Bromination Of E-Stilbene Lab Report

Discussion This experiment done in lab was the Bromination of (E)-Stilbene to produce dibromide stilbene. Though there are three products, the meso-stilbene product is the major product. In order to get theunderstand how to get the correct major product, the full mechanism must be done. In order to achieve the meso product, the double bond in between the carbons attackss molecular bromine which in turn breaks the bromine-bromine bond. The attacked bromine forms a cyclic bridged bromine ion intermediate with a positive formal charge on it. While centered in between phenyl groupscarbons, the bromine that was notn’t attacked gainsned the electrons from the bromine-bromine bond making the molecule negative. The nonattacked bromine then attacks one of the carbons breaking one of the the bridged bromine bonds. The nonattacked bromine ends up on the opposite side of the bromine intermediate. The product is the anti-configuration of dibromide stilbene. The meso product can be flipped in order to get the enantiomer of the product. The other products that are formed during the Bromination of (E)-Stilbene are the D- and L- configurations of dibromide stilbene. Similar in mechanism to the meso-product mechanism, the double bond attacks one of the bromines breaking the bromine-bromine bond. As far are the nonattacked

Typically, 90% of the final product is meso while only 10% is the D/L enantiomers. This is because the though both cations can form at the same time in lab, equilibrium favors the cyclic over an acyclic product due to stability. This causes more of the meso product to be formed rather than the D/L product to be formed. The cyclic product in addition, is favored more due to the delocalization of the positive charge. In other words, the charge is distributed over the carbons in the bridged bromine ion intermediate as opposed to being centralized. To this end, this means that the electron density is