Organic reactions are mostly named after the reagents added to react with organic substrate. For example, halogenations of alkenes refer to the addition of halogens in the presence of chloroform or carbon tetrachloride to alkene, resulting to an alkyl halide.
However, there are reactions named after the discoverer/s. These are chemists or scientists who had perfected the reaction by optimizing its conditions and finding its significance in the myriad of organic reactions.
Here are some of these named organic reactions.
1. Baeyer-Villiger Oxidation
This reaction involves the oxidation of a ketone in the presence of a peroxyacid to form an ester. The oxygen atom inserts itself between the carbonyl carbon and the bigger group attached.
2. Birch Reduction
Named after an Australian chemist, Arthur J. Birch, this reaction involves the reduction of arenes into nonconjugated 1,4-dienes. This utilized the sodium metal in combination with an alcohol (ethanol or methanol) and liquid ammonia. Its mechanism is similar with the conversion of alkynes into trans-alkenes in the presence of Li in liquid ammonia.
3. Claisen Condensation
This reaction is used to synthesize -keto ester from condensation of two molecules of esters in the presence of an alkoxide base. The starting ester has acidic hydrogen that can be abstracted by a base, generating an enolate ion. The ion reacts with the other ester via nucleophilic addition.
4. Clemmensen Reduction
This is a method that reduces a carbonyl group into a methylene (=CH2) group using zinc amalgam in concentrated hydrochloric acid.
5. Diels-Alder Reaction
This is an example of a cycloaddition reaction between a diene and dienophile forming a cyclic compound in a single step.
6. Edman Degradation
Phenylisothiocyanate (PITC) reacts with the amino acid residue at the N-terminal of a peptide chain, in the presence of trifluoroacetic acid. The amino acid is cleaved from the rest of peptide chain. The reaction can be repeated over the next N-terminal amino acid until all are exhausted.This method is used during peptide sequencing.
7. Fischer-Speier Esterification
This is the most common method of generating an ester from a carboxylic acid and an alcohol in the presence of concentrated sulfuric acid. The reaction is said to be reversible. Addition of the sulfuric acid forces the reaction forward, generating the ester.
8. Freidel-Crafts Acylation
The electrophile, acylium (R-C=O+), is generated using a Lewis base (usually AlCl3) to react with an aromatic ring, forming an aromatic ketone. A deactivated ring, those with electron-withdrawing groups, and -NH2-substituted rings are unreactive towards Freidel-Crafts acylation.
9. Freidel-Crafts Alkylation
This reaction generates a carbocation electrophile, R1+, in the presence of a Lewis base. This is attacked subsequently by an aromatic ring forming alkyl-substituted aromatic compound. However this reaction is limited by the factor mentioned in Freidel-Crafts acylation. Aryl and vinylic halides are also not a good source of the electrophile.
10. Grignard Reaction
A Grignard reagent (an alkylmagnesium halide, RMgX) comes from the reaction between Mg metal and an alkyl halide in water-free environment. Tetrahydrofuran (THF) and ether are used as solvents in lieu of water.
This reagent is a source of a carbanion, R3C1-, that reacts with ester and carbonyl compounds to form alcohols. As the carbanion is also a strong base, the reagent readily decomposes in the presence of compounds with acidic hydrogen, like alcohol and carboxylic acid.
11. Hell-Volhard-Zelinsky Reaction
This reaction involves alpha-halogenation of carboxylic acid. The hydrogen at the -carbon of carboxylic acid is acidic enough to dissociate and form a stable enough anion (conjugate base). This conjugate base can readily form an enol similar to aldehyde and ketone. This further stabilizes the conjugate base.
Bromination of the -hydrogen is the most common reaction to be carried out. This reaction is called Hell-Volhard-Zelinsky reaction. Since the amount of enol generated by carboxylic acids is not much as compared with the aldehydes and ketones, a catalyst is required, usually phosphorus trichloride or phosphorus.
The brominated product is significant as this can be displaced by nucleophilic substitution.
12. Hofmann Rearrangement
Named after August W. Hofmann, the reaction involves the conversion of an amide into amine in the presence of bromine in basic solution.
substituted amides do not work in this particular reaction.
13. Jones Oxidation
This reaction facilitates the oxidation of primary and secondary alcohols into carboxylic acid and ketones, respectively. Although at controlled settings, the primary alcohol can be partially oxidized into aldehyde.
The reagent, known as Jones reagent, is made by dissolving chromic acid in aqueous sulfuric acid. Sodium dichromate (Na2Cr2O 7) can also be used instead of chromic acid. The alcohol is also dissolved in acetone or acetic acid.
14. Kiliani-Fischer Synthesis
This reaction extends the length of the carbon chain of an aldose through the addition of hydrogen cyanide, thus, forming a cyanohydrin. Reducing the cyanohydrins leads to the formation of an imine which can be subsequently hydrolyzed into an aldehyde, or epimeric aldoses.
15. Lieben Iodoform Formation (Haloform Reaction)
Methyl ketones are converted into carboxylate salt in the presence of a halogen, usually iodine, and a base. The reaction of the halogen and the methyl ketones leads to the exhaustive substitution of the hydrogen atoms in the methyl group. Treatment of the base results to the cleaving of the iodoform (or haloform) from the carbonyl group.
Methyl groups attached to carbinol, -CH2OH, also yields the same results with halogen and base.
16. Malaprade Reaction
Vicinal diols react with periodic acid resulting to the cleavage of the carbon-carbon bond, forming two aldehydes. Compounds with an amino group and hydroxyl, attached to adjacent carbon atoms also react with periodic acid. Adjacent ketones also react in the same manner.
The periodic acid is reduced to iodic acid, as indicated when silver nitrate is added. Iodic acid reacts with AgNO3 to form silver iodate, a white precipitate.
HIO3(aq) + AgNO3(aq) HNO3(aq) + AgIO3(s)
17. The Wittig Reaction
This is a useful reaction between aldehydes and ketones and phosphorus ylides, yielding alkenes. What makes this reaction valuable over other alkene synthesis reactions is the absence of ambiguity over the location of the double bonds.
18. Williamson Ether Synthesis
This is an example of ether synthesis following the SN2 mechanism. A strong base, usually sodium alkoxide, is used to react with alkyl halides, alkyl sulfonate or alkyl sulfate. Synthesis of unsymmetrical ether usually used this reaction.
19. Wolff-Kishner Reduction
This method is a useful alternative to reduce aldehydes and ketones in the presence of hydrazine, H2NNH2, and KOH into alkanes. It does not discriminate against alkyl and aryl ketones, thus, a far better option than catalytic hydrogenation.
20. Wohl Degradation
This is the opposite of Kiliani-Fischer synthesis. This time an aldose is treated with hydroxylamine and acetic anhydride to yield a nitrile. Further treatment with a base causes the loss of HCN, thus, shortening the aldose by one carbon atom.