Aromaticity

Definition

In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone. The earliest use of the term was in an article by August Wilhelm Hofmann in 1855. There is no general relationship between aromaticity as a chemical property and the olfactory properties of such compounds.

Related concepts

(4+3) cycloaddition 1,2-Wittig rearrangement 1,2-rearrangement 1,3-Dipolar cycloaddition 2,3-Wittig rearrangement 2,3-sigmatropic rearrangement 2-Norbornyl cation 4+4 Photocycloaddition 6+4 Cycloaddition A value Acetoacetic ester synthesis Achmatowicz reaction Acyloin condensation Addition reaction Adenine Adkins–Peterson reaction Agostic interaction Akabori amino-acid reaction Alcohol oxidation Aldol condensation Aldol reaction Algar–Flynn–Oyamada reaction Aliphatic compound Alkane metathesis Alkyne metathesis Alkyne trimerisation Alkyne zipper reaction Alkynylation Allan–Robinson reaction Allen–Millar–Trippett rearrangement Allylic rearrangement Alpha-ketol rearrangement Alpha effect Amadori rearrangement Amide reduction Amino acid Andrussow process Angeli–Rimini reaction Aniline Annulation Annulene Anomeric effect Anthracene Antiaromaticity Arndt–Eistert reaction Aroma Aroma compound Aromantic Aromatic amine Aromatic hydrocarbon Aromatic ring current Aromaticity (cheminformatics)Aromatization Aryl Aspirin Atom Atomic orbital Atomic orbitals August Kekulé August Wilhelm Hofmann Aurophilicity Autoxidation Auwers synthesis Avoided crossing Aza-Baylis–Hillman reaction Aza-Cope rearrangement Aza-Diels–Alder reaction Azide-alkyne Huisgen cycloaddition Azo coupling BTX (chemistry)Baeyer–Emmerling indole synthesis Baeyer–Villiger oxidation Baird's rule Baker–Nathan effect Baker–Venkataraman rearrangement Baldwin's rules Bamberger rearrangement Bamberger triazine synthesis Bamford–Stevens reaction Banert cascade Barbier reaction Barbier–Wieland degradation Bartoli indole synthesis Barton–Kellogg reaction Barton–McCombie deoxygenation Barton–Zard reaction Baylis–Hillman reaction Bechamp reduction Beckmann rearrangement Bema Hapothle Benary reaction Benkeser reaction Bent bond Benzannulated Benzene Benzilic acid rearrangement Benzimidazole Bergman cyclization Bergmann degradation Bernthsen acridine synthesis Beta-silicon effect Bicycloaromaticity Biginelli reaction Bingel reaction Birch reduction Bischler–Möhlau indole synthesis Bischler–Napieralski reaction Blaise ketone synthesis Blaise reaction Blanc chloromethylation Blum–Ittah aziridine synthesis Bobbitt reaction Bodroux–Chichibabin aldehyde synthesis Boekelheide reaction Boger pyridine synthesis Bohlmann–Rahtz pyridine synthesis Bohn–Schmidt reaction Bond cleavage Bond length Boord olefin synthesis Borabenzene Borazine Borsche–Drechsel cyclization Bosch reaction Boudouard reaction Bouveault aldehyde synthesis Bouveault–Blanc reduction Boyland–Sims oxidation Bradsher cycloaddition Bredt's rule Brook rearrangement Bucherer carbazole synthesis Bucherer–Bergs reaction Buchner ring expansion Bürgi–Dunitz angle Cadiot–Chodkiewicz coupling Cadogan–Sundberg indole synthesis Camps quinoline synthesis Cannizzaro reaction Carbo-benzene Carbonyl allylation Carbonyl olefin metathesis Carbonyl reduction Carroll rearrangement Castro–Stephens coupling Catalytic resonance theory Cation–pi interaction Chalcogen bond Chan rearrangement Chan–Lam coupling Charge-shift bond Charge-transfer complex Charge remote fragmentation Cheletropic reaction Chemical Reviews Chemical bond Chemical compound Chichibabin pyridine synthesis Chirality (chemistry)Chlorophyll Chugaev elimination Claisen-Schmidt condensation Claisen condensation Claisen rearrangement Clar's rule Clemmensen reduction Closed shell Collins oxidation Combes quinoline synthesis Conformational isomerism Conia-ene reaction Conjugated system Conrotatory and disrotatory Cook–Heilbron thiazole synthesis Coordinate covalent bond Cope reaction Cope rearrangement Coplanar Corey–Fuchs reaction Corey–House synthesis Corey–Itsuno reduction Corey–Kim oxidation Corey–Winter olefin synthesis Cornforth rearrangement Coupling reaction Covalent bond Criegee oxidation Criegee rearrangement Cross-coupling partner Cross-coupling reaction Cross dehydrogenative coupling Curtin–Hammett principle Curtius rearrangement Cycloaddition Cyclobutadiene Cyclodecapentaene Cyclooctadecanonaene Cyclooctatetraene Cyclopentadienyl Cyclophane Cyclopropanation Cyclopropenyl Cyclotetradecaheptaene Cytosine C–H···O interaction DNA DNA oxidation Dakin oxidation Dakin–West reaction Darzens reaction Davis oxidation Davis–Beirut reaction De Kimpe aziridine synthesis Debus–Radziszewski imidazole synthesis Dehydrohalogenation Delocalization Delocalized electron Demjanov rearrangement Deoxygenation Dess–Martin oxidation Di-π-methane rearrangement Diazoalkane 1,3-dipolar cycloaddition Diazonium compound Dieckmann condensation Diels–Alder reaction Dihydrogen bond Dimroth rearrangement Divinylcyclopropane-cycloheptadiene rearrangement Doebner reaction Double bond Dowd–Beckwith ring-expansion reaction Dynamic binding (chemistry)Edman degradation Edwards equation Effective molarity Eight-center two-electron bond Einhorn–Brunner reaction Elbs persulfate oxidation Electrocyclic reaction Electromeric effect Electron Electron-rich Electron-withdrawing group Electron counting Electron deficiency Electronic effect Electrophile Electrophilic addition Electrophilic aromatic substitution Elimination reaction Emde degradation Empty orbital Ene reaction Enone–alkene cycloadditions Enyne metathesis Epoxidation of allylic alcohols Erich Clar Erich Huckel Erlenmeyer–Plöchl azlactone and amino-acid synthesis Eschweiler–Clarke reaction Esterification Ethenolysis Evelyn effect Favorskii reaction Favorskii rearrangement Feist–Benary synthesis Ferrario–Ackermann reaction Ferrier carbocyclization Ferrier rearrangement Fiesselmann thiophene synthesis Fischer indole synthesis Fischer oxazole synthesis Fischer–Hepp rearrangement Fischer–Tropsch process Fleming–Tamao oxidation Flippin–Lodge angle Four-center two-electron bond Free-energy relationship Friedel–Crafts reaction Friedländer synthesis Friedrich August Kekulé von Stradonitz Fries rearrangement Fritsch–Buttenberg–Wiechell rearrangement Fujimoto–Belleau reaction Fujiwara–Moritani reaction Fukuyama coupling Fukuyama reduction Functional group Furan Gabriel–Colman rearrangement Gallagher–Hollander degradation Ganem oxidation Gattermann reaction George S. Hammond Germanabenzene Gewald reaction Glaser coupling Glycol cleavage Graham reaction Grieco elimination Griesbaum coozonolysis Grignard reaction Grignard reagent Group transfer reaction Grundmann aldehyde synthesis Grunwald–Winstein equation Guanidine Guanine Haloform reaction Halogen bond Halogen dance rearrangement Hammett acidity function Hammett equation Hammick reaction Hammond's postulate Hantzsch ester Hantzsch pyridine synthesis Hapticity Harmonic oscillator model of aromaticity Hayashi rearrangement Heck reaction Hegedus indole synthesis Heme Hemetsberger indole synthesis Henry Edward Armstrong Henry reaction Herz reaction Heterocyclic compound Heterogeneous metal catalyzed cross-coupling Heterolysis (chemistry)Hexadehydro Diels–Alder reaction Hexasilabenzene High dilution principle Histidine Hiyama coupling Hofmann elimination Hofmann rearrangement Hofmann–Löffler reaction Hofmann–Martius rearrangement Homoaromaticity Homologation reaction Homologation reactions Homolysis (chemistry)Hooker reaction Horner–Wadsworth–Emmons reaction Hund's rule Hurd–Mori 1,2,3-thiadiazole synthesis Hydrazone iodination Hydrocyanation Hydrogen bond Hydrogenation Hydrogenolysis Hydrovinylation Hydroxylation Hydroxymethylation Hyperconjugation Hypervalent molecule Hückel's rule IUPAC nomenclature of organic chemistry Imidazole Inductive effect Intercalation (chemistry)Intermolecular force Intramolecular Diels–Alder cycloaddition Intramolecular force Inverse electron-demand Diels–Alder reaction Iodolactonization Ion Ionic bonding Ireland–Claisen rearrangement Isay reaction Isosaccharinic acid Ivanov reaction J. Am. Chem. Soc.J. J. Thomson Jacobsen epoxidation Jacobsen rearrangement Jemmis mno rules Johann Benedict Listing John Wiley & Sons Johnson–Corey–Chaykovsky reaction Jones oxidation Julia olefination Julia–Kocienski olefination Kauffmann olefination Kennedy J. P. Orton Ketene cycloaddition Kharasch–Sosnovsky reaction Kiliani–Fischer synthesis Kinetic isotope effect Knoevenagel condensation Knorr pyrrole synthesis Knorr quinoline synthesis Kolbe electrolysis Kolbe–Schmitt reaction Kornblum oxidation Kornblum–DeLaMare rearrangement Kowalski ester homologation Kröhnke pyridine synthesis Kulinkovich reaction Kumada coupling LFER solvent coefficients (data page)Larock indole synthesis Lectka enantioselective beta-lactam synthesis Left-handed Lehmstedt–Tanasescu reaction Leimgruber–Batcho indole synthesis Leuckart reaction Ley oxidation Liebeskind–Srogl coupling Lindgren oxidation Lipid peroxidation List of important publications in chemistry List of organic compounds List of organic reactions Lobry de Bruyn–Van Ekenstein transformation Lombardo methylenation London dispersion force Lone pair Lossen rearrangement Low-barrier hydrogen bond Luche reduction Madelung synthesis Malonic ester synthesis Mannich reaction Marcus theory Marker degradation Markovnikov's rule Markó–Lam deoxygenation McCormack reaction McFadyen–Stevens reaction McLafferty rearrangement McMurry reaction Mechanically interlocked molecular architectures Meerwein arylation Meerwein–Ponndorf–Verley reduction Metal-centered cycloaddition reactions Metal aromaticity Metallic bonding Metallophilic interaction Metal–ligand multiple bond Methionine sulfoxide Methoxymethylenetriphenylphosphorane Methylenation Meyer–Schuster rearrangement Michael reaction Minisci reaction Mislow–Evans rearrangement Miyaura borylation Mizoroki-Heck vs. Reductive Heck Molecular orbital More O'Ferrall–Jencks plot Mozingo reduction Mukaiyama hydration Mumm rearrangement Myers allene synthesis Möbius aromaticity Möbius strip Möbius–Hückel concept NMR Naphthalene Nazarov cyclization reaction Neber rearrangement Nef isocyanide reaction Nef synthesis Negative hyperconjugation Negishi coupling Neighbouring group participation Nenitzescu indole synthesis Newman–Kwart rearrangement Niementowski quinazoline synthesis Niementowski quinoline synthesis Nierenstein reaction Nitro-Mannich reaction Nitrone-olefin (3+2) cycloaddition Non-covalent interactions Noyori asymmetric hydrogenation Nozaki–Hiyama–Kishi reaction Nucleophile Nucleophilic aromatic substitution Nucleotide Nucleotide base Nucleus-independent chemical shift Nylon Olefin conversion technology Olefin metathesis Olfaction Olfactory Omega oxidation Oppenauer oxidation Orbital hybridisation Organic chemistry Organic compound Organic reaction Organic redox reaction Organic synthesis Overman rearrangement Oxazole Oxo-Diels–Alder reaction Oxy-Cope rearrangement Oxygen rebound mechanism Oxymercuration reaction Ozonolysis Paal–Knorr synthesis Palladium–NHC complex Paracetamol Paradromic Parikh–Doering oxidation Passerini reaction Passive binding Paternò–Büchi reaction Paul von Rague Schleyer Pauson–Khand reaction Pechmann condensation Pellizzari reaction Pericyclic reaction Peterson olefination Petrenko-Kritschenko piperidone synthesis Pfitzinger reaction Phenanthrene Phenol Phenyl Phenylalanine Phosphaethynolate Phosphorine Pi backbonding Pi bond Pi electron Pi interaction Pi stacking Piancatelli rearrangement Pictet–Spengler reaction Pinacol coupling reaction Pinacol rearrangement Pinnick oxidation Polar effect Polycyclic aromatic hydrocarbon Polyester Polyfluorene Polyhedral skeletal electron pair theory Polymerization Pomeranz–Fritsch reaction Povarov reaction Prato reaction Prilezhaev reaction Prins reaction Proton NMR Prévost reaction Pschorr cyclization Pummerer rearrangement Purines Pyrazine Pyrazole Pyridine Pyrimidines Pyrylium salt Quantum mechanical Quelet reaction Radical (chemistry)Ramberg–Bäcklund reaction Rauhut–Currier reaction Rearrangement reaction Reduction of nitro compounds Reductive amination Reed reaction Reformatsky reaction Regioselectivity Reimer–Tiemann reaction Reissert indole synthesis Resonance-assisted hydrogen bond Resonance (chemistry)Retro-Diels–Alder reaction Rieche formylation Right-handed Riley oxidation Ring-closing metathesis Ring expansion and contraction Ring forming reaction Ring strain Robert Robinson (organic chemist)Robinson annulation Robinson–Gabriel synthesis Rosenmund reduction Rubottom oxidation Ruff degradation Rupe reaction Sabatier reaction Sakurai reaction Salt bridge (protein and supramolecular)Sarett oxidation Saturate, Aromatic, Resin and Asphaltene Schmidt reaction Schotten–Baumann reaction Selenoxide elimination Semipinacol rearrangement Seyferth–Gilbert homologation Shapiro reaction Sharpless asymmetric dihydroxylation Sharpless epoxidation Sharpless oxyamination Sigma bond Sigmatropic reaction Silabenzene Simmons–Smith reaction Simple aromatic ring Single bond Singly even Skattebøl rearrangement Skraup reaction Smiles rearrangement Sommelet–Hauser rearrangement Sonogashira coupling Spectroscopy Spherical aromaticity Spiroaromaticity Stacking (chemistry)Stahl oxidation Stannabenzene Staudinger reaction Staudinger synthesis Stephen aldehyde synthesis Stereochemistry Stereoselectivity Stereospecificity Steric effects Stetter reaction Stevens rearrangement Stieglitz rearrangement Stille reaction Stollé synthesis Stork enamine alkylation Strecker degradation Styrene Substitution reaction Superaromaticity Suzuki reaction Swain–Lupton equation Swern oxidation Symmetric hydrogen bond Taft equation Takai olefination Terpenes Thermal rearrangement of aromatic hydrocarbons Thiazole Thiophene Thorpe reaction Thorpe–Ingold effect Three-center four-electron bond Three-center two-electron bond Thymine Tiffeneau–Demjanov rearrangement Toluene Transfer hydrogenation Trimethylenemethane cycloaddition Trinitrotoluene Tropone Tropylium Tryptophan Tyrosine Ugi reaction Ullmann condensation Ullmann reaction Unsaturated bond Uracil Urech hydantoin synthesis Van Leusen reaction Van der Waals force Vinylcyclopropane (5+2) cycloaddition Vinylcyclopropane rearrangement Vinylogy Von Braun amide degradation Wacker process Wagner-Jauregg reaction Wagner–Meerwein rearrangement Wallach rearrangement Walsh diagram Wave Weerman degradation Weinreb ketone synthesis Wenker synthesis Westphalen–Lettré rearrangement Wharton reaction Wheland intermediate Whiting reaction Willgerodt rearrangement Williamson ether synthesis Wittig reaction Wohl degradation Wohl–Aue reaction Wolff rearrangement Wolffenstein–Böters reaction Wolff–Kishner reduction Woodward's rules Woodward–Hoffmann rules Wulff–Dötz reaction Wurtz reaction Wurtz–Fittig reaction Xylene Y-aromaticity Yamaguchi esterification Yukawa–Tsuno equation Zaitsev's rule Zincke–Suhl reaction Zinin reaction Étard reaction Σ-aromaticity Σ-bishomoaromaticity

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