Aim The purpose of this lab experiment was to synthesize vicinal dihalides and to use the silver nitrate test to test whether bromine is present in the product. Introduction Halogenating an alkene will produce vicinal halides, which are compounds that have halogens on adjacent carbons. Halogenation occurs rapidly when Br2 or Cl2 are used as they give stable products. However, F2 is highly unstable and it gives side products thus, Br2 was used in this experiment. Bromination of alkenes occurs through the process of electrophilic addition reaction. Electrophilic addition reaction is when a nucleophile, which is the alkene which bears the negative charge as it has a pi () bond and is able to donate electrons, attacks an electrophile halogen atom which bear the partially positive charge. …show more content…
This polarization causes a partial positive charge on one bromine (electrophile) and a partial negative charge on the other bromine. The pi bond of the carbons break and a sigma bond of carbon and bromine is made. Instead of a carbocation, the other carbon also forms a nonbonding electron pair with the bromine. This cyclic bromonium ion stabilizes the positive charge and there is no need of a carbocation formation. Then the other bromide ion acts as the nucleophile and attacks the other carbon which bears the partial positive charge and breaks the cyclic interaction. This bromide ion forms a carbon and bromide sigma bond and adds to the side opposite the other carbon bromine bond. This is known as the anti-addition of bromine and it produces trans vicinal dihalides. Thus, stereochemistry is very important in the formation of vicinal dihalides and if the alkene was not symmetrical substituted then a pair of enantiomers will