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.
Name Reaction Mechanism Organic Chemistry Pdf Free
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.
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.
The Etard Reaction is named after Alexandre Léon Étard, 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:
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.
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.
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.
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 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.
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.
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 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.
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).
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.
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.
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.
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).
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).
The reaction mechanism is not clearly understood, but the textbook mechanism revolves around a palladium cycle which is in agreement with the "classical" cross-coupling mechanism, and a copper cycle, which is less well known.[9]
Although beneficial for the effectiveness of the reaction, the use of copper salts in "classical" Sonogashira reaction is accompanied with several drawbacks, such as the application of environmentally unfriendly reagents, the formation of undesirable alkyne homocoupling (Glaser side products), and the necessity of strict oxygen exclusion in the reaction mixture. Thus, with the aim of excluding copper from the reaction, a lot of effort was undertaken in the developments of Cu-free Sonogashira reaction. Along the development of new reaction conditions, many experimental and computational studies focused on elucidation of reaction mechanism.[12] Until recently, the exact mechanism by which the Cu-free reaction occurs was under debate, with critical mechanistic questions unanswered.[7] It was proven in 2018 by Košmrlj et al. that the reaction proceeds along the two interconnected Pd0/PdII catalytic cycles.[13][14]
While a copper co-catalyst is added to the reaction to increase reactivity, the presence of copper can result in the formation of alkyne dimers. This leads to what is known as the Glaser coupling reaction, which is an undesired formation of homocoupling products of acetylene derivatives upon oxidation. As a result, when running a Sonogashira reaction with a copper co-catalyst, it is necessary to run the reaction in an inert atmosphere to avoid the unwanted dimerization. Copper-free variations to the Sonogashira reaction have been developed to avoid the formation of the homocoupling products.[19][25] There are other cases when the use of copper should be avoided, such as coupling reactions involving substrates which potential copper ligands, for instance free-base porphyrins.[9]
Recently, a nickel-catalyzed Sonogashira coupling has been developed which allows for the coupling of non-activated alkyl halides to acetylene without the use of palladium, although a copper co-catalyst is still needed.[27] It has also been reported that gold can be used as a heterogeneous catalyst, which was demonstrated in the coupling of phenylacetylene and iodobenzene with an Au/CeO2 catalyst.[28][29] In this case, catalysis occurs heterogeneously on the Au nanoparticles,[29][30] with Au(0) as the active site.[31] Selectivity to the desirable cross coupling product was also found to be enhanced by supports such as CeO2 and La2O3.[31] Additionally, iron-catalyzed Sonogashira couplings have been investigated as relatively cheap and non-toxic alternatives to palladium. Here, FeCl3 is proposed to act as the transition-metal catalyst and Cs2CO3 as the base, thus theoretically proceeding through a palladium-free and copper-free mechanism.[32]
While the copper-free mechanism has been shown to be viable, attempts to incorporate the various transition metals mentioned above as less expensive alternatives to palladium catalysts have shown a poor track record of success due to contamination of the reagents with trace amounts of palladium, suggesting that these theorized pathways are extremely unlikely, if not impossible, to achieve.[33]
The issues dealing with recovery of the often expensive catalyst after product formation poses a serious drawback for large-scale applications of homogeneous catalysis.[9] Structures known as metallodendrimers combine the advantages of homogeneous and heterogeneous catalysts, as they are soluble and well defined on the molecular level, and yet they can be recovered by precipitation, ultrafiltration, or ultracentrifugation.[36] Some recent examples can be found about the use of dendritic palladium complex catalysts for the copper-free Sonogashira reaction. Thus, several generations of bidentate phosphine palladium(II) polyamino dendritic catalysts have been used solubilized in triethylamine for the coupling of aryl iodides and bromides at 25-120 C, and of aryl chlorides, but in very low yields.[37]
More recently, the dipyridylpalladium complex has been obtained and has been used in the copper-free Sonogashira coupling reaction of aryl iodides and bromides in N-methylpyrrolidinone (NMP) using tetra-n-butylammonium acetate (TBAA) as base at room temperature. This complex has also been used for the coupling of aryl iodides and bromides in refluxing water as solvent and in the presence of air, using pyrrolidine as base and TBAB as additive,[40] although its efficiency was higher in N-methylpyrrolidinone (NMP) as solvent. 2ff7e9595c
Comments