TCHM 232. Organic Chemistry

Transcription

1 TM 232 rganic hemistry حل الامتحان KEY Final Exam Review Questions Examples of the types of questions you can expect to see on the final

2 1. The IUPA name for the formula 2 2 = 2 is 1. 5-hexene-3-ol 2. 1-hexene-3-ol 2. 1-hexene-5-ol 4. n-propyl ally alcohol allyl n-butyl ether 2. What is the order of reactivity toward S N 2 displacement in the following series? A. B.. l l 3 2 l 1. A>B> 2. A>>B 3. B>A> 4. B>>A >A>B 3. The principal organic product formed in the reaction below is 2 =( 2 ) 8 + peroxide 1. ( 2 ) ( 2 ) =( 2 ) =( 2 ) 7 none of these 4. Treatment of with l gives l l l 2 2 l

3 A compound which is insoluble in cold, concentrated sulfuric acid is 1. n-hexane 2. 1-hexene 3. 2-hexyne 4. ethyl acetate benzyl alcohol 6. Which reagent would convert cyclohexene into a cis-glycol? 1. sodium tert-butoxide in chloroform 2. hydrogen peroxide and aqueous acetic acetic acid 3. ozone and moist zinc dust 4. periodic acid cold dilute potassium permanganate 7. Which statement is correct for an S N 1 reaction at a chiral carbon atom? 1. the product will be optically active, but have the opposite configuration 2. the reaction will involve racemation 3. a carbanion is formed as an intermediate 4. the rate of the reaction is a function of the concentration of the nucleophile the attacking group will be a strong electrophile 8. Which does NT involve a carbocation? 1. ( ) 3 l + AgN 3 2. ( ) 3 + l 3. ( ) 3 + l 2 + uv light 4. = The reagent which would distinguish between 1-hexyne and 1-hexene is 1. + Ag(N 3 ) 2 2. KMn in l S 4 Na 10. In methyl alcohol solution, bromine reacts with ethylene (ethene) to yield 2 2 in addition to 1,2-dibromoethane because 1. the methyl alcohol solvates the bromine. 2. the ion formed initially may react with 1- or. 3. this is a free radical reaction. 4. the reaction follows Markovnikov s rule. of none of these reasons.

4 11. The important minor product from the reaction of sodium cyanide with 2-iodopentane in anhydrous acetone is 1. 1-pentene 2. 2-pentene 3. pentane 4. 2-pentanol 4,5-dimethyloctane 12. The monochloroisomer that predominates in the mixture resulting from the free radical chlorination of 2 2 = 2 is 1. l = 2 2. l 2 = l= l= =l 13. When a solid organic compound is recrystallized, the cold filtrate from the cooled mixture is 1. saturated with the compound. 2. an unsaturated solution of the compound. 3. entirely free of the compound. 4. pure solvent. supersaturated with the compound. 14. Sodium iodide in anhydrous acetone reacts most rapidly with ( ) = 1 = 2 reacts with to give which two bromobutenes? 1. = 2 + = 2. = 2 + = = == = = = = 2

5 16. What is the possible number of stereoisomers having the structure below? 2 1. two optically active and one meso 2. None optically active 3. four optically active 4. two optically active and two meso one optically active and one meso 17. The addition of 2 to trans-2-butene giving meso-2,3-dibromobutane can be explained by a mechanism involving 1. a free radical. 2. a carbocation. 3. a cyclic bromonium ion. 4. a carbanion. simultaneous attack by to bromine atoms. 18. Which metal catalyzed reaction would release the greatest amount of heat per 2 unit? 1. cyclopropane + 2 propane 2. cyclobutane + 2 butane 3. cyclopentane + 2 pentane 4. cyclohexane + 2 hexane cyclododecane + 2 dodecane 19. What is the IUPA name for the compound shown below? 1. 2,3-dimethyl-4-pentene 2. 1,1-dimethyl-2-isopropylethene 3. 2,3-dimethyl-2-pentene 4. All of the above None of the above 20. Which dimethylcyclobutane has two optically forms? 1. trans-1,2-2. cis-1,2-3. trans-1,3-4. cis-1,3-1,1-

6 21. The --N angle in acetonitrile, N is Which is NT characteristic of a free radical chain reaction? 1. It produces a mole of product for a mole of free radical initiated. 2. It gives the product derived from the most stable free radical. 3. It may be initiated by peroxides. 4. It may be initiated by high heat. It may be initiated by ultraviolet light. 23. A reaction at a chiral carbon of an optically pure isomer which takes place exclusively by an S N 2 reaction, and in which priorities do not change, proceeds with 1. inversion and no racemization. 2. inversion and some racemization. 3. inversion and complete racemization. 4. retention of configuration and some racemization. retention of configuration and no racemization. 24. Which would yield 2-methyl-2-pentene when refluxed with zinc dust in alcohol? Which anion is the weakest base? N N 1-

7 26. Which compound would be the major product when ( ) 2 2 is treated with alcoholic K? 1. ( ) ( ) ( ) ( ) 2 = ( ) 2 = If tert-butyl bromide and sodium amide (NaN 2 ) react, the product formed is 1. tert-butylamine. (amines are R-N 2 ) 2. tert-butylammonium bromide. 3. a mixture of butylamines. 4. isobutylene. (2-methylpropene) none of these. 28. In the reaction below, the product would be a mixture of diastereomers. 2. opticaly active. 3. unresolvable. 4. a racemate. a meso compound. 29. The rate of an S N 2 reaction run in a polar aprotic solvent relative to the same reaction in a polar protic solvent would be 1. the same. 2. slower. 3. faster. 4. unpredictable. unimolecular. 30. Which of the amines listed below would have the lowest boiling point? N N 3. ( ) 3 N 4. ( ) 3 N 2 ( ) 2 N Racemic 2,3-dibromobutane can be made by adding bromine to 1. cis-2-butene butene. 3. 1,3-butadiene. 4. trans-2-butene.

8 32. Which species represents the electrophile in aromatic substitution? 1. :N 2-2. N N 2 4. N 3 - S Which could NT be prepared directly from 4-bromobenzene-diazonium ion? 1. Phe Phe Phe-F Phe-N 4--Phe- 34. A good starting material for the preparation of 4-chlorobenzenesulfonic acid would be 1. benzenesulfonic acid 2. 1,4-dinitrobenzene 3. chlorobenzene 4. 4-chlorobenzioc acid 1,4-dichlorobenzene 3 Which represents an intermediate formed in the reaction of toluene and chlorine at elevated temperature in sunlight? l l l 36. The reaction of benzyl chloride with sodium isopropoxide yields 1. benzaldehyde and 2-chloropropane 2. 1,2-diphenylethane and acetone 3. acetone and toluene 4. benzyl isopropyl ether isopropyl ether and the sodium salt of benzyl alcohol 37. An aromatic hydrocarbon yields a single mononitro derivative. The hydrocarbon is 1. ethylbenzene 2. o-xylene 3. propylbenzene 4. naphthalene p-xylene

9 38. Which is the best way to prepare meta-bromoaniline? 1. Phe-N 2 2 S Phe- 2 N 3 Sn l 3. Phe-N 2 ( ) N Phe-N 3 (N 4 ) 2 S NaN 2 u Sn / l 2 2 S 4 Phe-N 2 2 S 4 Na Na Sn fuse l 39. Which is the principal product when benzaldehyde is allowed to react with propionaldehyde in the presence of dilute aqueous sodium hydroxide at room temperature? Which does NT represent a Diels-Alder type of reaction? == = 4. + = Which statement about the aldol condensation is correct? 1. A Lewis acid is commonly used as a catalyst. 2. The initial step is probably the formation of a carbanion. 3. A Lewis base is employed to induce carbocation formation. 4. The carbon chain is lengthened through the elimination of 1 mole of water.

10 42. Which is the strongest acid in water? 1. Phenol 2. 3-nitrophenol 3. 4-aminophenol 4. 4-nitrophenol hydroquinone 43. The most direct malonic ester synthesis of 3-phenylpropanoic acid would involve the use of l l l l l A compound gives a positive test with I 2 /Na and is extracted from benzene by saturated NaS 3. It may be 1. ( 2 ) 4 2. ( 2 ) ( 2 ) 4 2 ( 2 ) 3 ) 4 Which is an L-sugar that on oxidation gives an optically inactive dibasic acid (2 groups)?

11 46. Select the final product from this sequence of reactions. l 3 Na N 3 2 S 4 Sn l N N N N N N N N 2 N N 47. In the reaction below, the product would be + N N 1. a racemate. 2. optically active. 3. a meso compound. 4. a mixture of diastereomers. unresolvable. 48. A group which deactivates the benzene ring towards EAS but which directs the incoming group principally to the ortho and para positions is 1. -N l 3. -N N

12 49. What is true for the equilibrium reaction cat The use of equimolar quantities of and will give the greatest yield of the ester at equilibrium. 2. Removal of water will increase the amount of ester at equilibrium. 3. Addition of will cause the formation of equal an equal number of moles of water. 4. Application of pressure increases the amount of ester at equilibrium. hanging the catalyst will affect the position of the equilibrium. 50. Which reagent would bring about this transformation? R R 2 1. Sn and l 2. Zn and l 3. 2 and Pt 4. LiAl 4 and ether Na and alcohol 51. The reaction between carbon dioxide and a Grignard reagent will yield 1. an alkane. 2. an alkylmagnesium halide. 3. an alcohol. 4. magnesium carbonate. a carboxylic acid. 52. Which is a practical method for the preparation of iodobenzene? 1. iodine + benzene + iron 2. iodine + benzene + UV light 3. potassium iodide + chlorobenzene 4. sodium hypoiodite + benzamide potassium iodide + benzenediazonium ion 53. Which reaction sequence would be best to prepare 3-chloroaniline from benzene? 1. chlorination, nitration, reduction 2. nitration, chlorination, reduction 3. nitration, reduction, chlorination 4. nitration, chlorination nitration, reduction, acetylation, chlorination, hydrolysis 54. The catalyst used in the halogenation of benzene is 1. a proton donor. 2. an electron donor. 3. a Lewis base 4. a Lewis acid a proton acceptor

13 5 The reaction of 2 /Fe 3 with benzene to form bromobenzene is know as 1. free radical substitution 2. nucleophilic substitution 3. electrophilic substitution 4. ionic addition elimination 56. Which reagent will lengthen the carbon chain by two carbons in one step when reacted with an organolithium reagent? 1. acetic acid 2. formaldehyde 3. iodomethane 4. ethylene oxide ethanol 57. Which aromatic compound behaves most like benzoic acid when it undergoes reaction with concentrated nitric acid and sulfuric acid? 1. Phenol 2. hlorobenzene 3. Phenyl methyl ketone 4. Benzene Toluene 58. An explanation of the addition of sodium bisulfite to heptanal and 2-heptanone but not to 3- heptanone is 1. steric inhibition of resonance. 2. steric hinderance. 3. steric inhibition of solvation. 4. differences in resonance effects. the lower dipole moment of 3-heptanone. 59. Which will undergo a Friedel-rafts alkylation reaction? 2 N 2 A B D 1. a, b, c 2. a and c 3. b and d 4. a and b c and d 60. The reaction of diethylmalonate with sodium ethoxide produces ethanol and a 1. free radical 2. carbocation 3. molecular species 4. carbanion carboxylate ion

14 61. The principal product of the reaction between methyl butanoate and 2 moles of Mg after hydrolysis is ()( ) ( ) Which reaction sequence would be best to prepare 1,4-diaminobenzene from benzene 1. nitration, sulfonation, nitration, hydrolysis, reduction 2. nitration, reduction, nitration, reduction 3. nitration, reduction, acetylation, nitration, reduction 4. nitration, reduction, acetylation, nitration, hydrolysis, reduction nitration, reduction l 63. The correct name for is 1. 7,9-dichloronaphthalene 2. 3,5- dichloronaphthalene 3. 2,4- dichloronaphthalene 4. 1,3- dichloronaphthalene 6,8- dichloronaphthalene 64. Which of the following would react most rapidly with sodium ethoxide to produce an ether? 1. chlorobenzene 2. p-nitrotoluene 3. p-nitrochlorobenzene 4. m-(chloromethyl)-toluene m-chlorotoluene 6 Select the final product from this sequence of reactions. Acetoacetic ester l NaEt I NaEt