Reaction intermediate (general organic chemistry)
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This document discusses various reactive intermediates in organic chemistry including free radicals, carbanions, carbocations, carbenes, and nitrenes. It notes that free radicals contain an unpaired electron and are generated by photolysis, heat, or peroxides. Carbocations are carbon intermediates with a positive charge that are stabilized through effects like resonance, hyperconjugation, or induction. They can rearrange through 1,2 shifts or ring expansions/contractions to form more stable structures. Carbenes are neutral divalent carbons that exist fleetingly, while nitrenes contain an incomplete octet on nitrogen, making them highly reactive.
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Reaction intermediates
Reaction intermediates such as carbocation, carbanion, free radicals, carbene, nitrene and ylides were discussed.
Mannich reaction
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an aldehyde such as formaldehyde, and an amine to form a β-amino carbonyl compound known as a Mannich base. The reaction proceeds via the initial addition of the amine to the aldehyde to form an iminium ion intermediate, which then reacts with the enol form of the carbonyl compound to eliminate a proton and form the Mannich base product. While versatile building blocks in organic synthesis, the Mannich reaction has limitations in terms of substrate scope and control of regio- and stereoselectivity. Examples of applications include the synthesis of tropinone, a precursor of atropine, as well
Carbanions
Carbanions are carbon atoms with a negative charge that are formed through various mechanisms. They can be classified based on their formation method such as through heterocyclic cleavage, proton abstraction using a base, decarboxylation, addition of a nucleophile to an alkene, or formation of an organometallic compound. Carbanion stability depends on factors like the electronegativity of the carbon, inductive effects, resonance effects, and attachment to sulfur or phosphorus. Aromatic carbanions and those with electron-withdrawing groups are particularly stable due to resonance delocalization. Carbanions have applications in reactions like the Perkin reaction, Claisen condensation, benzoin condensation,
Elimination reaction
- Elimination reactions occur by either an E1 or E2 mechanism. E1 is a one-step reaction involving a carbocation intermediate, while E2 is a concerted, single-step reaction.
- The E1 mechanism is favored by good leaving groups, stable carbocations, and weak bases. It is non-stereospecific and does not occur with primary alkyl halides. The E2 mechanism is favored by strong bases and polar aprotic solvents. It is stereospecific and proceeds through an anti-periplanar transition state.
- Key factors that determine the mechanism include the stability of carbocation intermediates, the strength of the leaving group and base, and steric
Organic Intermediates
1) Heterolytic and homolytic bond fission can result in the formation of short-lived reaction intermediates called carbocations.
2) Carbocations are positively charged carbon ions that are electrophilic and undergo three reaction types: capture a nucleophile, lose a proton to form a pi bond, or rearrange.
3) Carbocation stability increases with increased substitution and the presence of electron donating groups, double bonds, or heteroatoms which delocalize the positive charge. Carbocations are key intermediates in SN1, E1, and rearrangement reactions.
Sn2 reaction
The document summarizes key aspects of SN2 reactions including reaction mechanism, kinetics, stereochemistry, and factors that affect the rate of the reaction. It describes the SN2 reaction as a bimolecular nucleophilic substitution where the nucleophile attacks the substrate simultaneously as the leaving group departs, resulting in an inversion of configuration. Rate depends on both the nucleophile and substrate concentrations. The stability of the transition state is affected by substrate structure, nucleophilicity, leaving group ability, solvent properties, and conjugation effects in allylic and benzylic systems. Cyclic substrates and those without available orbital overlap do not undergo SN2 reactions as easily.
Birch reduction
The Birch reduction is a reaction where aromatic compounds undergo partial reduction to unconjugated cyclohexadiene compounds in the presence of alkali metals like sodium or lithium in liquid ammonia. The solvated electrons from the reaction of the metal with liquid ammonia give the solution an intense blue color. The mechanism begins with single electron transfer from the metal to the aromatic ring, forming a radical anion. Regioselectivity in the reduction depends on whether substituents on the aromatic ring are electron donating groups or electron withdrawing groups. The Birch reduction can selectively reduce the less electron-rich ring in bicyclic aromatic compounds.
Structural determination of alkaloids
This document outlines general methods for determining the molecular structures of alkaloids. It discusses determining the molecular formula, identifying functional groups, analyzing nitrogen and oxygen functionalities, and performing degradation reactions. Physical methods like UV/Vis spectroscopy, IR spectroscopy, mass spectrometry, and NMR spectroscopy are also used to elucidate alkaloid structures. The overall procedure involves purification, elemental analysis, functional group identification, and degradation or synthesis to confirm tentative structures determined through analytical evidence.
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Reaction intermediates
Reaction intermediates such as carbocation, carbanion, free radicals, carbene, nitrene and ylides were discussed.
Mannich reaction
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an aldehyde such as formaldehyde, and an amine to form a β-amino carbonyl compound known as a Mannich base. The reaction proceeds via the initial addition of the amine to the aldehyde to form an iminium ion intermediate, which then reacts with the enol form of the carbonyl compound to eliminate a proton and form the Mannich base product. While versatile building blocks in organic synthesis, the Mannich reaction has limitations in terms of substrate scope and control of regio- and stereoselectivity. Examples of applications include the synthesis of tropinone, a precursor of atropine, as well
Carbanions
Carbanions are carbon atoms with a negative charge that are formed through various mechanisms. They can be classified based on their formation method such as through heterocyclic cleavage, proton abstraction using a base, decarboxylation, addition of a nucleophile to an alkene, or formation of an organometallic compound. Carbanion stability depends on factors like the electronegativity of the carbon, inductive effects, resonance effects, and attachment to sulfur or phosphorus. Aromatic carbanions and those with electron-withdrawing groups are particularly stable due to resonance delocalization. Carbanions have applications in reactions like the Perkin reaction, Claisen condensation, benzoin condensation,
Elimination reaction
- Elimination reactions occur by either an E1 or E2 mechanism. E1 is a one-step reaction involving a carbocation intermediate, while E2 is a concerted, single-step reaction.
- The E1 mechanism is favored by good leaving groups, stable carbocations, and weak bases. It is non-stereospecific and does not occur with primary alkyl halides. The E2 mechanism is favored by strong bases and polar aprotic solvents. It is stereospecific and proceeds through an anti-periplanar transition state.
- Key factors that determine the mechanism include the stability of carbocation intermediates, the strength of the leaving group and base, and steric
Organic Intermediates
1) Heterolytic and homolytic bond fission can result in the formation of short-lived reaction intermediates called carbocations.
2) Carbocations are positively charged carbon ions that are electrophilic and undergo three reaction types: capture a nucleophile, lose a proton to form a pi bond, or rearrange.
3) Carbocation stability increases with increased substitution and the presence of electron donating groups, double bonds, or heteroatoms which delocalize the positive charge. Carbocations are key intermediates in SN1, E1, and rearrangement reactions.
Sn2 reaction
The document summarizes key aspects of SN2 reactions including reaction mechanism, kinetics, stereochemistry, and factors that affect the rate of the reaction. It describes the SN2 reaction as a bimolecular nucleophilic substitution where the nucleophile attacks the substrate simultaneously as the leaving group departs, resulting in an inversion of configuration. Rate depends on both the nucleophile and substrate concentrations. The stability of the transition state is affected by substrate structure, nucleophilicity, leaving group ability, solvent properties, and conjugation effects in allylic and benzylic systems. Cyclic substrates and those without available orbital overlap do not undergo SN2 reactions as easily.
Birch reduction
The Birch reduction is a reaction where aromatic compounds undergo partial reduction to unconjugated cyclohexadiene compounds in the presence of alkali metals like sodium or lithium in liquid ammonia. The solvated electrons from the reaction of the metal with liquid ammonia give the solution an intense blue color. The mechanism begins with single electron transfer from the metal to the aromatic ring, forming a radical anion. Regioselectivity in the reduction depends on whether substituents on the aromatic ring are electron donating groups or electron withdrawing groups. The Birch reduction can selectively reduce the less electron-rich ring in bicyclic aromatic compounds.
Structural determination of alkaloids
This document outlines general methods for determining the molecular structures of alkaloids. It discusses determining the molecular formula, identifying functional groups, analyzing nitrogen and oxygen functionalities, and performing degradation reactions. Physical methods like UV/Vis spectroscopy, IR spectroscopy, mass spectrometry, and NMR spectroscopy are also used to elucidate alkaloid structures. The overall procedure involves purification, elemental analysis, functional group identification, and degradation or synthesis to confirm tentative structures determined through analytical evidence.
Metal carbonyls
Metal carbonyls are coordination complexes of transition metals with carbon monoxide ligands. They were first synthesized in 1868 by passing carbon monoxide over platinum. Metal carbonyls typically obey the 18 electron rule and are often diamagnetic. They have applications as catalysts in organic synthesis and in producing pure metals like nickel. Precautions must be taken when using metal carbonyls due to their toxicity.
Reactions intermediate
This document provides an overview of various carbon-based reaction intermediates including carbocations, carbanions, carbenes, free radicals, nitrenes, and nitrenium ions. It discusses their generation, structure, stability, reactions, and detection methods. Key points include that carbocations are positively charged carbon species that react as electrophiles, while carbanions are negatively charged carbon species that react as nucleophiles. Carbenes contain a carbon with six valence electrons in a triplet or singlet state. Free radicals contain one or more unpaired electrons. Nitrenes and nitrenium ions involve a reactive nitrogen species. Detection methods include NMR, EPR, UV-Vis spectroscopy, and trapping reactions.
Elimination reaction
The overall rate equation for this reaction is:
Rate = k[R-R-OH][H2O]
Where k is the rate constant and [R-R-OH] and [H2O] are the concentrations of the reactants R-R-OH and H2O, respectively.
Grignard reaction
The Grignard reaction involves adding an organomagnesium halide (Grignard reagent) to a ketone or aldehyde. This forms a carbon-carbon bond and produces a tertiary or secondary alcohol. The Grignard reagent is prepared by reacting an organic halide with magnesium. François Grignard discovered these reactions in 1900 and was awarded the Nobel Prize for his work. The reaction occurs when the carbon attached to magnesium acts as a nucleophile that attacks the electrophilic carbon in the carbonyl group, typically through a six-membered ring transition state.
E2 reaction
1. The document outlines different elimination reaction mechanisms including E2, E1, and E1cb.
2. It discusses the regiochemistry and stereochemistry of elimination reactions and how Zaytzeff's rule and Hofmann's rule apply.
3. The key differences between the E2, E1, and E1cb mechanisms are described along with factors that determine whether substitution or elimination will occur for a given reaction.
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Aromatic electrophilic substitution
This document provides an overview of aromatic electrophilic substitution reactions (AES). It defines important terms like arenium ions, electrophiles, nucleophiles and discusses the effects of substituents on reactivity. The mechanisms of common AES reactions like nitration, sulfonation, Friedel-Crafts alkylation and acylation are covered. The document also discusses topics like the mesomeric and inductive effects of substituents, the synthesis of tribromobenzene, and the relative reactivities of benzene and substituted benzenes in bromination. Examples of AES on phenols, xylenes, cresols and other aromatic compounds are provided.
Wolf rearrangement
The document discusses carbenes, which are molecules containing a neutral carbon atom with two unshared valence electrons. Carbenes can be classified as singlets or triplets based on their electronic structure. The document also describes the Wolff rearrangement, where α-diazoketones lose nitrogen to form reactive ketenes. Some applications of the Wolff rearrangement include the synthesis of carboxylic acid analogues, acid amides from carboxylic acids, and esters from carboxylic acids.
organic chemistry
1. Diazonium salts are organic compounds containing the diazonium functional group (R-N+=N) that are important intermediates in organic synthesis.
2. They are commonly used to produce azo dyes by coupling with electron-rich aromatic compounds. This document discusses their preparation, properties, applications in dye synthesis and nanotechnology, and reactions such as forming phenols, iodobenzenes, and other aromatic derivatives.
3. Diazonium salts are also used as indicators in acid-base chemistry due to changes in color between their conjugate acid and base forms.
Alkyl halides
This document discusses alkyl halides, including their structure, properties, and reactions. It begins by defining alkyl halides as compounds where halogen atoms are bound to alkyl groups. It then discusses the polarity of carbon-halogen bonds and how bond lengths and dipole moments vary depending on the halogen. The document goes on to cover the nomenclature, preparation, and common reactions of alkyl halides, focusing on nucleophilic substitution and elimination reactions. It discusses factors that influence the rates and mechanisms of these reactions such as nucleophile strength, solvent effects, and steric hindrance.
Claisen condensation.pptx
The Claisen-Schmidt reaction is a condensation reaction that joins two carbonyl compounds, an aldehyde and a ketone, forming a β-hydroxylcarbonyl compound. It involves the reaction of an aldehyde or ketone with an α-hydrogen and an aromatic carbonyl compound. The Claisen-Schmidt condensation has played an important role in synthetic organic chemistry by allowing two carbonyl compounds to join together.
Asymmetric synthesis
This document discusses asymmetric synthesis, which is a chemical reaction that produces stereoisomeric products in unequal amounts by creating new chiral centers. It provides examples of important biological molecules that are enantiopure, such as amino acids, sugars, and proteins. Common methods for obtaining enantiopure compounds include isolation from natural sources, resolution of racemic mixtures, and asymmetric synthesis. Asymmetric synthesis is described as a reaction where a chiral reagent, auxiliary, or solvent directs the formation of new stereocenters. Examples of important asymmetric reactions mentioned include Sharpless epoxidation and asymmetric reductions.
Aromaticity
The document summarizes aromaticity and related topics for chemistry students. It discusses:
- Benzenoid and non-benzenoid aromatic compounds, including their properties and reactions.
- Resonance structures of benzene and how it follows Huckel's rule for aromaticity.
- Classification of compounds based on aromaticity and examples of antiaromatic compounds.
- Aromatic ions and heterocyclic aromatic compounds like pyrrole, furan and pyridine.
Amines
This document discusses the properties and reactions of amines. It defines amines as organic derivatives of ammonia with one or more alkyl or aryl groups bonded to the nitrogen atom. Amines are classified as primary, secondary, or tertiary depending on the number of alkyl or aryl groups attached to the nitrogen. The document discusses nomenclature, physical properties, basicity, reactions including salt formation and reactions with acids, and uses of amines such as in the synthesis of nylon and azo dyes.
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The document summarizes various reactions of aldehydes and ketones. It describes how aldehydes and ketones undergo nucleophilic addition reactions, with the nucleophile attacking the carbonyl carbon. This forms an alkoxide intermediate which gives an alcohol upon protonation. It also discusses the relative reactivities of aldehydes and ketones, hydrate and cyanohydrin formation, imine formation, oxidation and reductions of carbonyl compounds, acetal formation, and the Wittig reaction.
Phase transfer catalysis
Phase transfer catalysis involves using a catalyst to transfer a reactant from one immiscible liquid phase to another where the reaction takes place. Common phase transfer catalysts are quaternary ammonium and phosphonium salts. The catalyst forms an ion pair with the reactant anion, transporting it into the organic phase where it undergoes nucleophilic substitution or other reactions. Phase transfer catalysis allows reactions between ions and organic molecules that would otherwise not interact due to being in separate phases. It has many applications in organic synthesis and pharmaceutical manufacturing.
FGIs
The document discusses functional group interconversions (FGIs) in organic synthesis. It defines FGIs as writing one functional group for another to help with retrosynthetic planning. FGIs are important for identifying suitable disconnections in retrosynthesis when a molecule contains multiple functional groups. The document categorizes common functional groups containing heteroatoms, such as carboxylic acids, aldehydes/ketones, and alcohols/amines. It also discusses methods for oxidizing and reducing functional groups, as well as removing functional groups altogether.
Common named reactions
The document discusses several carbon-carbon bond forming reactions:
1. Aldol condensation allows aldehydes and ketones to undergo self-condensation in the presence of a base to form β-hydroxy carbonyl compounds.
2. The Perkin reaction uses an acid anhydride to form α,β-unsaturated aromatic acids from aromatic aldehydes.
3. The Wittig reaction converts a carbonyl group to an alkene using a phosphonium ylide.
Mannich Reaction
The document discusses various nitrogen substitution and addition reactions including the Mannich reaction where nucleophilic nitrogen adds to saturated or unsaturated carbons. It specifically mentions the reaction of primary amines with aldehydes and ketones to form imines and the formation of amino acids through reactions like the Hell-Volhard Zelensky reaction, Gabriel procedure, nitrosation, and Strecker method.
Mannich reaction
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an amine or ammonia, and formaldehyde to form an aminomethyl derivative known as a Mannich base. Ketones are most commonly used as the carbonyl compound. The reaction proceeds via the generation of an imine intermediate from the carbonyl compound and amine, which then reacts with formaldehyde to form the Mannich base. Mannich bases have applications in synthesizing natural products like alkaloids and building ring systems.
Organometallics notes 1
This document discusses reaction intermediates in organic chemistry reactions. It defines reaction intermediates as transient species that exist between reactants and products but cannot be isolated. The main types of reaction intermediates discussed are:
1) Free radicals which have unpaired electrons and are reactive species
2) Carbonium ions which are carbocations with a positively charged carbon atom
3) Factors that influence the stability of carbonium ions such as substituents, conjugation, and resonance structures
Unit 1 (Part A).pptx
Addition reactions involve two or more molecules combining to form a larger molecule. There are two main types of addition reactions for compounds with multiple bonds: electrophilic addition and nucleophilic addition. Electrophilic addition reactions are characteristic of alkenes, in which the alkene acts as a nucleophile that reacts with an electrophile. When hydrogen halides are added to unsymmetrical alkenes, the halogen attaches to the carbon with fewer hydrogen atoms according to Markovnikov's rule.
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Metal carbonyls
Metal carbonyls are coordination complexes of transition metals with carbon monoxide ligands. They were first synthesized in 1868 by passing carbon monoxide over platinum. Metal carbonyls typically obey the 18 electron rule and are often diamagnetic. They have applications as catalysts in organic synthesis and in producing pure metals like nickel. Precautions must be taken when using metal carbonyls due to their toxicity.
Reactions intermediate
This document provides an overview of various carbon-based reaction intermediates including carbocations, carbanions, carbenes, free radicals, nitrenes, and nitrenium ions. It discusses their generation, structure, stability, reactions, and detection methods. Key points include that carbocations are positively charged carbon species that react as electrophiles, while carbanions are negatively charged carbon species that react as nucleophiles. Carbenes contain a carbon with six valence electrons in a triplet or singlet state. Free radicals contain one or more unpaired electrons. Nitrenes and nitrenium ions involve a reactive nitrogen species. Detection methods include NMR, EPR, UV-Vis spectroscopy, and trapping reactions.
Elimination reaction
The overall rate equation for this reaction is:
Rate = k[R-R-OH][H2O]
Where k is the rate constant and [R-R-OH] and [H2O] are the concentrations of the reactants R-R-OH and H2O, respectively.
Grignard reaction
The Grignard reaction involves adding an organomagnesium halide (Grignard reagent) to a ketone or aldehyde. This forms a carbon-carbon bond and produces a tertiary or secondary alcohol. The Grignard reagent is prepared by reacting an organic halide with magnesium. François Grignard discovered these reactions in 1900 and was awarded the Nobel Prize for his work. The reaction occurs when the carbon attached to magnesium acts as a nucleophile that attacks the electrophilic carbon in the carbonyl group, typically through a six-membered ring transition state.
E2 reaction
1. The document outlines different elimination reaction mechanisms including E2, E1, and E1cb.
2. It discusses the regiochemistry and stereochemistry of elimination reactions and how Zaytzeff's rule and Hofmann's rule apply.
3. The key differences between the E2, E1, and E1cb mechanisms are described along with factors that determine whether substitution or elimination will occur for a given reaction.
Furan presentation
Furan is a heterocyclic organic compound consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. It is a colorless, flammable, and highly volatile liquid. Some important drugs containing furan rings include ranbezolid, nifurzide, and ranitidine. Furan can be synthesized through several methods, such as from pentosans, oxidation of cis-but-2-ene-1,4-diol, and from diacetosuccinic ester. It undergoes various reactions including electrophilic substitution, nitration, sulfonation, halogenation, acylation, and Diels-Alder reactions. Furaneol and ran
Aromatic electrophilic substitution
This document provides an overview of aromatic electrophilic substitution reactions (AES). It defines important terms like arenium ions, electrophiles, nucleophiles and discusses the effects of substituents on reactivity. The mechanisms of common AES reactions like nitration, sulfonation, Friedel-Crafts alkylation and acylation are covered. The document also discusses topics like the mesomeric and inductive effects of substituents, the synthesis of tribromobenzene, and the relative reactivities of benzene and substituted benzenes in bromination. Examples of AES on phenols, xylenes, cresols and other aromatic compounds are provided.
Wolf rearrangement
The document discusses carbenes, which are molecules containing a neutral carbon atom with two unshared valence electrons. Carbenes can be classified as singlets or triplets based on their electronic structure. The document also describes the Wolff rearrangement, where α-diazoketones lose nitrogen to form reactive ketenes. Some applications of the Wolff rearrangement include the synthesis of carboxylic acid analogues, acid amides from carboxylic acids, and esters from carboxylic acids.
organic chemistry
1. Diazonium salts are organic compounds containing the diazonium functional group (R-N+=N) that are important intermediates in organic synthesis.
2. They are commonly used to produce azo dyes by coupling with electron-rich aromatic compounds. This document discusses their preparation, properties, applications in dye synthesis and nanotechnology, and reactions such as forming phenols, iodobenzenes, and other aromatic derivatives.
3. Diazonium salts are also used as indicators in acid-base chemistry due to changes in color between their conjugate acid and base forms.
Alkyl halides
This document discusses alkyl halides, including their structure, properties, and reactions. It begins by defining alkyl halides as compounds where halogen atoms are bound to alkyl groups. It then discusses the polarity of carbon-halogen bonds and how bond lengths and dipole moments vary depending on the halogen. The document goes on to cover the nomenclature, preparation, and common reactions of alkyl halides, focusing on nucleophilic substitution and elimination reactions. It discusses factors that influence the rates and mechanisms of these reactions such as nucleophile strength, solvent effects, and steric hindrance.
Claisen condensation.pptx
The Claisen-Schmidt reaction is a condensation reaction that joins two carbonyl compounds, an aldehyde and a ketone, forming a β-hydroxylcarbonyl compound. It involves the reaction of an aldehyde or ketone with an α-hydrogen and an aromatic carbonyl compound. The Claisen-Schmidt condensation has played an important role in synthetic organic chemistry by allowing two carbonyl compounds to join together.
Asymmetric synthesis
This document discusses asymmetric synthesis, which is a chemical reaction that produces stereoisomeric products in unequal amounts by creating new chiral centers. It provides examples of important biological molecules that are enantiopure, such as amino acids, sugars, and proteins. Common methods for obtaining enantiopure compounds include isolation from natural sources, resolution of racemic mixtures, and asymmetric synthesis. Asymmetric synthesis is described as a reaction where a chiral reagent, auxiliary, or solvent directs the formation of new stereocenters. Examples of important asymmetric reactions mentioned include Sharpless epoxidation and asymmetric reductions.
Aromaticity
The document summarizes aromaticity and related topics for chemistry students. It discusses:
- Benzenoid and non-benzenoid aromatic compounds, including their properties and reactions.
- Resonance structures of benzene and how it follows Huckel's rule for aromaticity.
- Classification of compounds based on aromaticity and examples of antiaromatic compounds.
- Aromatic ions and heterocyclic aromatic compounds like pyrrole, furan and pyridine.
Amines
This document discusses the properties and reactions of amines. It defines amines as organic derivatives of ammonia with one or more alkyl or aryl groups bonded to the nitrogen atom. Amines are classified as primary, secondary, or tertiary depending on the number of alkyl or aryl groups attached to the nitrogen. The document discusses nomenclature, physical properties, basicity, reactions including salt formation and reactions with acids, and uses of amines such as in the synthesis of nylon and azo dyes.
Carbonyl Compounds 2
The document summarizes various reactions of aldehydes and ketones. It describes how aldehydes and ketones undergo nucleophilic addition reactions, with the nucleophile attacking the carbonyl carbon. This forms an alkoxide intermediate which gives an alcohol upon protonation. It also discusses the relative reactivities of aldehydes and ketones, hydrate and cyanohydrin formation, imine formation, oxidation and reductions of carbonyl compounds, acetal formation, and the Wittig reaction.
Phase transfer catalysis
Phase transfer catalysis involves using a catalyst to transfer a reactant from one immiscible liquid phase to another where the reaction takes place. Common phase transfer catalysts are quaternary ammonium and phosphonium salts. The catalyst forms an ion pair with the reactant anion, transporting it into the organic phase where it undergoes nucleophilic substitution or other reactions. Phase transfer catalysis allows reactions between ions and organic molecules that would otherwise not interact due to being in separate phases. It has many applications in organic synthesis and pharmaceutical manufacturing.
FGIs
The document discusses functional group interconversions (FGIs) in organic synthesis. It defines FGIs as writing one functional group for another to help with retrosynthetic planning. FGIs are important for identifying suitable disconnections in retrosynthesis when a molecule contains multiple functional groups. The document categorizes common functional groups containing heteroatoms, such as carboxylic acids, aldehydes/ketones, and alcohols/amines. It also discusses methods for oxidizing and reducing functional groups, as well as removing functional groups altogether.
Common named reactions
The document discusses several carbon-carbon bond forming reactions:
1. Aldol condensation allows aldehydes and ketones to undergo self-condensation in the presence of a base to form β-hydroxy carbonyl compounds.
2. The Perkin reaction uses an acid anhydride to form α,β-unsaturated aromatic acids from aromatic aldehydes.
3. The Wittig reaction converts a carbonyl group to an alkene using a phosphonium ylide.
Mannich Reaction
The document discusses various nitrogen substitution and addition reactions including the Mannich reaction where nucleophilic nitrogen adds to saturated or unsaturated carbons. It specifically mentions the reaction of primary amines with aldehydes and ketones to form imines and the formation of amino acids through reactions like the Hell-Volhard Zelensky reaction, Gabriel procedure, nitrosation, and Strecker method.
Mannich reaction
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an amine or ammonia, and formaldehyde to form an aminomethyl derivative known as a Mannich base. Ketones are most commonly used as the carbonyl compound. The reaction proceeds via the generation of an imine intermediate from the carbonyl compound and amine, which then reacts with formaldehyde to form the Mannich base. Mannich bases have applications in synthesizing natural products like alkaloids and building ring systems.
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Similar to Reaction intermediate (general organic chemistry)
Organometallics notes 1
This document discusses reaction intermediates in organic chemistry reactions. It defines reaction intermediates as transient species that exist between reactants and products but cannot be isolated. The main types of reaction intermediates discussed are:
1) Free radicals which have unpaired electrons and are reactive species
2) Carbonium ions which are carbocations with a positively charged carbon atom
3) Factors that influence the stability of carbonium ions such as substituents, conjugation, and resonance structures
Unit 1 (Part A).pptx
Addition reactions involve two or more molecules combining to form a larger molecule. There are two main types of addition reactions for compounds with multiple bonds: electrophilic addition and nucleophilic addition. Electrophilic addition reactions are characteristic of alkenes, in which the alkene acts as a nucleophile that reacts with an electrophile. When hydrogen halides are added to unsymmetrical alkenes, the halogen attaches to the carbon with fewer hydrogen atoms according to Markovnikov's rule.
Carbene
This document discusses carbenes, which are neutral carbon molecules with two unshared valence electrons. It describes the different types of carbenes, including singlet and triplet carbenes, and their electronic structures and bonding properties. Methods of forming carbenes are presented, such as alpha elimination reactions and decomposition of diazo compounds. The major reactions of carbenes are also summarized, including insertion, addition, and rearrangement reactions. Carbene reactivity depends on whether they are in singlet or triplet states.
Carbocation ppt
An organic species which has a carbon atom bearing only six electrons in its outermost shell and has a positive charge is called carbocation.
The positively charged carbon of carbocation is sp2 hybridized.
The unhybridized p-orbital remains vacant.
They are highly reactive and act as reaction intermediate.
They are also called carbonium ion.
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Advanced Level
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The document discusses several organic chemistry concepts including inductive effect, hyperconjugation, isomerism, hydrocarbons, mechanisms of aromatic substitution reactions, and the structure of benzene. It provides details on types of inductive and electromeric effects, sources of isomerism like geometrical and optical isomerism, Baeyer's strain theory explanation for cycloalkane stability, electrophilic aromatic substitution reactions like halogenation and nitration, and the historical elucidation of benzene's structure including objections to early proposals.
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Chem VIT Module 3
Organic intermediates and reaction transformations discusses carbocations, carbanions, and radicals as reactive intermediates in organic reactions. Aromatics and heterocycles are examined, specifically discussing their structure and stability. Organic transformations are used to make drugs and dyes by targeting specific disease pathways.
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This document discusses carbanions, which are negatively charged organic species where carbon carries three bond pairs and one lone pair. Carbanions are stabilized through conjugation, resonance effects, field effects, and aromaticity. They are generated through heterolytic bond cleavage or addition of a negative ion to a carbon-carbon multiple bond. As nucleophiles, carbanions undergo reactions such as alpha-halogenation of ketones, additions to carbonyls, nucleophilic acyl substitutions, substitutions with alkyl halides, and Michael additions.
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This document discusses various reaction intermediates including carbocations, carbanions, carbenes, free radicals, nitrenes, and nitrenium ions. It provides details on their generation, structure, stability, and common reactions. Carbocations are discussed including factors that stabilize them such as hyperconjugation. The document also covers detection methods for different reaction intermediates including NMR spectroscopy and electron paramagnetic resonance spectroscopy.
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This document discusses various types of organic reaction intermediates. It explains that reaction intermediates are transient chemical species that are formed in one step of a reaction mechanism and consumed in a subsequent step. Common types of intermediates discussed include radicals, carbocations, and carbanions. The document compares the stability of primary, secondary, and tertiary carbocations and carbanions based on factors like inductive effects, hybridization, and resonance. It also provides examples and structures of different organic reaction intermediates.
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Reaction intermediate (general organic chemistry)
- 1. Presented by Dr. Neelam Department of chemistry
- 2. Homolytic fission of covalent bonds Heterolytic fission of covalent bonds Bond cleavage
- 3. Free radical: An uncharged intermediate which has three bond pair and an unpaired electron on carbon. Homolysis of covalent bond results into free radical intermediates possess the unpaired electrons.
- 4. It is generated in presence of sun light, peroxides or high temperature
- 5. A carbon intermediate which contain three bond pair and a negative charge on it, is called carbanion. Hybridisation: sp3, sp2 or sp
- 7. CARBOCATION A carbon intermediate which contain three bond pair & a positive charge on it is called carbocation. Hybridisation: Carbocation may be sp2 or sp hybridized.
- 8. They have only six electrons in their valence shell, and because of this, carbocations act as Lewis acids. Carbocations are electron deficient. Most of the carbocations are short-lived and highly reactive, they occur as intermediates in some organic reactions.
- 9. Stability: Carbocations are stabilised by (i) +M effect (ii) Delocalisation of charge (iii) Hyperconjugation (iv) +I effect
- 10. Whenever an Intermediate carbocation is formed in reaction it may rearranges. Only those carbocation will rearrange which can produce more stable species. It can be done either by (i) Shifting of H, alkyl, aryl, bond (1, 2 shifting) (ii) Ring expansion (more strained ring to less strained ring) (iii) Ring contraction (i) Shifting of H, alkyl, aryl, (1, 2 shift)
- 12. There is a group of intermediates in which carbon forms only two bonds. These neutral divalent carbon species are called carbenes. Most carbenes are highly unstable that are capable of only fleeting existence.
- 14. NITRENES The nitrogen analog of carbenes are nitrenes. They are very much reactive since in them octet of N is incomplete. In nitrenes only one valencies of N are satisfied. BENZYNE The benzene ring has one extra C–C π bond in benzyne.
- 15. 15