In this post you will find a comprehensive collection of organic chemistry reactions which are exceedingly beneficial for CBSE Board Exams as well as for JEE and NEET aspirants. Immerse yourself in the vast pool of organic chemistry reactions and enhance your understanding in these subjects.
Aldol Condensation
Two molecules of aldehydes or ketones having a-hydrogen condense together in the presence of a base [dilute NaOH, Na2CO3, Ba(OH)2]. This reaction leads to the formation of β-hydroxyaldehyde or β-hydroxyketone, which are collectively referred to as aldol. This condensation reaction occurs through the nucleophilic attack of the enolate anion on the carbonyl carbon atom of the other molecule, followed by the elimination of a water molecule. The resulting β-hydroxyaldehyde or β-hydroxyketone products can undergo further reactions, such as dehydration, to form α,β-unsaturated aldehydes or ketones.
These compounds find applications in various organic syntheses and are important intermediates in the production of pharmaceuticals and other organic compounds. The aldol reaction is a fundamental transformation in organic chemistry and has been extensively studied and utilized in the synthesis of complex molecules.
Birch Reduction
In case of disubstituted alkynes reduction with sodium in liq. ammonia gives trans-alkene predominantly. This type of reduction is known as Birch-reduction.
Beckmann Rearrangement
Oximes, when subjected to various catalysts such as concentrated H2SO4, SOCl2, PCl5, and others, experience a rearrangement process resulting in the formation of substituted amides. This chemical reaction is commonly referred to as the Beckmann rearrangement.
It is worth noting that this transformation plays a crucial role in organic synthesis, allowing the conversion of oximes into more useful compounds such as amides with different substituents. The Beckmann rearrangement finds broad applications in the pharmaceutical and agrochemical industries, where the introduction of specific functional groups is highly desired. By harnessing the power of suitable catalysts, chemists can efficiently manipulate the structure of oximes, leading to the synthesis of valuable products.
Balz-Scheimann’s Reaction
This is the method to prepare fluorobenzene from benzene diazonium salt by first converting it to benzene diazonium tetrafluoroborate. In this process, benzene diazonium salt is reacted with tetrafluoroboric acid to form benzene diazonium tetrafluoroborate. Then, this intermediate compound is further reacted with a reducing agent to yield fluorobenzene.
This method is widely used in organic synthesis for the preparation of fluorinated aromatic compounds due to its simplicity and efficiency.
Clemmenson Reduction
In this particular approach, aldehydes and ketones are effectively reduced by employing the combination of Zn – Hg amalgam and concentrated hydrochloric acid. This method has proven to be quite efficient in achieving the desired outcome of reduction.
Corey-House Reaction
In this reaction, an alkyl halide (1°, 2° or 3°) undergoes a series of transformations. Initially, the alkyl halide is converted into lithium dialkyl copper. Subsequently, this intermediate compound is then combined with another alkyl halide, preferably one that is 1° in nature. This reaction results in the formation of an alkane, which corresponds to the desired product.
Cope Elimination
Tertiary amines are organic compounds that do not undergo oxidation when exposed to KMnO4. Instead, alternative oxidizing agents such as Caro’s acid, ozone, or hydrogen peroxide are employed to convert them into amine oxides. This transformation allows for the introduction of an oxygen atom into the amine molecule, creating a new functional group known as an amine oxide.
Tertiary amine oxide containing a β-hydrogen atom forms an alkene. This reaction is called Cope reaction or Cope elimination.
Carbylamine Reaction
Primary amines, whether aliphatic or aromatic, undergo a transformation when heated with chloroform and an alcoholic solution of potassium hydroxide. This transformation results in the formation of isocyanides or carbylamines.
It is worth mentioning that these compounds possess an exceedingly displeasing smell. The offensive odor emitted by these isocyanides or carbylamines is quite distinctive and unpleasant to the human senses.
Claisen-Schmidt Reaction
It is a base catalysed cross-aldol condensation in which an aromatic aldehyde condenses with aliphatic aldehyde or ketone. It is also known as simply Claisen reaction. The base catalysed cross-aldol condensation is a highly significant reaction in organic chemistry. It involves the condensation of an aromatic aldehyde with an aliphatic aldehyde or ketone, resulting in the formation of a β-hydroxy aldehyde or ketone.
This reaction is widely utilized in the synthesis of various organic compounds and plays a vital role in the development of pharmaceuticals and other chemical products. The Claisen reaction, as it is commonly referred to, is named after the German chemist Ludwig Claisen, who first described it in the late 19th century. His ground breaking work paved the way for the understanding and application of this chemical transformation. The Claisen reaction has since become a fundamental tool in the field of organic chemistry, serving as a key process in the synthesis of numerous valuable compounds. It continues to be a topic of extensive research and has greatly contributed to advancements in the field of chemical synthesis.
In conclusion, the base catalysed cross-aldol condensation, also known as the Claisen reaction, is a crucial reaction in organic chemistry with widespread applications and significance.
Cannizzaro Reaction
It is a self oxidation-reduction reaction in which aldehydes that do not have any a-hydrogen atom undergo disproportionation reaction (i.e. self-redox reaction) in the presence of 50% aqueous or ethanolic solution of alkali in which one of the molecule being reduced to alcohol and other being oxidised to the salt of corresponding acid.
Claisen Condensation
Esters containing a-hydrogen atoms undergo self -condensation in presence of strong base like sodium ethoxide to give b-keto esters.
Curtius Rearrangement
In this method an acyl azide (obtained from reaction of carboxylic acid chloride and sodium azide), on heating in acidic or alkaline medium yields primary amine. The reaction involves an intermediate isocyanate which is hydrolysed to give primary amine.
Diels-Alder Reaction
This reaction involves the addition of a conjugated diene (4pi-electron system) to an unsaturated compound called dienophile (2pi-electron system) to yield a cyclic system.
Etard Reaction
Aromatic hydrocarbons on treatment with mild oxidising agents such as chromyl chloride CrO2Cl2 yield aldehydes.
Frankland Reaction
This is similar to Wurtz reaction with the difference that instead of sodium, zinc is used here in inert solvent.
Dialkyl zinc compounds react with tertiary alkyl halides to give hydrocarbons with quaternary carbon atoms only.
Finkelstein Reaction
Iodoalkanes can be conveniently prepared by treating alkyl chloride or bromides with sodium iodide in acetone or methanol. This is known as Finkelstein reaction.
Friedel-Crafts Reaction
Simple aromatic hydrocarbons can be converted to substituted hydrocarbons by reaction with alkyl halide in presence of Lewis acid like AlCl3 or FeCl3, etc.
Fries Rearrangement
Phenyl esters on heating with anhydrous AlCl3 undergo Fries rearrangement in which acyl group (acetyl, benzoyl, etc.) migrates from phenolic oxygen to ortho or para position of benzene ring resulting in the formation of mixture of o- and p-hydroxyketone.
Gabriel phthalimide synthesis
Phthalimide on reaction with caustic potash forms potassium phthalimide which on treatment with alkyl halide gives N-alkyl phthalimide. This N-alkyl phthalimide on hydrolysis with hydrochloric acid yields primary amines.
Gattermann-Koch reaction
Benzene on reaction with a mixture of CO + HCl in presence of AlCl3 forms benzaldehyde.
Hydroboration-Oxidation of alkenes
Alkenes react with diborane to give alkyl boranes which on oxidation with hydrogen peroxide in presence of hydroxide forms alcohol.
Borodine Hunsdiecker reaction
This reaction involves the treatment of silver salt of carboxylic acid with bromine in refluxing CCl4 to yield alkyl bromide with one carbon atom less than the original acid used.
Hofmann Mustard oil reaction
This reaction is given by aliphatic and aromatic primary amines only, hence it can be used as a test for primary amines.
Alkyl isothiocyanates have a characteristic unpleasant smell of mustard oil. Hence, this reaction is known as Hofmann mustard oil reaction.
Haloform reaction
Methyl ketones on oxidation with sodium hypohalite (NaOX i.e. NaOH + X2) yield haloform along with sodium salt of carboxylic acid with one carbon atom less than the starting ketone.
Hell-Volhard-Zelinsky reaction (HVZ reaction)
Aliphatic carboxylic acids on reaction with bromine or chlorine in presence of small amount of red phosphorous produce alpha-haloacids.
Hofmann Bromamide reaction
Primary amides on reaction with bromine in presence of an alkali yield primary amine with one carbon atom less than the parent amide.
Knoevenagel reaction
In this reaction, aldehydes and ketones condense with compounds containing active methylene group like acid (e.g. malonic acid), ester (e.g. acetoacetic ester, malonic ester) or nitrile, etc. leading to the formation of alpha, beta-unsaturated compound.
Kolbe’s Electrolytic Method
In this method, a concentrated solution of sodium or potassium salt of a carboxylic acid is electrolysed to give higher alkanes.
Leuckart reaction
An aldehyde or ketone on heating with ammonium formate or ammonium formamide, undergoes reductive amination to form formyl derivative of primary amine which on hydrolysis either with acid or base yields primary amine.
Meerwein-Ponndorf-Verley reduction
In this reaction, ketones are reduced to secondary alcohols on heating with iso-propyl alcohol in presence of catalyst aluminium iso-propoxide. In the reaction iso-propyl alcohol gets oxidised to acetone.
Ozonolysis
Ozone on passing through a solution of alkenes in an inert solvent like CCl4 or CHCl3 at low temperature oxidises the alkene to a cyclic product called ozonide, which is unstable and on reduction with reducing agents like zinc and water or hydrogen in presence of palladium gives aldehydes and/ or ketone depending upon structure of alkene, i.e., C= part of the alkene gets converted to C=O.
Oppenauer Oxidation
In this reaction, secondary alcohols are oxidised to ketones in a good yield using aluminium tert- butoxide in excess of acetone.
Oxo Process
In this process, an alkene on heating with water gas (CO + H2) under pressure in the presence of catalyst cobalt carbonyl hydride [CoH(CO)4] yields aldehyde.
Perkin Condensation
It is a condensation reaction in which an aromatic aldehyde condenses with aliphatic acid anhydride in presence of sodium salt of same acid to give a condensate which upon hydrolysis yields a,b-unsaturated acid.
Reimer-Tiemann reaction
Concentrated solution of CHCl3 reacts with phenol in presence of alc. KOH to yield salicylaldehyde.
Reformatsky reaction
It involves the reaction of zinc and alpha-halogenated ester, which add to carbonyl compound to yield beta-hydroxy ester.
Rosenmund reduction
Acid chlorides are reduced to aldehydes by palladised barium sulphate partially poisoned with sulphur or quinoline. (—COCl is reduced to —CHO).
Sandmeyer reaction
In this reaction Diazonium salt react with CuX/HX and respective halide is formed.
Schotten-Baumann reaction
Benzoylation of alcohols or phenols in presence of NaOH is called Schotten-Baumann reaction.
Stephen’s reduction
In this reaction cyanides are reduced to aldehyde in presence of SnCl2/HCl followed by hydrolysis.
Schmidt’s reaction
Carboxylic acids on heating with hydrazoic acid (HN3) at 50-55°C in presence of conc. H2SO4 produce primary amines with one carbon atom less than original carboxylic acid.
Sabatier-Senderens reaction
The method involves the reduction of unsaturated hydrocarbons (alkenes and alkynes) with nickel catalyst. Raney nickel is more reactive than supported nickel catalyst.
Tishchenko reaction
All aldehydes (with or without a-hydrogen atom) in presence of aluminium ethoxide, [Al(OC2H5)3] undergo simultaneous oxidation (to carboxylic acid) and reduction (to alcohol) to form an ester.
Ullmann Reaction
Aryl halides especially iodides on reaction with copper metal yield biphenyls.
Williamson’s synthesis
Metal alkoxides on treatment with alkyl halides yield ethers. The reaction is known as Williamson’s synthesis.
Wacker process
Alkenes are directly oxidised by the catalyst palladium chloride-cupric chloride (PdCl2-CuCl2) in the presence of air or oxygen.
Wolff-Kishner Reduction
In this method, aldehydes and ketones are reduced with hydrazine (NH2–NH2) and KOH.
Wurtz Reaction
In this reaction, ether solution of alkyl halide is treated with sodium to form alkane.
Wittig Reaction
It is an important reaction to change a carbonyl compound into alkene by treating carbonyl compound with a ylide. Ylides are the species which in their ground state have negative carbon adjacent to a positive heteroatom like P,As, Sb, etc. For example, phosphorus ylide, Ph3P+ – –CHR.
Wohler’s reaction
Acetylene is prepared by action of water on calcium carbide. This method is used for laboratory as well as industrial preparation.
Wurtz-Fittig Reaction
When a mixture of aryl halide and alkyl halide reacts with sodium metal in dry ether, substituted arenes are obtained.
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