Important Name Reactions of Chemistry in Class 12th CBSE and ISC Board

INDEX

1. Sandmeyer Reaction
2. Gattermann Reaction
3. Balz-Schiemann Reaction
4. Finkelstein Reaction
5. Swartz Reaction
6. Wurtz Reaction
7. Fitting Reaction
8. Wurtz – Fittig Reaction
9. Kolbe’s Reaction
10. Reimer- Tiemann Reaction
11. Rosenmund Reduction
12. Gattermann – Koch Reaction
13. Stephen Reaction or Stephen Reduction
14. Clemmensen Reduction
15. Wolff – Kishner Reduction
16. Haloform Reaction (Iodoform Reaction)
17. Aldol Condensation
18. Cannizzaro Reaction
19. Friedel – Crafts Reaction
20. Grignard Synthesis
21. Esterification Reaction or Fischer Esterification
22. Williamson Synthesis
23. Diazotisation Reaction
24. Etard Reaction
25. Hell – Volhard Zelinsky Reaction
26. Decarboxylation Reaction
27. Hofmann Bromide Reaction
28. Gabriel Phthalimide Synthesis
29. Coupling Reaction
30. Carbylamine Reaction

1.    SANDMEYER REACTION

The DIAZONIUM (C₆H₅N₂Cl) is prepared by treating ice cold solution of ANILINE (C₆H₅NH₂) in excess of dilute HCl with an aqueous solution of NaNO₂ at low temperature (0-5)°C and the reaction is known as DIAZOTIZATION REACTION. BROMO and CHLORO ALKANES can be prepared by treating a freshly prepared DIAZONIUM SALT with CUPPEROUS BROMIDE or CUPPEROUS CHLORIDE and

this reaction is called as SANDMEYER REACTION.

2.    GATTERMANN REACTION

This Reaction is same as SANDMEYER REACTION. But the only difference between both of them is that here we use COPPER POWDER (Cu) in the presence of HCl/HBr, and in SANDMEYER REACTION we use Cu₂Cl₂/Cu₂Br₂ as catalyst.

3.   BALZ-SCHIEMANN REACTION

It is a method of preparation of FLOUROBENZENE. In this method DIAZONIUM SALT is reacted with FLOUROBORIC ACID, followed by heating the complex compound formed.

4.   FINKELSTEIN REACTION

ALKYL IODIDE (R-I) are often prepared by the Reaction of ALKYL CHLORIDE (R- Cl) or ALKYL BROMIDE (R-Br) with SODIUM IODIDE (NaI) in Dry Acetone.

5.    SWARTZ REACTION

FLOUROALKANE (ex. – CH₃CH₂F) are prepared by  treating  ALKYL  CHLORIDE (ex. – CH₃CH₂Cl) or BROMIDE (ex. – CH₃CH₂Br) in the presence of metallic FLOURIDES such as AgF, Hg₂F₂, CoF₂ etc.

6.    WURTZ REACTION

ALKYL HALIDE/HALOALKANE react with metallic SODIUM in the presence of DRY ETHER to form ALKANE containing double the no. of CARBON atom as  present in parent ALKYL HALIDE.

7.    FITTIG REACTION

Aryl Halides prepared with Sodium (Na) in dry ether to give analogous compounds where two aryl groups joined.

8.    WURTZ-FITTIG REACTION

When a mixture of Alkyl Halide and Aryl Halide gets treated with sodium in dry ether, we get an Alkyl Arene.

9.    KOLBE-SCHMITT REACTION

SODIUM PHENOXIDE (C₆H₅ONa) when heated with CARBON DIOXIDE (CO₂) at

400 Kelvin under a pressure of (4-7)atm followed by acidification gives 2-HYDROXYBENZOIC ACID (SALICYLIC ACID) as the main product. This Reaction is called KOLBE’S REACTION.

10.    REIMER TIEMANN REACTION

When PHENOL (C₆H₅OH) reacts with CHLOROFORM (CHCl₃) in the presence of NaOH (SODIUM HYDROXIDE), a CHO group is introduced at ortho position of the Ring. This Reaction is known as REIMER TIEMANN REACTION.

11.    Roesnmund Reaction

The Rosenmund Reduction is a hydrogenation process in which an Acyl Chloride is selectively reduced to an Aldehyde. The reaction is catalysed by Palladium on Barium Sulphate.

12.    GATTERMAN-KOCH REACTION

When Benzene or its derivative is treated with Carbon Monoxide (CO) and Hydrogen Chloride (HCl) in the presence of Anhydrous AlCl₃ or CuCl_2, it gives Benzaldehyde or substituted benzaldehyde. This Reaction is called Gatterman Koch Reaction.

13.  STEPHEN REACTION

When Ethereal solution of a Nitrile is reduced with STANNOUS CHLORIDE (SnCl₂) in the presence of HYDROCHLORIC ACID (HCl) at room temperature, Imine Hydrochloride (R–CH=NH.HCl) is formed. This up on Hydrolysis with boiling H₂O give Aldehyde and the Reaction is called STEPHEN REACTION.

14. CLEMMENSEN REDUCTION

Aldehyde and Ketone are reduced to corresponding hydrocarbon when they are reacted with a mixture of Zinc Mercury Alloy and Concentrated HCl. This reaction is called as Clemmensen Reduction.

15.    WOLFF – KISHNER REDUCTION

Carbonyl group of Aldehydes and Ketones on treatment with Hydrazine which on heating with Potassium Hydroxide in high boiling solvent (ethylene glycol) reduced to CH₂ group.

17.    ALDOL CONDENSATION

In this Reaction two Molecules of an ALDEHYDE or a KETONE condense in presence of a Dilute ALKALI (Dilute NaOH, Na₂CO₃, Ba(OH)₂ etc.) to form a

b-hydroxyaldehyde or b-hydroxyketone resp. These b-hydroxyaldehydes or ketones are collectively called ALDOLS.

18.    CANNIZZARO REACTION

ALDEHYDES which do not contain a a–hydrogen atom when treated with concentrated  ALKALI  SOLUTION  (NaOH)  undergo  disproportionation reaction,

i.e.    self-Oxidation/Reduction.    As    a    result    one    molecule    is    oxidized         to

CARBOXYLIC ACID and another molecule is reduced to ALCOHOL.

22.  WILLIAMSON SYNTHESIS

It is an important Laboratory method for the preparation of Symmetrical and Unsymmetrical ETHER. In this method an ALKYL HALIDE is allowed to react with SODIUM ALKOXIDE.

24.  ETARD REACTION

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

25. HELL – VOLHARD ZELINSKY (HVZ) REACTION

Carboxylic acids having an α-hydrogen are halogenated at the α-position on treatment with chlorine (Cl) or bromine (Br) in the presence of small amount of red phosphorus to give α-halocarboxylic acid. This reaction is known as HVZ reaction.

27.   HOFMANN BROMIDE REACTION

When a Primary AMIDE is treated with an Aqueous or Alcoholic NaOH (SODIUM HYDROXIDE) or KOH (POTASSIUM HYDROXIDE) solution and BROMINE, it gives a Primary AMINE which has one CARBON atom less than the original AMIDE.

28.                                                      GABRIEL PHTHALIMIDE SYNTHESIS

Phthalimide prepared with Ethanolic Potassium Hydroxide produces Potassium salt of Phthalimide when heated with Alkyl Halide followed by Alkaline hydrolysis forms the corresponding primary Amine.

29.  COUPLING REACTION

Benzene diazonium chloride gets reacted with phenol in which the phenol molecule at its para position is mixed with the diazonium salt to give p- hydroxyazobenzene.

30.   CARBYLAMINE REACTION

Primary amine (both aliphatic and aromatic) when warmed with chloroform and alcoholic KOH, gives isocyanides (carbylamines). This is called carbylamine reaction. Carbylamines has an offensive smell. This reaction is answered only by primary amine and hence to distinguish primary amine from other classes of amines.

Preparation of Iodobenzene

Replacement of the DIAZONIUM Group by IODINE is done simply by Shaking the

DIAZONIUM SALT with KI.