INTRODUCTION
The purpose of this experiment was to demonstrate the stereochemistry of the electrophilic addition using (E)-Stilbene, a trans-isomer of ethylene. Bromine was added and reacted with (E)-Stilbene to form an alkene. A product was made with both a meso-stilbene dibromide and a d/l-stilbene dibromide, which is trans-stilbene dibromide.
DISCUSSION AND CONCLUSION
For the reaction to form these two different compounds with the same starting reactants, the double bond of (E)-Stilbene has to attack one bromide. One of the possible intermediates are a cyclic bromonium ion and the other is a secondary carbocation. For the first intermediate, the second bromine ion attacks from under the bromine ion that is already present in the structure because of steric hindrance. It can attack either left or right carbon but each would make the same compound. This forms the product meso-stilbene dibromide. For the second intermediate, the bromine ion can attack in two ways, from either side. The result is either a cis or trans product forming fifty percent of the meso-stilbene dibromide and fifty percent of the d/l-stilbene dibromide, a 1:1 ratio. Even with the d/l-stilbene dibromide formation, most of the compound formed will be meso since the intermediates are formed at equilibrium. …show more content…
A stir bar was added to make sure the mixture is homogenous and also to know that the reaction is going at a reasonable rate. The flask was swirled while the bromine solution was being added to mix the contents and after the addition was complete, the reaction flask was loosely stoppered so that the high vapor pressure of the gas would not build up inside the flask. The mixture was then stirred for about 15
The purpose of this experiment was to demonstrate the stereochemistry of the electrophilic addition using (E)-Stilbene, a trans-isomer of ethylene. Bromine was added and reacted with (E)-Stilbene to form an alkene. A product was made with both a meso-stilbene dibromide and a d/l-stilbene dibromide, which is trans-stilbene dibromide.
DISCUSSION AND CONCLUSION
For the reaction to form these two different compounds with the same starting reactants, the double bond of (E)-Stilbene has to attack one bromide. One of the possible intermediates are a cyclic bromonium ion and the other is a secondary carbocation. For the first intermediate, the second bromine ion attacks from under the bromine ion that is already present in the structure because of steric hindrance. It can attack either left or right carbon but each would make the same compound. This forms the product meso-stilbene dibromide. For the second intermediate, the bromine ion can attack in two ways, from either side. The result is either a cis or trans product forming fifty percent of the meso-stilbene dibromide and fifty percent of the d/l-stilbene dibromide, a 1:1 ratio. Even with the d/l-stilbene dibromide formation, most of the compound formed will be meso since the intermediates are formed at equilibrium. …show more content…
A stir bar was added to make sure the mixture is homogenous and also to know that the reaction is going at a reasonable rate. The flask was swirled while the bromine solution was being added to mix the contents and after the addition was complete, the reaction flask was loosely stoppered so that the high vapor pressure of the gas would not build up inside the flask. The mixture was then stirred for about 15