Chemistry Reference
In-Depth Information
(a) Classify the reaction type.
(b) Is the product chiral? Why?
(c)
Write a mechanism for the reaction as shown.
Q 7.19
Explain why the following reaction sequence is not favorable:
Give a better solution.
Q 7.20
Show how the following interconversions can be performed. More than
one step may be required.
(a) CH
3
CH
2
CH
2
CHO → CH
3
CH
2
CH
2
CH
2
OCH
3
(b) CH
3
CH
2
CO
2
CH
3
→ CH
3
CH
2
CH
2
OH
(c) CH
3
CH
2
OCH
3
→ CH
2
]
CH
2
(d) CH
3
CH
2
CH
2
CO·CH
3
→ CH
3
CH
2
CH
2
CO
2
H
Q 7.21
The chiral substance
A
(C
6
H
12
) reacts with HBr to give a chiral second-
ary alkyl halide
B
(C
6
H
13
Br). Alternatively, if A is treated with Pt/H
2
(hydrogenation), it gives
C
(C
6
H
14
) which is not chiral. Write a reaction
scheme to show the structures of
A
-
C
.
Q 7.22
A symmetrical ether C
6
H
14
O is treated with excess boiling HI to give a
secondary alkyl halide C
3
H
7
I. This iodide reacts with NaCN to give a
product which, on warming with dilute acid, gives 2-methylpropanoic
acid. Draw the reactions which have occurred.
Q 7.23
Suggest a method for the following multistep transformation:
CH
3
CH
2
CH(CH
3
)CH
2
OCH
2
CH(CH
3
)CH
2
CH
3
→ CH
3
CH
2
CH(OH)CH
3
Q 7.24
The compound
A
(C
3
H
6
O) reacts with aqueous NaCN and H
2
SO
4
to
give a racemic cyanohydrin
B
. Hydrolysis of
B
with aqueous acid affords
C
, and further, dehydration of
C
yields
D
which decolourizes a Br
2
test
solution.
D
also reacts with MeOH (excess)/H
2
SO
4
to give
E
(C
5
H
8
O
2
).
Identify the compounds
A
-
E
.
Q 7.25
An aldehyde
A
(C
5
H
10
O) can be reduced by LiAlH
4
to
B
. Treatment of
B
with concentrated H
2
SO
4
at 180 °C gives an alkene
C
. Ozonolysis of
C
gives methanal and
D
(C
4
H
8
O), which has a positive iodoform reac-
tion. Identify
A
-
D
.
Q 7.26
The compound
A
(C
5
H
10
) undergoes ozonolysis to
B
and methanal.
B
when treated with NaOH/I
2
followed by aqueous acid gives a yellow
precipitate and
C
(C
3
H
6
O
2
). C bubbles when it is treated with NaHCO
3
.
Identify
A
-
C
.
Q 7.27
A chiral amide
A
(C
6
H
11
NO) decolorizes a Br
2
test solution.
A
can be
hydrolyzed to an acid
B
(C
5
H
8
O
2
) which on ozonolysis gives
C
(C
4
H
6
O
3
) which is still chiral. Identify
A
-
C
and write a reaction
sequence for the conversions.
Q 7.28
The three isomeric dibromobenzenes were each mononitrated. One
gave a single product, another gave two products, and the third gave
three products. Write equations to explain these results.
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