(A)(B) (C) (D) (E)

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CHEM 2OA3

Test 1 October 5, 2007

VERSION 1

NAME (First & Last): _____________________ ID#: _______________

Lab Station: ______

(Print ‘E’ if you are exempt from the labs)

Please circle your lab section in the table below.

Group Monday Tuesday Wednesday Thursday Friday

I L01 L02 L03 L04 L05

II L06 L07 L08 L09 L10

Duration: 90 minutes

Instructors: Drs. Harrison and Stöver

Instructions:

This examination paper consists of 20 pages, containing 20 (twenty) multiple choice (MC) questions, and 3 short answer questions. You are responsible for ensuring your copy of the question paper is complete. A mini-periodic table and spectral correlation charts are provided on the last two pages.

Answer all the MC questions on optical scan sheets. Each MC question is worth two 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 all answers are in the correct place, and that you follow the correct procedure for filling out the scan sheet.

Mark your student number in the space provided on the sheet on Side 1 AND FILL IN THE CORRESPONDING BUBBLES UNDERNEATH. Now enter your version number, which can be found on the top right hand corner of this page, by filling in the BUBBLE in the “version” column provided. You MUST sign the sheet in the space provided.

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. A program designed to detect similar answers will be used for this exam.

You MUST also complete ALL the information at the top of this page.

MC

Written Section

Q21

Q22

Q23

Written Total

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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. Then fill in your section number; section 01 is Dr. Harrison’s section, section 02 is Dr. Stöver’s section. 3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each

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Questions 1-20; 2 marks each.

1. Which of the following compounds is (Z)-4-propyldec-4-en-9-ynal?

O H O H O H O H O

(A)

(B)

(C)

(D)

(E)

2. Which orbital drawing best represents the π* orbital of ethanal (acetaldehyde)?

C C H O H H H C C H O H H H C C H O H H H C C H O H H H C C H O H H H

.. ..

.. ..

.. ..

..

..

.. ..

(A) (B) (C)

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3. In butadiene (H2C=CH-CH=CH2), four atomic orbitals combine to form the four π-type molecular orbitals (MO’s) A through D shown below, where the shading

represents the phase.

A B C D

Indicate which of the following statement(s) is/are true about the molecular orbital diagram for butadiene

i) B represents the relative energy of electrons in the π* MO ii) The 4 p electrons in butadiene are located in MO’s B and C

iii) A is the most stable bonding MO

iv) Excitation of the molecule using ultraviolet light would promote an electron from π bonding MO B to π* antibonding MO C

v) Excitation of the molecule using ultraviolet light would promote an electron from σ bonding MO A to σ* antibonding MO D

A) all are true B) iii and iv C) i, ii, iv D) iii, v E) v only

4. Indicate which of the following structures are resonance structures of compound

A that obey the octet rule?

O O O O O O O O O O O O O O O O O O

-+ + + +

--

+

A i ii

iii iv v

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5. 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: “butanal has a higher boiling point than propanal” BECAUSE

Statement 2: “aldehyde molecules are attracted to each other by their permanent dipole moments”.

(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

Questions 6-9 relate to Taxol, a cancer fighting drug originally isolated from the bark of the Yew tree, whose structure is shown below:

6. What functional group is marked a in Taxol?

(A) alcohol (B) amide (C) ester (D) ether (E) aldehyde

7. What functional group is marked b in Taxol?

(A) alcohol (B) ketone (C) ester (D) ether (E) aldehyde

8. What functional group is marked c in Taxol?

(A) alcohol (B) amide (C) ester (D) ether (E) aldehyde

9. What functional group is marked d in Taxol?

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10. Which of the following best describes the direction of the dipole in nitrobenzene, shown below?

(A) (B) (C) (D) (E)

11. Indicate the false statements below:

B

NMe2 ONa

COOH

OH

1 2 3 4 5

i. Compounds 1 and 3 form a classical Lewis acid / Lewis base pair ii. Compounds 4 and 5 can both act as Bronsted acids

iii. Compound 3 can act as a Bronsted base but not as a Lewis base iv. Compounds 2 and 3 are both good nucleophiles

v. Compound 1 is a good electrophile

vi. Compounds 1 and 2 would not react with each other

(A) iv and vi (B) iii and vi (C) ii and v (D) i, iii and iv (E) ii and vi

12. Indicate the correct number of constitutional isomers of C5H12:

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13. For the compound whose IR spectrum is shown below, which of the following statement(s) is TRUE?

A. The compound contains BOTH a carbonyl group AND an alcohol, but is NOT a carboxylic acid

B. The compound contains a carbonyl group, but NOT an alcohol or a carboxylic acid

C. The compound contains an alcohol, but NOT a carbonyl group or a carboxylic acid

D. The compound contains a carboxylic acid AT LEAST, and could contain an alcohol &/or a carbonyl group

E. The compound does NOT have a carbonyl group, NOR an alcohol, NOR a carboxylic acid

14. Which of the following statements about the infrared spectrum shown in the question above is TRUE?

A. In an infrared spectrum, ENERGY increases from left to right along the x axis, AND ABSORBANCE (amount of light absorbed) increases from top to bottom

on the y axis

B. In an infrared spectrum, ENERGY decreases from left to right along the x axis, AND ABSORBANCE (amount of light absorbed) increases from top to bottom

on the y axis

C. In an infrared spectrum, ENERGY increases from left to right along the x axis, AND ABSORBANCE (amount of light absorbed) decreases from top to bottom

on the y axis

D. In an infrared spectrum, ENERGY decreases from left to right along the x axis, AND ABSORBANCE (amount of light absorbed) decreases from top to bottom

on the y axis

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15. Which of the following statements about chromatography are FALSE?

i) The Rf of a compound on a silica gel TLC plate is given by the distance traveled by the compound divided by the distance traveled by the solvent

ii) A more polar compound travels less far on a silica gel TLC plate than a less polar compound in a non-polar solvent

iii) A more polar solvent makes all compounds elute more quickly in a chromatography column composed of silica gel

A) None are false B) i C) ii D) iii E) All are false

16. When the following three compounds are separated on a chromatography column of silica gel, the order in which they elute from the column (first, second, third) is:

O OH

X Y Z

A) X,Y,Z B) X,Z,Y C) Y,X,Z D) Y,Z,X E) Z,X,Y

17. When the following three compounds are separated by distillation, the order in which they boil (first, second, third) is:

CH3CH2OH

C

H3 H

O

O

X Y Z

A) X,Y,Z B) X,Z,Y C) Y,X,Z D) Y,Z,X E) Z,Y,X

18. The column chromatography and Thin Layer Chromatography (TLC) used in experiment #1 is based on what technique?

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19. Which of the following statements about the carbon-13 nmr spectrum shown is TRUE (assume there are no sp hybridized carbon atoms)?

(A)The compound has exactly three carbon atoms: one is sp2 hybridized and the other two are sp3

(B)The compound has exactly three carbon atoms: two are sp2 hybridized and the other is sp3

(C)The compound has three or more carbon atoms: some are sp2 hybridized and the others are sp3

(D)The compound has three, six, nine…etc. carbon atoms: some are sp2 hybridized and the others are sp3

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20. Which of the following compounds best matches the following carbon-13 nmr spectrum shown below?

O O

O

OH O

OH O

H

OMe OMe

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21. [21] Fill in suitable reagents or compounds missing from the boxes in the two reaction schemes below:

OH O OH

O

OH

HBr

H

+

/ H

2

O

1. Mg

2. product A

3. dilute acid

PCC

product A

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22. [20] The reaction of Grignard reagents with alkyl halides is a very useful way to make new carbon-carbon bonds. By considering the reaction of methyl magnesium bromide with tert-butyl bromide outlined below, answer the following questions to lead to a mechanism for this process:

Br

CH3MgBr

+

MgBr2

+

(i) Indicate, using the δ+ and δ- convention, the polarity of the C-Mg bond in the Grignard reagent

(ii) Indicate, using the δ+ and δ- convention, the polarity of the C-Br bond in the alkyl halide

(iii) Use curly arrows to indicate the cleavage of the C-Mg bond in the Grignard reagent. Do not show the alkyl halide yet, just the bond cleavage. Be sure to clearly indicate the heads and tails of all curly arrows, and to show the products of the bond cleavage, along with all charges.

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(v) Use curly arrows to indicate the cleavage of the C-Br bond in the alkyl halide. Do not show the Grignard reagent yet, just the bond cleavage. Be sure to clearly indicate the heads and tails of all curly arrows, and to show the products of the bond cleavage, along with all charges.

(vi) Now use curly arrows to show the formation of the new carbon-carbon bond between the intermediates you generated in parts (iii) and (v).

(vii) Considering your mechanism for the step in part (vi), clearly indicate which component is acting as the nucleophile, and which the electrophile:

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23. [19] A CHEM 2OA3 student took some butan-2-ol, mixed it with concentrated aqueous HCl in a pressure vessel, and heated the mixture. They isolated the crude reaction products, and separated them by column chromatography. Because the student did not allow the reaction to proceed long enough, they isolated some unreacted butan-2-ol (A), in addition to the compounds B-E shown below.

OH Cl

A B C D E

HCl

+

+

+

Part 1 [7]:

(a) What TYPE of alcohol is butan-2-ol (e.g. tertiary)?

(b) Indicate which product(s), if any, have been formed by (a) substitution reaction(s).

(c) Indicate which product(s), if any, have been formed by (an) elimination reaction(s).

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(e) Indicate which product(s), if any, are constitutional isomers.

(f) Indicate which product(s), if any, are geometric isomers (aka stereoisomers).

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i) Based on the IR spectrum of X ALONE, what compound or compounds CANNOT correspond to this fraction?

ii) Based on the carbon-13 NMR spectrum of X ALONE, what compound or compounds CANNOT correspond to this fraction?

iii) Based on both spectra together, provide a structure or structures for this fraction that are consistent with the data provided.

iv) Explain how the spectra provided are consistent with the structure of X you chose (1 sentence each for IR and 13C NMR)

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Figure

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References

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