Motivating Effect Of Aniline

Introduction:The purpose of this lab was to determine the activating effect of aniline, phenol, anisole and acetanilide after reacting with pyridinum tribromide in order to undergo electrophilic aromatic substitution. The melting point of the isolated products were measured against the standards in order to determine how strong of an ortho/para activator the compound was based on the product(s) and melting point obtained.
Theory: Electrophilic aromatic substitution is an organic reaction that takes place when an atom that is bound to an aromatic ring is replaced by an electrophile. The electrophile replaces a hydrogen atom on the ring. When a substituent group is present on the original compound, this substituent affects both the regioselectivity of the reaction, as well as the speed. Some substituents act as ortho, para directors, meaning the electrophile will be directed to the 2 or 4 position respectively, while other substituents act as meta directors, directing the electrophile to the 3 position. Substituents are either activating or deactivating with regards to where the electrophile will add. All four of the compounds used were
Phenol, also a strong electron donating group had a melting point similar to the literature value for 2,4,6-tribromophenol. This was expected since phenol is strongly activating and would add bromine to all ortho, para positions. Acetanilide is not as strongly activating, and is sterically hindered with a bulky group. Thus the melting point is the same as the literature value for 4-dibromoacetanilide which adds to the para position. Similarly, anisole which was not tested in lab should show a para addition to produce 4-dibromoanisole. Since it is not as strongly activating only one addition of Br should be