McMurry Reactions

Electrophilic Addition Reactions

Reactions where an electrophile adds to a nucleophile, typically across a double or triple bond

Hydrohalogenation (Electrophilic Addition of HX)

Addition of hydrogen halide (HCl, HBr, HI) to an alkene, following Markovnikov's rule where the hydrogen adds to the carbon with the most hydrogen atoms, and the halide adds to the carbon with fewer hydrogens

Hydrohalogenation with Peroxides (Anti-Markovnikov)

In the presence of peroxides (ROOR), the addition of HX (e.g., HBr) to an alkene proceeds via a radical mechanism, and the halide adds to the less substituted carbon (Anti-Markovnikov addition)

Halogenation of Alkenes (X₂ Addition)

Addition of a halogen (Br₂ or Cl₂) across the double bond of an alkene, forming a vicinal dihalide (anti addition)

Halohydrin Formation

Addition of X₂ (Cl₂, Br₂) and H₂O to an alkene, leading to the formation of a halohydrin, where the halide and hydroxyl group add to adjacent carbons in anti stereochemistry

Hydration of Alkenes (Electrophilic Addition of Water)

Addition of water (H₂O) to an alkene in the presence of an acid catalyst (e.g., H₂SO₄ or H₃PO₄) following Markovnikov’s rule, producing an alcohol

Oxymercuration-Demercuration

Addition of water to an alkene via an intermediate mercurinium ion, followed by demercuration with NaBH₄ to form an alcohol, avoiding carbocation rearrangement

Hydroboration-Oxidation (Anti-Markovnikov Hydration)

Addition of borane (B₂H₆) to an alkene, followed by oxidation with H₂O₂ to produce an alcohol, where the hydroxyl group adds to the less substituted carbon (Anti-Markovnikov addition)

Electrophilic Addition of Acid to Alkynes

Addition of H₂SO₄ to an alkyne, resulting in an intermediate vinyl cation which reacts with H₂O to form a ketone (tautomerization) after hydration

Elimination Reactions

Reactions in which atoms or groups are removed from a molecule, forming a double or triple bond

E1 Mechanism (Unimolecular Elimination)

A two-step elimination mechanism where the leaving group departs first, forming a carbocation intermediate, followed by the removal of a proton to form a double bond (often occurs with tertiary carbocations)

E2 Mechanism (Bimolecular Elimination)

A one-step elimination reaction where the base removes a proton from the β-carbon while the leaving group departs simultaneously, forming a double bond

Dehydrohalogenation (E2 with Alkyl Halides)

The elimination of HX (HCl, HBr, etc.) from an alkyl halide in the presence of a strong base (e.g., KOH or NaOEt), resulting in the formation of an alkene

Dehydration of Alcohols (E1 Mechanism)

The removal of water (H₂O) from an alcohol in the presence of an acid catalyst (e.g., H₂SO₄) to form an alkene, often following Markovnikov's rule

Alcohol Dehydration (via H₂SO₄ or H₃PO₄)

Acid-catalyzed dehydration of alcohols where the reaction follows an E1 mechanism to form alkenes, typically leading to the formation of a more substituted alkene due to carbocation stability

Substitution Reactions

Reactions where one group in a molecule is replaced by another group

SN1 Mechanism (Unimolecular Nucleophilic Substitution)

A two-step mechanism where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack

the rate of reaction depends on the concentration of the substrate

SN2 Mechanism (Bimolecular Nucleophilic Substitution)

A one-step mechanism where the nucleophile attacks the electrophilic carbon as the leaving group departs simultaneously, resulting in inversion of configuration at the carbon center

SN2 Reaction with Inversion of Configuration

A type of SN2 reaction where the nucleophile attacks the carbon center opposite to the leaving group, leading to inversion of the stereochemistry

Nucleophilic Substitution of Alkyl Halides (SN2)

Nucleophile (e.g., OH⁻, CN⁻) replaces a halide (e.g., Br, Cl) in an alkyl halide, following the SN2 mechanism, resulting in a direct substitution with inversion of configuration

SN1 with Tertiary Alkyl Halides

Tertiary alkyl halides undergo SN1 substitution due to the stability of the resulting tertiary carbocation, which allows the reaction to proceed via a two-step mechanism

Reactions with Alkynes

Hydrohalogenation of Alkynes

Acid-Catalyzed Hydration of Alkynes

Addition of H₂SO₄ to an alkyne in the presence of HgSO₄ forms an enol intermediate, which tautomerizes to a ketone (Markovnikov addition)

Hydroboration-Oxidation of Alkynes

Addition of diborane (B₂H₆) to an alkyne, followed by oxidation with H₂O₂, forms an aldehyde (in the case of terminal alkynes), following Anti-Markovnikov’s rule

Reduction of Alkynes to Alkanes

The addition of hydrogen (H₂) in the presence of a catalyst (Pd/C) reduces alkynes to alkanes by adding two hydrogen atoms across the triple bond

Partial Hydrogenation of Alkynes to Alkenes (Lindlar's Catalyst)

Hydrogenation of alkynes with Lindlar's catalyst (Pd/CaCO₃) results in the formation of cis-alkenes (Z-isomer), typically used for the conversion of alkynes to alkene in the case of terminal alkynes

Alkyne to Diene (Electrophilic Addition)

The reaction of an alkyne with HX (e.g., HBr) under certain conditions can lead to the formation of a diene, where the second equivalent of HX adds to the alkyne to form a conjugated alkene system

Cycloaddition Reactions

Reactions in which two molecules combine to form a ring structure

Diels-Alder Reaction

A [4+2] cycloaddition reaction between a diene and a dienophile (usually an alkene or alkyne), forming a six-membered cyclic product

Electrophilic Cycloaddition of Alkenes (Diels-Alder)

A reaction in which a conjugated diene reacts with a dienophile (often an alkene or an alkyne) in a concerted mechanism to form a six-membered ring

Free Radical Reactions

Reactions involving free radicals as intermediates

Free Radical Halogenation

A reaction where halogen radicals (Cl•, Br•) abstract a hydrogen atom from an alkane, creating a new radical, leading to substitution

Polymerization of Alkenes

Free radical initiation of alkene polymerization, such as in the polymerization of ethene to polyethylene, where radicals initiate the addition of successive monomers to form long polymer chains

Peroxide Effect

A reaction where the presence of peroxides in the addition of HX (e.g., HBr) to alkenes leads to an Anti-Markovnikov addition (the halide adds to the less substituted carbon)

Anti-Addition Reactions

Reactions where the added groups (e.g., halogen, hydroxyl) add to opposite faces of the molecule, typically seen in halogenation and hydroxylation reactions

Anti-Hydroxylation

Addition of hydroxyl groups (OH and OH) to an alkene in an anti fashion, typically catalyzed by peracid to form an epoxide intermediate, which then undergoes acid-catalyzed opening

Radical Addition to Alkenes

Reactions where a radical adds to an alkene, such as in the case of the addition of a halogen to an alkene in the presence of a radical initiator (peroxides)