Electrophilic Aromatic Substitution Lab Report

When an aromatic compound such as phenol undergoes nitration, it does so through an Electrophilic Aromatic Substitution (EAS). Undergoing this reaction requires two steps. The first step is the addition of the electrophile, which in this lab was the Nitronium ion formed by the dilute nitric acid solution. This is the rate determining step for this reaction, as during this step aromaticity is lost and the arenium ion is formed. The position of the electrophile to be added is determined by how well the arenium ion can be stabilized once the initial addition occurs. In the case of phenol the greatest stabilization occurs when the electrophile is added to the ortho or para positions due to the ability of the alcohol to donate electrons into the ring system. Meta addition does not occur as it does not lead to an as stable arenium ion intermediate. This is seen

This reaction was able to happen during designated lab time due to the fact that a phenol was used. Phenols or more reactive than unsubstitued benzene rings due to the presence of the alcohol on the benzene ring. The alcohol is considered an activating group due to the oxygen’s ability to donate its lone pairs into the benzene ring thus giving it more electrons and thus making it more nucleophilic and more likely to react with the introduced electrophilic species. As aforementioned, there are various products formed in this reaction the two major products formed though are the ortho and para products. It is debatable which product is more prominent due to steric reasons and the capability of each product to conduct in hydrogen bonding. The ortho products allows for extra stabilization due to hydrogen bonding between the alcohol and nitro group adjacent to one another. The issue here is that these are both fairly large molecules therefore there may be a bit of steric hindrance making this a bit less