Friedel-Craft Alkylation-Reflux,Extraction

and Distillation

ABSTRACT:

          The purpose of this investigation was to attain Cumene by mixing benzene, isopropyl alcohol, and a catalyst, sulfuric acid.  In doing so we practiced calculating the formula weights of each solution, converting each solution from moles to grams, and finding the volumes of each by using the masses and the densities.  As we preformed the experiment we were able to utilize the materials in our laboratory to attain our result, a solution, cumene.  Another essential part of this experiment was separating aqueous from non-aqueous solutions in order to attain only an organic solution as a result.

          Some of the basic procedures include isolating each solution in a flask and placing them in an ice bath for at least 15 minutes.  Then the benzene and the sulfuric acid were mixed and stirred.  After that, the isopropanol was mixed into the solution by adding drops at a time.  Next we separated the layers by washing (adding water and discarding the first layer) the new solution.  This was done in order to attain only the organic solution, which was the cumene.

          What is this solution and what can it be used for?  Cumene is mixture of benzene and isopropanol.  This solution can be used as paint thinner and enamels.  Cumene can also be dangerous to our environment by contaminating the air and water.   It can also be released by the combustion of petroleum and is released by the use of cigarettes (Summary of Data for Chemical Selection Cumene, 3/96.)  

TABLE:

PROCEDURES AND OBSERVATIONS:

1. Before we began the experiment, we had to calculate the volume of each solution that was to be used.  The mass and density of each was known so the formula for density could be rearranged from D=m/v to V=m/D.  First we had to convert the moles of each solution to grams (moles x formula weight).

Benzene:  1.0 moles x 78.11g/1mol = 78.11g Benzene

Isopropanol:  1.0 moles x 60.1g/mol = 60g Isopropanol

Sulfuric Acid:  0.5 moles x 98.08g/mol = 49.04g Sulfuric Acid

          Then we used the mass and density to find the volume (V=m/D).

                   Benzene:  78g/0.8748g/mL= 89.2mL

                   Isopropanol:  60g/0.782g/mL= 76.4mL

                   Sulfuric Acid:  49.04g/1.840g/mL= 26.65mL

2. After that, while under a hood, we measured out our volumes of each solution in a graduated cylinder and put them each in a different Erlenmeyer flask and placed a stopper in each to prevent the vapors from escaping.
3. The next step was to put each flask with each solution in an ice bath for 15 minutes in order to cool down to room temperature.
4. As I let the flasks sit in the solution I began set up the rest of my experiment.  I gathered the rest of my materials (ring stand, clamps, large beakers) and set them up in the hood for safety precautions. 
5. Then we put the stirrer then the benzene in the round bottom flask then added the sulfuric acid thereafter.
6. We placed the new solution on the ring stand after shaking it in order for the solution to mix well.  This was done for 15 minutes while leaving the round bottom flask in the ice bath (it was placed over the stirrer).
7. Then next thing that was done while we waited for the solution to stir was to place the isopropyl alcohol in the separatory funnel, which would be added later. 
8. In order to stop the reaction we had to add 100mL of ice to a beaker and add our solution that contained the benzene, sulfuric acid, and the isopropanol, to the ice. 
9. We left the beaker on the stirrer for approximately another 15 minutes.  We       began to visualize the two different layers in the container. 
10. Then we put the solution in the separatory funnel again in order to remove the inorganic material.  We emptied out the first layer then discarded it in its proper container.
11. The next step was to add 25mL of water to the remaining solution in order to attain another two layers.  This process is called washing.  As I let my layers separate, the bottom layer looked foggy and the top layer was clear. 
12. We continued to wash, adding 25mL of water two more times. 
13. Finally, after washing and separating, we attained our organic solution (containing carbon) while putting it in a clean, dry Erlenmeyer flask and discarded all of the inorganic solution (not containing carbon).
14. After that, we added the Magnesium sulfate, MgSO4, and checked if the MgSO4 would clump at the bottom of the flask after being swirled.  Since the Magnesium sulfate did clump, we were able to perform the last step.
15. Finally, the last step was to filer all the MgSO4 out of the new organic                                   solution called Cumene.  The cumene was the organice layer, which contained Benzene and isopropanol.  The other layer, which was inorganic, contained sulfuric acid and water (maybe a little bit of propanol.)
16. The distillation is to be preformed this week in order continue the Friedel-Craft alkylation process. 

CONCLUSION:

          In essence, we were able to attain the solution, Cumene, by following the procedures given to us by our instructor in order to make and separate the solutions.  It was important to calculate and measure out the correct volumes that were to be used.  Though we did not complete the lab and perform the distillation, and were not able to finish the experiment, thus nor calculated the percent yield; we were still able to achieve our final solution of Cumene.