Chem 2320 Final 210 points Dr. Luther Giddings

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1 Chem 2320 Final 210 points Dr. Luther Giddings Name Phone or Instructions: This is a closed book, closed notebook test. You may not discuss this exam with anyone, either during or after the exam, until it has been graded and returned to you in class. You may not use any outside materials - including Periodic Tables - on this exam, except two 3" x 5" index cards and an English-foreign language dictionary if necessary. A calculator will not be necessary on this exam and may not be used. Each question is worth 6 points. All questions are of equal value. Select the best single answer of those available.

2 1. Which compound undergoes 1,4-addition with Br 2? 1) 3) 2) 4) 2. Rank the following carbocations in decreasing order of stability. ( ) 2 C=CHCH 2 CH=CHCH 2 H 2 C=CHCH 2 A B C 1) A>B>C 2) C>B>A 3) B>A>C 4) they are of equal stability 3. Identify the diene and dienophile which would give the following product. H N 2 1) + H 2 C=CHN 2 3) + H 2 C=CHN 2 2) + CH=CHN 2 4) + H 2 C=CH 2 N2 4. Which of the following is not true concerning the structure of benzene? 1) All C-C-C bond angles are exactly ) The carbon-carbon bonds rapidly alternate between single and double bonds. 3) The six hydrogens are equivalent. 4) The bonds are completely conjugated. Page 1

3 5. The benzyl carbocation is shown below. Besides the benzylic carbon, identify any other carbon atoms which carry a partial positive charge based on resonance theory. CH 2 1) ortho and para carbon atoms 2) meta carbon atoms 3) meta and para carbon atoms 4) ortho, meta, and para carbon atoms 6. Cyclopentadiene is unusually acidic for a hydrocarbon. Why? 1) Cyclopentadiene is aromatic. 2) The conjugate base of cyclopentadiene is aromatic. 3) Cyclopentadiene is an unstable diradical. 4) The conjugate base of cyclopentadiene is an unstable diradical. 7. Which species below best depicts the electrophile in the FeBr 3 -catalyzed bromination of benzene? 1) Br 2 2) FeBr 4 - δ δ 3) Br Br FeBr 3 4) FeBr 3 8. Which of the following is the best method to make n-butylbenzene? 1) benzene + CH 2 CH 2 CH 2 Cl/AlCl 3 2) benzene + CH 2 CH=CH 2 /H 2 S 4 3) (1) benzene + CH 2 CH 2 CCl/AlCl 3 (2) H 2 NNH 2 /KH, heat 4) (1) benzene + CH 2 CH 2 CH 2 H/H 2 S 4 9. Nitration of chlorobenzene has a reaction rate which is than the nitration rate of benzene and gives primarily the product(s). 1) faster, ortho/para products 2) faster, meta 3) slower, ortho/para 4) slower, meta Page 2

4 10. A compound is either cyclononane or cyclodecane. Which of the following is the most useful technique in identifying the compound? 1) IR spectroscopy 2) mass spectrometry 3) proton NMR 4) C-13 NMR 11. How many different sets of equivalent protons are there in the following compound? Cl CCH 2 C( ) 3 1) three 2) four 3) five 4) six 12. Which C-C bond would most likely break and give fragments in the mass spectrum of butyl benzene? CH 2 CH 2 CH What is the major product of the following reaction? CH 2 CHCH 2 Br Mg, diethyl ether (1) H 2 C= (2) H 3 + 1) 2-ethyl-1-pentanol 2) 2-ethyl-1-butanol 3) 3-pentanol 4) 3-methyl-1-pentanol 14. What is the product of the following reactions? CCH 2 2 CH 2 CH 2 Li H 3 + diethyl ether H 1) CCH 2 CH 2 3) CHCH 2 CH 2 H H 2) CCH 2 CH 2 4) CCH 2 CH 2 Page 3

5 15. What is the product of the following reaction? CH 2 CH2I2, Zn(Cu) diethyl ether 16. Which of the following is not readily oxidized by K 2 Cr 2 7 in H 2 S 4 /H 2? 1) n-butyl alcohol 2) sec-butyl alcohol 3) isobutyl alcohol 4) tert-butyl alcohol 17. As a reducing agent, NaBH 4 donates a(n) to a ketone or aldehyde. 1) proton 2) hydrogen atom 3) hydride ion 4) hydrogen molecule 18. Which of the following reagents will convert cyclohexene into cis-1,2-cyclohexanediol? 1) s 4, ( ) 3 CH, ( ) 3 CH, H - 2) HI 4 3) 3 followed by Zn/H 2 4) C 3 H (peroxyacetic acid) 19. Which one of the following would not give butyl acetate when reacted with 1-butanol? CCH 2 CH 2 CH 2 butyl acetate 1) CCl (with pyridine) 3) C 2 H (with H 2 S 4 ) 2) CC (with pyridine) 4) CH (with H 2 S 4 ) Page 4

6 20. Consider the three compounds below. A. CH 2 CH 2 B. CH 2 CH 2 CH 2 C. CH 2 CH 2 CH 2 H The two most similar in boiling point are and the two most similar in solubility in water are. 1) A and C, B and C 2) A and B, A and C 3) B and C, A and B 4) A and C, A and C 21. f the following, which yields isopropyl methyl ether as the major product with little or no byproducts? 1) ( ) 2 CH - Na + + I 2) - Na + + ( ) 2 CHI 3) ( ) 2 CHH + H H 2 S 4 4) all three give isopropy methyl ether as the major product 22. What is the major product of the following reaction? NBS, benzoyl peroxide NaCH 2 CCl 4, heat CH 2 H Br CH 2 CH 2 CH 2 Br CH 2 CH 2 Br Br CH 2 CH 2 CH 2 Page 5

7 23. Identify the correct IUPAC name of the compound below? H 1) 4-benzyl-5-methylhexanal 2) 5-isopropyl-5-phenylbutanal 3) 2-methyl-3-phenylhexanal 4) 5-methyl-4-phenylhexanal 24. The compound shown to the right is the hemiacetal formed between: H CH 2 CH CH( ) 2 1) propanal and 2-propanol 2) 2-methylpropanal and ethanol 3) acetone and 1-propanol 4) ethanal and 2-methyl-1-propanol 25. Acid-catalyzed hydrolysis of the cyclic acetal below gives: Cl 1) ethanal and 2-chlorocyclohexanol 2) 1,2-ethanediol and 2-chlorocyclohexanol 3) ethanol and 2-chlorocyclohexanol 4) 1,2-ethanediol and 2-chlorocyclohexanone 26. Identify the most acid hydrogen for the following compound. H 3 C CH 2 C CH 2 Page 6

8 27. What is the relationship between keto and enol tautomers? 1) resonance forms 2) stereoisomers 3) constitutional isomers 4) different conformations of the same compound 28. How many different aldol addition products can be formed in the reaction of equal amounts of propanal and butanal with aqueous sodium hydroxide at 0 C? (consider only constitutional isomer - not stereisomers) 1) only one 2) two 3) three 4) four 29. Rank the following compounds in decreasing order of acidity. A. CH 2 C B. CH 2 CH 2 CH C. CCH 2 C 1) B>A>C 2) B>C>A 3) C>B>A 4) C>A>B 30. Rank the following three carboxylic acids in order of increasing acidity. A. 4-chlorobutanoic acid B. 3-chlorobutanoic acid C. 2-chlorobutanoic acid 1) A<B<C 2) A<C<B 3) C<A<B 4) C<B<A 31. Which of the following is the product of the reaction sequence below? NBS, CCl 4, heat (1) Mg/ether H 3 + benzoyl peroxide (2) C 2 C( ) 3 C 2 H CH 2 C 2 H H 2 C C( ) 3 C( ) 3 H 3 C C C( ) 3 CH 2 C 2 H Page 7

9 32. Which of the following is the tetrahedral intermediate in the acidcatalyzed Fischer esterification reaction of acetic acid, C 2 H, and ethanol, CH 2 H? CH 2 CH 2 H 1) H 3 C C H 2) H 3 C C H 3) H 3 C C H 4) H 3 C H C H CH 2 CH 2 CH 2 CH What is the name of the following compound? Cl CH 2 1) 2-chlorohexyl ethanoate 2) 1-chlorohexyl ethanoate 3) ethyl 2-chlorohexanoate 4) ethyl 1-chlorohexanoate 34. Rank the following in order of decreasing rate of hydrolysis. A. acetyl chloride B. acetic anhydride C. ethyl acetate D. acetamide 1) A>B>C>D 2) D>C>B>A 3) A>C>B>D 4) B>C>D>A 35. Saponification and neutralization of 18 labeled ethyl acetate, as shown below, yields which of the following isotopically labeled products. C 18 CH 2 (1) NaH, H 2, heat (2) H ) CH + CH 2 H 3) CH + CH 18 2 H 2) C 18 H + CH 2 H 4) approximately equal amounts of 1 and 2 Page 8