and update it to contain the reactions in the Key Reactions section of this chapter. Because of their highly specifi c nature, do not use reactions 1, 2, 4, 9, and 10 on your roadmap.

Write the products of the following sequences of reactions. Refer to your roadmaps to see how the combined reactions allow you to navigate between the different functional groups. Note that you will need both your old Chapters 611 roadmap and your new Chapters 1517 roadmap for these. (a) 1. Mg, ether 2. CO2 3. HCl, H2O 4. SOCl2 Br A haloarene (b) 1. NBS 2. Mg, ether 3. CO2 4. HCl, H2O 5. CH2N2 6. m-CPBA An alkene (c) 1. LiAlH4 2. H2O 3. PCC 4. Br2, CH3CO2H O OH A carboxylic acid (d) 1. BH3 2. H2O2 3. H2CrO4 4. Heat 5. Ph3P1 2CH2 O An alkene

Using your roadmaps as a guide, show how to convert propane into propyl propanoate. You must use propane as the source of all carbon atoms in the target molecule. Show all reagents needed and all molecules synthesized along the way. ? Propane Propyl propanoate O O

Using your roadmaps as a guide, show how to convert 4-methyl-1-pentene and carbon dioxide into 5- methylhexanoic acid. You must use 4-methyl-1-pentene and carbon dioxide as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. ? 1 CO2 4-Methyl-1-pentene 5-Methylhexanoic acid O OH

Using your roadmaps as a guide, show how to convert cyclohexane into adipoyl dichloride. Show all reagents and all molecules synthesized along the way. ? Cyclohexane Adipoyl dichloride O O Cl Cl

Using your roadmaps as a guide, show how to convert 5-chloro-2-pentanone and carbon dioxide into racemic tetrahydro-6-methyl-2-pyranone. You must use 5-chloro-2-pentanone and carbon dioxide as the source of all carbon atoms in the racemic target molecule. Show all reagents and all molecules synthesized along the way. Tetrahydro-6-methyl-2-pyranone (racemic) 5-Chloro-2-pentanone O O O Cl ? O O 1 CO2

Diazomethane, CH2N2, is used in the organic chemistry laboratory despite its danger because it produces very high yields and is selective for reaction with carboxylic acids. Write the products of the following reactions. excess CH2N2 CH3OH (a) O O O O H N N OH OH 5498X_17_ch17_p649- 679.indd 678 12/13/10 3:49:01 PM Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Problems 679 CH2N2 CH3OH (b) O OH O HO H H H H OMe excess CH2N2 CH3OH (c) O O O O NH CH3 CH3 CH3 H H H O OH OH

So far, you have seen a number of reducing agents used in reactions. Functional groups react differently with each of these reagents. With this in mind, complete the following reaction, which is the last step in a synthesis of fexofenadine, a nonsedating antihistamine sold under the trade name of Allegra. NaBH4, NaOH, H2O/EtOH Fexofenadine pH 78, 35 hours O O N OH HO