Experiment not reach the surface of the water
Experiment #3Mark A.
Bruder 07. T. A. Michael Hall Alkanes: Chlorination Introduction: The purpose of this experiment is to determine the reactivity of hydrogen atoms on a carbon chain using free radical chlorination. In this experiment 1-chlorobutane will be chlorinated with the combination of sulfuryl chloride and ABCN as an initiator to produce the chlorine radicals.
The combination of 1-chlorobutane and sulfur chloride will produce four dichlorobutane isomers. The isomers produced and their reactivity will be analyzed by the amounts of isomers produced in the product and by gas chromatography.Procedure: 1) Assemble the apparatus in the hood using a Thermowell Heater 2) Use a 25-mL round bottom flask fitted with a reflux condenser which will be connected through a vacuum adapter to a 500-mL filter flask. a. close vacuum adapter w/ cork and make sure the inlet tube does not reach the surface of the water in the filter flask b. make sure any water from the trap does not get sucked back into the reaction flask c.
glass tube must not dip below the surface of the water in the trap 3) Note the differences on pg. 77 of G&M fig. . 65(b) a. it does not use a water aspirator or house vacuum b.
Fit #7 one-hole rubber stoppers w/ a length of glass tubing about 15cm long. c. Tubing needs to be fire-polished on both ends and lubricate hole in stopper with glycerin. d. Use cloth towel to protect your hands as you insert the tubing into the stopper and wipe off excess glycerin.
4) Add stirbar, . 1g of 2,2-azobis(cyclohexanenitrile), 5mL of 1-chlorobutane and 2-mL of sulfuryl chloride and place in flask 5) Stopper and weigh. Then hook flask to reflux condenser 6) Heat solution or 20 minutes, let cool below reflux temperature and check weight.
If the weight loss is not enough continue to next step 7) Add a second . 1g of 2,2-azobis(cyclohexanenitrile) and heat for another 10 minutes. 8) Weigh flask.
If proper amount of weight in not lost after both heating periods, just continue with experiment. 9) Cool reaction mixture in ice-bath, then add 15-mL of ice cold saturated to aqueous sodium chloride (brine) 10) Transfer the resulting two-phase solution to a separatory funnel and separate layers. 11) Wash the organic layer with 10-mL of . M sodium carbonate solution (don’t forget to vent) 12) Use pH paper to determine whether the aqueous layer is basic a. If it is not basic, wash organic layer with another 10-mL of sodium carbonate solution until it becomes basic. 13) After washing the organic layer with brine transfer to Erlenmeyer flask and add several scoops of anhydrous sodium sulfate 14) Swirl for 10-15 minutes during drying period ( the liquid should start to become clear, if not add more drying agent) 15) Decant organic layer into a dry, tarred container 6) Calculate the following: a.
Theoretical yield of product b. Amount of unreacted 1-chlorobutane c. theoretical weight of material (product plus unreacted starting material) expected d.
percentage yield of material recovered 17) Analyze the organic mixture directly by gas chromatography 18) From chromatography data, determine percentage composition of the mixture of the four isomeric dichlorobutanes produced in the reaction Main Reaction and Mechanism: Initiation: pic Termination: pic Preliminary Calculations: pic Table of Reagents: Compound |Amounts Used |Molecular Weight |Boiling Point|Melting Point |Density | | | |(amu) |(0C) |(0C) |(g/mL) | |1-chlorobutane |5. 0-mL |92. 57 |78. 4 |-123. 1 |0. 886 | |pic | | | | | | | |0.
4768 mol | | | | | |Sulfuryl Chloride |2. 0-mL |134. 97 |69. 1 |-55. 1 |1. 667 | |pic | | | | | | | |0. 0247 mol | | | | | |2,2’-azobiscyclonexanenitrile |0.
g |244. 34 | |114 | | | | | | | | | | | | | | | | |pic | | | | | |Table of Products: |Compound |Theoretical |Actual |Theoretical |Theoretical |Theoretical | | |Yield |Yield |Molecular Weight |Boiling Point |Density | | |(grams) |(grams) |(amu) |(0C) |(g/mL) | |1,1-dichlorobutane |3. 37 total for |. 22 |127. 01 |112 |1. 086 | | |all 4 isomers | | | | | |pic | | | | | | |1,2-dichlorobutane | |.
9 |127. 01 |124 |1. 112 | | | | | | | | |pic | | | | | | |1,3-dichlorobutane | |2.
06 |127. 1 |134 |1. 115 | | | | | | | | |pic | | | | | | |1,4-dichlorobutane | |1.
12 |127. 01 |153. 9 |1.
41 | | | | | | | | |pic | | | | | | Data: |Apparatus |Mass (grams) | |Mass of empty flask and stopper |28. 82 g | |Mass of ABCN added initially |. 2 g | |Mass of 1-Chlorobutane |4. 43 g | |Mass of Sulfuryl Chloride |3. 33 g | |Mass of stir bar |2. 21g | |Mass of flask, stir bar, reactants and stopper |37. 90 g | |2nd Mass after ABCN added |37.
9 g | |Total Mass after 1st Reflux |36. 28 g | |Total Mass after 2nd Reflux |35. 77 g | |Final Mass after Reflux |6. 87 g | |Total Mass lost during Reflux |2.
8 g | |Theoretical Yield |4. 49 g | Results: Calculations: % Recovery Mass of dichlorobutane isomers % Recovery = ————————————- x 100 Mass of Reactants 3. 14 g % Recovery = ———– x 100 = 46% 6. 87 g Relative Reactivity of Hydrogen Atoms: % isomer 5. 917 C1 Carbon R. R.
= —————— = ————– = 2. 59 # C-H Bonds 2 % isomer 22. 517 C2 Carbon R. R.
= —————– = ————— = 11. 259 # C-H Bonds 2 % isomer 46. 039 C3 Carbon R. R. = —————– = ————– = 23. 020 # C-H Bonds 2 % isomer 25.
527 C4 Carbon R. R. = —————— = ————– = 8. 509 # C-H Bonds 3Relative Reactivates: 2. 959 C1 = ———- = . 3477 8. 509 11.
259 C2 = ———- = 1. 323 8. 509 23.
020 C3 = ———- = 2. 705 8. 509 8. 509 C4 = ———- = 1.
000 8. 509 C1: C2: C3: C4 .3477:1. 323:2. 705:1. 000 Observations: The reflux apparatus was assembled and a 25-mL round bottom flask, a stir bar, and stopper were all assembled.
The flask, stir bar and stopper were weighed. .12g of ABCN was weighted and added to the flask.
5. 1-mL of 1-chlorobutane and 2. 0-mL of sulfuryl chloride were also added to the flask and everything collected was weighed.The mixture of the ABCN, 1-chlorobutane and sulfuryl chloride was a clear solution inside the flask.
The flask was then attached to the apparatus. The amount of hydrogen chloride and sulfur dioxide gas that will be lost during the process was pre-calculated. The pre-calculations determined that the reaction would be 90% complete were 2.
24 g of gas had been removed. The reaction would be heated to bring the solution to a reflux. Once the reaction was brought to reflux this would be allowed to occur for 20 minutes. Then the flask would could and be massed to determine the about of gas lost.An error occurred when the heating process only took place for 20 minutes when it should have been allowed to heat and then reflux for 20 minutes. The initial lost of gas was only 1. 41 grams.
Another . 10 grams of ABCN was added and the flask was heated again. This time the flask was heated and allowed to reflux for 15 minutes. The flask was then cooled and the amount of gas lost was measured again. After the second reflux only 1. 92 grams was lost.
The flask was then heated again; reflux began and occurred for another 15 minutes.The flask was then cooled and the mass was taken and 2. 38 grams of gas was lost.
Once the proper amount of gas was lost, the mixture was then placed in 50-mL Erlenmeyer flask which contained 15-mL chilled sodium chloride (brine) solution. After allowing sitting the flask formed an organic layer on the top and aqueous layer on the bottom. This mixture was then placed in a separatory funnel. Then 10-mL of .
5 M sodium carbonate solution was used to wash the solution. The pH needed to be tested to make sure the solution was slightly acidic.The original solution was not acidic so another 10-mLs of . 5 M sodium carbonate was added to the solution. The solution was re-tested and the solution was slightly acidic.
The layers were then separated. The aqueous layer was discarded and the organic layer was drained into a 25-mL Erlenmeyer flask. Roughly 3 g of the drying agent anhydrous sodium sulfate was placed in the flask for the drying of the water. After 20 minutes the solution was not dry and more drying agent was placed in the flask. After the second amount of drying agent the solution became dry.The solution was slightly cloudy which meant it was not completely dry but enough had dried for gas chromatography to occur. The product was decanted into another flask then weighed to determine the mass of the product.
The product was then placed in the gas chromatography to determine the isomers of dichlorobutane. Significant Side Reactions: No significant side reactions occurred during this experiment. Method of Purification: The original solution was purified from any residual sulfuryl chloride gas be adding . 5 M sodium carbonate solution.This process had to be repeated because the original carbonate solution did not completely remove all of the residual gas. Once the aqueous layer was removed, the organic layer was then dried with two different doses of anhydrous sodium sulfate.
This then produced 1-chlorobutane, and the four dichlorobutane isomers. 2. 5-mLs of solution was then analyzed via gas chromatography to determine the percent of the four dichlorobutane isomers.
Conclusion: This experiment was performed to determine the % of the four isomers on 1-chlorobutane by the process of free radical chlorination.Once the free radical chlorination process occurs the free radical electron would be attracted to the C1 and C2 carbons. This would make those two carbon radicals less stable. This would then require more energy to form the free radicals. Since this process takes awhile to occur the products also take awhile to form.
Since it takes awhile for the product to occur on the first carbon this makes it the least reactive. This also makes the second carbon slightly more reactive, the third carbon the most reactive and the fourth carbon slightly more reactive then first carbon.The third carbon is most reactive because removing the hydrogen atoms from that carbon allows it to become more stable and have a lower 20 radical. Exercises: 2.
In this reaction a theoretical yield was determined for how much sulfuryl chloride should be to produce enough of the product. During the reaction some of the sulfuryl chloride reacts with the 1-chlorobutane instead of completely reacting with the dichlorobutane isomers. This is during the termination process and since the various radicals combine during this process, it decreases the net radical concentration and it decreases the rate of reaction.
The termination process does completely allow all of the sulfuryl chloride to go to the original products as determined. 9. Relative Reactivity of Hydrogen Atoms: % isomer 5. 917 C1 Carbon R. R.
= —————— = ————– = 2. 959 # C-H Bonds 2 % isomer 22. 517 C2 Carbon R. R. = —————– = ————— = 11. 259 # C-H Bonds 2 % isomer 46. 039 C3 Carbon R.
R. —————– = ————– = 23. 020 # C-H Bonds 2 % isomer 25. 527 C4 Carbon R.
R. = —————— = ————– = 8. 509 # C-H Bonds 3 Relative Reactivates: 2. 959 C1 = ———- = . 3477 8. 509 11. 259 C2 = ———- = 1.
323 8. 509 23. 020 C3 = ———- = 2. 705 8. 509 8. 509 C4 = ———- = 1. 000 8.
509 C1: C2: C3: C4 .3477:1. 323:2. 705:1. 00 Gas Chromatography Results: pic