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NAMIBIA UNIVERSITY OF SCIENCE AND TECHNOLOGY

FACULTY OF HEALTH AND APPLIED SCIENCES

DEPARTMENT OF NATURAL AND APPLIED SCIENCES

QUALIFICATION: BACHELOR OF SCIENCE

QUALIFICATION CODE: 07BOSC LEVEL: 7

COURSE CODE: OCH701S COURSE NAME: ORGANIC CHEMISTRY 2

SESSION: JULY 2019 PAPER: THEORY

DURATION: 3 HOURS MARKS: 100

SUPPLEMENTARY / SECOND OPPORTUNITY EXAMINATION QUESTION PAPER

EXAMINER(S) | DR. MARIUS MUTORWA

MOpERATOR: | DR. RENATE HANS

INSTRUCTIONS

Answer ALL the questions.

Write clearly and neatly.

Number the answers clearly

All written work must be done in blue or black in and sketches

must be done in pencil

wey

5. No book, notes and other additional aids are allowed

PERMISSIBLE MATERIALS

Non-programmable Calculators

ATTACHMENTS

Solvent Chart, pKa Chart and Periodic Table

THIS QUESTION PAPER CONSISTS OF 15 PAGES

(Including this front page and attachments)

SECTION A [50]

QUESTION 1: Multiple Choice Questions [50]

e There are 25 multiple choice questions and each question carries 2 marks.

e Answer ALL questions by selecting the letter of the correct answer.

e Choose the best possible answer for each question, even if you think there is

another possible answer that is not given.

1.1 Which one of the following compounds will have the lowest wavenumber for carbonyl

absorption? O o O NHp oO O

AN DA AA AA AA. I Hl MI IV Vv

oe eee

1.2 Which of the following compounds will show a broad absorption around 3300 cm™ and at 1650

cm???

OH \ 3 | : OH _—OH

I I Ill IV Vv

A. |

B. Il

C. Il

D. IV

E.V

1.3 Which of the following compounds will have odd m/z value for the molecular ion? Br Oo Oo |

and AKL pet gpl gg i ANY

I Il | Il | IV

A. |

Br

B. Il

C. Ill

D. IV

E. None of the above

of 15

1.4 Which of the following is not a prominent peak in the mass spectrum of 2-methyl-2-pentanol?

A. M-15

B. M-18

C. M-29

D. M-16


1.5 Which of the following is true about the number of signals in aH NMR spectrum?

A. it indicates the number of neighboring protons

B. it indicates the electronic environment of neighboring protons

C. it indicates the number of different kinds of protons

D. it indicates the electronic environment of absorbing protons

E. it indicates the number of protons in the signal

1.6 How many signals would you expect to find in the 7H NMR spectrum of the following

compound?

A.4

B.5

C.6

D.7

E, 9

1.7 Which of the following compounds will display a singlet, a triplet and a quartet in the +H NMR

spectrum?

A. 2-chloro-4-methylpentane

B. 3-chloro-2-methylpentane

C. 3-chloropentane

D. 1-chloro-2,2-dimethylbutane

E. 3-chloro-3-methylpentane

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1.8 Rank the following dienes in increasing order of stability (least to most).

I I <

A. I<IV<lll<ll

B. III<II<I<IV

C. IV<II<Ill<l

D. II<IV<ilI<I

E. I<III<II<IV

1.9 Which one of the following compounds is not a product of reaction between 1,3-butadiene and

HBr?

A. (S)-3-bromo-1-butene

B. (R)-3-bromo-1-butene

C. (E)-1-bromo-2-butene

D. (Z)-1-bromo-2-butene

E. (Z)-2-bromo-2-butene

1.10 The Diels Alder reaction is a concerted reaction, which means:

A. The product contains a cyclic ring

B. The diene must be in the s-cis conformation to react.

C. All changes in bonding (bond making and bond breaking) occur simultaneously.

D. It is an endothermic reaction

E. Both exo and endo products are formed

1.11 Which one of the following compounds is most acidic?

H H

[> . | N

I U N Ill

o0f 15

A. |

B. Il

C. Ill

D. land Ill

E. Il and III

1.12 Which one of the following compound is aromatic?

© S

(gol!) YO O

l H I IV

A. |

B. Il

C. Ill

D. IV


1.13 What is the correct structure for 4-amino-2-chlorophenol?

NO, NO, OH NH» NH»

; ‘cl ; er “cl ‘cl cl

I OH Il OCHs I] NH, OH CH

y v || Oo

A. |

B. Il

C. Ill

D.IV

E.V

1.14 Predict the major product for the following reaction.

(CH3),CHCH,CI SE cael

AICI;

of 15

CH CHs Us

CHCH(CHs)2 CHCH,CH, ce CH2CH2CH2CH3 CH3

A. |

B. Il

C. Ill

D. IV


1.15 Which one of the following compounds does not undergo Friedel-Crafts reaction?

A. Benzene

B. Chlorobenzene

C. Nitrobenzene

D. Toluene

E. tert-Butylbenzene

1.16 Which one of the following compounds would be most reactive toward electrophilic aromatic

substitution? 9

NH» CH; Cl lo CF3

I II Ill IV V

A. |

B. Il

C. Ill

D. IV

E.V

1.17 What is the IUPAC name for the following compound?

OH

SS

of 15

A. 4-penten-2-methyl-2-ol

B. 4-methyl-1-penten-2-ol

C. 2-methyl-4-penten-2-ol

D. 4-methyl-1-penten-4-ol

E. 4-hydroxy-4-methyl-1-pentene

1.18 Predict the product for the following reaction.

1. Hg(OAc),, H,0

———$$$__——_——_$___> 2. NaBH,

ay CH,OH

OH

Bt Ul I SH IV

A. |

B. Il

C. Ill

D. IV


1.19 Provide the reagents necessary to carry out the following conversion.

O

ADV Non _ AK

A. KMnO4/NaOH/H20

B. CrO3/H2SO4/H20

C. PCC/CH2Cl2

D. Br2, CCla


of 15


OH O

A. 4-oxo-5-phenyl-2-hexanol

B. 5-hydroxy-2-phenyl-3-hexanone

C. 2-hydroxy-5-phenyl-4-hexanone

D. 2-hydroxypropyl-1-phenylethyl ketone

E. 5-hydroxy-3-keto-2-phenylhexane


PCC 2-hexanol_ ———">>

CH,Cl,

A. hexanal

B. hexanoic acid

C. 2-hexanone

D. 2-chlorohexane

E. 1-hexanol

1.22 Provide the structure of the product, when cyclohexanecarbaldehyde reacts with excess 2-

propanol in presence of sulfuric acid.

OH ST

or oN

I II

OH a a O

oe a a

Ill IV Vv

of 15

A. |

B. Il

C. Il

D.IV

E.V

1.23 Rank the following acids in decreasing order of acidity.

9 0 QO

ay - a

Ic T = Br

9 0

SI au

IV V i

A. V>llI>I>1I>1V

B. II>I>II>V>IV

C. IV>III>1>11>V

D. IV>V>III>I>I1

E. V>I>III>1I>1V


kk —™

A. 2-methylbutyl-3-methylbutanoate

B. 3-methylbutyl-3-methylbutanoate

C. 2-methylbutyl isovalerate

D. 2-methylbutyl-2-methylbutanoate


of 15


O

2. LiAl[OC(CH;)3]H

O 5 5

OH Cl 3 |

Ill IV

och, SOCI

A. |

B. Il

C. Ill

D. IV


SECTION B:

I

QUESTION 2 —

What is (are) the product(s) of the following reactions?

Note: Each question carries 2 marks.

of 15

Ach

Cc;

COCH3

1. LiAIHy excess ce

2. H,0

O

d. OH 0

A A H,SO,

H >

e.

1. Mg/ ether

2. CO,

a Br ——_—_—_—_—_—_—_—_> 3. H,O*

QUESTION 3 [16]

Identify the lettered intermediates (A-H) in the following reaction sequence.

“e, 2 am ie

“Be NaCN HjO* _ SOClp _ [1] (CHa),Culi ] A B SD >

we es Lj IH, [2] HsO

~ Wnts As | CHOH, Ht pce H]DIBAL-H [1] CHeLi

F ~G > H [2] H,0 [2}H,0

of 15

QUESTION 4 [14]

Draw a stepwise detailed reaction mechanism for the transformation below. In order to receive full

marks, show the flow of electrons using appropriate arrows and all the intermediates.

Ak [H"] ° ON

HO H EtOH

QUESTION 5 [10] Use the +H NMR spectral table provided to identify the structure of a compound with Molecular

Formula Ci1H1402, a strong IR absorption at 1712 cm™ and the following +H NMR spectral data:

Signal # Shift (ppm Multiplicity Proton Ratio pignal # VEUITIDICILTY, Froton kavlo | 0.94 triplet 1.5

2 1.30-1.70 multiplet 2

3 2.67 triplet |

4 7.27 doublet 1

5 8.03 doublet ]

6 12.27 singlet 0.5

THE END

GOOD LUCK

of 15

1H NMR SPECTRAL DATA

Characteristic Chemical Shifts of Common Types of Protons

Type of proton Chemical shift (ppm) Type of proton Chemical shift (ppm)

H \

b 4 09-2 PK 4.5-6 sp? | . sp?

« RCHa ~0.9

* RxCH2 21.3 Cp 6.5-8 * RCH ~1.7

%, bon 15-25 t a re aon 9-10 ROH

Z=C,O,N

m —C=C-H ~2.5 oom 10-12

ROH

by 2.5-4 a1 RO-H or RON-H 1-5 sp Z

Z=N.O,X Important IR Absorptions

Bond type Approximate ¥V (cm) Intensity

O-H 3600-3200 strong, broad

N-H 3500-3200 medium

C-H ~3000

° Cs2-H 3000-2850 strong

¢ C.2-H 3150-3000 medium

© Css-H 3300 medium

C=C 2250 medium

C=N 2250 medium

C=0 1800-1650 (often ~1700) strong

C=C 1650 medium

Ty

| J 1600, 1500 medium

of 15

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