Sun. Dec 15th, 2019

Important Named Reactions in Organic Chemistry

Important Named Reactions in Organic Chemistry

Named reactions are chemical reactions that have been named after their discoverers or developers. In the field of organic chemistry, several commercially important chemical reactions have been named after the chemists who are credited with their discovery. A brief description of some important named reactions in organic chemistry is provided in this article.

The Etard Reaction

The Etard reaction (named after the French chemist Alexandre Leon Etard) is an organic chemical reaction that involves the oxidation of aromatic methyl groups. This reaction is often used for the oxidation of toluene into benzaldehyde.

The use of a reducing environment is pivotal to this reaction because the lack of one would result in excessive oxidation (of the aldehyde into a carboxylic acid).

The Hell Volhard Zelinsky Reaction

The Hell Volhard Zelinsky reaction is an organic halogenation reaction which is often used for the halogenation of a carboxylic acid at the site of the alpha carbon. This reaction is named after the German chemists Carl Magnus von Hell, Jacob Volhard, and Nikolay Zelinsky. This reaction is often abbreviated to the ‘HVZ reaction’.

It is interesting to note that this reaction does not require a halogen carrier and its mechanism proceeds in the absence of one. Instead, a catalytic quantity of phosphorus tribromide is used. This compound proceeds to replace the OH group with a bromide anion.

The Balz-Schiemann Reaction

The Balz-Schiemann reaction is an organic reaction that involves the diazotization of aromatic amines with the help of nitrous acid. This reaction is named after its German discoverers Gunther Balz and Gunther Schiemann. After the diazotization of the aromatic amine, fluoroboric acid is added to the reaction mixture in order to afford an aryl diazonium salt.

The subsequent heating of this aryl diazonium salt (in order to cause a thermal decomposition reaction) yields an aryl fluoride as the final product (along with boron trifluoride and nitrogen gas).

Fischer Esterification

Fischer esterification is an organic chemical reaction in which a carboxylic acid is converted into an ester (in the presence of a strong acid and an alcohol in excess). The final products of the reaction include the required ester and water. The mechanism of this organic reaction involves the continuous removal of water from the system in which the reaction is taking place. It also involves the use of alcohol (in large excess) and a strong acid (which acts as a catalyst). Water can be removed from the system via azeotropic distillation or via adsorption (with the help of molecular sieves). The mechanism can be broken down into the following steps:

  • The protonation of the carbonyl group
  • A nucleophilic attack on the carbonyl group
  • Transfer of a proton to the OH group
  • Removal of water from the system
  • Deprotonation of the charged oxygen

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