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Unformatted text preview: CEM 251
Fall 2007 - Prof. Rathke 2nd Sample Problem Set
(Chapters 7-9) Suggested Problems from Textbook:
Chapter 7: Chapter 8: Chapter 9: 1. 3-18, 24-31, 43 1, 3-13, 19, 23-32 1-4, 6, 7, 9, 12, 15, 16, 21, 22-26, 31, 44, 50 Draw the structure of the fastest-formed intermediate and the structure of the major product for the reaction of the olefins: 1-pentene, 2-methyl-1-pentene, 1-methylcyclopentene, 2-methyl-2-pentene with each of the following reagents: a) Br2, H2O b) Br2 c) HBr 2. Draw the structure of the major product. Indicate stereochemistry where important:
a) + Br2 CH3 b) CH3 KMnO4 H2O, O C CH3 d) + OsO4 + H2 Pt c) 1) H2O 2) NaHSO3 e) 1) O3 2) Zn/H3O+ CEM 251 - Dr. Rathke, Fall 2007 2nd Sample Problem Set.... page 2 f) CH2 1) Hg(OAc)2, H2O 2) NaBH4 g) CH2CH3 1) BH3 2) H2O2, NaOH 3. Deduce the structure of X, Y, and Z.
1) O3 2) H3O+, Zn O b) (C4H6) Y O c) (C8H12) Z 1) O3 2) H3O , Zn
+ O O
+ O C H H
+ a) (C9H16) X (CH3)2C O 1) O3 2) H3O+, Zn H O H H O H (2 mols per mol of Z) 4. Draw the structure of the major organic product (indicate stereochemistry where important) for the reaction of the following alkynes: 1-hexyne, 3-hexyne with each of the following reagents: (in one case, there is no reaction). a) b) c) d) e) f) g) h) i) j) HCl (one equivalent) HCl (two equivalents) Br2 (one equivalent) Br2 (two equivalents) H2 (excess), Pd H2, Pd, BaSO4, quinoline 1. Li/NH3 2. H2O NaNH2 1) BH3 2) NaOH,H2O2 H2O, HgSO4, H2SO4, D CEM 251 - Dr. Rathke, Fall 2007 2nd Sample Problem Set.... page 3 5. Outline the steps in an efficient synthesis of the following compounds starting with acetylene:
a) CH3CH CHCH2C C H c) trans-2-hexene b) cis-2-hexene 6. Draw the structure of the polymer formed from the following olefin monomers:
a) b) C H2 C H2 CHCl CH O O C C H3 7. For each of the structures below, answer the following questions: a) Is the molecule chiral or achiral? b) Does the molecule possess a plane of symmetry? (This should be understood to include any available conformation of the molecule.) c) Would a sample of the compound be optically active or inactive?
CH3 CH3 CH3 CH3 CH3 a
CH3 H b
H CH3 c CH3 d CH2 CH3 e CH2 CH3 Cl H CH3 CH3 H H Br H Br H CH3 CH2 CH3 H Cl f
H Br Br H H g
Br CH3 h
OH H Br H OH i
OH H H j k
H H Cl Cl l H m
CH3 H CH3 CH3 H OH H CH3 n o p OH CEM 251 - Dr. Rathke, Fall 2007 2nd Sample Problem Set.... page 4 8. Name the configuration by the sequence rule at each chiral center in the following molecules:
CH3 H H H H CH3 Br CH3 CH3 OH Br H b a H CO2H H OH OH Br CH3 CH3 c d 9. Indicate the isomeric relationship (diastereomers, enantiomers or identical) between the following pairs:
a) H and H H b) H H Br and H Br H H H CH3 CH2 CH3 and CH3 c) H H Br d)
and H Br H CH2 CH3 H H CEM 251 - Dr. Rathke, Fall 2007 2nd Sample Problem Set.... page 5
Br CH3 and Br CH3 Br Br e) f) CH3 and Br CH3 g) CH3 and Br CH3 10. How many configurational isomers exist for molecules with the following constitution: a) b) c) d) e) f) 1-chloropentane 2-chloropentane 3-chloropentane 1-hexene 2-hexene 3-hexene g) h) i) j) k) 1-ethyl-2-methylcyclopentane 1,2-diethylcyclopentane 2,3-dimethylpentane 2,3-dibromobutane 2-bromo-3-chlorobutane 11. Draw a wedge-dotted line structure for the meso form of: a) 1,3-dibromocyclopentane b) 2,3-dibromobutane 12.
H Br H Br Br H Br H Br H H Br Br H H Br a) b) c) d) a) b) c) Which two structures of the above are identical? Which two are optically active? Which two if mixed in equal amounts would constitute a racemic mixture? CEM 251 - Dr. Rathke, Fall 2007 2nd Sample Problem Set.... page 6 13. Answer Question 9 for the following four structures:
OH OH OH OH OH OH OH OH a) b) c) d) 14.
H Br H Br Br H Br H OH H H OH OH H H OH a) b) c) d) a) b) c) d) If a) has a rotation of +30, what compound of the above must have a rotation of 30 under the same conditions? If achiral reagents are used to synthesize b), what other compound must be formed in equal amounts? If achiral reagents are used to synthesize c), what other compound must be formed in equal amounts? If c) has a boiling point of 180C and d) has a boiling point of 179C, what are the boiling points of a) and b)? 15. Answer question 13 for the following structures:
Br Br Br Br OH OH OH OH a) b) c) d) ...
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- Fall '07