Terms
α-carbon
-
The carbon adjacent to the leaving group .
β-carbon
-
The carbon(s) adjacent to the α-carbon.
β-hydrogen
-
The hydrogen(s) attached to the β-carbon.
Aprotic
-
A solvent that is not a hydrogen bond donor.
Leaving Group
-
The group that leaves in a substitution or elimination reaction.
Nucleophile
-
A group characterized by it's SN2 reactivity. Good nucleophiles tend to be good bases,
though they need not be. A nucleophile has a lone pair of electrons which makes up the business
end of the molecule. See the
nucleophilicity section.
Protic
-
A solvent that is a hydrogen bond donor.
Rate
-
The speed of a reaction. Often measured in moles per second.
Rate law
-
A mathematical equation that relates the rate of a reaction to the concentration of its reactants. For a generic reaction:
The rate law is expressed as:
Rate-limiting step
-
The slowest step in a reaction that determines the overall rate.
Reaction order
-
In the rate law, the value of "a" and "b" for reactants "X" and "Y," respectively. The overall
order of a reaction is the sum of "a" and "b" and tells how many molecules of reactant are involved in
the transition state of the rate-limiting step.
Reaction intermediate
-
An intermediary molecule that accumulates in negligible quantities during a reaction.
Transition state
-
An extremely unstable molecule that forms between the reactants and their intermediates/products. A
transition state exists at the peaks of an energy diagram, in contrast to intermediates and products,
which form in the troughs. The ‡ symbol and brackets denote a transition state structure.
The number of reactant molecules present in the rate-limiting transition state is equal to the
reaction order.
