[Chemistry Class Notes] on Electrophilic Addition Reactions of Alkenes Pdf for Exam

Electrophilic Addition Reactions of Alkenes

As we are about to move in-depth with the addition of alkenes through an electrophilic reaction, it is important to know the 2 other ways this process happens. They are namely ozonolysis and oxidation reactions (particularly with alkenes). Common examples for electrophilic addition reactions with hydrogen halides include hydrogen chloride and hydrogen bromide. 

It can happen through the procedure of Free Radical Mechanism as well. Free radical mechanism reactions follow the hierarchy of Chain Initiation, Chain Propagation and Chain Termination in the free radical group of compounds (reaction with stable molecules). 

The widely accepted order of hydrogen halide is HI > HBr > HCl. symmetrical alkenes (double bonds have the same ligands) such as ethene are easily predictable in their end products, as compared to non-symmetrical like propene (double bonds have a varied count of ligands) alkenes. This phenomenon is also sometimes referred to as Markownikoff’s or Markovnikov rule.

Markovnikov Rule for Electrophilic Addition Reaction

According to the Markovnikov rule, considering the negative part of an adding molecule, it will get linked to that 1 carbon atom that already has a fewer count of hydrogen atoms.

The Oxidation Reaction of Alkenes

When alkenes get oxidized, it leads to the production of alcohols and ketones. Oxidation reactions are also termed as the Baeyer test. 

Let us consider an example with potassium permanganate (KMnO₄). When potassium permanganate, in an aqueous and cool state, is used in the oxidation process of alkenes, this will help in the formation of vicinal glycols.

Oxidation Reaction Of Potassium Permanganate

Note that an oxidising agent like Potassium Permanganate and the presence of a cold condition is necessary for oxidation reactions to take place.