Butan-1ol + Hydrogen 1-Bromobutane + water
Apparatus
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250 cm3 beaker
- small beaker
-
10 cm3 measuring cylinder
- Reflux condenser
- pear shape flask
- thermometer and holder
- test tubes
- Glass rod
- clamp and stand
- tap funnel and stopper
- Bunsen burner
- long teat pipette
Method
Firstly I put on lab coat, gloves and goggles then gently poured 7.5cm3 of butan-1-ol into a 10cm3 measuring cylinder. This chemical is very dangerous I had to keep the bottle stopper on when I wasn’t using it because it is very dangerous for you to inhale the fumes. I also had to ware gloves when handling the chemical because it is very corrosive. weighed the measuring cylinder then pour the butan-1-ol into a 50cm3 pear shaped flask. I had to weigh the empty measuring cylinder and I had to record the extra mass of butan-1-ol that I had added to the flask.
I had to add 10g of sodium bromide and 10cm3 of water to the flask. I had to set up the apparatus shown in the diagram on the right, which will allow you to cool the mixture while making additions to it.
I placed 10cm3 of concentrated sulphuric acid into the tap funnel. I had to steadily add the acid to the reaction mixture over a period of about 5 minutes. After each addition I had to place a stopper in the funnel I had to hold the funnel with one hand and the stand with the other hand. I had to gently swirl the assembly to help mix the contents of the flask. I had to remove the stopper before attempting to add more acid.
I had to remove the tap funnel and distillation head from the top of the flask and the cooling bath from around the flask. I had to dry the outside of the flask and add a few anti-bumping granules. Set up the apparatus as shown in diagram on the right which I used to heat up the mixture under reflux. I attached a guard tube filled with soda lime I had to take caution when handling the chemical to the top of the condenser. I adjusted the apparatus until the flask rests on a gauze and tripod. I had to make sure that the condenser water supply is on.
I had to gently heat the reaction mixture with a small flame until the mixture starts to boil and then allow it to reflux for around 50 to 45 minutes.
I took about 7.5 cm3 of butan-1-ol
Observations
When the droplets fall into the butan-1-ol solution, it starts to boil viciously. In about 5 minutes the solution started to separate from the sodium bromide.
Then the sodium bromide is starting to dissolve. As the sodium bromide dissolves the higher the solution floats. Then the butan-1-ol solution has turned really dark. Now it has turned brown.
Identifying the product and testing its purity
Apparatus
• Glass rod
• Small funnel with cotton wool plug
• Small beaker
• Thermometer
• Specimen tube
• Distillation apparatus
I had to set up the apparatus like in the diagram below. I had to transfer the dried bromobutane into a distillation flask by pouring it through a small funnel fitted with a small cotton wool plug to catch the drying agent. I had to press the cotton wool gently with a glass rod to extract as much liquid as possible. I had to add a few anti-bumping granules to the flask.
I had to weigh a clean dry specimen tube. Gently heat the liquid in the distillation flask using a small Bunsen burner flame or a electric mantle. At first I saw the butan-1-ene coming out of the solution but nothing will condense in the receiver. Then I saw the temperature of the vapour rise. When the reaction had finished I had to put it into a specimen tube. Then I had to weigh it and record its mass
Problems
Some of the problems that we encountered that we had to stop the reflux half way through the reaction because we ran out of time and had to pack away our apparatus. To try and solve that the next day we reheated the solution put for just a bit longer to make sure every thing had reacted.
Another problem was that we had was caused an error in my finished product were we didn’t put any anti-bumping granules in at the start of the reaction when we were refluxing. To solve that problem I put them in during the reaction when the solution stated to separate.
Another problem was the temperature wasn’t constant because we had to lower the heat because it was too high and turn it up because it was too low.
Method: section 2
CH3CH2CH2CH2-OH CH3CH2CH2CH2-Br
RMM
Carbon= 12
Hydrogen=12 Carbon=48
Oxygen= Hydrogen= 9
Bromine= 80 Bromine= 137
C= 48
H= 10
O= 74
Theoretical yield
(Maximum yield possible) = 74g 137g
1g 137
74
∴6g 137 X6
74
Theoretical yield = 11.12
Percentage yield= Actual yield X 100
Theoretical yield
Theoretical yield = 2.3 X100
= 21%
Now I can calculate the mass using the Density formula but have to rearrange: Density= Mass _
Volume
Mass= Density x Volume= 6.8 X 7.5 = 6g of butan-1-o
Analysis of the results The melting point of my sample of 1-brmobutane was 83 0C and the literature value of the melting point of 1-brmobutane is 1020C so the purity of my product is 85% pure which is quite pure. my sample was not pure because there were same impurities, Some of it didn’t get converted properly and I did something wrong in the preparation.
But I don’t really think that the distillation was that accurate.
The evidence that I have that the substitution reaction was a success is at the end of the experiments I produced 1-brmobutane.
The percentage yield that that was produced was very a small yield because there may be some impurities present. Or I didn’t purify my product properly.
Evaluation
The reason why I did the boiling point is to test if it is pure the boiling point was 88°C and melting point was 96°C the published data of the 1-bromobutane is 102°C and Melting point: -112 °C (this data was obtained from the following website: physchem.ox.ac.uk/MSDS/BR/1-bromobutane). This shows that my sample of 1-bromobutane is not pure. This may be because there were some impurities or we did something wrong or when we were doing the reflux and at the end we had to use a puppet maybe we took some of the clear liquid which may have caused an error.
In industry 1-bromobutane is made with precision and the process is faster at a larger scale and done by machines or computers. The automation makes the production of 1-bromobutane very easy and quicker because computers controlled everything that would normally been done by hand. The equipment and chemicals are transported on conveyor belts
Advantages of automation
- Made the process more efficient.
- Saved more money and time in the long run.
- Reduces labour costs by employing less personal.
- Allows producing economy of scale: a continuous.
Disadvantages of automation
- The automation cost would expensive
- The system will consume large amount electricity.
References:
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- www. physchem.ox.ac.uk/MSDS/BR/1-bromobutane.html
-
GNVQ chemistry science book
