Chapter 4 Alkanes - Review Questions

1/22 Chapter 4: Alkanes - Review Questions Connect Homework Assignment 1. Click the "draw structure" button to activate the drawing utility. Draw the missing constitutional isomer of C6H14. CH3 CH3CH2CH2CH2CH2CH3 | CH3CH2CH2 ― C ―CH3 | H CH3 CH3 | CH3CH2 ― C ― CH2CH3 | H | CH3CH2 ― C ― CH3 | CH3 2. Click the "draw structure" button to activate the drawing utility. Draw the structure corresponding to the IUPAC name. 4−isopropyl−2,4,5−trimethylundecane 2/22 3. Be sure to answer all parts. Give the IUPAC name for the following compound. 5-sec butyl-3-ethyl-2,7-dimethyl decane 4. The following IUPAC name is incorrect. Explain why it is incorrect and give the correct IUPAC name. 2,2−dimethyl−4−ethylheptane A. The compound name is spelled incorrectly. B. The compound has an incorrectly labeled parent chain. C. The compound name is alphabetized incorrectly. D. The compound has incorrectly labeled substituents. Which of the following is the correct IUPAC name? A. 4−ethyl−2,2−dimethylheptane 3/22 B. 2,2−dimethyl−4−propylhexane C. 4−ethyl−6,6−dimethylheptane D. 3−propyl−5,5−dimethylhexane 5. Be sure to answer all parts. Give the IUPAC name for the following compound. 3-cyclobutylpentane 6. Be sure to answer all parts. Give the IUPAC name for the following compound. CH3CH2CH(CH3)CH(CH3)CH(CH2CH2CH3)(CH2)3CH3 3,4-dimethyl-5-propylnonane 7. Be sure to answer all parts. For each compound, which isomer, cis or trans, is more stable and why? 4/22 A. The cis isomer is more stable than the trans since one conformation has both groups equatorial. B. The trans isomer is more stable than the cis since one conformation has both groups equatorial. C. The trans isomer is more stable than the cis since one conformation has both groups equatorial. 8. Select the single best answer. Give the IUPAC name for the compound. A. 5-methyl-4-propylhexane B. 4-isopropylheptane C. 4-propylheptane D. 2-methyl-3-propylhexane 9. Select the single best answer. Choose the chair conformation of cyclohexane with one CH3CH2 group and one CH3 group that fits the description: A −1,2−disubstituted cyclohexane with an axial CH3 group 5/22 10. Select the single best answer. Give the IUPAC name for the compound. A. 3-ethyl-3-propyl-4-methylheptane B. 4,4-diethyl-5-methyloctane C. 5-ethyl-5-propyl-4-methylheptane D. 5,5-diethyl-4-methyloctane 11. Be sure to answer all parts. Part 1 One structure below represents menthol and one represents isomenthol. Menthol, 6/22 the more stable isomer, is used in lip balms and mouthwash. Below structures [1] and [2] are a selection of 4 chair conformations. Identify the one structure, from each group, that represents the most stable chair conformation of [1] and [2]. [1] [2] [1] [2] 7/22 Part 2 Which structure corresponds to menthol? A. [1] B. [2] 12. Select all that apply. Considering the following compounds, which two structures represent the same compound? A. CH3CH2CH(CH3)CH2CH2CH3 B. C. CH3(CH2)3CH(CH3)2 CH3CH2CH(CH3)CH2CH2CH3 CH3(CH2)3CH(CH3)2 8/22 13. Click the "draw structure" button to activate the drawing utility. Enter the structure corresponding to the IUPAC name. 3,5,5−trimethyloctane or 14. Be sure to answer all parts. The following IUPAC name is incorrect. Explain why it is incorrect and give the correct IUPAC name. 2−methyl−2−isopropylheptane A. The compound name contains incorrectly alphabetized substituents. B. The compound has incorrectly labeled substituents. C. The longest chain was not chosen. D. The compound name is spelled incorrectly. Which of the following is the correct IUPAC name? A. 2,3,3−trimethyloctane B. 1,1,2,2−tetramethylheptane C. 2,3,3−methyloctane 9/22 D. 2−isopropyl−2−methylheptane 15. Click the "draw structure" button to activate the drawing utility. Enter the structure corresponding to the IUPAC name. 3−methylhexane or 16. Be sure to answer all parts. Give the IUPAC name for the following compound. 4-isopropyloctane 17. Click the "draw structure" button to launch the drawing utility. Draw the structure for the following compound using wedges and dashes. −1−ethyl−2−methylcyclopentane 10/22 or 18. Ethylene glycol (CH2OHCH2OH) is unusual in that the gauche conformation is more stable than the anti conformation. Offer an explanation. Be sure to answer all parts. The gauche conformation can intramolecularly hydrogen bond, making it the more stable conformation. 19. Select the single best answer. Choose the chair conformation of cyclohexane with one CH3CH2 group and one CH3 group that fits the description: A −1,2−disubstituted cyclohexane with an axial CH3 group 11/22 20. Be sure to answer all parts. Give the IUPAC name for the following compound. (CH3)3CCH2CH(CH2CH3)2 4-ethyl-2,2-dimethylhexane 21. For each compound drawn below, label each OH, Br, and CH3 group as axial or equatorial. Be sure to answer all parts. The axial groups in [1] are: a. OH b. H c. OH d. H The equatorial groups in [1] are: a. OH b. H c. OH d. H The axial groups in [2] are: e. Br f. H g. CH3 h. H 12/22 The equatorial groups in [2] are: e. Br f. H g. CH3 h. H The axial groups in [3] are: i. OH j. H k. OH l. H The equatorial groups in [3] are: i. OH j. H k. OH l. H 22. Classify the ring carbons as C's or C's. Identify the bonds highlighted in bold as axial or equatorial. Be sure to answer all parts. The ring carbons are identified as follows: a: b: c: The bonds are identified as follows: d: e: axial f: equatorial d: axial e: axial f: axial 13/22 equatorial equatorial equatorial 23. Be sure to answer all parts. Considering rotation around the indicated bond in the following compound, label the following Newman projections for the most stable and least stable conformations. Enter each substituent in the corresponding labeled box that matches the correct position in the Newman projection. Most Stable a = CH2CH3 b=H c=H d=H e=H f = CH2CH3 14/22 Least Stable a = CH2CH3 b=H c=H d = CH2CH3 e=H f=H 24. Be sure to answer all parts. Give the IUPAC name for the following compound. CH3(CH2)3CH(CH2CH2CH3)CH(CH3)2 4-isopropyloctane 25. Click the "draw structure" button to activate the drawing utility. Enter the structure corresponding to the IUPAC name. 3−ethyl−5−isobutylnonane or 15/22 26. Be sure to answer all parts. Give the IUPAC name for the following compound. 4-tert-butyl-4-methyloctane 27. Be sure to answer all parts. Give the IUPAC name for the following compound. 6-isopropyl-3-methylnonane 28. Be sure to answer all parts. Show the conformation of the following wedge-dash structure as a Newman projection. Assume that the front carbon of the Newman projection is the carbon on the left side of the molecule. Br Cl 16/22 C C Cl Br H eclipsed H staggered a = Br b=H c = Cl d = Cl e = Br f=H 29. Be sure to answer all parts. Show the conformation of the following wedge-dash structure as a Newman projection. Assume that the front carbon of the Newman projection is the carbon on the left side of the molecule. Cl H C C Br H Br Cl 17/22 eclipsed staggered a = Cl b = Br c=H d=H e = Cl f = Br 30. Be sure to answer all parts. For each compound shown below, draw representations for the cis and trans isomers using a hexagon for the six-membered ring, and wedges and dashes for substituents. [1] cis: trans: 18/22 [2] cis: [3] cis: trans: trans: 31. Click the "draw structure" button to activate the drawing utility. Draw the missing constitutional isomer that has molecular formula C5H10 and contains one ring. 19/22 or 32. Be sure to answer all parts. Give the IUPAC name for the following compound. 8-ethyl-4-isopropyl-2,6-dimethyldecane 33. Be sure to answer all parts. Give the IUPAC name for the following compound: 1-sec-butyl-2-isopropylcyclohexane 20/22 34. Be sure to answer all parts. Show the conformation of the following wedge-dash structure as a Newman projection. Assume that the front carbon of the Newman projection is the carbon on the left side of the molecule. H Br C C Cl Br H Cl eclipsed staggered a=H b = Cl c = Br d = Br e=H f = Cl 35. Be sure to answer all parts. Give the IUPAC name for the following compound: 21/22 3-butyl-1,1-dimethylcyclohexane 36. Select the single best answer. Decide which conformation is present in higher concentration at equilibrium. 37. Be sure to answer all parts. Give the IUPAC name for the following compound. 3-ethyl-2,5-dimethylheptane 22/22 38. Be sure to answer all parts. Give the IUPAC name for the following compound: 1,2,3-trimethylcyclopentane 39. Be sure to answer all parts. Give the IUPAC name for the following compound. 4-tertbutyl-4-methyloctane 40. Click the "draw structure" button to activate the drawing utility. Draw the structure corresponding to the IUPAC name. −1−ethyl−3−methylcyclopentane