Nucleophilic Substitution and Reaction Mechanisms

These flashcards cover essential vocabulary related to nucleophilic substitution reactions, including key concepts and mechanisms.

Nucleophilic Substitution

A chemical reaction where a nucleophile forms a bond with a carbon atom, replacing a leaving group.

SN1 Reaction

A type of nucleophilic substitution where the rate-determining step is the formation of a carbocation intermediate, leading to a unimolecular reaction.

SN2 Reaction

A type of nucleophilic substitution where the reaction occurs in a single concerted step, involving a nucleophile and an alkyl halide, resulting in bimolecular kinetics.

Carbocation

An intermediate in a chemical reaction that contains a positively charged carbon atom.

Leaving Group

The atom or group that departs with a pair of electrons in a nucleophilic substitution reaction, forming a stable species.

Protic Solvent

A solvent that can donate hydrogen bonds, often slowing SN2 reactions by stabilizing reactants.

Polar Aprotic Solvent

A solvent that does not have hydrogen-bonding capabilities, allowing faster SN2 reactions due to weaker interactions with the substrate.

Sterics

The influence of the spatial arrangement of atoms in determining the reactivity of molecules in chemical reactions.

Reflux

A laboratory technique where a mixture is heated and vapors are condensed back into the mixture to obtain a desired reaction.

Stereochemistry of SN2

In SN2 reactions, the stereochemistry of the product is inverted due to the backside attack of the nucleophile.

Nucleophile

An electron-rich chemical species that donates a pair of electrons to an electrophile to form a new covalent bond.

Factors Favoring SN1 Reactions

1. Substrate: Tertiary (3^\circ) alkyl halides due to stable carbocation formation.2. Nucleophile: Weak nucleophiles.3. Leaving Group: Good leaving groups.4. Solvent: Polar protic solvents to stabilize the carbocation intermediate.

Factors Favoring SN2 Reactions

1. Substrate: Primary (1^\circ) or methyl alkyl halides due to minimal steric hindrance; secondary (2^\circ) alkyl halides react more slowly. Tertiary (3^\circ) alkyl halides are unreactive via SN2.2. Nucleophile: Strong nucleophiles.3. Leaving Group: Good leaving groups.4. Solvent: Polar aprotic solvents to enhance nucleophile reactivity.