Make An Electrophilic Addition Reaction By The Bromination Of Cinnamic Acid

The purpose of the experiment was to perform an electrophilic addition reaction by the bromination of cinnamic acid. The product of this reaction is 3-Phenyl-2,3-dibromo propionic acid, which is purified by recrystallization.
Cinnamic acid (3-phenylprop-2-enoic acid) is an unsaturated carboxylic acid. The electron rich π cloud (see Figure 1) in the double bond of this structure is nucleophilic and can be considered a Lewis base. It can therefore be saturated by the addition of a halogen to the double bond. Both of the reactants are non-polar but there is an induced polarity during the reaction due to the electron-rich site at the double bond, which results in bromine acting as an electrophile. In this reaction, the cinnamic acid reacts as an alkene.
Alkenes are unsaturated hydrocarbons with a carbon-carbon double bond. In a double bond, a pair of electrons lies between the carbon atoms in a σ bond and the other pair of shared electrons lie above and below the plane in a π bond. This electron rich area of the molecule is fairly exposed for electrophilic attack.
An electrophile is a species that is attracted to an electron-rich site and can accept a lone pair of electrons. As it is attracted to a negative site, an electrophile is usually positively charged, electropositive (δ+) or has an induced positive
The overall addition reaction is: C=C + X2 → X-C-C-X (see Figure 2). It is not regioselective because both of the bonds formed (C-X) are identical but it is stereoselective. The C-X bonds form in two separate steps resulting in anti-addition. The reagent for halogenation by addition is usually bromine (liquid) or sometimes chlorine (gas). Fluorine is too reactive due to its high electronegativity and small radius. Iodine would react by reversible addition, as the low reactivity is due to its lower electronegativity and large size, making it a weak