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 + H2SO4 → HBr + NaHSO4
Secondary reactions：
；
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
Relative
density
Melting
point
Boiling
point
Refractive
index
n-bromobutane
137.03
colorless and
transparent
liquid
1.299
-122.4
101.6
1.4399
n-butyl alcohol
74.12
colorless and
transparent
liquid
0.8098
-89.2
117.7
1.3993
化学实验报告
五、Apparatus
                       
                                 
六、Procedure
（1）50mLboiling flask+50mLwater+6mLconcentrated sulfuric acid
    Cool down
（2）Assembling equipment
(3)  Stop and simple distill
(4) 
Distillate
（crude product）
(5) Dry（CaCl2）
七、Experimental  records
(1) Sulfuric acid soluble in water gives off a lot of heat
(2) The solution of the distillation flask become yellow and the sodium bromide dissolve
(3) Solution is divided into two layers and liquid of the distillation  become clear
(4) Liquid layer, upper as the water phase, the lower is positive bromobutane and liquid for the milky haze
(5) Liquid at 99 ℃ and stable distillation, after rising to 103 ℃, 103 ℃ after fractions and the former part of the don't mix.
八、Data recording
Output:1.3g    theoretical yield:5.8g    productivity:21.7%
Character: colorless and transparent liquid    Refractive index:1.4372
九、Experiment Discussion
1、Turbidity is because it contains a variety of organic phase to organic impurities
2、Plus the bottle stopper of calcium chloride anhydrous dry battery in order to prevent the water vapor in the air into the conical flask, at the same time prevent product turbidity