CHM 138H 2015 TT1 Wednesday 23.51.26

7/25/2019 CHM 138H 2015 TT1 Wednesday 23.51.26

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CHM 138H

INTRODUCTORY ORGANIC CHEMISTRY I

TERM TEST I

October 21st2015

TOTAL MARKS: 70

FAMILY NAME, FIRST NAME (PRINT): _________________________________________

Student #: ________________________

TUTORIAL GROUP #: T________

Answer allquestions in the spaces provided on the accompanying answer sheet.

It is attached to the back of the test paper. You may detach the answer sheet.Nothing written on this question sheet will be graded. All answers must bewritten on the answer sheet within the time allowed.

PRINT YOUR NAME, STUDENT NUMBER, and TUTORIAL GROUP

NUMBER on this test paper and on the answer sheet. Write all answers inblue or black ink.

You may use unboxedmolecular models. Calculators are not permitted.

A periodic table and some useful physical values are included on page 4 of the

test.

At the end of the test, place the answer sheet inside the test paper and HAND

BOTH IN.


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Part I (20 marks) - Multiple Choice Questions (2 marks each)

Jasmolin II is a pyrethrin compound that occurs in the seed cases of the perennial plantpyrethrum (Chrysanthemum cinerariaefolium). Pyrethrins have been used as insecticides for

thousands of years and are considered to be of low toxicity from a human health standpoint.

Questions 1 to 10 are about jasmolin II. Choose the correct option for each question.

O

O

O

O

O

jasmolin IIC2

C1

O1

1. The number of carbon atoms that are best described as being sp3-hybridized is

(a) 9 (b) 10 (c) 11 (d) 12 (e) 13

2. The number of primary carbon atoms present in jasmolin II is

(a) 2 (b) 3 (c) 4 (d) 5 (e) 6

3. The number of pi bond electrons in the compound is

(a) 10 (b) 12 (c) 14 (d) 16 (e) 18

4. The stereochemistry of the double bond contained in a ring and the carbon atom C1is beststated by the descriptors

(a)Z,R (b)Z, S (c)E,R (d)E, S (e) none of (a), (b), (c) or (d)

5. The number of ester functional groups contained in jasmolin II is

(a) 0 (b) 1 (c) 2 (d) 3 (e) 4

6. The source(s) of strain within the jasmolin II molecule is/are

(a) steric strain (b) angle strain (c) torsional (eclipsing) strain (d) all of (a), (b) and (c)(e) none of (a), (b) or (c)

7. Which of the following terms best describes the relationship between the two methyl groups

attached to the carbon atom labelled as C2?(a) trans (b) eclipsed (c) cis (d) staggered (e) none of (a), (b), (c) or (d)

8. The oxygen atom labelled O1in jasmolin II can act as a

(a) Brnsted base (b) Lewis acid (c) Lewis base (d) both (a) and (c)(e) both (a) and (b)

9. Which of the following terms is an incorrectdescription of the jasmolin II molecule?(a) aromatic (b) saturated (c) a hydrocarbon (d) acyclic (e) all of (a), (b), (c) and (d)

are incorrect

10. The compound is likely to be soluble in which of the following solvents?

(a) diethyl ether (b) H2O (c) hexane (d) two of (a), (b) and (c)(e) all of (a), (b) and (c)
https://en.wikipedia.org/wiki/Chrysanthemumhttps://en.wikipedia.org/wiki/Chrysanthemumhttps://en.wikipedia.org/wiki/Chrysanthemum


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Part II. Short Answer Questions

1. (12 marks) Draw appropriate skeletal structures for each of the following molecules. Note

no credit will be given for drawing either condensed or Kekul structures for each partof this question.

(a). two carboxylic acid constitutional isomers of molecular formula C4H8O2

(b). trans-1-ethyl-2-methylcyclopentane

(c). the compound formed by monochlorination of an alkane that has one quaternary and four

primary carbon atoms (the alkane molecular formula is C5H12)

2. (12 marks) When a strong base is added to the compound below, several monoanions could

theoretically be formed by deprotonation at different atoms.

NH2HO

OHH3C

(a). Draw the separate structures of the threemonoanionsmost likely to be formed.

(b). In practice, the monoanion that is actually formed has a formal negative charge on aheteroatom directly attached to the benzene ring. Draw threeadditional contributingresonance forms of this monoanion, and draw twoelectron flow arrows on one resonanceform onlyto show how it is related to a second additional resonance form. Lone pairs of

electrons should be included on all resonance forms.

3. (16 marks)

(a). Complete the partial Newman projection template on the answer sheet to represent the

lowest energy conformation of 2-fluoro-2-methylhexane, looking fromC3 toC2. Use thefollowing abbreviations where necessary: H = hydrogen, Me = methyl, Et = ethyl,

Pr = n-propyl, iPr = isopropyl, Bu = n-butyl.

(b). Complete the partial Newman projection template on the answer sheet to represent thehighest energy conformation of 2-fluoro-2-methylhexane, looking from C3 toC2 and usingthe same alkyl group abbreviations as in 3.(a)).

(c). Using the provided templates and skeletal structure convention, and clearly showing

substituent orientation, draw the least stable and the most stable chair conformations ofcis-1-n-butyl-4-tert-butylcyclohexane. Note that C1 has been defined in each

conformation.

4. (10 marks) On August 12th

2015, a chemical explosion in Tianjin, China killed over 100people. One substance involved was calcium carbide (CaC2) which contains the carbide

dianion (C22-

).

(a). Draw a Kekul structure for the carbide dianion, being sure to include any lone pairs ofelectrons and formal charges on atoms where appropriate.

(b). The carbide dianion reacts with water to form ethyne (acetylene) in two steps. The

organic product at the end of the first step is an acetylide anion (HC2-). Write a balanced

equation and draw appropriate curved arrows to indicate electron flow in the reaction betweenthe carbide dianion and water to form HC2

-.

(c). For the second step, write a balanced equation and draw appropriate curved arrows to

indicate electron flow in the reaction between HC2-and water to form ethyne.

------ END OF TEST ------


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Periodic Table For Term Test #1

YH

13

strain energy of one H-Y 1,3-diaxial interaction

Y kJ/mol Y kJ/mol

-F 0.5 -CH2CH3 4.0

-Cl 1.0 -CH(CH3)2 4.6

-Br 1.0 -C(CH3)3 11.4

-OH 2.1 -C6H5 6.3

-CH3 3.8 -COOH 2.9

-CN 0.4

CHM 138H 2015 TT1 Wednesday 23.51.26

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