Bromination of E-Stilbene

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Discussion and Conclusion In this experiment, the bromination of an alkene will be observed and a mechanism to account for the occurrence distribution of the products will be determined. In the first part of the experiment the 0.9 grams of E-stilbene will be put in a flask with 10ml of dichloromethane and then stirred to affect dissolution of the E-stilbene, since dichloromethane is a nonpolar solvent which can dissolve the nonpolar alkene. After the E-stilbene has been dissolved, 5ml of bromine in dichloromethane will be added, which will be stirred for thirty minutes until the solution is white, to ensure that the reaction has gone to completion. Bromine in dichloromethane is used because dichloromethane works as a good solvent for bromination reactions, due to the fact that it doesn’t react with bromine or most other organic molecules. The reddish color of bromine is discharged upon addition to an alkene as the bromine reacts, making this reaction a useful qualitative test for unsaturation when the reaction has gone to completion. The mixture will still be stirred for thirty minutes, regardless of the change in color; since there is a production of an intermediate, the reaction goes by an SN2 mechanism and is dictated by second order kinetics. The dissipation of color will only indicate that the bromine in solution has reacted and not necessarily that the rest of the solution has gone to completion. While this solution is being stirred, the molecules of the mixture are coming in contact and the bromination reaction is occurring. The electrons of the polarizable pi bond in the alkene E-stilbene acts as a nucleophile, a chemical species that donates an electron pair, and attacks one of the bromines in the dibromide molecule, which then causes the sigma bond to break as well. This results in an intermediate, which can either be an acyclic planar carbocation or
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