Chapter 6 Flashcards
An organic halide in which the halogen atom is bonded to an alkyl carbon
Alkyl halide
An organic halide in which the halogen atom is bonded to an alkene carbon
Alkenyl halides
An organic halide in which the halogen atom is attached to an aromatic ring, such as a benzene ring
Aryl halide
An organic halide in which the halogen atom is bonded to a benzene ring; a specific type of aryl halide
Phenyl halide
A reaction in which a nucleophile reacts with a substrate to replace a leaving group (a group that departs with an unshared electron pair)
Nucleophilic substitution reaction
A Lewis base, an electron pair donor that seeks a positive center in a molecule
Nucleophile
The substituent that departs from the substrate in a nucleophilic substitution reaction
Leaving group
The molecule or ion that undergoes reaction
Substrate
Cleavage by the solvent. A nucleophilic substitution reaction in which the nucleophile is a molecule of the solvent
Solvolysis
A term that refers to rates of reactions
Kinetics
A reaction whose rate-determining step involves two initially separate species
Bimolecular
The number of species involved in a single step of a reaction (usually the rate-determining step)
Molecularity
Literally, substitution nucleophilic bimolecular. A bimolecular nucleophilic substitution reaction that takes place in a single step. A nucleophile attacks a carbon bearing a leaving group from the back side, causing an inversion of configuration at this carbon and displacement of the leaving group
SN2
A state on a potential energy diagram corresponding to an energy maximum (i.e., characterized by having higher potential energy than immediately adjacent states). The term transition state is also used to refer to the species that occurs at this state of maximum potential energy; another term used for this species is the activated complex
Transition state
A reaction where bond forming and bond breaking occur simultaneously (in concert) through a single transition state
Concerted reaction
A reaction that proceeds with a negative free-energy change
Exergonic reaction
A reaction that proceeds with a positive free-energy change
Endergonic reaction
A plot of free-energy changes that take place during a reaction versus the reaction coordinate. It displays free-energy changes as a function of changes in bond others and distances as reactants proceed through the transition state to become products
Free-energy diagram
The abscissa in a potential energy diagram that represents the progress of the reaction. It represents the changes in bond orders and bond distances that must take place as reactants are converted to products
Reaction coordinate
The difference in free energy between the transition state and the reactants
Free energy of activation
Chemical studies that take into account the spatial aspects of molecules
Stereochemistry
A reaction whose rate-determining step involves only one species
Unimolecular
Literally, substitution nucleophilic unimolecular. A multi step nucleophilic substitution in which the leaving group departs in a unimolecular step before the attack of the nucleophile. The rate equation is first order in substrate but zero order in the attacking nucleophile
SN1 reaction
If a reaction takes place in a series of steps, and if one step is intrinsically slower than all of the others, then the rate will be the same as (will be determined by) the rate of this slow step
Rate-determining step
A transient species that exists between reactants and products in a state corresponding to a local energy minimum on a potential energy diagram
Intermediate
Electron delocalization (via orbital overlap) from a filled bonding orbital to an adjacent unfilled orbital; generally has a stabilizing effect
Hyperconjugation
A reaction that transforms an optically active compound into a racemic form is said to proceed with racemization; takes place whenever a reaction causes chiral molecules to be converted to an achiral intermediate
Racemization
Literally, cleavage by the solvent. A nucleophilic substitution reaction in which the nucleophile is a molecule of the solvent
Solvolysis
An effect on relative reaction rates caused when the spatial arrangement of atoms or groups at or near the reacting site hinders or retards a reaction
Steric hinderance
A postulate stating that the structure and geometry of the transition state of a given step will show a greater resemblance to the reactants or products depending on which is closer to the transition state in energy. This means that the transition state of an endothermic step will resemble the products of that step more than the reactants, whereas the transition state of an exothermic step will resemble the reactants of that step more than the products
Hammond-Leffler postulate
The relative reactivity of a nucleophile in an SN2 reaction as measured by relative rates of reaction
Nucleophilicity
A polar solvent that doesn’t have a hydrogen atom attached to an electronegative element; doesn’t hydrogen bond with a Lewis base (e.g., a nucleophile)
Polar aprotic solvent
A polar solvent that has at least one hydrogen atom bonded to an electronegative element. These hydrogen atoms of the solvent can form hydrogen bonds with a Lewis base (e.g., a nucleophile)
Polar protic solvent
An effect on relative rates of reaction caused by the solvent. For example, the use of a polar solvent will increase the rate of reaction of an alkyl halide in an SN1 reaction
Solvent effect
A measure of a solvent’s ability to insulate opposite charges from each other. The dielectric constant of a solvent roughly measures its polarity. Solvents with high dielectric constants are better solvents for ions than are solvents with low dielectric constants
Dielectric current
The susceptibility of the electron cloud of an uncharged molecule to distortion by the influence of an electron charge
Polarizability
A process that converts one functional group into another
Functional group interconversion
