Download Draw the complete line-bond formula for the following condensed

1
KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
ORGANIC CHEMISTRY
CHEM 201
Term-092
Major Exam-2
Saturday, May 15, 2010
100 Minutes
Dr. Mohammad Raziq Al Imam
Dr. Mohammad Nahid Siddiqui
NAME……………………….….
Questions
Value
1-7
46
Section 1
Section 2
ID#……………
SEC. #……….
Score
1
3
2
H
Li
4
Be 5B
6
C
7
N
8
O
9
He
F 10Ne
8 - 11
22
12 - 15
32
35
Total
100
53
11
Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar
Br
I
2
(4 points)
Q1. Which alkyl halide in each of the following pairs would undergo more rapid SN2 reaction?
(a)
Br
or
A
CH2Br
B
(b)
Cl
or
C
Cl
D
(c) CH3(CH2)2CH2Cl
E
or
CH3(CH2)2CH2I
F
Br
(d)
Cl
or
G
H
(4 points)
Q2. Which alkyl bromide would give only the following alkenes on dehydrohalogenation
(elimination reaction) using CH3CH2ONa in ethanol? Show stereochemistry when necessary.
Structure of the alkyl bromide
(a)
(b)
(c)
(d)
CH3CH2ONa
C2H5OH
CH3CH2ONa
C2H5OH
CH3CH2ONa
C2H5OH
CH3CH2ONa
C2H5OH
C(CH3)3
3
(5 points)
Q3. The following reaction proceeds with an SN2 mechanism:
O
H3C
H
ONa
+
H3C
Br
A (C4H7DO2)
+
NaBr
D
(a). Draw the structure of the product (A) and indicate stereochemistry.
(b). Draw the structure of the transition state of the reaction.
(c). Draw an energy diagram for the reaction. Label the axes, the starting materials, the
transition state, the products, Ea and H in the diagram. Assume the reaction is exothermic.
(5 points)
Q4. Write a complete mechanism of the following chemical reaction. Use curved arrows to
show the flow of electrons and indicate all the reactive species/ intermediates involved in the
formation of both the products.
Br
CH3OH
50 °C
OCH3
+
4
(6 points)
Q5. Consider the following reaction of 2-bromo-3-phenyl butane:
C6H5
H3C CH CH CH3
Br
CH3ONa, heat
E2
Products (A, B, C)
(a). Predict the major (two) and minor (one) products of the reaction.
A
C
B
+
+
minor
major
(b). If (2R, 3R)-2-bromo-3-phenylbutane was used, only one of the two major
products from the above would form. Described the product by clearly showing the
stereochemistry of the starting alkyl halide.
(c). If (2S, 3R)-2-bromo-3-phenylbutane is used what would be the product?
5
(6 points)
Q6. Two elimination (E2) products are obtained from cis-1-bromo-2-isopropylcyclohexane,
whereas, only one product is obtained from the corresponding trans- isomer.
(a). Draw structural formula for all the E2 products obtained from both cis- and trans 1-bromo-2-isopropylcyclohexane.
C2H5ONa
Br
+
E2
MAJOR
MINOR
C2H5ONa
Br
E2
ONLY
(b). Explain the difference in the major products by clearly drawing the chair
conformation of the starting materials.
6
(16 points)
Q7. Draw a structural formula for the major organic product(s) of each of the following
reactions and specify the most likely mechanism (SN1, SN2, E1 or E2) for formation of the
product(s) you have drawn. Indicate the stereochemistry of the product (s) when it is
applicable.
(a)
Br
CH3OH
Br
(b)
H
(c)
Br
NaN3
DMF
OK
(CH3)3COH
CH3OH
(d)
Cl
C2H5ONa
(e)
Br
Cl
H2O
(f)
(g)
55 °C
Cl
OK
C2H5OH
(h)
Cl
NaI
CH3COCH3
7
(4 points)
Q.8 Rank the relative rate of indicated H abstraction by Br2 in presence of light.
H
H
H
A
B
H
C
Slowest
D
Fastest
(10 Points)
Q.9 Give the major product(s) in the following reactions:
O
CH3 CH3
(a).
CH3CH CHCH3 + 2Br2
hv
N
O
CH3
NBS
(b).
+ O2
CH3
(c).
CH3CHCH3
+ Cl2
350
oC
CH3
(d).
(e).
+ NBS
initiator
CCl4
hv
+ Br2
Br
8
(4 Points)
Q.10 Show the mechanism of the head-to-tail trimer formation of styrene using any radical
initiator. Show the initiation and propagation steps only.
CH2
CH
(4 Points)
Q.11 Write either True or False in the given boxes for the following statements:
(a).
Copolymer is formed by the combination of two same monomers.
(b).
Pyrolysis reaction takes place in presence of oxygen.
(c).
Phenol is used as an initiator in polymerization reactions.
(d).
Less stable radicals tend to undergo rearrangement to more-stable radical.
(6 points)
Q.12 Give the IUPAC name for the following alcohols:
OH
OH
(b)
(a)
Cl
Cl
CH3
Br
(c)
CH3
OH
(d)
OH
9
(15points)
Q.13 Give reactants, reagents and major product in the following reactions:
MgBr
+
(a)
CH3COOH
CH3
(b) CH3
C OH
+ K
CH3
CH2OH
CH2Br
(c)
+
OH
H+
(d)
+ H2O
OH
O
(e)
(f)
+
O
+
CH2CH2CH2CH2OH
CH3
OH
(g)
+
SOCl 2
Pyridine
CH3
O
(h)
H+
COH + CH3CH2OH
HO
(i)
+ H2SO4
Heat
O
CH2OH
(j)
+
CH
10
(6 points)
Q.14 Fill appropriate reactant, reagent or product in the given boxes of the A and B reactions.
OH
CH3CH=CHCCH3
(A) CH3CH CHI
(B)
OH
NaH
CH3CH2Br
(5 points)
Q. 15 Propose a synthesis of compound B starting from compound A. Use any reagents or
organic compounds required to complete this conversion. (more than one steps are needed).
OH
CH=CHCH3
CH=CHCH2C
H
A
B