Nucleophilic substitution reactions. Biological & Biomedical Sciences

Lab Report
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Observations
It is commonly observed that reactive halides give relevant precipitates in only 180 seconds at room temperature. On the other hand, the least reactive halides do not give relevant precipitates at room temperature and even when they are heated. During this lab, it was noticed that Sn2 reaction worked perfectly with that of primary alkyl halides and had the good leaving group. At the same time, we found that Cl was not a better leaving group than that of Br, meaning 1-bromobutane could easily react with Nal and 1-chlorobtane failed to show any type of reaction. And when allyl chlorides were combined with primary alkyl halides benzyl bromide and reacted with NaI under the Sn2 mechanism, we found that the Sn2 reaction did not work with tertiary alkyl halides as perfectly as we had expected. This was all because of steric crowding and the poor leaving group of secondary alkyl halides especially Cl.
In the Sn1 reaction, the very first step was losing the leaving group in order to form the carbocation intermediates. This ensured that primary alkyl halides with a good leaving group like Br would definitely generate unstable carbocation. At the same time, alkyl halides with a poor leaving group formed tight shells of ions in the solution and the entire reaction proceeded once the samples were heated. The secondary and tertiary alkyl halides were found to be giving easy Sn1 reactions because of the formation of a stable and reliable carbocation intermediate during the experiment. We also observed that allyl halides and benzyl contained stabilized carbocation; all this was because of the resonance effects. Almost a...