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Electrophilic Aromatic Substitution- Nitrationharding/summaries/14D25.pdfElectrophilic Aromatic...

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Electrophilic Aromatic Substitution- Nitration Sources: - Hardinger, Steven. “Chapter 23: Aromatic Substitution Reactions” OCATSA, page 31. 2012. Web -Hardinger, Steven. “Chemistry 14D: Lecture Supplement” 4 th Ed. Hayden McNeil. 2016. Print #Step 1: An Acid/Base Reaction. - protonation of the hydroxyl group of the nitric acid -this provides a better leaving group #Step 2: Leaving Group (i.e., water) Departure -this forms the nitronium ion, a reactive electrophile #Step 3: Rate-Determining Step *Nitronium ion (electrophile) reacts with the nucleophilic C=C of the benzene ring è rate determining step because it destroys aromaticity of the benzene #Step 4: Regains Aromaticity *Water functions as a base to remove the proton from the nitro group -reforms the C=C & regains the aromaticity Overview J *Overall transformation: Ar-H to Ar-NO 2 *Reagent: benzene, aq. HNO 3 , aq. H 2 SO 4 *Electrophilic species: the nitronium ion (NO 2 +) formed by the loss of water from the nitric acid
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ElectrophilicAromaticSubstitution-Nitration

Sources: - Hardinger, Steven. “Chapter 23: Aromatic Substitution Reactions” OCATSA, page 31. 2012. Web -Hardinger, Steven. “Chemistry 14D: Lecture Supplement” 4th Ed. Hayden McNeil. 2016. Print

#Step1:AnAcid/BaseReaction.-protonationofthehydroxylgroupofthenitricacid

-thisprovidesabetterleavinggroup

#Step2:LeavingGroup(i.e.,water)Departure-thisformsthenitroniumion,areactiveelectrophile

#Step3:Rate-DeterminingStep*Nitroniumion(electrophile)reactswiththe

nucleophilicC=Cofthebenzeneringèratedeterminingstepbecauseitdestroys

aromaticityofthebenzene

#Step4:RegainsAromaticity*Waterfunctionsasabasetoremovetheproton

fromthenitrogroup-reformstheC=C&regainsthearomaticity

OverviewJ *Overalltransformation:Ar-HtoAr-NO2*Reagent:benzene,aq.HNO3,aq.H2SO4*Electrophilicspecies:thenitroniumion(NO2+)formedbythelossofwaterfromthenitricacid

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