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CHAPTER 5
Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics
Important Terms
active site
the pocket of an enzyme where all the bond-making and bond-breaking steps of an
enzyme-catalyzed reaction occur.
acyclic
noncyclic.
addition reaction
a reaction in which atoms or groups are added to the reactant.
alkene
a hydrocarbon that contains a double bond.
allyl group
2
CH
2
CHCH
allylic carbon
an
sp
3
carbon adjacent to a vinyl carbon.
allylic hydrogen
a hydrogen bonded to an allylic carbon.
Arrhenius equation
an equation that relates the rate constant of a reaction to the energy of activation
and the temperature at which the reaction is carried out
1
k
=
Ae
-
E
a
>
RT
2
.
catalyst
a species that increases the rate at which a reaction occurs without being consumed
or changed in the reaction.
catalytic hydrogenation
the addition of hydrogen to a double or a triple bond with the aid of a metal
catalyst.
coupled reactions
an endergonic reaction followed by an exergonic reaction.
degree of unsaturation
the sum of the number of
p
bonds and rings in a hydrocarbon.
electrophile
an electron-deficient atom or molecule.
electrophilic addition
an addition reaction in which the first species that adds to the reactant is an
reaction
electrophile.
endergonic reaction
a reaction with a positive
∆
G
°
; it consumes more energy than it releases.
endothermic reaction
a reaction with a positive
∆
H
°
.
enthalpy
the heat given off
1
if
∆
H
°
6
0
2
or the heat absorbed
1
if
∆
H
°
7
0
2
during the
course of a reaction.
entropy
a measure of the freedom of motion in a system.
enzyme
a protein that is a biological catalyst.
exergonic reaction
a reaction with a negative
∆
G
°
; it releases more energy than it consumes.