[PDF] Heterocyclic Chemistry Pyridines – Nucleophilic Reactions. Regiochemical Outcome

What is a nucleophilic addition-elimination reaction?

In terms of mechanisms, this is a nucleophilic addition-elimination reaction. The 2,4-dinitrophenylhydrazine first adds across the carbon-oxygen double bond (the addition stage) to give an intermediate compound which then loses a molecule of water . The reaction has two uses in testing for aldehydes and ketones.

What are the types of nucleophilic substitution reactions?

(ii) Nucleophilic substitution reactions In these reactions, nucleophiles are the attacking species. These are of two types : (a) S N 1 ( Nucleophilic substitution unimolecular) reaction is a two step process, e.g., (b) S N 2 ( Nucleophilic substitution bimolecular) reaction is a single step process e.g.,

What are the electrophilic and nucleophilic reactions of pyridines?

This review covers the carbon-nitrogen (C–N) bond forming reactions of pyridines that include both electrophilic as well as nucleophilic substitution reactions. The electrophilic reactions, such as nitration and nitrosation, include both the classical methods and their recent modifications.

What are electrophilic addition reactions?

(i) Electrophilic addition reactions In these reactions, H + (or electrophile) is added to the substrate in the rate determining step. These reactions are given by alkenes and alkynes. e.g.,