NEB Grade 12 Organic Chemistry: Most Important Name Reactions

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Aldol condensation reaction:

Aldehyde or ketone having at least one alpha hydrogen undergoes self-condensation in presence of dil. NaOH to give beta hydroxy aldehyde or beta hydroxy ketone. This is known as aldol condensation.

$\begin{array}{*{20}{c}}{C{H_3} - CHO}\\{Ethanal}\end{array} + \begin{array}{*{20}{c}}{C{H_3} - CHO}\\{Ethanal}\end{array}\mathop  \to \limits^{dil.NaOH} \begin{array}{*{20}{c}}{C{H_3} - \mathop {CH}\limits^{\mathop |\limits^{OH} }  - C{H_2} - CHO}\\{\beta  - Hydroxy{\rm{ }}\beta  - Methyl{\rm{ Ketone}}}\end{array}$

Cannizaro’s reaction

Aldehyde having no alpha hydrogen undergoes self-oxidation and reduction in presence of conc.NaOH to give carboxylic Acid and Alcohol. It is known as Cannizaro’s Reactions.

$\begin{array}{*{20}{c}}{HCHO}\\{Methanal}\end{array}\overrightarrow {Conc.NaOH} \begin{array}{*{20}{c}}{HCOOH}\\{Formic\,Acid}\end{array} \to \begin{array}{*{20}{c}}{C{H_3} - OH}\\{Methanol}\end{array}$

Perkins condensation

Benzaldehyde reacts with acid anhydride in presence of sodium salt of some carboxylic acid at about 180⁰C to give α, β unsaturated carboxylic acid (Cinnamic Acid).

Claisen Condensation reaction:

Ester having at least 1A hydrogen undergoes shelf condensation in presence of strong base like sodium ethoxide to give β-keto Ester.

$2C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - O - C{H_2} - C{H_3}\mathop  \to \limits^{{C_2}{H_5}ONa} \begin{array}{*{20}{c}}{C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - C{H_2} - \mathop C\limits^{\mathop {||}\limits^O }  - o - C{H_2} - C{H_3}}\\{{\rm{Ethyl 3 keto butanoate}}}\end{array} + C{H_3} - C{H_2} - OH$

Benzoin condensation

Benzaldehyde on heating in alcoholic solution of KCN gives bimolecular condensation to form α-hydroxy ketone. This reaction is called Benzoin Condensation.

Carbylamine reaction

Chloroform when gently warm with primary amine in presence of alcoholic NaOH or KOH gives alkyl isocyanide with very offensive order.

CH₃-CH­₂-NH₂ + CHCl₃ + KOH à CH₃-CH­₂-NC + 3KCl + 3H₂O

Reimer Tie mann reaction

Chloroform react with phenol in presence of requests anyway it’s about 60⁰C to 70⁰C to give Salicyaldehyde.

Coupling reaction

Phenol couples with benzene diazonium chloride salt in alkaline medium at ice cold condition to give p-hydroxy azobenzene, an orange red dye.

Diazotization reaction

Aniline reacts with Nitrous acid in presence of NaNO₂ and Conc.HCL at ice cold condition to give benzene diazonium chloride salt, this is known as diazotization reaction.

Friedel- Craft’s reaction:

Haloarene reacts with alkyl halides in presence of Anhydrous AlCl3 to give ortho and para products. This reaction is known as Fridel Craft Alkylation.

Hoffmann’s Bromamide reaction (Decarboxylation reaction)

When Alkane-amide is heated with bromide in presence of aqueous or alcoholic KOH, it gives primay amine having one carbon less than parent amide.

$C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - N{H_2} + B{r_2} + aq.KOH \to 2KBr + \begin{array}{*{20}{c}}{C{H_3} - N{H_2}}\\{Methanamide}\end{array} + {K_2}C{O_3} + 2{H_2}O$

Esterification reaction

The process of formation of Ester is knows as Esterification. When an alcohol is treated with carboxylic acid in presence of conc. Sulphuric acid Ester is formed.

$\begin{array}{*{20}{c}}{C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - OH}\\{Ethanoic{\rm{ Acid}}}\end{array} + C{H_3} - C{H_2} - OH\mathop  \to \limits^{Conc.{H_2}S{O_4}} \begin{array}{*{20}{c}}{C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - O - C{H_2} - C{H_3}}\\{Ethyl{\rm{ Ethanoate}}}\end{array}$

Carbonylation reaction (Oxo process)

Ethan reacts with water gas in presence of cobalt carbonyl as a catalyst to give aldehyde which on further catalytic reduction gives alcohol.

$\begin{array}{*{20}{c}}{C{H_2} = C{H_2}}\\{Ethene}\end{array} + \begin{array}{*{20}{c}}{CO + {H_2}}\\{Water{\rm{ Gas}}}\end{array}\mathop  \to \limits^{CO{{(CO)}_4}} \begin{array}{*{20}{c}}{C{H_3} - C{H_2} - CHO}\\{\Pr opanoal}\end{array}\mathop  \to \limits^{Ni/{H_2}} \begin{array}{*{20}{c}}{C{H_3} - C{H_2} - C{H_2} - OH}\\{\Pr opan = 1ol}\end{array}$

Williamson’s etherification reaction

Haloalkane reacts with alcoholic sodium or potassium alkoxide to give corresponding ether. This reaction is known as Williamsons Etherification.

$\begin{array}{*{20}{c}}{C{H_3} - C{H_2} - ONa}\\{Soadiium\,{\rm{Ethoxide}}}\end{array} + C{H_3} - Cl \to \begin{array}{*{20}{c}}{C{H_3} - C{H_2} - O - C{H_3}}\\{Methoxy{\rm{ Ethane}}}\end{array} + NaCl$

Rosemond reduction

When is daylight is reduced with hydrogen in presence of a Rosamund catalyst to give aldehyde is known as Rosemond reduction.

$\begin{array}{*{20}{c}}{C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - Cl}\\{Ethanoyl{\rm{ Chloride}}}\end{array} + {H_2}\mathop  \to \limits^{Pd/BaS{O_4}} \begin{array}{*{20}{c}}{C{H_3} - \mathop C\limits^{\mathop {||}\limits^O }  - H}\\{Ethanal}\end{array} + HCl$

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