Chemistry 261

Quiz 4, Take Home

Fall 2017

Out: 12/04/17

Due: 12/06/17 (6 pm)

The following cumulative quiz contains 52 questions valued at ¾ point/question and

reflects Thursday’s 150 point final exam, which will also contain 52 questions (at 3

points/question). Both quiz and exam cover the first 7 chapters in Loudon and

Parise’s Organic Chemistry, 6th ed.

Name: _____________________________________________________

DISTRIBUTION OF VALENCE ELECTRONS, FORMAL CHARGE

1. What is the charge on oxygen with 3 bonds and a single pair of non-bonded electrons?

a. -2

b. -1

c. 0

d. +1

e. +2

LEWIS STRUCTURES (& BASIC NOMENCLATURE)

2. Please draw the complete Lewis structure for the citric acid cycle intermediate

fumaric acid ((2E)-But-2-enedioic acid).

LEWIS STRUCTURES AND FORMAL CHARGES

3. In which of the following compounds does the central atom have a formal charge = 0?

a.

HFH

b.

OH3C CH3

H

c.

BF F

F

F d.

NH3C CH3

H

H e.

None of the above

ELECTRONEGATIVITY, POLARITY, AND DIPOLE MOMENTS

4. Which of the following common solvents has the smallest dipole moment?

a. Chloroform, CHCl3

b. Acetone, (CH3)2CO

c. Dimethylsulfoxide, DMSO, (CH3)2SO

d. Acetonitrile, CH3CN

e. Methanol, CH3OH

MOLECULAR GEOMETRY

5. The bond angle for the C-C-N bond in acetonitrile (CH3CN) is expected to be?

a. 90o

b. 109o

c. 120o

d. 145o

e. 180o

HYBRIDIZATION & MOLECULAR GEOMETRY

6. The lone pair of electrons in pyridine are contained in what type of orbital?

a. 2sp2

b. 2sp3

c. 2p

d. 2s

e. 2sp

CURVED ARROW METHOD AND RESONANCE

7. Using the curved arrow approach, please show the deprotonation of diethylmalonate

by sodium hydride, followed by the principal contributing resonance structures,

using the curved arrow approach to move from one form to the other

CURVED ARROW METHOD AND RESONANCE

8. Which of the following is not a resonance form of the boxed cationic compound

shown?

a. I

b. II

c. III

d. IV

e. N/A; All are legitimate resonance structures

N

I IIIII IV

SCH3 SCH3 SCH3 SCH3 SCH3

STABILITY/RELATIVE CONTRIBUTION OF RESONANCE FORMS

9. Upon heterolytic decomposition1 to the boxed cationic compound shown, which of

the following forms contributes most to the overall hybrid?

a. II

b. III

c. IV

d. The boxed compound

e. All contribute equally

ATOMIC ORBITALS, MOLECULAR ORBITALS, & HYBRIDIZATION

10. According to molecular bonding theory, in the case of a carbon-carbon double bond,

the carbon-carbon bonding electrons of highest energy occupy which molecular

orbital?

a. bonding MO

b. bonding MO

c. * antibonding MO

d. * antibonding MO

e. * bonding MO

1 Heterolytic decomposition removes both electrons in a bond to one of the bonding atoms, unlike homolytic

cleavage to form radical species. Envisioning a chloro group at the site of the carbocation in the boxed compound may be helpful; such a molecule would be especially susceptible to SN1 type reactions due to the resonance and carbon substitution shown

I IIIII IV

SCH3 SCH3 SCH3 SCH3 SCH3

NEUMAN PROJECTIONS AND CONFORMATIONAL ANALYSIS

11. Which staggered Newman projection(s), looking down the C2-C3 bond (C2 in front,

C3 in back) is consistent with the boxed compound shown?

a. I, II, & V

b. II & V

c. III & IV

d. V only

e. None of the above

CLASSIFICATION OF CARBON CONNECTIVITY

12. How many tertiary carbons exist in (1R,2S)-1,2-dimethylcyclopentane?

a. 0

b. 1

c. 2

d. 3

e. 4

OH

III

OHH

CH3

CH=CH2

CH3H

V

III

IV

HHO

CH3

CH=CH2

CH3H

HO H

CH3

CH=CH2

H3C H OHH

CH3

CH=CH2

HH3C

HHO

CH3

CH=CH2

HH3C

FUNCTIONAL GROUPS, NOMENCLATURE AND REPRESENTING MOLECULES

13. Please draw the bond-line structure for (Z)-3-phenyl-2-buten-1-ol

FUNCTIONAL GROUPS, NOMENCLATURE AND REPRESENTING MOLECULES

14. Please draw the bond-line structure for para-(1-methylpropyl)-styrene (para-sec-

butyl-vinylbenzene)

INTERMOLECULAR FORCES & PHYSICAL PROPERTIES

15. Which of the following would have the poorest solubility in hexane?

a. Acetone

b. Isopropyl alcohol

c. Propanoic acid

d. Sodium propanoate

e. Benzene

ELECTRON DEFICIENT COMPOUNDS AND LEWIS ACID-BASE DEFINITIONS

16. Which of the following is not a Lewis acid?

a. H3O+

b. H2O

c. BF3

d. PhCH2+

e. N/A; all of the above are Lewis acids

NUCLEOPHILES, ELECTROPHILES, AND LEAVING GROUPS

17. Which of the following is the poorest leaving group?

a. H-

b. CH3O-

c. H2O

d. OH-

e. NH3

BRØNSTED-LOWRY ACIDS AND BASES – CONJUGATE ACID AND BASE DEFINITION

18. In the following equilibrium, which species act as Brønstead-Lowry bases?

a. PO4-3 and HPO4

-2

b. PO4-3 and OH-

c. PO4-3 and H2O

d. H2O and OH-

e. H2O and HPO4-2

FUN WITH pKa’s

19. Which of the following contains a hydrogen of pKa 10-11?

a. CH3CH2CH2CH2CO2H

b. PhOH

c. CH3CH2CH2CCH

d. CH3CH2CH2CH2NH3Cl

e. More than one of the above

FREE ENERGY AND CHEMICAL EQUILIBRIUM

20. In what way does the acidity constant Ka differ from the equilibrium constant Keq

when the acid in question is placed in water under the same pressure, temperature,

and concentration conditions?

a. Ka can be determined less accurately than Keq

b. Ka is used for strong acids only; Keq for weak acids

c. Ka is the reciprocal of Keq

d. Keq = Ka/[H2O]

e. Ka = Keq/[H2O]

PO43- + H2O HPO4

2- + HO-

STRUCTURE-ACIDITY RELATIONSHIPS

21. For each of the following compounds, rank the indicated hydrogen from most acidic

to least acidic

a. I > IV > II > V > III

b. II > IV > I > V > III

c. II > IV > V > I > III

d. IV > I > II > V > III

e. IV > II > I > V > III

STRUCTURE-ACIDITY RELATIONSHIPS

22. Rank the bold-faced hydrogens in the following compounds from most acidic to least

acidic.

a. III > IV > I > V > II

b. II > III > V > IV > I

c. II > V > III > IV > I

d. V > III > II > IV > I

e. III > I > IV > V > II

I II III IV V

N

O

H

CO2CH3

NHH

H H

O

OH

I II III IV V

H H

OH

O

H

OHO

CH3

H

ACID-BASE REACTION PRODUCT PREDICTION – CURVED ARROW APPROACH

23. What is/are the product(s) of the following acid-base reaction?

a.

b.

c.

d.

e. None of the above

STRUCTURE AND BONDING IN ALKENES

24. Which of the following is not a characteristic of an alkene bond?

a. 90o and 180o bond angles

b. Planarity

c. Restricted rotation about the p bond

d. The ability to participate in resonance if conjugated

e. More than one of the above

O

H

HH

N

Li

H

O

CH3

Li+ + (CH3)2NH

Li ON

OH

+ (CH3)2NH

Li

O + (CH3)2NH

DOUBLE BOND STEREOISOMERS/CIS-TRANS & E,Z NOMENCLATURE

25. Please draw the structure for (2E,4E)-hexa-2,4-dienoic acid

UNSATURATION NUMBER OR INDEX OF HYDROGEN DEFICIENCY

26. What is the unsaturation number for trans-decalin (bicyclo[4.4.0]decane)?

a. 0

b. 1

c. 2

d. 3

e. 4

PHYSICAL PROPERTIES OF ALKENES

27. Which of the following has the greatest solubility in water?

a. Styrene (vinylbenzene)

b. Cumene (isopropylbenzene)

c. Phenylacetone (2-phenylpropanone)

d. (E)-4-amino-3-phenyl-3-buten-2-one

e. All have less than a 1.0 % v/v H2O solubility

RELATIVE STABILITIES OF ALKENE ISOMERS

28. What is the major product for the following reaction sequence?

a.

b.

c.

d.

e.

An equal mixture of (b) & (c)

ADDITION OF HYDROGEN HALIDES/CARBOCATION STABILITY/CARBOCATION REARRANGEMENTS

29. Isoprene (2-methyl-1,3-butadiene) forms 2 products when treated with HCl. The

major product is 3-chloro-3-methyl-1-butene. The minor product is 1-chloro-3-methyl-

2-butene. Using resonance and a curved arrow approach, explain this finding

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1. EtOH, EtONa, heat

2a. BH3:THF

2b. H2O2, NaOHCl

HO

+ enantiomer

OH

+ enantiomer

OH

REACTION RATE CONSIDERATIONS

30. Referring to the previous question, which of the products should form by the lowest

energy pathway? Which of the products is most stable? How do you think it might be

possible to change the ratio of the 2 to favor 1-chloro-3-methyl-2-butene?

Lowest energy path: ________________________________________________________________

Most stable product: _______________________________________________________________

Method to change the ratio to favor 1-chloro-3-methyl-2-butene: __________________

______________________________________________________________________________________

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CATALYSIS/CATALYTIC HYDROGENATION OF ALKENES

31. Which of the following will convert 1-butyne to 1-butene?

a. H2 + Pd/C

b. H2 + Pd/CaCO3 + Pb(OAc)2 + quinoline

c. H2 + Raney Ni

d. O3, followed by (CH3)2S

e. More than one of the above

ELECTROPHILIC ADDITION REACTIONS – BASIC REACTION OUTCOMES

32. How many products are formed when Br2 reacts with 2,3-dimethylbutene?

a. 0

b. 1

c. 2

d. 3

e. 4

ELECTROPHILIC ADDITION REACTIONS – MECHANISM OF OXYMERCURATION/REDUCTION

33. What is the principal product observed when 1-butyne is treated with aqueous mercuric

acetate, followed by reduction with a mixture of sodium borohydride and sodium

hydroxide? Hint: A tautomerization occurs following initial borohydride reduction

a.

b.

c.

d.

e.

(c) and (d) in equal amounts

ELECTROPHILIC ADDITION REACTIONS – MECHANISM OF HYDROBORATION/OXIDATION

34. Why does “borane” react with alkenes in a 1:3 ratio

a. Borane has 3 empty orbitals available

b. Borane has 3 hydrogens available

c. In losing hydrogen as hydride after the initial reaction, an additional empty

orbital is made available on the boron

d. After the initial addition, the alkyl boron is susceptible to direct nucleophilic

attack by another alkene

e. None of the above correctly explains the above ratio

ALKENE TO ALCOHOL PRODUCT OUTCOMES

35. Which of the following would convert an alkene to an alcohol, with or without the

presence of other functional groups?

a. Treatment of the alkene with aqueous H2SO4

b. Treatment of the alkene with aqueous Br2

c. Treatment of the alkene with O3 @ -78 oC, followed by CH3SCH3, followed by

treatment with NaBH4 (no NaOH)

d. More than one of the above

e. All of the above

ELECTROPHILIC ADDITION REACTIONS – IN DEPTH REACTION OUTCOMES

36. Unknown compound X was found by mass spectrometric accurate mass determination to

have molecular formula C7H12. On catalytic hydrogenation, 1 mol of X absorbs 1 mol of

hydrogen yielding a compound with the molecular formula C7H14. On ozonolysis and

subsequent treatment with zinc and acetic acid, X yields only 6-oxo-heptanal. Which

of the following is compound X?

I II III

IV V a. I

b. II

c. III

d. IV

e. V

GENERATION OF RADICAL SPECIES

37. Which of the following is least likely to generate radicals upon exposure to UV EMR?

a. F2

b. H2O2

c. CH3CH3

d. (CH3)2CHCH(CH3)2

e. (CH3)3COOC(CH3)3

RADICAL ADDITION TO ALKENE PRODUCT OUTCOME

38. Which of the following would be the most likely radical intermediate produced if 2,2-

dimethylpentane is treated with HBr in the presence of AIBN?

a.

b.

c.

d.

e.

(a) and (b) are equally likely

TYPES OF ISOMERISM

39. I & II are

a. Constitutional isomers

b. Enantiomers

c. Diastereomers

d. Identical

e. Not isomeric

Cl

OH

O

Cl

O

OH

I II

IDENTIFICATION OF PLANES OF SYMMETRY AND CHIRAL CENTERS

40. How many stereogenic centers are found in the molecule adamantane?

a. 0

b. 1

c. 2

d. 3

e. 4

NAMING CHIRAL COMPOUNDS

41. The Cahn-Ingold-Prelog stereochemical designations for the isomer of 1,1,2,4-

tetrachlorocyclopentane shown are

H

ClH

Cl

Cl

Cl a. 2R,4S

b. 2S,4R

c. 2R,4R

d. 2S,4S

e. The “R,S” designation does not apply here

PROPERTIES OF CHIRAL COMPOUNDS

42. The pair of compounds shown below would have

CH3

CH2CH3

FH

I

CH2CH3

CH3

FH

II

a. the same melting point

b. different boiling points

c. equal but opposite optical rotations

d. more than one of the above

e. all of the above

DETERMINATION OF ENANTIOMERIC EXCESS

43. Pure L-phenylalanine has a specific rotation of -35.1o. What is the enantiomeric

excess of a 10.0 g/mL solution of phenylalanine which when placed in a standard

1.00 dm cell and analyzed in a polarimeter rotates plane polarized light -31.6o?

Enantiomeric excess: _____________________

DIFFERENTIATION BETWEEN ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS

44. The 2 compounds shown are

Br

HBr

H Br

H

Br

H

and

a. Identical

b. Enantiomers

c. Diastereomers

d. Conformational isomers

e. Meso forms

DIFFERENTIATION OF ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS

45. The 2 compounds shown are

CH3

F

FH

CH3H2N

F

FH3C

CH3

NH2

H

a. Constitutional isomers

b. Enantiomers

c. Diastereomers

d. Identical

e. None of the above applies

RESOLUTION OF CHIRAL COMPOUNDS

46. Knowing hydrogenation occurs at a single face to a bond, you have decided to reduce

pyruvic acid (2-ketopropanoic acid) via hydrogenation in an attempt to synthesis L-

lactic acid, just as L-lactate dehydrogenase does. Upon workup, much to your dismay

you find your product does not appear to rotate plane polarized light. Briefly (but

specifically, and a figure may help) what went wrong?

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ELECTROPHILIC ADDITION REACTIONS – STEREOCHEMISTRY OF Br2 ADDITION

47. Counting stereoisomers separately, how many compounds are possible from the addition

of Br2 to 3-methylcyclohexene in an aqueous environment?

a. 2

b. 4

c. 6

d. 8

e. 10

STABILITY OF CYCLIC ALKANES

48. Which of these C10H18 isomers is most stable?

I II III

IV V

H

H

H

H

a. I

b. II

c. III

d. IV

e. V

CYCLOHEXANE CONFORMATIONAL ANALYSIS

49. Which of the following is expected to be the most stable?

a. cis-1,2-diphenylcyclohexane

b. trans-1,3-diphenylcyclohexane

c. cis-1,4-diphenylcyclohexane

d. trans-1,4-diphenylcyclohexane

e. All of the above are equally stable

NAMING BICYCLIC COMPOUNDS

50. Please provide the IUPAC name for the following compound

Name: _____________________________________________________

REACTIONS OF STEREOISOMERS

51. Noting SN2 reactions proceed with an inversion of configuration, the major

product(s) of the following reaction is(are)

CH2Cl

H CH3

OH

CH2OH

H3C H

CH2Cl

HO CH3

I

III

II

IV

CH2Cl

H OH

CH2OH

H CH3

SN2

a. I

b. II

c. III

d. IV

e. Equal amounts of I and II

HYDROGENATION STEREOCHEMICAL OUTCOME

52. What is/are the products formed when (E)-3,4-dimethyl-3-hexene is subjected to

hydrogenation conditions on a platinum surface?

a. 1:1 (3S,4S)-3,4-dimethylhexane and (3R,4R)-3,4-dimethylhexane

b. 1:1 (3R,4S)-3,4-dimethylhexane and (3S,4R)-3,4-dimethylhexane

c. (3S,4S)-3,4-dimethylhexane alone

d. (3R,4R)-3,4-dimethylhexane alone

e. All of the above in equal proportions