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1 UNIVERSITY OF SWAZILAND FINAL EXAMINATION 2016, DECEMBER..-.._._ TITLE OF PAPER Functional group chemistry & stereochemistry or Introductory Organic Chemistry COURSE NUMBER CE 232/ C 203 TIME Three ours INSTRUCTIONS Answer Section A and any TREE questions from Section B. Each question carries 2S marks ----_._--_._.._._----_.._ _..._----_..._- This Examination Paper Contains TEN Printed Pages Including This Page You are not supposed to open the paper until permission to do so have been granted by the Chief Invigilator.

2 Section A: (compulsory - answer all questions) 1. Which ofthe following molecules is the least soluble in water? a. -C 3 CO b. 2 C=CC 2 C 3 c. 2 C=CC 2 0 d. C 3 C What is the total charge of the following species? I II '0 C-C-C-N 3 " I a. +1 b. +2 c. 0 d What is the relationship between the structures shown? o 6 3C-C--C-C3 I \I _I 0 3C-C--C-C3 C3 C 3 I 6 A. Resonance forms B. The same compounds C. Different compounds D. Isomers 4. Which of the following is an isomer for cycloheptanol? 2

3 .N 5. Which of the following alkyl halides gives only one alkene as the product in the E2 reaction? c. O (\jbr ~C3 d. 6. What would be the major organic product of the reaction scheme shown below? o 1. Excess MeMgBr 2.p7 a) o---z~ n t b) C)~Me d) 7. The ozonolysis of limonene (an oil from lemon) gives formaldehyde and compound X. choose the correct structure for compound X. C, 1.0, 2. (CJhS 3

4 0 0 3C C3 a) 0 b) c) C 3 C 3 C 3 d) 0 e) 0 8. Which ofthe following reactions is incorrect? A OBr ;:,.-O ;:. / E B c 9. What is the IUPAC name of: CI C 3 Br O CI Ca a. (2R,3S,4S)-3-bromo-3,4-dichloro-2-pentanol b. (lr,2r,3r)-2-bromo-2,3-dichloro-l,3-dimethyl-propanol 4

5 c. (lr,2s,3r)-2-bromo-1,2-dichloro-1,3-dimethyl-3-propanol d. (2R,3S,4R)-3-bromo-3,4-dichloro-2-pentanol 10. Which of the following is the most stable carbocation having the molecular formula (49+? 11. Which ofthe following is a 3 amine? C 3 3C-C-C3 I C 3C-~ / 3 I -N a. N2 b. "- C3 12. Which of the following has a meso stereoisomer? o CI >=< b) CI d) )=< CI CI 13. Which of the following will give the transformation shown? +.. a) (1 2, 2 0 b) PBr3 followed by 30+ c) g(oac)j 2 S0 4, water d) B 3, TF followed by 2 0 2, O 5

6 Section B: Answer any 3 Questions Question 1 a. What is the correct IUPAC name for the following compound? (12) i. ii. iii. iv. C'-+ CI+ =fcosr Sr v. C 3 vi.? i. Draw Fisher projections for (2R,3S)-2-bromo-3-chlorobutane and (25, 3R)-2-bromo- 3 chlorobutane, with the carbon chain on the vertical line. label each structure as (2R, 35) or (25, 3R). (6) C. Assume that you have a mixture of equal amounts of each of the above compounds in (b). Can they be separated into two containers based on physical properties such as boiling point (b.p), melting point (m.p) etc.? If yes, which technique would you use? If no, briefly explain why. (4) d. Briefly explain the following terms and give appropriate examples (3) (i) (ii) (iii) Diastereoisomers Meso compound Dextrorotatory compound 6 a

7 Question 2 a. State how the two structures in each of the following pairs are related to each other. (8) i. ii. 0:13 O+ -t-bl Ci C3 +O TBr (,.~ iii. C1 >=< >=< Cl Cl C1 iv. b. Provide the missing reagents, product and/or reaction conditions where necessary for accomplishing the following transformations. Mechanisms are not necessary 0 d'~? i) (4) ii) )=0 +?? )=N-~-Ph Nz (3) Bf l. NaN0 2, 2 S C? iii) (2).. 7

8 iv) O 6? base 6':''"' 0 II C3COO (1) C 3 C 3 CC,-N I base? +? C)C 2 COCI V) C 3...? (3) vi) (2) c. Rank the following alkyl halides in order of decreasing reactivity in; (i) (ii) SN1 mechanism SN2 mechanism (1) (1) Question 3 (a) What would be the products of the hydration of 3,3-dimethyl-1-pentene {C3C2Cz(CshC=Cz} using: (i) (ii) (iii) Acid-catalysed hydration (identify major and minor product) Oxymecuration-demercuration ydroboration-oxidation (5) (5) (5) (b) Propose a mechanism for the aldol condensation of propanal (C 3 CzCO) (10) Question 4 (a) (b) Write a valid mechanism for the esterification of benzoic acid and ethanol Write the equations for the reaction of 1-heptanol with (i) Pyridiniumchlorochromate (PCe) in dichloromethane (8) (4) (ii) Acidified potassium dichromate (4).. 8

9 (c) (i) Explain the reaction oftolien's reagent with butanal and how this reaction could be used to differentiate butanal from butanone (5) (ii) Write the steps involved in the reaction of butanone with iodine in aqueous sodium hydroxide and name the product (4) 9

10 UNIVERSITY OF SWAZILAND CEMISTRY DEPARTMENT C203 SECriON A ANSWER SEET STUDENT 10 NUMBER: The correct answer must be indicated by putting a circle on the letter for that answer on the answer sheet provided. If you change your answer, please cancel the wrong answer with a cross and then put a circle around the correct one. If more than one option has a circle around it a zero will be given for that question. 1 A B C D E I 2 A B C 0 E 3 A B C D E 4 A B C D E 5 A B C D E 6 A B C D E 7 A B C D E 8 A B C D E 9 A B C D E 10 A B... D E 11 A B C D E 12 A B C D E 13 A B C D E.. 10

UNIVERSITY OF SWAZILAND FINAL EXAMINATION 2013, DECEMBER

UNIVERSITY OF SWAZILAND FINAL EXAMINATION 2013, DECEMBER TITLE OF PAPER COURSE NUMBER Introductory Organic Chemistry C203 TIME Three Hours INSTRUCTIONS Section A is compulsory. Answer any three questions