Sergey Nikolaevich Reformatsky discovered Reformatsky reaction

Sergey Nikolaevich Reformatsky – discoverer of Reformatsky reaction

Category : Personalities
Published by : Data Research Analyst, Worldofchemicals.com

Biography & Contributions

Sergey Nikolaevich Reformatsky (S.N. Reformatsky) was a Russian chemist born on April 01, 1860 – died on July 28,1934. Reformatsky was credited for his discovery of Reformatsky reaction, which is the major method for forming beta-hydroxycarbonyl compounds.

Reformatsky reaction


The Reformatsky reaction is an organic reaction which condenses aldehydes (or ketones), with α-halo esters, using a metallic zinc to form β-hydroxy-esters followed by an acid work-up.The Reformatsky reaction begins with oxidative addition of the zinc metal to the carbon-halogen bond of the α-haloester. Two of the resulting compounds coordinate to each other forming a dimer,which then undergoes a rearrangement to give two molecules of O-zinc enolates.This step is the oxidative addition.The enolate does a nucleophile substitution on the benzaldehyde and forms a chelate.

The oxygen of the aldehyde or ketone reagent then coordinates to the zinc and another rearrangement ensues which joins the two reagents with a carbon-carbon bond. An acid work-up then cleaves the zinc-oxygen bond to give the final β-hydroxyester product and a zinc(II) salt.

Reformatsky reaction in laboratory

30mL of toluene solvent is dried under a N2 atmosphere,on sodium. Small pieces of the metal are slowly added in the flask containing the solvent. A balloon filled with N2 is fixed to the condenser.

A spoon of benzophenone is added to the solution to show the change of color when the water and the Oare no longer in the solvent.

When it was dried, the solvent was distilled (under the N2 atmosphere) at about 112°C.The same is done to 25mL of ether, distilled at about 37°C. All the equipment was dried before use. In a twinneck bottom flask of 250mL, dried zinc 8g was placed with a magnetic agitator.

The addition funnel was filled with 11.1mL of ethyl-2-bromoacetate,12.4mL of freshly distilled benzaldehyde,16mL of toluene (distilled on Na under N2) and 5mL of ether. The solution was slowly (1h) poured into the flask, after the reaction began.Then, the solution was refluxed for 30min, cooled down with an ice/water bath and sulfuric acid 50mL 10% was added. In a separatory funnel the aqueous phase was separated and the organic phase was washed successively with H2SO10per cent (2x50mL),water 50mL,saturated NaHCO3(2x30mL), H2O(2x20mL) and 20mL saturated NaCl.

Then,the organic phase was dried on MgSO4,the solvent was separated on the rotary evaporator.After the solvent was evaporated, the product was distilled under vacuum at about 160°C.

Reference

[1] © From, http://www.asso-etud.unige.ch/aecb/rapports/2eme/chiorg/p27reformatsky_pacho.pdf

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