Synthesis Of 1-Bromobutane
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November 15, 2007
Synthesis of 1-Bromobutane
Introduction:
The purpose of this experiment is to synthesize 1-bromobutane from 1-butanol and sodium bromide. In order for this reaction to reach completion there are four major operations that need to be performed. The four major operations include refluxing, simple distillation, separation, and drying.
To begin, in order for the compounds to react they will be dissolved in water and sulfuric acid will be added. The addition of sulfuric acid will then generate hydrobromic acid, an important product in the reaction mixture. The hydrobromic acid will react with the 1-butanol when heat is added to the flask during refluxing. Refluxing is the heating of a flask to boiling and then allowing the vapors to condense and run back into the reaction flask. Refluxing is a good way of keeping a reaction at a constant temperature.
After refluxing is complete the reaction is allowed to distill by way of simple distillation. The simple distillation process is used to help remove and purify a particular substance, in this case the 1-bromobutane, from other components in the reaction flask. However, since the boiling point of 1-bromobutane is 101oC and the boiling point of water is 100oC it would be expected that there would be a large amount of water that will distill out of the flask along with the 1-bromobutane. Other remaining reactants such as a small amount of alcohol and/or acid may also be distilled out along with the water or 1-bromobutane.
Since there is such a high probability of other components in the distillate, separation processes will need to be carried out. Sulfuric acid is first added to the 1-bromobutane layer to remove any leftover starting material and after the 1-bromobutane layer is isolated sodium hydroxide solution is added to remove any remaining acid. Drying using anhydrous calcium chloride pellets is then used to remove any remaining water in the solution and then the simple distillation process is performed again on the dried 1-bromobutane.
It would be hypothesized that the amount of recovered 1-bromobutane will be relatively low since there are many techniques involved, which allow for many places for error and product loss. Also, the theoretical yield for the experiment is 1.5g, which is relatively low.
After the recovered 1-bromobutane is weighed, infrared spectroscopy will be performed. It would be hypothesized that the 1-bromobutane spectrum would produce peaks at the characteristic alkane and halogen peaks; an alkane C-H bond at less than 300cm-1 and a halogen compound peak at less than 650cm-1.
Chemical Chart:
Structure
Formula
Molecular Weight
Melting Point
Boiling Point
Density
Vapor Pressure
Water Solubility
1-butanol
C4H10O
74.12 g
-89.5oC
117.6o
0.81 g/cm3
4 kpa
Soluble 6.32 g/100mL
1-bromo butane
C4H9Br
137.02 g
-112oC
101oC
1.276 g/cm3
0.06 g/100mL Insoluble
Water
18.02 g
100oC
.995 g/cm3
3.2 kpa at 25oC
>= 10g/100mL at 19oC
Sodium Bromide
102.89 g
755oC
1390oC
Sulfuric Acid
H2SO4
98.07 g
280oC
1.84 g/cm3
Soluble; Miscible; Reactive
1-butene
56.11 g
-185.3 oC
-6.1oC
Insoluble
Di-n-butyl ether
C8H18O
130.23 g
-95oC
141oC
.764 g/cm3
4.8 kpa
Insoluble <0.1 g/100mL at 22.5oC
Acetone
C3H6O
58.08 g
-94.3oC
56.2oC
.7857 g/cm3
181 kpa
Miscible
Ethanol
C2H6O
46.07 g
-114.1 oC
78.3oC
.789 g/cm3
7.87 kpa at 25oC
Miscible >= 10g/100mL at 23oC
Sodium Hydroxide
39.997 g
318oC
1390oC
1.11 g/cm3
0 kpa
50 g/100mL Highly Soluble
Calcium Chloride
CaCl2
110.986 g
782oC
1600oC
P-xylene
C8H10
106.167 g
13.3oC
138.3 oC
.861 g/cm3
8.6 kpa
Insoluble
Safety Precautions:
While performing this experiment a lab coat, gloves, and goggles were worn at all times to protect skin, clothes, and eyes. Caution was taken in handling sulfuric acid since it is a highly reactive substance and can cause serious burns. Care was taken with acetone, ethanol, butyl ether, 1-butanol, and vapors of 1-butene because they are all flammable. Care was also taken while handling glassware. All filtrates and chemicals were disposed of in the proper waste containers.
Reaction Mechanism:
NaBr, H2SO4
CH3CH2CH2CH2OH CH3CH2CH2CH2Br + NaHSO4 + H2O
(1-Butanol) (1-Bromobutane)
Flowchart:
-Reflux for 30 minutes
-Perform Simple Distillation
-Simple Distillation
-Infrared Spectroscopy
Observations:
After adding sulfuric acid to the mixture of NaBr, 1-butanol, and water there was a brief yellow stream that appeared