GLOSSARY OF TERMS USED IN PHYSICAL ORGANIC CHEMISTRY
(IUPAC Recommendations 1994)

Index

Quick move to A, B, C, D, E, F, G, H, I, K, L, M, N, O, P, Q, R, S, T, U, V, W, Y, Z.


abstraction
acceptor number (AN)
acid
acidity
acidity function
activated complex
activation energy See energy of activation.
addend See addition reaction.
addition
addition reaction
additivity principle
adduct
A-factor See energy of activation.
agostic
alcoholysis See solvolysis.
allylic substitution reaction
alternant
ambident
amphiphilic
amphiprotic (solvent)
amphoteric
anchimeric assistance See neighbouring group participation.
anionotropic rearrangement (or anionotropy)
anion radical See radical ion.
annelation
annulation
annulene
antarafacial, suprafacial
anti
antiaromatic See aromatic.
anti-Hammond effect See More O'Ferrall-Jencks diagram.
anti-Markownikoff addition See Markownikoff rule.
aprotic (solvent)
aquation
aromatic, aromaticity
Arrhenius equation See energy of activation.
aryne
association
asymmetric induction
atomic orbital
attachment
autocatalytic reaction
automerization
autoprotolysis
autoprotolysis constant
"A" value
+ azacarbene See nitrene.
+ azene See nitrene.
+ azylene See nitrene.
[alpha]-addition (alpha-addition)
[alpha]-effect
[alpha]-elimination

Baldwin's rules
base
basicity
basicity function See acidity function.
bathochromic shift (effect)
Bell-Evans-Polanyi principle
benzyne
bifunctional catalysis
bimolecular See molecularity.
binding site
biradical
Bodenstein approximation See steady state.
bond
bond dissociation
bond-dissociation energy
bond energy (mean bond energy)
bond migrationSee migration.
bond number
bond order
borderline mechanism
Bredt's rule
bridged carbocation
bridging ligand
Brønsted acid (Brönsted acid)
Brønsted base (Brönsted base)
Brønsted relation (Brönsted relation)
Bunnett-Olsen equations

cage
cage compound
canonical form See contributing structure.
captodative effect
carbanion
carbene
carbenium centre
carbenium ion
carbenoid
carbocation
carbonium ion
carbyne
catalysis
catalysis law See Brønsted relation.
catalyst
catalytic coefficient
cationotropic rearrangement (cationotropy)
cation radical See radical ion.
chain reaction
chain transfer
charge density See electron density.
charge population
charge-transfer complex
chelation
cheletropic reaction
chelotropic reaction
chemical flux
chemically induced dynamic nuclear polarization (CIDNP) See CIDNP.
chemical reaction
chemical relaxation
chemical shift (NMR)
chemical species
chemoselective, chemoselectivity
+ chemospecificity See chemoselectivity.
chromophore
CIDNP (Chemically Induced Dynamic Nuclear Polarization)
cine-substitution
class (a) metal ion
class (b) metal ion
clathrate See host, inclusion compound.
colligation
common-ion effect (on rates)
compensation effect
complementary binding sites See binding site.
complex
composite reaction
comproportionation
concerted process
condensation reaction
configuration (electronic)
configuration (molecular)
conformation
conjugate acid-base pair
conjugated system, conjugation
conjugative mechanism See electronic effect.
connectivity
constitution
conrotatory See electrocyclic reaction.
contact ion pair See ion pair.
contributing structure
coordinate covalence (coordinate link) See coordination.
coordination
coordination number
coordinatively saturated
coordinatively unsaturated
coronate See crown.
correlation analysis
cosphere See cybotactic region.
coupling constant (spin-spin coupling constant)
covalent bond
Cox-Yates equation
critical micelle concentration (cmc)
cross-conjugation
crown
cryptand
Curtin-Hammett principle
cybotactic region
cyclization
cycloaddition
cycloelimination
+ cycloreversion See cycloelimination.

+ dative bond See coordination.
decomposition, chemical
+ de-electronation See oxidation.
degenerate chemical reaction See identity reaction.
degenerate rearrangement
delocalization
deshielding See shielding.
detachment
detailed balancing, principle of
diamagnetic
diastereoisomerism
dielectric constant
dienophile
diffusion-controlled rate
dimerization
Dimroth-Reichardt ET parameter
dipolar aprotic solvent
dipolar bond
dipolar cycloaddition See cycloaddition.
dipole-dipole interaction
dipole-induced dipole forces See van der Waals forces.
diradical See biradical.
direct effect See field effect.
dismutation See disproportionation.
dispersion forces See London forces.
disproportionation
disrotatory See electrocyclic reaction.
dissociation
distonic radical cation
donor number (DN)
downfield See chemical shift.
driving force (also called the affinity) of a reaction
dual substituent-parameter equation
dyotropic rearrangement

ET-value See Dimroth-Reichardt ET parameter, Z-value.
+ educt
effective charge
effective molarity (or effective concentration)
eighteen-electron rule
electrocyclic reaction
electrofuge
electromeric effect
electron acceptor
electron affinity
electronation See electron attachment, reduction.
electron attachment
electron configuration See configuration (electronic).
electron-deficient bond
electron density
electron detachment
electron donor
+ electron-donor-acceptor complex
electronegativity
electroneutrality principle
electronic effect of substituents: symbols and signs
electron-pair acceptor
electron-pair donor
electron transfer
electron-transfer catalysis
electrophile, electrophilic
electrophilicity
element effect
elementary reaction
elimination
enantiomer
enantioselectivity See stereoselectivity.
encounter complex
encounter-controlled rate
ene reaction
energy of activation (Arrhenius energy of activation; activation energy)
energy profile See Gibbs energy diagram, potential-energy profile.
enforced concerted mechanism
enophile See ene reaction.
entering group
enthalpy of activation (standard entalpy of activation)
entropy of activation, (standard entropy of activation)
epimer
epimerization
equilibrium, chemical
equilibrium control See thermodynamic control.
equilibrium isotope effect See isotope effect.
ET-value See Dimroth-Reichardt ET parameter, Z-value.
excess acidity See Bunnett-Olsen equations, Cox-Yates equation.
excimer
exciplex
excited state
extended Hammett equation
external return See ion-pair return.
extrusion transformation
[eta]-symbol ("eta")

fast-atom bombardment (FAB) mass spectroscopy
field effect
flash vacuum pyrolysis (FVP)
fluxional
force-field calculations See molecular mechanics calculation.
fractionation factor, isotopic
fragmentation
free radical See radical.
frontier orbitals
functional group

gas-phase acidity
gas-phase basicity
geminate pair
geminate recombination
general acid catalysis
general base catalysis
Gibbs energy diagram
Gibbs energy of activation (standard free energy of activation)
ground state
group
Grunwald-Winstein equation
guest

half-life
halochromism
Hammett acidity function See acidity function.
Hammett equation (or Hammett relation)
Hammond principle (or Hammond postulate)
Hansch constant
hapto
hard acid
hard base
heat capacity of activation
+ hemileptic See homoleptic.
Henderson-Hasselbach equation
heterobimetallic complex
heteroconjugation
heteroleptic
heterolysis, heterolytic
heterolytic bond-dissociation energy
heterovalent hyperconjugation See hyperconjugation.
hidden return See ion-pair return.
Hildebrand parameter
Hofmann rule
homo
homoaromatic
homoconjugation
homoleptic
homolysis, homolytic
host
Hückel (4n + 2) rule
hybridization
hydration
hydrogen bond
hydrolysis
hydron
hydrophilic
hydrophobic interaction
hyperconjugation
hypsochromic shift

identity reaction
imbalance
+ imene See nitrene.
+ imidogen See nitrene.
+ imidonium ion See nitrene.
+ imin See nitrene.
+ imine radical See nitrene.
inclusion compound (or inclusion complex)
induction period
inductive effect
inductomeric effect
inert
inhibition
initiation
inner-sphere (electron transfer)
insertion
intermediate
intermolecular
internal return See ion-pair return.
intimate ion pair See ion pair.
intramolecular
intramolecular catalysis
intrinsic barrier
inverse kinetic isotope effect See isotope effect.
inverted micelle
ionic strength
ionization
ionization energy
ionizing power
ion pair
ion pair return
ipso-attack
isodesmic reaction
isoelectronic
isoentropic
isoequilibrium relationship
isokinetic relationship
isolobal
isomer
isomerization
isosbestic point
isoselective relationship
isotope effect
isotope effect, equilibrium see isotope effect, thermodynamic.
isotope effect, heavy atom
isotope effect, intramolecular
isotope effect, inverse
isotope effect, kinetic
isotope effect, primary
isotope effect, secondary
isotope effect, solvent
isotope effect, steric
isotope effect, thermodynamic
isotope exchange
isotopic perturbation, method of
isotopic scrambling
isotopologue
isotopomer
isovalent hyperconjugation See hyperconjugation.

Kamlet-Taft solvent parameters
Kekulé structure (for aromatic compounds)
kinetic ambiguity
kinetic control (of product composition)
kinetic electrolyte effect (kinetic ionic-strength effect)
kinetic equivalence
kinetic isotope effect See isotope effect.
Koppel-Palm solvent parameters
Kosower Z-value See Z-value.

labile
least nuclear motion, principle of
leaving group
Leffler's assumption See Hammond principle.
left-to-right convention
levelling effect
Lewis acid
Lewis acidity
Lewis adduct
Lewis base
Lewis basicity
Lewis formula (electron dot or Lewis structure)
lifetime (mean lifetime)
ligand
linear free-energy relation
linear Gibbs energy relation See linear free-energy relation.
linear solvation energy relationships
line formula
line-shape analysis
Lineweaver-Burk plot See Michaelis-Menten kinetics.
lipophilic
London forces
lone (electron) pair
loose ion pair See ion pair.
LUMO See frontier orbitals.
lyate ion
lyonium ion

macroscopic diffusion control See mixing control.
magic acid See superacid.
magnetic equivalence
magnetization transfer
Marcus equation
Markownikoff rule
mass-law effect
matrix isolation
mean lifetime See lifetime.
mechanism
mechanism-based inhibition
medium
Meisenheimer adduct
melting point (corrected/uncorrected)
mesolytic cleavage
mesomeric effect
mesomerism
mesophase
metastable (chemical species) See transient (chemical species).
metathesis
+ methylene See carbene.
+ methylidyne See carbyne.
micellar catalysis
micelle
Michaelis-Menten kinetics
microscopic chemical event See chemical reaction, molecularity.
microscopic diffusion control (encounter control)
microscopic reversibility, principle of
migration
migratory aptitude
migratory insertion
minimum structural change, principle of See molecular rearrangement.
mixing control
Möbius aromaticity
moiety
molecular entity
molecularity
molecular mechanics calculation
molecular metal
molecular orbital
molecular rearrangement
molecule
More O'Ferrall-Jencks diagram
multi-centre bond
+ multi-centre reaction
multident See ambident.
[mu] (mu) and [mu]

+ narcissistic reaction
neighbouring group participation
NHOMO See subadjacent orbital.
NIH shift
nitrene
nitrenium ion
no-bond resonance See hyperconjugation.
nonclassical carbocation
normal kinetic isotope effect See isotope effect.
nucleofuge
nucleophile, nucleophilic
nucleophilic catalysis
nucleophilicity
n-[sigma]* delocalization (or n-[sigma]* no bond resonance)

onium ion
opposing reactions See composite reactions.
optical yield
orbital See atomic orbital, molecular orbital.
orbital steering
orbital symmetry
order of reaction
outer-sphere (electron transfer)
oxidation
oxidation number
oxidative addition
oxidative coupling

parallel reaction See composite reaction.
paramagnetic
partial rate factor
pericyclic reaction
periselectivity
perpendicular effect See More O'Ferrall-Jencks diagram
persistent
pH-rate profile
phase-transfer catalysis
phenonium ion See bridged carbocation.
photolysis
+ polar aprotic solvent See dipolar aprotic.
polar effect
polar solvent See polarity.
polarity
polarizability
polydent See ambident.
potential-energy profile
potential-energy (reaction) surface
pre-association
precursor complex See encounter complex.
pre-equilibrium (or prior equilibrium)
pre-exponential factor See energy of activation, entropy of activation.
primary kinetic electrolyte effect See kinetic electrolyte effect.
primary kinetic isotope effect See isotope effect.
primitive change
prior equilibrium See pre-equilibrium.
product-determining step
product development control
promotion See pseudo-catalysis.
propagation See chain reaction.
protic See protogenic.
protogenic (solvent)
+ protolysis
proton affinity
proton transfer reaction
protophilic (solvent)
prototropic rearrangement (or prototropy) See tautomerism.
pseudo-catalysis
pseudo-first order rate coefficient See order of reaction.
+ pseudomolecular rearrangement
pseudopericyclic
+ pseudo-unimolecular
pyrolysis
[pi]-adduct (pi-adduct)
[pi]-bond (pi bond) See sigma, pi.
+ [pi]-complex See [pi]-adduct.
[pi]-electron acceptor, [pi]-electron donor group
[pi]-orbital See sigma, pi.

quantitative structure-activity relationships (QSAR)
quantum yield

radical (or free radical)
radical anion See radical ion.
radical centre(s)
radical combination See colligation.
radical ion
radical pair (or geminate pair)
radiolysis
rate coefficient See order of reaction, kinetic equivalence.
rate constant
rate-controlling step
rate-determining step, rate-limiting step
rate law (or empirical differential rate equation)
rate of appearance See rate of reaction.
rate of reaction
reacting bond rules
reaction
reaction coordinate
reaction mechanism See mechanism.
reaction path
reaction stage
reaction step
reactive, reactivity
reactivity index
reactivity-selectivity principle (RSP)
rearrangement See degenerate rearrangement, molecular rearrangement, sigmatropic rearrangement.
rearrangement stage
reduction
reductive elimination
regioselectivity, regioselective
relaxation
reorganization energy
resonance
resonance effect
resonance energy
+ retroaddition See cycloelimination.
+ retrocycloaddition See cycloelimination.
retro-ene reaction See ene reaction.
reverse micelle (or reversed micelle) See inverted micelle.
Ritchie equation
[rho]-value (rho-value)
[rho][sigma]-equation (rho-sigma equation)

sacrificial hyperconjugation See hyperconjugation.
+ salt effect See kinetic electrolyte effect.
saturation transfer
Saytzeff rule
scavenger
scrambling See isotopic scrambling.
secondary kinetic electrolyte effect See kinetic electrolyte effect.
secondary kinetic isotope effect See isotope effect.
selectivity
selectivity factor
shielding
sigma, pi ([sigma], [pi])
sigmatropic rearrangement
silylene
single-electron transfer mechanism (SET)
single-step reaction
Slater-type orbital
soft acid See hard acid.
soft base See hard base.
solvation
solvatochromic relationship
solvatochromism
solvent isotope effect See isotope effect.
solvent parameter
solvent polarity See polarity.
solvent-separated ion pair See ion pair.
solvolysis
solvophobicity parameter
SOMO
sonication
special salt effect
species See chemical species.
specific catalysis
spectator mechanism
spin adduct See spin trapping.
spin counting See spin trapping.
spin density
spin label
spin trapping
stable
stationary state
steady state (or stationary state)
stepwise reaction
stereoelectronic
stereoelectronic control
stereoselectivity, stereoselective
stereospecificity, stereospecific
steric-approach control
steric effect
steric isotope effect See isotope effect, steric.
steric hindrance
stoichiometric number See rate of reaction.
stopped flow
strain
subjacent orbital
substituent
substituent electronegativity See electronegativity.
substitution reaction
substrate
successor complex
suicide inhibition See mechanism-based inhibition.
superacid
superbase See superacid.
suprafacial See antarafacial.
supramolecule
Swain-Lupton equation
Swain-Scott equation
symbiosis
symproportionation
syn See anti.
synartetic acceleration See neighbouring group participation.
synchronization (principle of nonperfect synchronization)
synchronous
[sigma]-adduct (sigma adduct)
[sigma]-bond (sigma bond) See sigma, pi.
[sigma]-constant (sigma constant)
[sigma]-orbital (sigma orbital) See sigma, pi.

T-jump See chemical relaxation.
Taft equation
+ tautomeric effect See electromeric effect.
tautomerism
tautomerization
tele-substitution
telomerization
termination
tetrahedral intermediate
thermodynamic control (of product composition)
thermolysis
tight-ion pair See ion pair.
T-jump See chemical relaxation.
torquoselectivity
transferability
transformation
transient (chemical) species
transition coordinate
transition state
transition state analogue
transition structure
transmission coefficient See transition state.
transport control See microscopic diffusion control.
trapping
tunnelling

umpolung
unimolecular See molecularity.
unreactive
unstable
upfield See chemical shift.

valence
valence isomer
valence tautomerization
van der Waals forces
volume of activation

Wheland intermediate See Meisenheimer adduct, [sigma]-adduct
Woodward-Hoffmann rules See orbital symmetry

Ylide
Yukawa-Tsuno equation

Z-value
Zaitsev rule See Saytzeff rule.
zwitterionic compound
Zucker-Hammett hypothesis

Z-value