Arenes

Anenes BENZENE qqfqunhymidisedeo aoab.istau.fm planaracloud eaboveandbelow I88 benzene rings sp2 hybrid 14resonancestructures resonance guesextrastabilitytonngstructure v j v Physicalproperties preferentiallyundergoeselectrophilicsubstitutionto Nonpolaronlyweakdispersion preservearomaticitystabilityforcesbetweenmolecules 41 v lowmeltingandboilingpoints itsstabilityalsomakesitlesssusceptibleto volatileandflammable attackbyelectrophilesthanGCbondsin solubleinnonpolarsolventslike alkenes requiresstrongerelectrophilesformcclinsolubleinH2O Benzeneisacolourlessliquid atroomtemperature REACTIONSINVOLVINGBENZENEELECTROPHILICSUBSTITUTION AugFeltzCSIwarm or Generationofelectrophile UzcgsFeeswarm Obvdecolonisationofgreenishyellow Cl UscgandwhitefumesofHucg concHNOsconcHIOacatalyst55C Obupaleyellowoilyliquidformed N2 FriedelWattsalkylation UtsaAlllseswarm ObvwhitefumesofHeegformed Vtb

MECHANISMOFELECTROPHILICSUBSTITUTION FeBrcs6h12l1Braces warm2ClothBrtHBr FeBrtBE BrttFeBrq Reactiononlyoccursin strongelectrophilegenerated anhydrousconditions H2OwillcompetewithBra HBr forFeBrsasanacceptorofa Brtslow lonepairofelectronsThis v t preventstheformationof strongelectrophileBrt T BrHBr LFEB.iq fast HBRtFeBB byprod Lewisacidcatalystregenerated Notes Has04isastrongerLenisacidthanHMOsthusH2S04protonalesHNosto generateNOI NosiselectronwithdrawinganddeactivatesthebenzeneringMorerigorous conditionsarerequiredforfurthernitration Nosisa3directingsubstituent furthergroupsaddedtobenzeneringareaddedatCs LkIV NoteUseBrzcaqasadistinguishingtestbetweenalkenesandanenes EgAddBrcapdropwisewithshakingtoLcm'sof2methylcyclohexaneandbenzene Bkcalls noreaction yelloworangeBracapnotdecolourised Br OH Bracaq Her YelloworangeBracageisdecolourised major

AIZUMETHYLBENZENE AugUVlightonlymajorproductsshown Freeradicalsubstitution Alkylsidechain reactions COOH KMnOCaqdiH2804heat Oxidation Utz Otb UtzCtAldsCsroomtemp ES Utz Utz AugFedsCsrtabsenceofUVEg U U CH3 concHNosconcHI04catalyst30CEs Noa NotebecauseUtsiselectrondonatingit9electrondensityofthebonzeringthus itisanactivatingsubstituentThereforeconditionsforelectrophilic substitutionaremilderthanforbenzene EFFECTSOFSUBSTITUENTSONBENZENERING Inductiveeffect electrondonatingsubstituentsincreaseelectrondensityofthebenzeneringthroughtheSigmabondlegUtzOHNHa Theyareactivating converselyelectronwithdrawingsubstituentsreduceelectrondensity legBr CHO NODTheyaredeactivating Resonanceeffect substituentswithalonepairofelectronsresidingintheporbitalcandonatethemintothebenzeneringviaresonance 8 f throughtheTIbondCdelocalisationofeLeg IOHNth Electronegativesubstituentscanwithdrawelectronsfromthe N benzeneringviaresonancethroughtheTIbondlegCOOHCN sts Uto

Activatinggroupsandhalogensare2,4directingwhiledeactivatinggroupsare3directing substituent Effectonbenzeneringto Effectonpositionof electrophilicattack electrophilicattack Ralkylgroup Activating 2,4directing OHORNHz 2,4directing MtrNra stronglyactivating ClBr2 Deactivating 2,4directing CHOWR UH stronglydeactivatingGRNHINO 3detecting W OH OH OHI Et I E IG 2 6 2 6 2 s s s s s 3 4 4 4 ENos Nos PEtG e s I G z s s s 34 E SIDECHAINOXIDATION AHalkylgroupsexcept30sidechainsualgetoxidisedtoWOH KMnoacaq UtzUtzGEO dtheHaffo COOHt21120tCO2 PurpleKMnogisdecolourised whitepptofbenzoicacidisfarmed Benzoicacid Cuhaeppt KMnoacaq UtzUtzUtz btodthetaffo GOHtHaot41300011 µ3 KMnoacaql cUt daH2S04 noreaction I heat Utz OH KMnoacaql I daNaOH gCtb 8Eo heat ONa131120t202PurplekMnOqisdecolourised 3 sodiumbenzoate BmmpptofMnaisformed solubleinH2O 0 KMnoacaql cUtzt46 dthetaffo CoottH2O coz