The specific rotation of (R)-(+)-glyceraldehyde is +8.7.

Disregarding stereoisomers, draw the structures of all compounds with molecular formula C 5 H 10 . Which ones can exist as stereoisomers?

Draw all possible stereoisomers for each of the following. Indicate if no stereoisomers are possible. a. 1-bromo-2-chlorocyclohexane b. 2-bromo-4-methylpentane c. 1,2-dichlorocyclohexane d. 2-bromo-4- chloropentane e. 1-bromo-4-chlorocyclohexane f. 1,2-dimethylcyclopropane g. 4-bromo-2-pentene h. 3,3-dimethylpentane i. 1-bromo-2-chlorocyclobutane j. 1-bromo-3-chlorocyclobutane

Which of the following has an asymmetric center? CHBr2Cl BHFCl CH3CHCl2 CHFBrCl BeHCl

Name the following compounds using R,S designations: a. CH2CH3 HO H H Cl CH3 b. CH2CH2CH2OH HO CH3 CH2OH c. CH3CH2 Br H CH

Mevacor is used clinically to lower serum cholesterol levels. How many asymmetric centers does Mevacor have?

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Which of the following are optically active?

For many centuries, the Chinese have used extracts from a group of herbs known as ephedra to treat asthma. A compound named ephedrine has been isolated from these herbs and found to be a potent dilator of air passages in the lungs. a. How many stereoisomers does ephedrine have? b. The stereoisomer shown here is the one that is pharmacologically active. What is the coni guration of each of the asymmetric centers?

Name each of the following

Which of the following has an achiral stereoisomer? a. 2,3-dichlorobutane b. 2,3-dichloropentane c. 2,3-dichloro-2,3-dimethylbutane d. 1,3-dichlorocyclopentane e. 1,3-dibromocyclobutane f. 2,4- dibromopentane g. 2,3-dibromopentane h. 1,4-dimethylcyclohexane i. 1,2-dimethylcyclopentane j. 1,2-dimethylcyclobutane

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Citrate synthase, one of the enzymes in the series of enzyme-catalyzed reactions known as the citric acid cycle ( Section 25.10 ) , catalyzes the synthesis of citric acid from oxaloacetic acid and acetyl- CoA. If the synthesis is carried out with acetyl-CoA that contains radioactive carbon ( 14 C) in the indicated position ( Section 1.1 ) , the isomer shown here is obtained. (If two isotopesatoms with the same atomic number, but different mass numbersare being compared, the one with the greater mass number has the higher priority.) CH2COOH CH2COOH 14 COOH CH3CSCoA C 14 HO O HOOCCH2CCOOH O + citric acid oxaloacetic acid citrate synthase acetyl-CoA a. Which stereoisomer of citric acid is synthesized, R or S ? b. Why is the other stereoisomer not obtained? c. If the acetyl-CoA used in the synthesis contains 12 C instead of 14 C, will the product of the reaction be chiral or achiral?

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

The specii c rotation of ( R )-( + )-glyceraldehyde is +8.7 . If the observed specii c rotation of a mixture of ( R )-glyceraldehyde and ( S )-glyceraldehyde is +1.4 , what percent of glyceraldehyde is present as the R enantiomer?

Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane.

A solution of an unknown compound (3.0 g of the compound in 20 mL of solution), when placed in a polarimeter tube 2.0 dm long, was found to rotate the plane of polarized light 1.8 in a counterclockwise direction. What is the specii c rotation of the compound?

Butaclamol is a potent antipsychotic that has been used clinically in the treatment of schizophrenia. How many asymmetric centers does it have?

Explain how R and S are related to ( + ) and ( - ).

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

a. Draw all possible stereoisomers of the following compound: OH HOCH2CH CHCH CH 2OH OH OH b. Which stereoisomers are optically inactive?

What is the coni guration of the asymmetric centers in the following structures?

a. Draw all the isomers with molecular formula C 6 H 12 that contain a cyclobutane ring. ( Hint: There are seven.) b. Name the compounds without specifying the coni guration of any asymmetric centers. c. Identify: 1. constitutional isomers 2. stereoisomers 3. cistrans isomers 4. chiral compounds 5. achiral compounds 6. meso compounds 7. enantiomers 8. diastereomers

A compound has a specii c rotation of -39.0 . A solution of the compound (0.187 g/mL) has an observed rotation of -6.52 when placed in a polarimeter tube 10 cm long. What is the percent of each enantiomer in the solution?

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Draw structures for each of the following: a. (S)-1-bromo-1-chlorobutane b. (2R, 3R)-2,3- dichloropentane c. an achiral isomer of 1,2-dimethylcyclohexane d. a chiral isomer of 1,2- dibromocyclobutane e. two achiral isomers of 3,4,5-trimethylheptane

Explain why the enantiomers of 1,2-dimethylaziridine can be separated, even though one of the groups attached to nitrogen is a lone pair.

A sample of (S)-(+)-lactic acid was found to have an enantiomeric excess of 72%. How much R isomer is present in the sample?

Indicate whether each of the structures in the second row is an enantiomer of, a diastereomer of, or is identical to the structure in the top row.

a. Using the wedge-and-dash notation, draw the nine stereoisomers of 1,2,3,4,5,6- hexachlorocyclohexane. b. From the nine stereoisomers, identify one pair of enantiomers. c. Draw the most stable conformation of the most stable stereoisomer.

Tamiflu is used for the prevention and treatment of flu. What is the configuration of each of its asymmetric centers? (How Tamiflu Works is explained on page 1124.)

A student decided that the coni guration of the asymmetric centers in a sugar such as d -glucose could be determined rapidly by simply assigning the R coni guration to an asymmetric center with an OH group on the right and the S coni guration to an asymmetric center with an OH group on the left. Is he correct ? (We will see in Chapter 21 that the d in d-glucose means the OH group on the bottommost asymmetric center is on the right.)

What the coni guration of each of the asymmetric centers in the following compounds?

a. Draw the two chair conformers for each of the stereoisomers of trans -1- tert -butyl-3 -methylcyclohexane. b. For each pair, indicate which conformer is more stable.

a. Do the following compounds have any asymmetric centers? 1. CH2CCH2 2. CH3CHCCHCH3 b. Are the compounds chiral? ( Hint: Make models.)

Is the following compound optically active?

a. How many asymmetric centers does the following compound have? b. How many stereocenters does it have?

Draw enantiomers for each of the following using a. perspective formulas. b. Fischer projections.

Assign relative priorities to the groups or atoms in each of the following sets: \(-\mathrm{CH}_{2} \mathrm{OH} \quad-\mathrm{CH}_{3} \quad-\mathrm{H} \quad-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) \(-\mathrm{CH}_{2} \mathrm{Br} \quad-\mathrm{OH} \quad-\mathrm{CH}_{3}-\mathrm{CH}_{2} \mathrm{OH}\) \(-\mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br} \quad-\mathrm{CI} \quad-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}\) \(-\mathrm{CH}=\mathrm{CH}_{2} \quad-\mathrm{CH}_{2} \mathrm{CH}_{3} \quad-\mathrm{CH}_{3}\) Equation Transcription: Text Transcription: -CH_2 OH -CH_3 -H -CH_2 CH_2 OH -CH_2 Br -OH -CH_3 -CH_2 OH -CH(CH_3 )_2 -CH_2 CH_2 Br -CI -CH_2 CH_2 CH_2 Br -CH=CH_2 -CH_2 CH_3 -CH_3

Naproxen, a nonsteroidal anti-inflammatory drug that is the active ingredient in Aleve (page 118), has a specific rotation of +66 . One commercial preparation results in a mixture with a 97% enantiomeric excess. a. Does naproxen have the \(R\) or the \(S\) configuration? b. What percent of each enantiomer is obtained from the commercial preparation?

The following compound has only one asymmetric center. Why then does it have four stereoisomers?

Problem 27P Are the following statements correct? a. A compound can have a maximum of 2n stereoisomers, where n equals the number of stereocenters. b. A compound can have a maximum of 2n stereoisomers, where n equals the number of asymmetric centers.

Problem 37P Which of the following compounds has a stereoisomer that is a meso compound? A 2,4-dibromohexane D 1,3-dichlorocyclohexane B 2,4-dibromopentane E 1,4-dichlorocyclohexane C 2,4-dimethylpentane F 1,2-dichlorocyclobutane

Problem 38P Draw all the stereoisomers for each of the following: a. 1-bromo-2-methylbutane h. 2,4-dichloropentane b. 1-chloro-3-methylpentane i. 2,4-dichloroheptane c. 2-methyl-1-propanol j. 1,2-dichlorocyclobutane d. 2-bromo-1-butanol k. 1,3-dichlorocyclohexane e. 3-chloro-3-methylpentane l. 1,4-dichlorocyclohexane f. 3-bromo-2-butanol m. 1-bromo-2-chlorocyclobutane g. 3,4-dichlorohexane n. 1-bromo-3-chlorocyclobutane

Problem 39P Draw all the stereoisomers for each of the following: a. 1-bromo-2-methylbutane h. 2,4-dichloropentane b. 1-chloro-3-methylpentane i. 2,4-dichloroheptane c. 2-methyl-1-propanol j. 1,2-dichlorocyclobutane d. 2-bromo-1-butanol k. 1,3-dichlorocyclohexane e. 3-chloro-3-methylpentane l. 1,4-dichlorocyclohexane f. 3-bromo-2-butanol m. 1-bromo-2-chlorocyclobutane g. 3,4-dichlorohexane n. 1-bromo-3-chlorocyclobutane

The reaction of \((R)-1-i o d o-2\)-methylbutane with hydroxide ion forms an alcohol without breaking any bonds to the asymmetric center. The alcohol rotates the plane of polarization of plane polarized light counterclockwise. What is the configuration of \((+)-2\)-methyl-1-butanol? Equation Transcription: Text Transcription: (R) - 1 - iodo - 2 (+) - 2

Limonene exists as two different stereoisomers. The \(R\) enantiomer is found in oranges and the \(S\) enantiomer is found in lemons. Which of the following molecules is found in oranges? Equation Transcription: Text Transcription: R S

Explain why compound \(A\) has two stereoisomers, but compounds \(B\) and \(C\) exist as single compounds. Equation Transcription: Text Transcription: A B C

Problem 62P Which of the following has an achiral stereoisomer? a. 2,3-dichlorobutane b. 2,3-dichloropentane c. 2,3-dichloro-2,3-dimethylbutane d. 1,3-dichlorocyclopentane e. 1,3-dibromocyclobutane f. 2,4-dibromopentane g. 2,3-dibromopentane h. 1,4-dimethylcyclohexane i. 1,2-dimethylcyclopentane j. 1,2-dimethylcyclobutane

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Citrate synthase, one of the enzymes in the series of enzyme-catalyzed reactions known as the citric acid cycle ( Section \(25.10\) ) , catalyzes the synthesis of citric acid from oxaloacetic acid and acetyl-CoA. If the synthesis is carried out with acetyl-CoA that contains radioactive carbon (\({ }^{14} \mathrm{C}\)) in the indicated position ( Section \(1.1\) ) , the isomer shown here is obtained. (If two isotopes—atoms with the same atomic number, but different mass numbers—are being compared, the one with the greater mass number has the higher priority.) a. Which stereoisomer of citric acid is synthesized, \(R\) or \(S\) ? b. Why is the other stereoisomer not obtained? c. If the acetyl-CoA used in the synthesis contains \({ }^{12} \mathrm{C}\) instead of \({ }^{14} \mathrm{C}\), will the product of the reaction be chiral or achiral? Equation Transcription: Text Transcription: 25.10 ^14 C 1.1 R S ^12 C

Problem 74P a. Draw all the isomers with molecular formula C 6H 12 that contain a cyclobutane ring. (Hint: There are seven.) b. Name the compounds without specifying the configuration of any asymmetric centers. c. Identify: 1. constitutional isomers 2. stereoisomers 3. cis–trans isomers 4. chiral compounds 5. achiral compounds 6. meso compounds 7. enantiomers 8. diastereomers

Problem 75P A compound has a specific rotation of -39.0. A solution of the compound (0.187 g/100 mL) has an observed rotation of -6.52o when placed in a polarimeter tube 10 cm long. What is the percent of each enantiomer in the solution?

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Problem 86P a. Do the following compounds have any asymmetric centers? 1. CH2=C=CH2 2. CH3CH=C=CHCH3 b. Are the compounds chiral? (Hint: Make models.)

Problem 1P a. Draw three constitutional isomers with molecular formula C3H8O. ________________ b. How many constitutional isomers can you draw for C4H10O?

Problem 2P Draw the cis and trans isomers for the following: a. 1-bromo-4-chlorocyclohexane b. 1-ethyl-3-methylcyclobutane

a. Which of the following compounds can exist as \(\text { cis }\)–trans isomers? b. For those compounds that can exist as cis and trans isomers, draw and label the isomers. Equation Transcription: Text Transcription: cis

Do the following compounds have the \(R\) or the \(S\) configuration? Equation Transcription: Text Transcription: R S

What is the configuration of each of the following compounds?

Do the following structures represent identical compounds or a pair of enantiomers?

Problem 28P a. Stereoisomers with two asymmetric centers are called____________ if the configuration of both asymmetric centers in one stereoisomer is the opposite of the configuration of the asymmetric centers in the other stereoisomer. ________________ b. Stereoisomers with two asymmetric centers are called___________ if the configuration of both asymmetric centers in one stereoisomer is the same as the configuration of the asymmetric centers in the other stereoisomer. ________________ c. Stereoisomers with two asymmetric centers are called___________ if one of the asymmetric centers has the same configuration in both stereoisomers and the other asymmetric center has the opposite configuration in the two stereoisomers.

The stereoisomer of cholesterol found in nature is shown here. a. How many asymmetric centers does cholesterol have? b. What is the maximum number of stereoisomers that cholesterol can have?

Draw the stereoisomers of the following amino acids. Indicate pairs of enantiomers and pairs of diastereomers.

Problem 40P Draw the four stereoisomers of 1,3-dichloro-2-pentanol using a. Fischer projections. b. Perspective formulas.

Name the isomers you drew in Problem 40.

Chloramphenicol is a broad-spectrum antibiotic that is particularly useful against typhoid fever. What is the configuration of each of its asymmetric centers?

Problem 53P Disregarding stereoisomers, give the structures of all compounds with molecular formula C5H10. Which ones can exist as stereoisomers?

Problem 54P Draw all possible stereoisomers for each of the following. Indicate if no stereoisomers are possible a. 1-bromo-2-chlorocyclohexane b. 2-bromo-4-methylpentane c. 1,2-dichlorocyclohexane d. 2-bromo-4-chloropentane e. 1-bromo-4-chlorocyclohexane f. 1,2-dimethylcyclopropane g. 4-bromo-2-pentene h. 3,3-dimethylpentane i. 1-bromo-2-chlorocyclobutane j. 1-bromo-3-chlorocyclobutane

Problem 55P Which of the following has an asymmetric center? CHBr2Cl BHFCl CH3CHCl2 CHFBrCl BeHCl

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Problem 66P The specific rotation of (R)-(+)-glyceraldehyde is +8.7. If the observed specific rotation of a mixture of (R)-glyceraldehyde and (S)-glyceraldehyde is +1.4, what percent of glyceraldehyde is present as the R enantiomer?

Indicate whether each of the following structures is ( \(R\) )-2-chlorobutane or ( \(S\) )-2-chlorobutane. Equation Transcription: Text Transcription: R S

Problem 77P Draw structures for each of the following: a. (S)-1-bromo-1-chlorobutane b. (2R,3R)-2,3-dichloropentane c. an achiral isomer of 1,2-dimethylcyclohexane d. a chiral isomer of 1,2-dibromocyclobutane e. two achiral isomers of 3,4,5-trimethylheptane

Explain why the enantiomers of \(1,2\)-dimethylaziridine can be separated, even though one of the “groups” attached to nitrogen is a lone pair. Equation Transcription: Text Transcription: 1, 2

Problem 79P A sample of (S)-(+)-lactic acid was found to have an enantiomeric excess of 72%. How much R isomer is present in the sample?

Problem 5P Draw three compounds with molecular formula C5H10 that have carbon–carbon double bonds but do not have cis–trans isomers.

Draw skeletal structures for all the compounds in Problem 3, including any cis–trans isomers.

Which of the following compounds have a dipole moment of zero?

Problem 18P a. Draw a perspective formula for each of the following: (S)-2-chlorobutane ________________ b. (R)-1,2-dibromobutane

Convert each Fischer projection to a perspective formula.

Problem 20P a. Is (R)-lactic acid dextrorotatory or levorotatory? ________________ b. Is (R)-sodium lactate dextrorotatory or levorotatory?

Which of the following compounds has one or more asymmetric centers?

Problem 32P Draw all possible stereoisomers for each of the following: a. 2-chloro-3-hexanol c. 2,3-dichloropentane b. 2-bromo-4-chlorohexane d. 1,3-dibromopentane

Problem 33P Draw the stereoisomers of 2-methylcyclohexanol.

Problem 43P Draw a perspective formula for each of the following: a. (S)-3-chloro-1-pentanol c. (2S,3R)-3-methyl-2-pentanol b. (2R,3R)-2,3-dibromopentane d. (R)-1,2-dibromobutane

Name each of the following:

Threonine, an amino acid, has four stereoisomers. The stereoisomer found in nature is \((2, S, 3 R)\)- threonine. Which of the following structures represents the naturally occurring amino acid? Equation Transcription: Text Transcription: (2, S, 3 R)

Name the following compounds using \(R, S\) designations: Equation Transcription: Text Transcription: R, S

Mevacor is used clinically to lower serum cholesterol levels. How many asymmetric centers does Mevacor have?

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Problem 68P A solution of an unknown compound (3.0 g of the compound in 20 mL of solution), when placed in a polarimeter tube 2.0 dm long, was found to rotate the plane of polarization of polarized light 1.8° in a counterclockwise direction. What is the specific rotation of the compound?

Butaclamol is a potent antipsychotic that has been used clinically in the treatment of schizophrenia. How many asymmetric centers does it have?

Problem 70P Explain how R and S are related to (+) and (—).

Indicate whether each of the structures in the second row is an enantiomer of, a diastereomer of, or is identical to the structure in the top row.

a. Using the wedge-and-dash notation, draw the nine stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane. b. From the nine stereoisomers, identify one pair of enantiomers. c. Draw the most stable conformer of the most stable stereoisomer.

Tamil u is used for the prevention and treatment of l u. What is the configuration of each of its asymmetric centers? (How Tamil u Works is explained on page \(1124\).) Equation Transcription: Text Transcription: 1124

Problem 7P Which of the following objects are chiral? a. a mug with DAD written to one side of the handle b. a mug with MOM written to one side of the handle c. a mug with DAD written opposite the handle d. a mug with MOM written opposite the handle e. a wheelbarrow f. a remote control device g. a nail h. a screw

Which of the following compounds has an asymmetric center? d. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) Equation Transcription: Text Transcription; CH_3 CH_2 OH

Which of the compounds in Problem \(8\) can exist as enantiomers? d. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) Equation Transcription: Text Transcription: 8 CH_3 CH_2 OH

Problem 21P The observed rotation of 2.0 g of a compound in 50 mL of solution in a polarimeter tube 20-cm long is +13.4°. What is the specific rotation of the compound?

\((S)-(+)-\) Monosodium glutamate (\(M S G\)) is a flavor enhancer used in many foods. Some people have an allergic reaction to \(M S G\) (including headache, chest pain, and an overall feeling of weakness). “Fast food” often contains substantial amounts of \(M S G\), which is widely used in Chinese food as well. \((S)-(+)-\)\(M S G\) has a specific rotation of \(+24\). Equation Transcription: Text Transcription: (S)-(+)- MSG +24

Problem 23P (+)-Mandelic acid has a specific rotation of +158. What would be the observed specific rotation of each of the following mixtures? a. 50% (-)-mandelic acid and 50% (+)-mandelic acid b. 25% (-)-mandelic acid and 75% (+)-mandelic acid c. 75% (-)-mandelic acid and 25% (+)-mandelic acid

Problem 34P Of all the possible cyclooctanes that have one chloro substituent and one methyl substituent, which ones do not have any asymmetric centers?

Draw a diastereomer for each of the following compounds:

Problem 36P Draw the structures and give the common and systematic names for alkynes with molecular formula C7H12.

Convert each Fischer projection to a perspective formula.

Convert each perspective formula to a skeletal structure.

The following compound has two asymmetric centers and four stereoisomers. Two of these are d-erythrose and d-threose, which are naturally occurring sugars. The configuration of d-erythrose is \((2 R, 3 R)\), and the configuration of d-threose is \((2 R, 3 R)\). Equation Transcription: Text Transcription: (2 R, 3 R)

Which of the following are optically active?

For many centuries, the Chinese have used extracts from a group of herbs known as ephedra to treat asthma. A compound named ephedrine has been isolated from these herbs and found to be a potent dilator of air passages in the lungs. a. How many stereoisomers does ephedrine have? b. The stereoisomer shown here is the one that is pharmacologically active. What is the configuration of each of the asymmetric centers?

Name each of the following:

Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

a. Draw all possible stereoisomers of the following compound: b. Which stereoisomers are optically inactive?

What is the configuration of the asymmetric centers in the following structures?

A student decided that the configuration of the asymmetric centers in a sugar such as D-glucose could be determined rapidly by simply assigning the \(R\) configuration to an asymmetric center with an \(O H\) group on the right and the \(S\) configuration to an asymmetric center with an \(O H\) group on the left. Is he correct ? (We will see in Chapter \(21\) that the “\(D\)” in D-glucose means the \(O H\) group on the bottommost asymmetric center is on the right.) Equation Transcription: Text Transcription: R OH S 21 D

What is the configuration of each of the asymmetric centers in the following compounds?

Problem 85P a. Draw the two chair conformers for each of the stereoisomers of trans-1-tert-butyl-3 methylcyclohexane. b. For each pair, indicate which conformer is more stable.