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Important Name Reactions in Organic Chemistry

Name reactions in organic chemistry are very crucial from exam point of view. They are directly asked in exams for good amount of marks.

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Posted by Mahak Jain, 2/11/2020
Important Name Reactions in Organic Chemistry

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Name reactions are a chemical reactions named after its discoverers or developers.

Name reactions are very important from exam point of view as they are directly asked in exams.

The blog contains following name reactions in organic chemistry :

  1. Sandmeyer Reaction
  2. Gattermann Reaction
  3. Finkelstein Reaction
  4. Fittig reaction
  5. Swartz Reaction
  6. Wurtz Reaction
  7. Wurtz – Fittig Reaction
  8. Balz-Schiemann Reaction
  9. Kolbe’s Reaction
  10. Reimer Tiemann Reaction
  11. Stephen Reaction
  12. Rosenmund Reduction
  13. Wolff – Kishner Reduction
  14. Etard reaction
  15. Gatterman – Koch reaction
  16. Tollens’ test
  17. Fehling’s test
  18. Cannizzaro reaction
  19. Kolbe electrolysis
  20. Hell-Volhard-Zelinsky reaction
  21. Aldol condensation
  22. Coupling Reactions
  23. Hinsberg’s Test

Name Reactions in Detail :

1. Sandmeyer Reaction

Formation of aryl halides from aryl diazonium salts.

A primary aromatic amine, dissolved or suspended in cold aqueous mineral acid, when treated with sodium nitrite, forms a diazonium salt. Mixing the solution of freshly prepared diazonium salt with cuprous chloride or cuprous bromide results in the replacement of the diazonium group by −Cl or −Br. It is an example of a radical-nucleophilic aromatic substitution.

Sandmeyer reaction

2. Gattermann Reaction

benzenediazonium chloride  treated with Cu/HCl or Cu/HBr respectively and form chlorobenzene or bromobenzene

Gattermann reaction

3. Finkelstein Reaction

The Finkelstein reaction is named after the German chemist Hans Finkelstein. It is an SN2 reaction, that involves the exchange of one halogen atom for another. SN2 stands for Substitution Nucleophilic Bimolecular reaction

primary alkyl halide react with an alkali metal halide leads to replacement of the halogen via an SN2 Reaction.

Finkelstein Reaction

4. Fittig reaction

Two aryl halides coupled in presence of sodium metal in dry ether.

Fittig reaction

5. Swartz Reaction

Swartz reaction is a reaction in which alkyl bromide or chloride reacts with metal fluorides to form alkyl fluorides. 

In the reaction, higher alkyl halide(R-Cl) react with lower metal halide (AgF) to form lower alkyl halide(R-F).

Swartz reaction

6. Wurtz Reaction

Two alkyl halides reacts with sodium metal in dry ether solution to form a higher alkane. In this reaction alkyl halides are treated with sodium metal in dry ethereal (free from moisture) solution to produce higher alkanes.

Two alkyl halides reacts with sodium to form a new higher alkane-

2R–X + 2Na → R–R + 2Na+X

7. Wurtz – Fittig Reaction

Aryl halides reacts alkyl halides and sodium metal in the presence of dry ether to give substituted aromatic compounds.

Wurtz Fittig Reaction

8. Balz-Schiemann Reaction

The conversion of aryl amines to aryl fluorides via diazotisation and subsequent thermal decomposition of the derived tetrafluoroborates or hexafluorophosphates.

Balz-Schiemann Reaction

9. Kolbe’s Reaction

Kolbe reaction, also known as Kolbe Schmitt Reaction, is an addition reaction.

In this reaction phenol on treatment with sodium hydroxide forms phenoxide ion. This phenoxide ion is more reactive than phenol towards electrophilic aromatic substitution reaction. So, it undergoes electrophilic substitution reaction with carbon dioxide, which is a weak electrophile. Ortho-hydroxybenzoic acid (salicylic acid) is formed as the primary product.

Kolbes reaction

10. Reimer Tiemann Reaction

The Reimer–Tiemann reaction is a chemical reaction in which the ortho-formylation of phenols occurs. As a result, phenol converts to into salicylaldehyde.

Reimer Tiemann reaction

11. Stephen Reaction

Henry Stephen is the inventor of Stephen aldehyde synthesis. This reaction involves the preparation of iminium salt ([R-CH=NH2]+Cl) using tin(II) chloride (SnCl2) and hydrochloric acid (HCl). Furthermore, quenching the resulting iminium salt ([R-CH=NH2]+Cl) with water (H2O) to form aldehydes (R-CHO) from nitriles (R-CN).

Stephen reaction

12. Rosenmund Reduction

Synthesis of Aldehyde from acyl halide. The Rosenmund reduction is a hydrogenation process in which an acyl chloride selectively reduce to an aldehyde.

Rosenmund reaction

13. Wolff – Kishner Reduction

The reduction of aldehydes and ketones to alkanes. Condensation of the carbonyl compound with hydrazine forms the hydrazone, and treatment with base induces the reduction of the carbon coupled with oxidation of the hydrazine to gaseous nitrogen, to yield the corresponding alkane.

Wolff Kishner reaction

14. Etard reaction

Chromyl chloride oxidizes methyl group to get chromium complex which on hydrolysis provides corresponding benzaldehyde.

Etard reaction

15. Gatterman – Koch reaction

Benzene is prepared with carbon monoxide and hydrogen chloride in the presence of anhydrous aluminum chloride to give benzaldehyde.

Gatterman Koch reaction

16. Tollens’ test

Aldehyde heated with ammoniacal silver nitrate solution produces a bright silver mirror due to the formation of silver metal.

Tollen's reaction test

17. Fehling’s test

Fehling’s solution A and Fehling solution B mix in equal amounts to form Fehling’s reagent. Moreover, heating aldehyde with Fehling’s reagent forms a reddish brown precipitate. Formation of reddish brown precipitate confirms aldehyde.

Fehling solution A is aqueous copper sulfate. Fehling solution B is alkaline sodium potassium tartrate.

Fehling's test

18. Cannizzaro reaction

Aldehydes without α-hydrogen atom undergo self-oxidation. It involves the base-induced disproportionation of two molecules of a non-enolizable aldehyde to yield a carboxylic acid and a primary alcohol.

cannizzaro reaction

19. Kolbe electrolysis

An aqueous solution of sodium or potassium salt of a carboxylic acid gives alkane on electrolysis. It is to be noted that, the alkane formed contains even number of carbon atoms.

Kolbe's electrolysis

20. Hell-Volhard-Zelinsky reaction

Carboxylic acids having a α-hydrogen on halogenation at the α-position, give α-halo carboxylic acids. To serve the purpose, we use chlorine or bromine in the presence of small amount of red phosphorus.

Hell volhard zelinsky (HVZ) reaction

21. Aldol condensation

Aldol and Ketol lose water to provide α,β-unsaturated carbonyl compounds.

Aldol condensation

22. Coupling Reactions

Benzene diazonium chloride first reacts with phenol in which the phenol molecule at its para position. It is then mixed with the diazonium salt to give p-hydroxyazobenzene.

coupling reactions

23. Hinsberg’s Test

Benzenesulfonyl chloride (C6H5SO2Cl) reacts with primary and secondary amines to produce sulphonamides.

In this test, shake well the amine with Hinsberg reagent in the presence of aqueous alkali (either KOH or NaOH). Furthermore, we add a reagent containing an aqueous sodium hydroxide solution and benzenesulfonyl chloride to the substrate. 

A primary amine will form a soluble sulfonamide salt. Acidification of this salt then precipitates the sulfonamide of the primary amine. 

A secondary amine in the same reaction will directly form an insoluble sulfonamide. 

A tertiary amine will not react with the sulfonamide but is insoluble.

Heinsberg's reaction test

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Chemical Bonding and Molecular Structure


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