Synthesis of 1-Bromobutane

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November 15, 2007
Synthesis of 1-Bromobutane

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 101°C and the boiling point of water is 100°C 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:
StructureFormulaMolecular WeightMelting PointBoiling PointDensityVapor PressureWater Solubility 1-butanol
C4H10O74.12 g-89.5°C117.6°0.81 g/cm34 kpaSoluble 6.32 g/100mL 1-bromo butane
C4H9Br137.02 g-112°C101°C1.276 g/cm30.06 g/100mL Insoluble Water
H2O18.02 g0°C100°C.995 g/cm33.2 kpa at 25°C>= 10g/100mL at 19°C Sodium Bromide
NaBr102.89 g755°C1390°C
Sulfuric Acid
H2SO498.07 g3°C280°C1.84 g/cm3Soluble; Miscible; Reactive 1-butene
C4H856.11 g-185.3 °C-6.1°CInsoluble
Di-n-butyl ether
C8H18O130.23 g-95°C141°C.764 g/cm34.8 kpaInsoluble = 10g/100mL at 23°C Sodium Hydroxide
NaOH39.997 g318°C1390°C1.11 g/cm30 kpa50 g/100mL Highly Soluble Calcium Chloride
CaCl2110.986 g782°C1600°C
C8H10106.167 g13.3°C138.3 °C.861 g/cm38.6 kpaInsoluble

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,...
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