CHEM 122: Introduction to Organic Chemistry Homework 8 (Thursday June 3): Chapter 11: Carboxylic Anhydrides, Esters, and Amides

Subject:ChemistryPrice:19.86 Bought3

Share With

CHEM 122: Introduction to Organic Chemistry Homework 8 (Thursday June 3): Chapter 11: Carboxylic Anhydrides, Esters, and Amides. (9 problems) 1. Draw a structural formula for each compound. a) Dimethyl carbonate b) p-Nitrobenzamide c) Ethyl 3-hydroxybutanoate d) Diethyl oxalate e) Ethyl trans-2-pentenoate f) Butanoic anhydride 2. Write the IUPAC name for each compound. O O O a) b) CH3(CH2)8COCH3 O H2N c) CH3(CH2)4CNHCH3 NH 2 d) O e) O f) CH3CHCH2COCH2CH3 3. What product forms when ethyl benzoate is treated with each of the following sets? a) H2O, NaOH, heat b) H2O, HCl, heat 4. What product forms when benzamide, C6H5CONH2, is treated with each of the following sets? a) H2O, NaOH, heat b) H2O, HCl, heat 5. Phenobarbital is a long-acting sedative, hypnotic, and anticonvulsant. a) Name all functional groups in this compound. b) Draw structural formulas for the products from complete hydrolysis of all amide groups in aqueous NaOH. O H N O O N H Phenobarbital 6. Benzocaine, a topical anesthetic, is prepared by treating 4-aminobenzoic acid with ethanol in the presence of an acid catalyst, followed by neutralization. Draw a structural formula for benzocaine. 7. Chapter 14 discusses a class of compounds called amino acids, so named because they contain both an amino group and a carboxyl group. Following is a structural formula for the amino acid alanine. O CH3CHCONH3+ Alanine What would you expect to be the major form of alanine present in aqueous solution a) at pH 2.0, b) at pH 5-6, and c) at pH 11.0? Explain. 8. Starting with ethylene as the only source of carbon atoms, show how you could synthesize ethyl acetate. 9. Following are structural formulas for two local anesthetics use in dentistry. Lidocaine was introduced in 1948 and is now the most widely used local anesthetic for infiltration and regional anesthesia. Its hydrochloride salt is marketed under the name Xylocaine. Mepivacaine is faster-acting and somewhat longer in duration than licodaine. Its hydrochloride salt is marketed under the name Carbocaine. NH N O NH N O Lidocaine Mepivacaine (Xylocaine) (Carbocaine) a) Name the functional groups in each anesthetic. b) Which of these anesthetics are chiral? c) Which nitrogen atom in each is the more basic? d) What similarities in structure do you find between these compounds? CHEM 122: Introduction to Organic Chemistry 1) Fill in the missing reagents in each of the following reductions. O O O OH O H H OH OH H OH H 2) Fill in the missing intermediates and product in the following synthesis. O H+ Mg CH3Br 3) a)1-phenylethanol can be made by way of two different Grignard reactions. Outline both possibilities. OH b) Take the 1-phenylethanol you made in part a) and divide it in two. Add K2Cr2O7/H2SO4 to one half and PBr3 to the other—what products do you get? OH K2Cr2O7 A PBr3 B H2SO4 c) Take product B from above, add first Mg, then product A from above, and finally acid. Draw the structure of the resulting 3o alcohol. 4) Outline a synthesis of 4-ethyl-2,5,6-trimethyl-2-heptanol from starting materials of 3 carbons or less. Many steps (think 4 successive Grignard reactions!) are required; don’t draw all of the intermediates—about one per Grignard reaction is fine. many steps! OH CHEM 122: Introduction to Organic Chemistry Homework 7 (Thursday May 27): Chapter 9: Aldehydes and Ketones. (7 problems) Chapter 10: Carboxylic Acids. (20 problems) Chapter 9: 1. Draw all enol forms of each aldehyde and ketone. O O a) CH3CH2CH b) CH3CCH2CH3 O CH3 c) 2. Which compounds are hemiacetals, which acetals, and which are neither? OCH3 CHOCH3 a) b) O d) O CH2 CH3 O CH3CH2CHOCH3 e) c) OCH2 CH3 CH3OCH2OCH3 O f) OH 3. Draw the hemiacetal and then acetal formed in each reaction. In each case, assume an excess of the alcohol. a) Propanal + methanol → b) Cyclopentanone + methanol → 4. Draw the structures of the aldehydes or ketones and alcohols formed when these acetals are treated with aqueous acid and hydrolyzed. OCH3 OCH3 O a) OCH3 O b) OCH3 c) OCH3 d) O OCH3 5. 5-Hydroxyhexanal forms a six-membered cyclic hemiacetal, which predominates at equilibrium in aqueous solution. a) Draw a structural formula for this cyclic hemiacetal. b) How many stereoisomers are possible for 5-hydroxyhexanal? c) How many stereoisomers are possible for this cyclic hemiacetal? 6. The following molecule is an enediol; each carbon of the double bond carries an –OH group. Draw structural formulas for the ?-hydroxyketone and the ?-hydroxyaldehyde with which this enediol is in equilibrium. ?-hydroxyaldehyde HC OH C OH ?-hydroxyketone CH 3 An enediol 7. Glucose, C6H12O6, contains an aldehyde group but exists predominantly in the form of the cyclic hemiacetal shown here. We will discuss this cyclic form of glucose in Chapter 12. CH2OH O OH H H OH H HO H H OH ?-D-Glucose A cyclic hemiacetal is formed when the –OH group of one carbon bonds to the carbonyl group of another carbon. Which carbon in glucose provides the –OH group and which provides the CHO group? Chapter 10: 1. Name and draw structural formulas for the four carboxylic acids with the molecular formula C5H10O2. Which of these carboxylic acids are chiral? 2. Write the IUPAC name for each carboxylic acid. COOH OH HOOC a) COOH b) OH 3. Draw a structural formula for each carboxylic acid. a) 2-Aminopropanoic acid b) 3,5-Dinitrobenzoic acid c) Dichloroacetic acid d) o-Aminobenzoic acid 4. 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 c) CCl3COOH 5. Propanedioic (malonic) acid forms an intramolecular hydrogen bond in which the H of one COOH group forms a hydrogen bond with an O of the other COOH group. Draw a structural formula to show this internal hydrogen bonding. (There are two possible answers.) 6. The following compounds have approximately the same molecular weight: propanoic acid, 1-butanol, and diethyl ether. Arrange them in order of increasing boiling point. 7. Arrange these compounds in order of increasing solubility in water: acetic acid, pentanoic acid, decanoic acid. 8. Complete the equations for these acid-base reactions. OH + a) NaOH CH 3 COO-Na + + b) OH HCl COOH + c) H2NCH2CH2OH OCH 3 COOH + NaHCO3 d) 9. Formic acid is one of the components responsible for the stinging of biting ants and is injected under the skin by bee and wasp stings. The pain can be relieved by rubbing the area of the sting with a paste of baking soda (NaHCO3) and water, which neutralizes the acid. Write an equation for this reaction. 10. The normal pH range for blood plasma is 7.35 to 7.45. Under these conditions, would you expect the carboxyl group of lactic acid (pKa 4.07) to exist primarily as a carboxyl group or as a carboxylate anion? Explain. 11. The pKa of ascorbic acid is 4.10. Would you expect ascorbic acid dissolved in blood plasma, pH 7.35-7.45, to exist primarily as ascorbic acid or as ascorbate anion? Explain. 12. Complete the equations for the following acid-base reactions. Assume one mole of HCl per mole of amino acid. CH3CHCOO-Na+ a) + HCl(aq) + HCl(aq) NH2 CH3CHCOO-Na+ NH3+ b) 13. Complete these examples of Fischer esterification. In each case, assume an excess of the alcohol. H+ CH3COOH + HO CH3COOH + HO a) H+ b) COOH + CH3CH2OH H+ COOH c) 14. From what carboxylic acid and alcohol is each ester derived? O O O O O a) b) O O O c) CH3OCCH2CH2COCH3 d) 15. Methyl 2-hydroxybenzoate (methyl salicylate) has the odor of wintergreen. This compound is prepared by Fischer esterification of 2-hydroxybenzoic acid (salicylic acid) with methanol. Draw a structural formula for methyl 2-hydroxybenzoate. 16. Show how you could convert cinnamic acid to each compound. O OH O OH OH trans-3-Phenyl-2-propenoic acid (Cinnamic acid) O OCH 2 CH 3 17. Give the expected organic product formed with phenylacetic acid, C 6H5CH2COOH, is treated with each of the following reagents: a) NaHCO3, H2O b) NaOH, H2O c) NH3, H2O d) LiAlH4 then H2O e) NaBH4 then H2O f) CH3OH + H2SO4 (catalyst) g) H2/Ni 18. Procaine (its hydrochloride salt is marketed as Novocaine) was one of the first local anesthetics developed for infiltration and regional anesthesia. It is synthesized by the following Fischer esterification: O OH + N HO H2N 4-Aminobenzoic acid 2-Diethylaminoethanol a) Draw the structural formula of Procaine. Fischer esterification Procaine b) Which of the two nitrogen atoms in Procaine is the stronger base? c) Draw the structural formula of Novocaine (the hycrochloride salt of Procaine). d) Would you predict Procaine or Novocaine to be more soluble in blood? 19. Methylparaben and propylparaben are used as preservatives in foods, beverages, and cosmetics. Show how each of these preservatives can be prepared from 4-aminobenzoic acid. O OCH 3 H2N Methyl-4-Aminobenzoate (Methylparaben) O OH O H2N O 4-Aminobenzoic acid H2N Propyl-4-Aminobenzoate (Propylparaben) 20. When 5-hydroxypentanoic acid is treated with an acid catalyst, it forms a lactone (a cyclic ester). Draw a structural formula for this lactone.