C. Y. Yeung (AL Chemistry)
F7 AL Chemistry (Tutorial 25a)
~ Suggested Solution ~
1.
Draw an energy profile for the electrophilic addition reaction between propene and dry
hydrogen bromide.
potential
energy
+
CH3–CH–CH3
+ Br CH3–CH=CH2
+ HBr
CH3–CH–CH3
H < 0
Br
reaction coordinate
2.
Complete the following equations, and label the major product and minor product if
necessary.
(a)
dry HCl
CH3–CH=CH2
(major)
CH3–CH–CH3
(minor)
CH3–CH2–CH2–Cl
+
Cl
CH3
(b)
CH3
CH3
dry HBr
Br
(major)
(c)
CH3–CH=C(CH3)2
(d)
CH3–CH=CH2
(e)
+
dry HBr
I–Cl
+
Br
(minor)
CH3CH2–C(CH3)2Br
(major)
+
CH3CH(Br)–CH(CH3)2
(minor)
CH3CH(Cl)–CH2I
(major)
+
CH3CHI–CH2Cl
(minor)
H2SO4
OSO3H
(f)
dry HBr
CH2
CH3
CH2Br
+
Br
(major)
(minor)
(g)
CH2Br
CH2 + HOBr
CH2OH
Br
+
OH
(major)
(minor)
OH
(h)
+
H2O
OH
H3PO4
+
3000C, 65atm
(major)
(minor)
1/2
3.
C. Y. Yeung (AL Chemistry)
Draw the structure and name the major organic product from the reaction between
cyclohexene and
(a)
bromine water
Br
2-bromocyclohexanol
OH
(b)
bromine in CCl4
Br
1,2-dibromocyclohexane
Br
(c)
hydrogen bromide
Br
4.
bromocyclohexane
An alkane (X) with the molecular formula C5H12 reacts with bromine in the presence of
sunlight to give one monobrominated product Y only.
KOH to give an alkene.
Draw the structure of X and Y.
CH3
CH3
X:
Y does not react with hot alcoholic
Y:
CH3–C–CH3
CH3–C–CH3
CH2Br
CH3
(no H atom on adjacent C,
 no elimination)
5.
With no more than four steps, outline a synthetic route to accomplish each of the following
transformations.
In each step, give the reagent(s) used, the conditions required and the
structure of the product.
(a)
CH3CH2CH2CH2Br
alc. KOH

CH3CH2CHCH2Br
heat under
reflux
Br
Br2 in CCl4
electrophilic addition
dehydrohalogenation
CH3CH2CH=CH2
(b)
CH3CH2CH2CH2OH
conc. H2SO4

heat under
reflux
CH3CH2CHCH3
Br
dry HBr
electrophilic addition
dehydration
CH3CH2CH=CH2
2/2