CHEM 2OA3 FINAL EXAM June 16, 2011 VERSION 1 NAME …s3.amazonaws.com/prealliance_oneclass_sample/YzKXqlRRPq.pdf · page 2 continued on next page omr examination – student instructions

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CHEM 2OA3 FINAL EXAM June 16, 2011 VERSION 1

NAME (First & Last): ___ _____________ ID#: _______________

Please circle your lab section/E in the table below:

Group Monday Tuesday Wednesday Thursday Friday

Thursday AM

Exempt

I L01 L02 L03 L04 L05 L06 E

Duration: 3 hours Instructor: Teri Gullon Instructions:

This examination paper consists of 30 pages, containing 28 multiple choice (MC)

questions, and 8 short-answer questions. A mini-periodic table, spectral correlation

charts and scrap paper are provided on the last 4 pages. Feel free to detach these last

pages for easier use.

Answer all the MC questions on optical scan sheets. Each MC question is worth 1.5

marks and you will not be penalized for incorrect answers. Follow the instructions on

the optical scan sheets, and the University rules for OMR exams which are reproduced

on page 2. Failure to follow instructions may result in loss of credit.

You are responsible for ensuring your copy of the test is complete, no pages are

missing, that all answers are in the correct place, and that you follow the correct

procedure for filling out the scan sheet. BRING ANY DISCREPANCY TO THE ATTENTION

OF YOUR INVIGILATOR.

All McMaster rules and procedures relating to Academic Dishonesty and Academic

Integrity apply to this exam; all violations will result in a penalty. Students must do

their own work. You MUST also complete ALL the information at the top of this

page. Failure to do so may result in a loss of marks.

Markers Only:

Written Section

Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8

/16

/4

/8

/12

/12

/5

/4

/5

Written Section Total

/66

MC total = /42


OMR EXAMINATION – STUDENT INSTRUCTIONS

NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS

PROPERLY COMPLETED. YOUR EXAMINATION RESULT DEPENDS UPON

PROPER ATTENTION TO THESE INSTRUCTIONS.

The scanner, which reads the sheets, senses the bubble shaded areas by their non-

reflection of light. A heavy mark must be made, completely filling the circular

bubble, with an HB pencil. Marks made with a pen will NOT be sensed. Erasures

must be thorough or the scanner will still sense a mark. Do NOT use correction fluid on

the sheets. Do NOT put any unnecessary marks or writing on the sheet.

1. On SIDE 1 (red side) of the form, in the top box, print your student number, name, course name, and the date in the spaces provided, in pen. Then you MUST write your signature, in the space marked SIGNATURE.

2. In the second box, mark your student number and test or exam version number (1, 2, 3 …) by filling in the corresponding bubbles underneath, in pencil.

3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each question. The question number is to the left of the bubbles. Make sure that the number of the question on the scan sheet is the same as the number on the test paper. Begin answering Question # 1 using the first set of bubbles, marked “1”. Do Not use Side 2.


Written Section [Marks in square brackets]

1) [16]Complete the following reactions schemes with the MAJOR product(s) on the right.

Include stereochemistry if relevant:

OH PCC

CH2Cl2

OH

NaNH2

NH3 (l)

1) BH3:THF

2) H2O2, NaOH, H2O

Br NaOCH3

CH3OH

∆

OH

1) Ts-Cl

2) NaBr, DMSO

Br

NaOtBu/HOtBu

∆

Br

F NaCN (1 eq)

DMSO

IONa

O

DMF


2) [4]: Answer the following questions relating to the following mass spectrum:

A) [1] What heteroatom(s) (not C or H) is/are present in the compound?

B) [2] What is the molecular formula of the compound?

C) [1] When molecules and their fragments are separated in (EI) mass spectrometry, what

species are actually detected? (Circle the correct answer)

Neutral Species Radical Species Charged Species

Key Peak Data:

m/z Relative intensity % (rescaled so that M+ is 100%)

188.0 (M+) 100.0

189.0 13.6

190.0 32.5


3) Below is the spectral data for a compound with molecular formula: C8H10N2O

Answer the following questions concerning this compound.

∫2 ∫2

∫1

∫3

∫2

1H NMR

IR


A) [1] What is the index of hydrogen deficiency (IHD) for this molecule?

B) [1] What two atom stretch is leading to the peak at ~1680 cm-1

in the IR spectrum?

C) [1] How many unique carbon environments are present in the molecule?

C) [1] Why are the peaks at 4.8ppm and 5.8ppm in the 1H NMR so broad?

F) [4] Draw the structure of the compound in the box below:

13C NMR


4) [12] Provide suitable reagents and conditions IN THE GIVEN CHART to complete the

reaction equations below. You may need more than one reagent for some of these

reactions. Assume the given products are the major products. Ensure the shortest,

highest yielding synthesis for each transformation.

OH

Br

O OH

OH

(b)

+ enantiomer

(f)

(g)

+ enantiomer

(a)

(c)

(d)

(e)

A) ENTER YOUR ANSWERS IN THE FOLLOWING CHART :

(a)

(b)

(c)

(d)

(e)

(f)

(g)


5) [12] A) Complete the following scheme with intermediates A through F:

Br

HBr, H2O2

Br

HBr

BA

KMnO4, NaOH (aq)

heat

E F

+

Cl2, H2O

C

+

D

HBrNaOCH3

HOCH3

heat

B) How are A and B related to each other? (Circle your answer)

i) Enantiomers ii) Diastereomers iii) Constitutional Isomers iv) Conformational Isomers

C) How are C and D related to each other? (Circle your answer)

i) Enantiomers ii) Diastereomers iii) Constitutional Isomers iv) Conformational Isomers


6) [5] Draw a complete mechanism for the following reaction and the resulting product(s) in the

space provided. Include stereochemistry if relevant. If more than one pathway is possible

draw all possibilities:

Br2/H2O


7) [4] Show a mechanism for the following reaction (do not show termination steps)

CH4

Br2

νh

CH3Br

8) [5] Outline a synthesis to the following target molecule using only bromo-cyclohexane

and propan-2-one as the sources of carbon. Show each step of the synthesis and include

any other necessary reagents/conditions. Solvents or reagents may contain carbon as long

as they don’t add to the molecule.

Target Molecule: Molecules containing carbon to use:

Br O

Synthesis:


Multiple Choice Section (Each question worth 1.5 Marks): Answers must be

completed on the scantron provided

1. You are asked to test the following molecules for unsaturation, using cold basic

permanganate.

1 2 3 4

Rank the molecules in order of largest to smallest amount of permanganate

decolorized per millimole of compound.

A) 2 > 1 > 4 > 3

B) 3 > 2 > 4 > 1

C) 4 > 1 > 3 > 2

D) 2 > 3 > 4 > 1

E) 2 > 3 > 1 > 4

2. Which of the following is a meso compound?

A. (2R,3R)-2,3-Dibromobutane

B. (2R,3S)-2,3-Dibromopentane

C. (2R,4R)-2,4-Dibromopentane

D. (2R,4S)-2,4-Dibromopentane

E. (2R,4S)-2,4-Dibromohexane


3. Which of the following statements is true?

i ii iii iv

A) i and ii are enantiomers, while iii and iv are meso compounds

B) iii and iv are enantiomers, while i and ii are meso compounds

C) i and ii are diastereomers, while iii and iv are enantiomers

D) iii and iv are diastereomers, while i and ii are enantiomers

E) All four are the same compound

4. The following sentence has the format “Statement 1 BECAUSE Statement 2”.

Decide whether statement 1 is true, whether statement 2 is true, and whether the

REASONING (the ‘because’ relationship) between them is valid.

Statement 1: “Both carbocations and carbon-centered free radicals follow the stability

order tertiary > secondary > primary, but the order is REVERSED for carbanions”

BECAUSE

Statement 2: “Both carbocations and carbon-centered free radicals, being electron-rich,

are stabilized by alkyl groups, whereas carbanions, being electron-deficient are

destabilized by alkyl groups.”

A) Statement 1 and Statement 2 are both correct, and the reasoning is valid

B) Statement 1 and Statement 2 are both correct, but the reasoning is NOT valid

C) Statement 1 is correct but Statement 2 is NOT correct

D) Statement 1 is NOT correct, but Statement 2 is correct

E) Statement 1 and Statement 2 are both NOT correct


5. You are presented with a sample Y which contains a mixture of products. You

run the mixture Y on silica coated TLC plates using hexane as the mobile phase

and obtain the following results compared to standards I, II, III and IV:

Given the following table that indicates which components (I, II, III or IV) are

contained in each of the possible compounds, what is the identity of sample Y?

Compound

Name

Component

I

Component

II

Component

III

Component

IV

A

B

C

D

E


6. Indicate the CORRECT statement regarding the oxidation of 4-ethyl-1,2-

dimethyl-cyclopentene shown below:

KMnO4, NaOH (aq)

cold

A) The major product expected is a trans-1,2-diol

B) The major product would be a diol which is also meso compound, with no net optical

activity

C) If the conditions were changed from cold to hot, the product would be a linear

dicarboxylic acid

D) If the conditions were changed from cold to hot, the product would be a cyclic di-

ketone

E) None of the above answers are correct

7. What is the major product of the reaction,

Br

CH3OK

CH3OH

heat

?

A) (CH3)2C=C(CH3)2

B) (CH3)3C–CH=CH2

C) (CH3)2C=CHCH3

D) (CH3)2C=CHCH2CH3

E) None of these


8. The structure of the product, C, of the following sequence of reactions

would be:

ACH3CH2Br

BH2

CNH3(l) Ni2B [P-2]

NaNH2

A)

B)

C)

D)

E)

Br

None of the above

9. In the following hydrocarbon, which hydrogen would have the smallest value for

pKa? CH3CH2CH=CHCH2CH2C CH

A) CH3CH2CH=CHCH2CH2C CH

B) CH3CH2CH=CHCH2CH2C CH

C) CH3CH2CH=CHCH2CH2C CH

D) CH3CH2CH=CHCH2CH2C CH

E) CH3CH2CH=CHCH2CH2C CH

1) Li, C2H5NH2, cold

2) NH4Cl


10. Which alcohol would be most easily dehydrated?

A)

CH3CH2CCH2CH3

CH3

OH

B)

CH3CH2CHCHCH3

CH3

OH

C)

CH3CH2CHCH2CH2OH

CH3

D)

HOCH2CHCH2CH2CH3

CH3

E)

CH3CH2CHCH2CH3

CH2OH

11. Which of the following is/are NOT resonance structures for the conjugate

base of the following molecule?

HO

H2N

O

A)

OH2N

O

B)

OH2N

O

C)

HO

HN

O

D)

OH2N

O

E) More than one of the above


12. Ozonolysis of compound Z yields the products shown below. What is the structure

of Z?

O

H

O

I II III

IV V

O O O

Z 2HCH + CH3CCH2CH1) O3

2) Zn, HOAc

A) I

B) II

C) III

D) IV

E) V


13. Compound X has the molecular formula C6H10. X decolorizes bromine in

carbon tetrachloride. X also shows IR absorptions at about 3200 and 2150cm-1.

When treated with excess hydrogen and a nickel catalyst, X yields 2-

methylpentane. The most likely structure for X is:

A)

B)

C)

D)

E)

14. Treating 1-methylcyclohexene with dilute H2SO4 (aq) would yield primarily which

of these?

II III

IV V

I

HO HO

HO

HOOH

A) I and V

B) II

C) III and V

D) IV

E) I, III and V


15. A synthetic strategy for converting trans-2-butene into pure cis-2-butene would

consist of which of the following?

A) Reaction with H2, Ni2B (P-2)

B) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) Na, NH3 (l)

C) Reaction with H2SO4 (aq) dilute, heat

D) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) H2, Ni2B (P-2)

E) None of these will successfully effect the desired transformation

16. Which reaction of an alkene proceeds with anti addition?

A) Hydroboration/oxidation

B) Br2 addition

C) Oxidation with cold KMnO4

D) Hydrogenation

E) None of the above

17. Cyclohexene reacts with bromine to yield 1,2-dibromocyclohexane. Molecules

of the product would:

A) be a racemic mixture and, in their most stable conformation, they would have

both bromine atoms equatorial.

B) be a racemic mixture and, in their most stable conformation, they would have

one bromine atom equatorial and one axial.

C) be a meso compound and, in its most stable conformation, it would have both

bromine atoms equatorial.

D) be a meso compound and, in its most stable conformation, it would have one

bromine atom equatorial and one axial.

E) be a pair of diastereomers and, in their most stable conformation, one would

have the bromines equatorial and axial, and the other would have the bromines

equatorial and equatorial.


18. Which of the reactions listed below would be exothermic?

A) CH3–CH3 2CH3·

B) CH3· + CH4 CH4 + CH3·

C) 2(CH3)2CH· (CH3)2CH–CH(CH3)2

D) H· + (CH3)3CH (CH3)3CH + H·

E) None of the above

19. What product would result from the following reaction?

I II III IV V

Br Br HOO Br Br OOH

Br

+ HBrperoxides

?

A) I

B) II

C) III

D) IV

E) V


20. What would be the major product of the following two step reaction?

OH

1. SOCl2

Cl F F Cl

2. NaF, DMSO

A B C D E

OH

21. What would be the most efficient, stereospecific way to carry out the following

synthesis of the following possibilities?

OH Cl

A) PBr3

B) 1)

S

O

H3C Cl

O

2)SOCl2

C) HCl

D) 1)

S

O

Cl

O

2) NaCl, DMSO

E) NaCl, DMSO


22. Indicate the incorrect statement below:

A. Resonance stabilization can apply to anions, cations, and radicals

B. Resonance delocalization only extends over three atoms at most

C. Resonance structures can usually not be isolated as separate compounds

D. Resonance delocalization and electronegativity both contribute to the acidity

of carboxylic acids

E. Resonance delocalization can occur in neutral compounds such as amides

and esters.

23. Carbocations are NOT intermediates in which one of the following

reactions?

A) + HBr

Br

B) + H2SO4

OH

C)

+ HI

I

D) Br H2O OH

E) Br+ HBr

R-O-O-R


24. Which product(s) would you expect to obtain from the following sequence

of reactions?

CH3

CH3

OH

CH3

OH

CH3H3C CH2OH

OOH

+

enantiomer

+

enantiomer

+

enantiomer

I II III IV V

1. BH3-THF

2. H2O2, NaOH?

A) I

B) II

C) III

D) IV

E) V

25. Epoxidation followed by reaction with aqueous base (followed by acid

workup) converts cyclopentene into which of these?

I II III IV

H

OH

H

OH

H

OH

OH

H

H

OH

H

OH

OH

H

A) I

B) II

C) III

D) IV

E) Equal amounts of III and IV


26. Indicate the INCORRECT statement(s) concerning the reaction of the epoxide

(1S, 2R)-1-methyl cyclopentene oxide) shown below:

O

(i) Reaction with NaOH in water will lead to formation of a trans diol with (1S, 2S)

stereochemistry.

(ii) Reaction with H+/MeOH will produce the (1R, 2R)-1-methoxy-1-methyl-

cyclopenta-2-ol.

(iii) Reaction with sodium methoxide will lead to formation of the (1S, 2S)-1-methyl-

cyclopenta-1,2-diol.

A. i B. ii C. iii D. two are incorrect E. none are incorrect

27. The most efficient, regioselective way to carry out the following transformation

would be:

OH

A) NaOMe/MeOH/heat

B) NaOtBu/HOtBu/heat

C) H2SO4/H2O/heat

D) 1)SOCl2 2) NaOtBu/HOtBu/heat

E) 1)PBr3 2) NaOMe/MeOH/heat


28. The reaction co-ordinate diagram shown below most likely corresponds to which

reaction?

(A) i (B) ii (C) iii (D) iv (E) none of the above


[Space for rough work only – work drawn here will not be marked!]


[Space for rough work only – work drawn here will not be marked!]




THE END

IR correlation chart:

Documents

CHEM 2OA3 FINAL EXAM June 16, 2011 VERSION 1 NAME …s3.amazonaws.com/prealliance_oneclass_sample/YzKXqlRRPq.pdf · page 2 continued on next page omr examination – student instructions