Reformatsky Reaction: A Key Reaction in Organic Synthesis

by Yuvi K - December 17, 2023

Reformatsky Reaction:

Reformatsky reaction is one of the most important reaction in organic synthesis. It is a substitution reaction with various complexes being formed between an alkyl halide and an α-hydroxycarboxylic acid (e.g., lactic acid). It was discovered in 1887 by the Russian chemist Vladimir Vasilievich Reformatsky. This reaction is used for the synthesis of α-hydroxyketones, α-hydroxy-α-haloketones and β-hydroxy esters. It is also used to convert carboxylic acids into their corresponding alkyl derivatives.

Reaction Mechanism:

The overall mechanism of Reformatsky reaction can be divided into two parts:-
1. Formation of zinc carbenoid intermediate – In the first step of this reaction, zinc carbenoid (कार्बनल) intermediate is formed from an alkali metal salt of the carboxylic acid, usually zinc chloride(जिंक का च्लाराइड) or a zinc-containing organometallic reagent such as benzylzinc bromide, and a halide, usually bromide or iodide. This zinc carbenoid intermediate then undergoes a nucleophilic substitution reaction with the electrophilic alkyl halide to form the desired product.

2. Nucleophilic substitution reaction – In the second step of the reaction, the zinc carbenoid intermediate undergoes nucleophilic substitution reaction with the alkyl halide in the presence of a base, usually sodium hydroxide or potassium hydroxide, to form the desired product. The product formed is usually an α-hydroxyketone, β-hydroxy ester or an α-hydroxy-α-haloketone, depending on the reactants used.

Applications and Limitations:

Reformatsky reaction is a useful tool for the synthesis of various compounds, including α-hydroxyketones, α-hydroxy-α-haloketones and β-hydroxy esters. It is also used in the synthesis of organic compounds, such as dyes, pharmaceuticals, perfumes, and natural products.

Despite its utility, there are some drawbacks to Reformatsky reaction. The reaction is relatively slow, requiring a long reaction time, and the yields of the products tend to be low. Additionally, the reaction usually requires anhydrous (कोई विस्फोट नहीं ) conditions and the use of soluble zinc-containing organometallic reagents, which can be expensive and difficult to obtain.

Conclusion:

Reformatsky reaction is a useful tool for organic synthesis and is used for the synthesis of various organic compounds. Despite its drawbacks, it is still widely used for its versatility and ease of use. With further advances in synthetic methods, the use of this reaction will continue to grow in the coming years.