Nucleophilic Substitution Reactions in Organic Chemistry

As a kind of very important organic chemistry reactions,nucleophilic substitution reactions are generally di vided into four types: ① nucleophilic substitution reactions on the saturated carbon atoms(SN1 and SN2);②nucleophilic substitution reactions on the unsaturated carbon atoms(mainly aromatic ring);③nucleophilic substitution reactions through such intermediate as benzyne,④nucleophilic substitution reactions which substrates are carboxylic derivatives(acyl halides,anhydrides,esters,amides).These nucleophilic substitution reactions have an extremely wide range of ap plications,but due to the differences of reaction mechanisms,we have found it difficult for students to learn and master these reactions.In this paper,we will analyse and compare the four types of nucleophilic substitution reactions systemati cally and find out their regularities so as to meet the need of students.