NEET 2023 is approaching, and it is time to do thorough revisions and give your best for the entrance exam. There are often some important Name Reactions in Organic Chemistry that we tend to overlook while reading the theory. This One-Shot series has provided all the important Name Reactions in Organic Chemistry for NEET 2023.
Table of Contents
- Name Reactions
- Important Name Reactions
- List of Other Name Reactions
- Frequently Asked Questions (FAQs)
Name Reactions
In organic chemistry, name reactions are named after their discoverers or inventors. The name reaction is a type of simplification that avoids having to give a more detailed description of the properties of a specific transformation of interest.
The Grignard reaction, the Frankland reaction, the Wittig reaction, the Cannizzaro reaction, the Friedel-Crafts acylation, and the Diels-Alder reaction are all well-known examples in organic chemistry. Many significant name reactions have been studied and well-established in organic chemistry over many years.
Important Name Reactions
Aldol Condensation
Aldol condensation is a reaction that occurs when an Ξ±-hydrogen aldehyde reacts with a dilute base to produce Ξ²-hydroxy aldehydes termed aldols.
The condensation of two different aldehydes and ketones is known as crossed aldol condensation. It provides a mixture of four products when both of them include Ξ±-hydrogen atoms.
Balz-Schiemann Reaction
The Balz Schiemann Reaction Mechanism describes the synthesis and subsequent thermal degradation of an aromatic fluoroborate to yield the corresponding aryl fluoride. GΓΌnther Schiemann and GΓΌnther Balz, two German scientists, are credited with coining the term the reaction.
Aromatic amines, nitrous acid, and fluoroboric acid are the primary reactants. Aromatic amines perform diazotization under the impact of nitrous acid. Now, fluoroboric acid is added to produce the appropriate aryl diazonium salt. Now, the heat-sensitive aryl diazonium salt is thermally decomposed, yielding aryl fluoride, nitrogen, and boron trifluoride.
An example of a Balz-Schiemann reaction would be the following: the conversion of a phenyl amine into a phenyl fluoride using fluoroboric acid, nitrous acid, and the addition of heat:
Carbylamine Reaction
Hofmann isocyanide synthesis is another name for the Carbylamine reaction. Isocyanides are produced by combining a primary amine, chloroform, and base.
The addition of an amine to the intermediate formed by the dehydrohalogenation of chloroform is part of the Carbylamine reaction mechanism. Dichlorocarbene refers to this intermediate.
The carbylamine reaction can be written as:
R-NH2 + CHCl3 + 3KOH β RNC (Carbylamine) + 3KCl + 3H2O
Cannizzaro Reactionβ
The Cannizzaro reaction, named after Stanislao Cannizzaro, is a chemical reaction in which two molecules of a non-enolizable aldehyde are disproportionated by a base to produce a carboxylic acid and a primary alcohol.
The Cannizzaro Reaction Mechanism explains how two molecules of an aldehyde are converted into one molecule of alcohol and one molecule of carboxylic acid. A nucleophilic acyl substitution on an aldehyde is followed by the leaving group attacking another aldehyde, completing the reaction.
Clemmensen Reduction
Aldehydes or ketones can be converted to alkanes via the Clemmensen reaction, which involves zinc amalgam and hydrochloric acid. The Clemmensen reduction is given the name after a Danish chemist, Erik Christian Clemmensen.
This reaction is particularly efficient in aryl-alkyl ketones reduction produced in Friedel-Crafts acylation. The reduction of cyclic ketones or aliphatic compounds with zinc metal provides optimal results from the reaction.
Etard Reaction
The Etard Reaction is named after Alexandre LΓ©on Γtard, a French chemist. The Etard Reaction is a chemical reaction that uses chromyl chloride to directly oxidise a heterocyclic bound or aromatic methyl group to an aldehyde. Toluene, for example, can be converted to Benzaldehyde by the Etard reaction, as shown below:
Finkelstein Reaction
In the Finkelstein reaction, halogen atoms are exchanged in a Substitution Nucleophilic Bimolecular reaction (SN2 Reaction). It is named after Hans Finkelstein, a German chemist.
It is an organic reaction in which the metal halide salt is used to exchange one alkyl halide for another alkyl halide. By taking advantage of the poor solubility of acetone in newly formed metal halide salt, this reaction takes place in an equilibrium phase. The Finkelstein reaction has a single-step SN2 reaction with stereochemistry inversion as its mechanism.
Friedel-Crafts Reaction
Friedel Crafts reaction is another electrophilic substitution reaction. Alkylation and acylation reactions are the two main categories of Friedel-Crafts reactions. The American chemist James Crafts and the French chemist Charles Friedel developed these reactions in the year 1877.
Gabriel Phthalimide Synthesis
The Gabriel synthesis converts primary alkyl halides to primary amines through a chemical reaction. Traditionally, potassium phthalimide is used in the reaction.
There are three steps in the Gabriel Phthalimide Synthesis Mechanism. The synthesis is named after German chemist Siegmund Gabriel and is used to make primary amines from primary alkyl halides.
The Gabriel Phthalimide synthesis has the major advantage of avoiding excessive alkylation. The reaction of potassium hydroxide with phthalimide also produces a suitable nucleophile in the form of an imide ion. The imide ion performs a nucleophilic substitution reaction on the alkyl halide, yielding N-alkyl phthalimide as an intermediary.
Gattermann Reaction
A process of formylation of compounds with aromatic rings is known as the Gattermann reaction, after German scientist Ludwig Gattermann. Gattermann formylation and Gattermann salicylaldehyde synthesis are other names for the same reaction. The Friedel-Crafts reaction and the Gattermann reaction are similar.
By treating it with Cu/HCl or Cu/HBr, respectively, the Gattermann reaction is used to produce chlorobenzene or bromobenzene from benzenediazonium chloride.
Gattermann-Koch Reaction
The first step in the Gattermann-Koch reaction mechanism is the formation of reactive species with the help of acid. The main objective of the reaction is to attach a formyl group (-CHO group) to an aromatic system. The Gattermann-Koch reaction is illustrated in the example below.
Substrates made of phenol and phenol ether cannot be used in the Gattermann-Koch reaction. Traces of copper(I) chloride are usually needed when zinc chloride is used as a catalyst in the Gattermann-Koch reaction because it functions as a co-catalyst.
Grignard Synthesis
The addition of alkyl/vinyl/aryl magnesium halides to any carbonyl group in an aldehyde or ketone is explained by the Grignard reaction mechanism. The reaction is considered a significant technique for forming carbon-carbon bonds. The alkyl, vinyl, or aryl magnesium halides are known as Grignard reagents.
The Grignard reactions and reagents are named after the French scientist Francois Auguste Victor Grignard, who made the discovery and was honoured with the 1912 Nobel Prize in Chemistry.
Grignard reagents resemble organolithium reagents in that they are strong nucleophiles and capable of forming carbon-carbon bonds. The nucleophilicity of the reagent is further increased when an amido group substituent (amido magnesium halides are known as Hauser Bases) is used in place of the alkyl group substituent.
Kolbeβs Electrolysis Reaction
The Kolbe reaction, also known as the Kolbe Schmitt reaction, is a type of addition reaction that was named after Hermann Kolbe and Rudolf Schmitt. Phenoxide ion is produced when phenol is reacted with sodium hydroxide. When it comes to electrophilic aromatic substitution reactions, the phenoxide ion is more reactive than the phenol.
As a result, it conducts a weak electrophilic substitution reaction with carbon dioxide. The primary result is ortho-hydroxybenzoic acid (salicylic acid). This reaction is commonly known as Kolbeβs reaction.
The Kolbe reaction is initiated by the nucleophilic addition of phenoxide to carbon dioxide, which results in the formation of salicylate.
Ozonolysis
The process of using ozone to break the unsaturated bonds in alkenes, alkynes, and azo compounds (compounds with the functional diazenyl functional group)is known as ozonolysis. This is an organic redox reaction.
Alkenes can be oxidised by ozone to produce alcohols, aldehydes, ketones, or carboxylic acids. Alkynes are subjected to ozonolysis to produce acid anhydrides or diketones. The acid anhydride undergoes hydrolysis to produce two carboxylic acids if water is present in the reaction. Elastomer ozonolysis is also referred to as ozone cracking. The double bonds in elastomers are broken by a trace amount of ozone gas in the atmosphere. The ozonolysis of azo compounds produces nitrosamines.
Reimer-Tiemann Reaction
A type of substitution reaction called the Reimer-Tiemann reaction is named for the chemists Karl Reimer and Ferdinand Tiemann. The process involves ortho-formylation of C6H5OH (phenols).
An aldehyde group (-CHO) is added at the ortho position of the benzene ring when phenols, or C6H5OH, are treated with CHCl3 (chloroform) in the presence of NaOH (sodium hydroxide), resulting in the formation of o-hydroxybenzaldehyde. The Reimer Tiemann reaction is the common name for the reaction.
The conversion of phenol to salicylaldehyde (2-hydroxy benzaldehyde) is a notable example of the Reimer-Tiemann reaction.
Rosenmund Reduction
Rosenmund Reduction Mechanism describes the way acyl chlorides are preferentially reduced into aldehydes. The reaction was named after Karl Wilhelm Rosenmund since he initially described it in 1918.
In the Rosenmund reaction, molecular hydrogen reacts with the acyl chloride in the presence of a palladium on the barium sulfate-based catalyst. Due to its small surface area, barium sulphate reduces the palladium’s activity and prevents over-reduction. A poison can be added to completely deactivate the palladium catalyst should the necessity for additional palladium activity reduction arise (as in the case of highly reactive acyl chlorides).
By using hydrogen gas over palladium that has been poisoned by barium sulphate, the Rosenmund reduction converts acid chlorides into aldehydes. Below is an illustration of this catalytic hydrogenation of acyl chlorides to aldehydes.
Due to the strong reactivity of hydrogen gas, it easily initiates a substitution in the acyl chloride, producing HCl and the desired aldehyde.
Sandmeyer Reaction
Sandmeyer reaction is a form of substitution reaction which is widely used in the formation of aryl halides from aryl diazonium salts. Catalysts for this process include copper salts like chloride, bromide, or iodide ions. It is noted that unique transformations of benzene can be performed via the Sandmeyer reaction. The modifications comprise hydroxylation, trifluoromethylation, cyanation, and halogenation.
A good example of a radical-nucleophilic aromatic substitution is considered to be a Sandmeyer reaction. This reaction is a helpful method for substituting various amino groups on aromatic rings. The amino group that is joined to an aromatic ring is turned into a diazonium salt during the Sandmeyer reaction, which can then be converted into different functional groups.
Stephen Reduction Reaction
The addition of gaseous hydrogen chloride to the provided nitrile initiates the Stephen Reaction Mechanism. The reaction is called Stephen aldehyde synthesis after its inventor Henry Stephen. The reaction involves the formation of aldehydes from nitriles using tin(II) chloride and hydrochloric acid, followed by the quenching of the iminium salt with water. Another useful byproduct of this process is ammonium chloride.
The Stephan reaction is used to produce acetaldehyde from methyl cyanide, as shown in the diagram below.
As indicated above, when nitrile is reduced with stannous chloride and hydrogen chloride gas (in ethyl acetate solvent), an imine intermediate is generated. The equivalent aldehyde is obtained by hydrolysis of this imine intermediate.
Swarts Reaction
Alkyl fluorides are often produced from alkyl chlorides or alkyl bromides using the Swarts reaction. This is performed by heating the alkyl chloride/bromide in the presence of the fluoride of heavy metals (silver fluoride or mercurous fluoride). If potassium fluoride or sodium fluoride are used, the reaction will still proceed, but the yield will be much lower. This reaction was first confirmed by Frederic Jean Edmond Swarts in 1892.
The Swarts reaction mechanism is very straightforward: a new bond between fluorine and carbon is formed once the metal fluorine bond is broken. The displaced chlorine or bromine atoms now combine with the metal. The term “Swarts reagent” refers to the antimony trifluoride and chlorine combination. According to Swarts’ rule, the fluoride that is produced after fluorination will always have a lower boiling point than the corresponding chloride.
Williamson Ether Synthesis
The Williamson ether synthesis, which is the standard procedure for producing ether, involves the nucleophilic displacement of a halide ion or other suitable leaving group by an alkoxide ion.
The name of the reaction was popularised after Alexander William Williamson created it in 1850. Deprotonated alcohol and an organohalide are combined in the Williamson Ether Synthesis reaction to produce ether.
- Williamson Ether Synthesis usually occurs as an SN2 reaction of a primary alkyl halide with an alkoxide ion. This chemical reaction demonstrated how ethers are structured.
- This reaction can only be effective if the alkyl halide is primary or secondary, requiring the SN2 pathway for synthesis.
- The ethers produced in this method are more complex structures and include more carbon atoms than either of the initial materials.
Wolff Kishner Reduction
A hydrazone anion is first created in the Wolff Kishner reduction mechanism, which subsequently releases the nitrogen atom to produce a carbanion. This carbanion then produces a hydrocarbon when it interacts with the water in the system. The solvent used for this process is diethylene glycol.
Aldehydes and ketones are converted to alkanes in this organic reduction mechanism. Some carbonyl compounds can be easily reduced to alkanes because they are stable under strongly basic conditions (The carbon-oxygen double bond becomes two carbon-hydrogen single bonds).
Step 1:
The aldehyde or ketone undergoes hydrazine treatment. The hydrazone for the reaction is produced. The reaction is seen below.
Step 2:
Step 3:
Step 4:
Step 5:
Although the method generally begins with the condensation of hydrazine to produce hydrazone, using a pre-formed hydrazone can offer benefits including a shorter reaction time, reactions that happen at room temperature, or extremely mild reaction conditions. Different solvents and reaction temperatures are also required for the preformed hydrazone substrates that can be used in this reaction.
Wurtz Reaction
In Wurtz’s reaction, an example of an organic chemical coupling reaction, sodium metal reacts with two alkyl halides in the presence of a dry ether solution to produce a higher alkane and a compound that contains both sodium and the halogen.
This reaction has the name of the French chemist Charles Adolphe Wurtz, who also discovered the aldol reaction. For the synthesis of alkanes in organic and organometallic chemistry, the Wurtz reaction is a highly efficient process. With the use of sodium and dry ether solution, two distinct alkyl halides are coupled in this reaction to produce a longer alkane chain.
Wurtz Fittig Reaction
The Wurtz-Fittig reaction mechanism can be understood either through the organo-alkali mechanism or the radical mechanism. The Wurtz-Fittig reaction is named after the chemists Charles Adolphe Wurtz and Wilhelm Rudolph Fittig and refers to the chemical reaction that occurs when aryl halides, alkyl halides, sodium metal, and dry ether are combined to produce substituted aromatic compounds.
If the alkyl halide is chemically more reactive than the aryl halide, the alkyl halide will first form the carbon sodium bond and then act as an aryl halide’s nucleophile, which will aid in the formation of asymmetrical products in the reaction. If the reactants are created with halogens of different periods, the deviation in reactivity between the alkyl halide and aryl halide can be obtained conveniently.
Fischer Esterification
Fischer esterification is an organic reaction used to convert carboxylic acids in the presence of excess alcohol and a potent acid catalyst, producing an ester as the end product. This ester is produced along with water. Below are a few examples of Fischer esterification reactions.
Azeotropic distillation or adsorption using molecular sieves are two methods used for removing water from the system during this esterification process. It serves as an explanation of a nucleophilic acyl substitution reaction. The substitution is focused on the nucleophilicity of the alcohol and the electron affinity of the carbonyl carbon.
Haloform Reaction
The Haloform reaction is a chemical reaction that produces haloforms by halogenating methyl aldehyde or methyl ketone in the presence of a base.
As shown above, when the methyl ketone is treated with the bromine halogen in an aqueous sodium hydroxide solution, polyhalogenation occurs, followed by the cleavage of the methyl group. The carboxylate and tribromomethane, which is the necessary haloform, are the end products of the reaction.
HellβVolhardβZelinsky Reaction
Hell Volhard Zelinsky Reaction Mechanism is distinctive among halogenation reactions in that it occurs without the use of a halogen carrier. At the alpha carbon, the reaction is used to halogenate carboxylic acids.
Carl Magnus Von Hell, Jacob Volhard, and Nikolay Zelinsky are the chemists who gave their names to this reaction. The reaction is initiated by adding one molar equivalent of diatomic bromine and one molar equivalent of phosphorus tribromide (catalytic quantity).
The fluorination and iodination of carboxylic acids are not possible with the HVZ reaction. If the Hell Volhard Zelinsky reaction is carried out at extremely high temperatures, hydrogen halide may be eliminated from the product, resulting in the formation of beta-unsaturated carboxylic acids.
Hoffmann Bromamide Reaction
The standard Hoffmann Bromamide reaction process involves attacking the amide with a strong base such as an alkali, resulting in deprotonation and the subsequent formation of an anion.
A primary amide is converted into a primary amine with one less carbon atom using this reaction process. This is done by heating the primary amide with a solution of water, a strong base, and a halogen (chlorine or bromine). The following is an example of the reaction.
This method produces primary amines that are not affected by secondary or tertiary amines. The Hoffmann degradation of amide is another name for the reaction. The primary amide is converted into an isocyanate intermediate when bromine reacts with sodium hydroxide to produce sodium hypobromite (NaOBr).
Water now attacks this isocyanate intermediate, beginning a sequence of proton transfer steps. The ammonium cation, which was created when water attacked the isocyanate intermediate, is quenched by the heat conditions to produce the necessary amine product. This results in the explosion of carbon dioxide gas.
List of Other Name Reactions
- Fischer Indole Synthesis
- Walden Inversion
- Perkin Reaction Mechanism
- Diels-Alder Reaction Mechanism
- Michael Addition Mechanism
- Heck Reaction
- Mannich Reaction Mechanism
- Hydroboration oxidation reaction
- Claisen condensation
- Lindlar Catalyst
- Maillard Reaction
- Robinson Annulation
- Woodward Reaction
- Oppenauer Oxidation
Related Links:
- NEET Chemistry MCQs – Important Questions and answers
- MCQs on Organic Chemistry for NEET
- NEET Chemistry 2023 β Important Topics and Preparation Tips
- Flashcards for NEET Chemistry – Organic Chemistry β Some Basic Principles and Techniques
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Frequently Asked Questions
Give the reason for the fusion of an organic compound with sodium metal for testing nitrogen, sulphur and halogens.
Covalent bonds exist between halogens, nitrogen, and sulphur in organic compounds. If they are in the ionic state, they can be detected using Lassaigneβs test. The organic compound and sodium metal can be fused to accomplish this. These chemical reactions include the use of organic compounds to provide the C, N, S, and halogen.
- Na + C + N β NaCN
- Na + S + C + N β NaSCN
- 2Na + S β Na2S
- Na + X β NaX (X = Cl, Br, I)
How are organic compounds classified?
The organic compounds are classified as:
- (i) Acyclic or open chain compounds
- (ii) Alicyclic or closed chain or ring compounds
- (iii) Aromatic compounds
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