Problem Set_6 - Chemistry
2311
...

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Unformatted text preview: Chemistry
2311
 Homework
Problems‐
Chapter
6
 Section
I:

 (a) Which
compound
undergoes
substitution
by
the
SN1
mechanism
at
the
fastest
rate?
 
 
 (b) Which
compound
undergoes
substitution
by
the
SN2
mechanism
at
the
fastest
rate?
 
 (c) Write
the
structure
of
the
principal
organic
product
to
be
expected
from
the
reaction
of
1‐ b r o m o p r o p a n e 
w it h 
e a c h 
o f 
t h e 
f o llo w in g :
 ( 1 ) S o d iu m 
io d id e 
in 
a c e t o n e 
 ( 2 ) S o d iu m 
e t h o x id e 
in 
e t h a n o l
 
 
 
 ( 3 ) S o d iu m 
c y a n id e 
in 
d im e t h y l
s u lf o x id e 
 
 (d) In
each
of
the
following
circle
which
reaction
will
occur
faster.
 ( 1 ) 1 ‐ B r o m o b u t a n e 
o r 
1 ‐ Io d o b u t a n e 
w it h 
s o d iu m 
c y a n id e 
in 
d im e t h y l
s u lf o x id e .
 ( 2 ) 1 ‐ C h lo r o ‐ 2 ‐ m e t h y lb u t a n e 
o r 
1 ‐ c h lo r o p e n t a n e 
w it h 
s o d iu m 
io d id e 
in 
a c e t o n e .
 ( 3 ) 1 ‐ c h lo r o h e x a n e 
o r 
c y c lo h e x y l
c h lo r id e 
w it h 
s o d iu m 
a z id e 
in 
a q u e o u s 
e t h a n o l.
 ( 4 ) S o lv o ly s is 
o f 
1 ‐ b r o m o ‐ 2 ,2 ‐ d im e t h y lp r o p a n e 
o r 
t e r t ‐ b u t y l
b r o m id e 
in 
e t h a n o l.
 ( 5 ) S o lv o ly s is 
o f 
is o b u t y l
b r o m id e 
o r 
s e c ‐ b u t y l
b r o m id e 
in 
a q u e o u s 
f o r m ic 
a c id .
 (e) Give
the
mechanistic
symbols
(SN1,
SN2,
E1,
E2)
that
are
most
consistent
with
each
of
the
 f o llo w in g 
s t a t e m e n t s .
 ( 1 ) M e t h y l
h a lid e s 
r e a c t 
w it h 
s o d iu m 
e t h o x id e 
in 
e t h a n o l
o n ly 
b y 
t h is 
m e c h a n is m .
 ( 2 ) U n h in d e r e d 
p r im a r y 
h a lid e s 
r e a c t 
w it h 
s o d iu m 
e t h o x id e 
in 
e t h a n o l
m a in ly 
b y 
t h is 
 m e c h a n is m .
 ( 3 ) T h e 
s u b s t it u t io n 
p r o d u c t 
o b t a in e d 
b y 
s o lv o ly s is 
o f 
t e r t ‐ b u t y l
b r o m id e 
r e a c t s 
m a in ly 
b y 
t h is 
 m e c h a n is m .
 (f) Identify
the
product
in
each
of
the
following
reactions:
 
 































































 


























































 
 
































































 




























































 
 (g) What
is
the
effect
of
doubling
the
concentration
of
sodium
bromide
on
the
following
SN2
 r e a c t io n ? 

 
 
 (1 ) (2 ) (3 ) (4 ) 
 (1 ) (2 ) (3 ) (4 ) 
 (1 ) (2 ) (3 ) (4 ) 
 T h e 
r a t e 
c o n s t a n t ,
k ,
d o u b le s .
 T h e 
r a t e 
o f 
t h e 
r e a c t io n 
d o u b le s .
 T h e 
p r o d u c t s 
o f 
r e a c t io n 
c h a n g e .
 T h e r e 
is 
n o 
e f f e c t .
 (h) Which
of
the
following
is
a
polar
aprotic
solvent?
 M e th a n o l
 A c e t ic 
a c id 
 H exane
 N ,N ‐ d im e t h y lf o r m a m id e 
 (i) Which
of
the
following
ions
has
the
most
nucleophilic
reactivity
in
methanol”
 F lu o r id e 
io n 
 Io d id e 
io n 
 P o t a s s iu m 
io n 
 T e t r a f l u o r o b o r a t e 
 i o n , 
 B F 4 ‐
 S e c t io n 
II.

In d ic a t e 
T r u e 
( T ) 
o r 
F a ls e 
( F ) 
f o r 
e a c h 
o f 
t h e 
f o llo w in g 
s t a t e m e n t s .
 ( a ) I n c r e a s i n g 
 t h e 
 c o n c e n t r a t i o n 
 o f 
 t h e 
 n u c l e o p h i l i c 
 s p e c i e s 
 i n 
 a n 
 S N1 
 r e a c t i o n 
 i n c r e a s e s 
 t h e 
 r a t e 
 o f 
r e a c t io n .
 ( b ) T h e 
 S N2 
 r e a c t i o n 
 o c c u r s 
 b y 
 a 
 b a c k ‐ s i d e 
 a t t a c h 
 o f 
 t h e 
 n u c l e o p h i l e 
 a n d 
 t h e 
 c a r b o n 
 b e a r i n g 
 t h e 
 le a v in g 
g r o u p .
 ( c ) T h e 
d if f e r e n c e 
in 
f r e e 
e n e r g y 
b e t w e e n 
t h e 
r e a c t a n t s 
a n d 
t h e 
t r a n s it io n 
s t a t e 
is 
d e f in e d 
a s 
 t h e 
f r e e 
e n e r g y 
o f 
r e a c t io n .
 ( d ) T h e 
s m a lle r 
t h e 
f r e e 
e n e r g y 
o f 
a c t iv a t io n 
t h e 
s lo w e r 
t h e 
r e a c t io n .
 ( e ) T h e 
o v e r a ll
r a t e 
in 
a 
m u lt i‐ s t e p 

r e a c t io n 
is 
c o n t r o lle d 
p r im a r ily 
b y 
t h e 
s lo w e s t 
s t e p 
in 
t h e 
 r e a c t io n 
s e q u e n c e .
 ( f ) T h e 
 f i r s t 
 s t e p 
 i n 
 t h e 
 S N1 
 r e a c t i o n 
 o f 
 t e r t ‐ b u t y l 
 c h l o r i d e 
 i s 
 t h e 
 h e m o l y t i c 
 c l e a v a g e 
 o f 
 t h e 
 c a r b o n ‐ c h lo r in e 
b o n d .

 ( g ) C a r b o c a t io n s 
h a v e 
a 
t r ig o n a l
p la n a r 
g e o m e t r y .
 ( h ) C a r b o n ‐ h y d r o g e n 
a n d 
c a r b o n ‐ c a r b o n 
b o n d s 
lo c a t e d 
b e t a 
t o 
a 
c a r b o c a t io n ic 
c e n t e r 
s t a b iliz e 
 t h e 
c a t io n ic 
s p e c ie s 
b y 
h y p e r c o n ju g a t iv e 
e le c t r o n 
d e lo c a liz a t io n .
 ( i) T h e 
H a m m o n d ‐ L e f f le r 
p o s t u la t e 
s t a t e s 
t h a t 
t h e 
s t r u c t u r e 
o f 
a 
t r a n s it io n 
s t a t e 
r e s e m b le s 
t h e 
 s t a b le 
s p e c ie s 
t h a t 
is 
n e a r e s t 
it 
in 
f r e e 
e n e r g y .
 ( j) N u c le o p h ilic it ie s 
a r e 
r e la t e d 
t o 
r a t e s 
o f 
r e a c t io n 
w h ile 
b a s ic it ie s 
a r e 
r e la t e d 
t o 
e q u ilib r ia .
 ( k ) D im e t h y ls u lf o x id e 
is 
a 
p r o t ic 
s o lv e n t .

 S e c t io n 
III:
 C o m p le t e 
e a c h 
o f 
t h e 
f o llo w in g 
r e a c t io n s . 
 ...
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