Organic Chemistry - chapter 8-SN1 and E1 Reactions

Flashcards covering key vocabulary and concepts related to SN1, SN2, E1, and E2 reactions, including mechanisms, kinetics, and stereochemistry.

SN1 Reaction

A nucleophilic substitution reaction taking place in two steps and is an example of a unimolecular nucleophilic substitution mechanism.

Overall Reaction

The net changes that occur in a reaction, obtained by adding together all of the elementary steps.

Intermediate

A species produced in a mechanism but does not appear in the overall reaction.

Transition State

Occurs at a local energy maximum along the reaction coordinate in a free energy diagram.

E1 Reaction

Elimination reaction that takes place in two steps, via a unimolecular elimination.

SN1 and E1 Reactions - First Step

The first step in an E1 reaction is precisely the same as the first step in an SN1 reaction.

Reaction Kinetics

Important evidence supporting the different mechanisms proposed for SN1 and SN2 nucleophilic substitution reactions, as well as for the E1 and E2 reactions.

Theoretical Rate Law

Derived from a proposed mechanism. Each elementary step has an associated theoretical rate law.

Rate-Determining Step

The slowest step in a reaction mechanism that determines the overall rate of the reaction.

Standard Free Energy of Activation

The energy barrier that each step must overcome in a reaction, denoted as DG°‡.

Stereospecific

A stereochemically pure substrate that undergoes an SN2 reaction yields only one stereoisomer, which depends on the specific configuration of the substrate.

Walden Inversion

The inversion of stereochemistry that occurs at the chiral center during an SN2 reaction due to backside attack.

Anticoplanar/Antiperiplanar Conformation

The conformation in which the H and the leaving group are anti to each other in an E2 reaction.

Phosphorylation

A process that regulates the function of certain enzymes, such as glycogen phosphorylase, and involves nucleophilic substitution.

Solvent-Mediated Proton Transfer

The transfer of a proton from one site to another in a particular species, via solvent molecules.

Termolecular Step

An elementary step with three reactants, which is generally unreasonable.

Carbocation Rearrangement

Carbocations, because of their net positive charge and lack of an octet, are inherently quite reactive.

Resonance Structures

The choice of which resonance structure is used will impact the curved arrow notation.