5. An Overview of Organic Reactions Flashcards
The more electronegative atom has the greater electron
density
a change in electron distribution as a
response to change in electronic nature of the
surroundings
Polarization
tendency to undergo polarization
Polarizability
occur between regions of high
electron density and regions of low electron density
Polar reactions
electron poor; lewis acid
electrophile
electron rich; lewis base
nucleophile
The multiplied concentrations of the products
divided by the multiplied concentrations of the
reactant
equilibrium constant, Keq
this indicates
that at equilibrium most of the material is present as
products
value of Keq
is greater than 1
the concentration of the product
is ten times that of the reactant
Keq is 10
at
equilibrium most of the material is present as the
reactant
Keq is less than one
the concentration of the reactant is ten times that of the product
Keq is 0.10
The ratio of products to reactants is controlled by
their relative
Gibbs free energy
If Keq> 1, energy is
released to the surroundings; exergonic reaction
If Keq< 1, energy is
absorbed from the surroundings; endergonic reaction
The standard free energy change at 1 atm pressure
and 298 K is delta G degrees
amount of energy
required to break a given bond to produce two radical
fragments when the molecule is in the gas phase at
25 ̊ C
Bond dissociation energy
The highest energy
point in a reaction step
Transition state
The energy needed to go from reactant to transition state is the
activation energy
If a reaction occurs in more
than one step, it must
involve species that are
neither the reactant nor the
final product
reaction intermediates/ intermediates
two molecules combine
addition reaction
one molecule splits into two; acid catalyst
elimination reactions
parts from two molecules exchange; light
substitution
a molecule undergoes
changes in the way its atoms are connected; acid catalyst
rearrangement
one bonding electron stays with each product
symmetrical bond breaking
one bonding electron is donated by each reactant
symmetrical bond making
two bonding electrons stay with one product
unsymmetrical bond breaking
two bonding electrons are donated by one reactant
unsymmetrical bond making
homolytic
symmetrical
heterolytic
unsymmetrical
react to complete electron octet of valence
shell
can break a bond in another molecule
and abstract a partner with an electron, giving
substitution in the original molecule
can add to an alkene to give a new
radical, causing an addition reaction
radicals
homolytic formation of two reactive species with
unpaired electrons
initiation
reaction with molecule to generate radical
propagation
combination of two radicals to form a stable
product
termination
The arrow goes from the nucleophilic reaction site to
the electrophilic reaction site
delta H - negative
exothermic (releases heat)
delta H - positive
endothermic (absorbs heat)
delta S - negative
randomness decreases
delta S - positive
randomness increases
delta G - negative
favorable equililbrium constant, exergonic, and occur spontaneously
delta G - positive
unfavorable equilibrium constant, endergonic, and cannot occur spontaneously
