-
Preparation of
n
-bromobutane
一、
Purpose
1
、
Study the
principle and method of preparing n-butyl bromide
from n-butyl
alcohol by treatment with
sodium bromide and concentrated sulfuric acid
2
、
Learn the
technique of reflux with a gas trap apparatus and
washing.
二、
Principle
n-Butyl
bromide
can
be
easily
prepared
by
allowing
n-butyl
alcohto
react with sodium
bromide and concentrated sulfuric acid.
Main reactions
：
NaBr + H
2
SO4
→
HBr + NaHSO4
H
2
SO
4
CH
3
CH
2
CH
2
CH
2
OH
?
HBr
???
?
CH
3
CH
2
CH
2
CH
2
Br
?
H<
/p>
2
O
Secondary
reactions
：
H
2
SO
4
CH
3
CH
2
CH
2
CH
2
OH
???
?
CH
3
CH
2
CH=CH
2<
/p>
?
H
2
O
；
H
2
SO
4
2CH
3
CH
2
CH
2
CH
2
OH
???
?
?
CH
3
CH
2
CH
2
CH
2
?
2
O
?
H
2
O
H
2
< br>SO
4
?
HBr
??
?
Br
2
?
SO
2
?
< br>H
2
O
三、
Materials
n-butyl
alcohol
：
4mL
Sodium bromide
：
5g
Concentrated sulfuric
acid
：
2.5mL/6mL
Anhydrous calcium chloride:0.5g
10% aqueous sodium hydroxide:5mL
四
、
Primary reagent
And Product physical constants
Name
Relative
molecular
mass
Character
colorless and
transparent
liquid
colorless and
transparent
liquid
Relative
density
Melting
point
Boiling
point
Refractive
index
n
-bromobutane
137.03
74.12
1.299
0.8098
-122.4
-89.2
101.6
117.7
1.4399
1.3993
n-butyl alcohol
五、
Apparatus
11
10
10
11
10
10
六、
Procedure
（
1
）
50mLboiling
flask+50mLwater+6mLconcentrated sulfuric acid
Cool down
Add
4mLn-butyl alcohol+5gSodium
bromide
Reflux for 30min
（
2
）
Assembling equipment
(3)
Stop and
simple distill
(4)
Distill off
n
-bromobutane
5mLwater