Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)

ion 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. -addition (alpha-addition) -effect -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 -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 Michael