CHEMISTRY

Keghan
Chapter 8

MULTIPLE CHOICE QUESTIONS
Topic: Structure Elucidation
1. An alkene adds hydrogen in the presence of a catalyst to give 3,4-dimethylhexane.
Ozonolysis of the alkene followed by treatment with zinc and acetic acid gives a single organic product. The structure of the alkene is:
CH3
A)

CH3CH=C-CHCH2CH3

(cis or trans)

CH3
CH3

B)

CH3CH2C=CCH3

(cis or trans)

CH2CH3
C)

CH3
CH2=CCH2CHCH2CH3
CH3
CH2

D)

CH3CH2CCHCH2CH3
CH3
CH3

E)

CH3CH2CHCHCH=CH2
CH3

Ans: B

241

Keghan
Chapter 8

Topic: Structure Elucidation
2. Ozonolysis of compound Z yields the products shown below. What is the structure of Z?
O

Z

1) O3
2) Zn, HOAc

O

2HCH + CH3CCH2CH

O

I

II

III

O
H

IV
A)
B)
C)
D)
E)

O

V

I
II
III
IV
V
Ans: B

242

Keghan
Chapter 8

Topic: Structure Elucidation
3. Compound C has the molecular formula C7H12. On catalytic hydrogenation, 1 mol of C absorbs 1 mol of hydrogen and yields a compound with the molecular formula C7H14.
On ozonolysis and subsequent treatment with zinc and acetic acid, C yields only:
O
O

The structure of C is:

I

II

IV
A)
B)
C)
D)
E)

III

V

I
II
III
IV
V
Ans: E

Topic: Structure Elucidation

4. Compound X has the molecular formula C6H10. X decolorizes bromine in carbon tetrachloride. X also shows IR absorption at about 3300 cm-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)
Ans: D

243

Keghan
Chapter 8

Topic: Structure Elucidation
5. An unknown compound, A, has the molecular formula C7H12. On oxidation with hot aqueous potassium permanganate, A yields CH3CH2COOH and (CH3)2CHCOOH.
Which of the following structures best represents A?
A)
B)
C)
D)
E)
Ans: C

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Keghan
Chapter 8

Topic: Structure Elucidation
6. Determine a possible structure for an alkene, X, formula