Química Orgânica 2 · Aromatic systems
Revisão de substituição aromática para a prova: problemas de prática
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- Bromination of benzene with Br₂ and FeBr₃
- Azo coupling of benzenediazonium with phenoxide
- Bromination of phenol without a Lewis acid
- Chlorination of nitrobenzene
- Removing a sulfonic acid blocking group: 2-bromotoluene
- Friedel–Crafts acylation of benzene with propanoyl chloride
- Intramolecular Friedel–Crafts acylation: 1-tetralone
- Alkylation of benzene with cyclohexene and sulfuric acid
- Friedel–Crafts alkylation with 1-chloro-2-methylpropane: a hydride shift
Desenhe o mecanismo 39
- Azo coupling of benzenediazonium with phenoxideDraw the attack of phenoxide's para carbon on the terminal nitrogen of benzenediazonium, the deprotonation that restores the ring, and the acid workup that gives 4-(phenyldiazenyl)phenol.
- Bromination of benzene with Br₂ and FeBr₃Draw how FeBr₃ activates Br₂, how benzene attacks the activated bromine to give an arenium ion, and how FeBr₄⁻ removes the ring proton to give bromobenzene and regenerate the catalyst.
- Bromination of phenol without a Lewis acidDraw the attack of phenol's para carbon on Br₂, pushed by the hydroxyl lone pair, and the deprotonation by bromide that gives 4-bromophenol and HBr.
- Chlorination of nitrobenzeneDraw the activation of Cl₂ by FeCl₃, attack by the carbon meta to the nitro group, and deprotonation by FeCl₄⁻ to give 1-chloro-3-nitrobenzene.
- Removing a sulfonic acid blocking group: 2-bromotolueneDraw the ipso protonation of 3-bromo-4-methylbenzenesulfonate by hydronium and the loss of SO₃ that removes the blocking group and gives 2-bromotoluene.
- Friedel–Crafts acylation of benzene with propanoyl chlorideDraw the formation of the propanoyl acylium ion from propanoyl chloride and AlCl₃, its capture by benzene, and the deprotonation that gives 1-phenylpropan-1-one.
- Intramolecular Friedel–Crafts acylation: 1-tetraloneDraw acylium-ion formation from 4-phenylbutanoyl chloride, ring closure onto the ortho carbon of the same benzene ring to form a six-membered ring, and deprotonation to give 1-tetralone.
- Alkylation of benzene with cyclohexene and sulfuric acidDraw the protonation of cyclohexene by sulfuric acid, the attack of benzene on the cyclohexyl cation, and the deprotonation by hydrogen sulfate that gives cyclohexylbenzene.
- Friedel–Crafts alkylation with 1-chloro-2-methylpropane: a hydride shiftDraw how the 1-chloro-2-methylpropane–AlCl₃ complex ionises with a hydride shift to the tert-butyl cation, how benzene captures that cation, and how AlCl₄⁻ restores the ring to give tert-butylbenzene.
- Friedel–Crafts tert-butylation of tolueneDraw the formation of the tert-butyl cation, attack by the carbon para to the methyl group of toluene, the arenium contributor that puts the positive charge on the carbon bearing CH₃, and deprotonation to 1-tert-butyl-4-methylbenzene.
- Meta nitration of benzaldehydeDraw the attack of the ring carbon meta to the formyl group on nitronium, a resonance contributor of the arenium ion showing that the charge never reaches the carbon bearing CHO, and the deprotonation that gives 3-nitrobenzaldehyde.
- Nitration of chlorobenzeneDraw nitronium formation in mixed acid, para attack by chlorobenzene with the chlorine lone pair stabilising the arenium ion, and deprotonation by hydrogen sulfate to give 1-chloro-4-nitrobenzene.
- SNAr: methoxide displaces chloride from 1-chloro-2-nitrobenzeneDraw the addition of methoxide to 1-chloro-2-nitrobenzene with the ortho nitro group holding the negative charge of the Meisenheimer complex, then the loss of chloride that gives 2-nitroanisole.
- Regioselective SNAr of 1,2-difluoro-4-nitrobenzene with morpholineDraw the addition of morpholine to the ring carbon para to the nitro group, the proton transfer to a second morpholine, and the loss of fluoride that gives 4-(2-fluoro-4-nitrophenyl)morpholine.
- Sulfonation of toluene with fuming sulfuric acidDraw the attack of the carbon para to the methyl group of toluene on SO₃, the deprotonation that restores the ring, and the proton transfer that gives 4-methylbenzenesulfonic acid.
- Acoplamento azo do benzenodiazônio com 2-naftol formando Sudan IDesenhe a desprotonação do 2-naftol, o ataque do C1 do naftóxido ao benzenodiazônio, a rearomatização e a protonação que formam o 1-fenilazo-2-naftol.
- Azo coupling of benzenediazonium with N,N-dimethylaniline: methyl yellowDraw para attack of N,N-dimethylaniline on the benzenediazonium ion, the iminium-stabilised arenium ion and deprotonation by acetate to methyl yellow.
- Aminação via benzino do 3-bromobenzotrifluoretoDesenhe a desprotonação do 3-bromobenzotrifluoreto pelo amideto, a perda de brometo formando o arino, a adição regiosseletiva do amideto e a protonação que formam a 3-(trifluorometil)anilina.
- Triptycene from benzyne and anthraceneDraw benzyne formation from bromobenzene and sodium amide, then its Diels–Alder addition across C9 and C10 of anthracene to give triptycene.
- Benzino de um triflato de sililarila capturado por furanoDesenhe o ataque do fluoreto ao silício, a perda de triflato formando o benzino e sua reação de Diels–Alder com furano, que dá o 1,4-di-hidro-1,4-epoxinaftaleno.
- Bromação do 2-metoxinaftaleno em C1Desenhe o ataque do C1 do 2-metoxinaftaleno ao bromo, o íon arênio estabilizado pela metoxila e a perda do próton de C1 que forma o 1-bromo-2-metoxinaftaleno.
- Bromação do 4-metilanisol a 2-bromo-4-metilanisolDesenhe o ataque do 4-metilanisol ao bromo em orto à metoxila, o íon arênio do tipo oxocarbênio e a perda do próton do anel que forma o 2-bromo-4-metilanisol.
- Bromação da 4-nitroacetanilida em C2Desenhe o ataque da 4-nitroacetanilida ao bromo em orto ao grupo acetamido, o íon arênio C=N⁺ e a perda do próton do anel que forma a 2-bromo-4-nitroacetanilida.
- Bromination of acetanilide to 4-bromoacetanilideDraw para attack of acetanilide on bromine, the nitrogen-stabilised arenium ion and loss of the ring proton to give 4-bromoacetanilide.
- Anisol e anidrido glutárico: um cetoácido de Friedel–CraftsDesenhe a abertura do anel do anidrido glutárico pelo AlCl3 a um íon acílio, o ataque do anisol pela posição para, a rearomatização e o tratamento ácido que libera o ácido 5-(4-metoxifenil)-5-oxopentanoico.
- Friedel–Crafts acetylation of chlorobenzene to 4-chloroacetophenoneDraw acylium ion formation from acetyl chloride and AlCl3, para attack by chlorobenzene and deprotonation to 4-chloroacetophenone.
- Propanoilação de Friedel–Crafts do mesitilenoDesenhe a formação do íon acílio a partir do cloreto de propanoíla e AlCl3, o ataque do mesitileno e a perda do próton do anel que formam a 1-(2,4,6-trimetilfenil)propan-1-ona.
- tert-Butylation of anisole to 4-tert-butylanisoleDraw the tert-butyl cation forming from tert-butanol in sulfuric acid, para attack by anisole and deprotonation to 4-tert-butylanisole.
- Alquilação do benzeno com 2-cloro-3-metilbutano: deslocamento de hidretoDesenhe a ionização do 2-cloro-3-metilbutano pelo AlCl3, o deslocamento 1,2 de hidreto ao cátion terciário e o ataque do benzeno a ele, formando o (2-metilbutan-2-il)benzeno.
- Isopropilação de Friedel–Crafts do p-xilenoDesenhe a ionização do 2-cloropropano pelo AlCl3, o ataque do p-xileno ao cátion isopropila e a perda do próton do anel que formam o 2-isopropil-1,4-dimetilbenzeno.
- Nitração do 4-fluoroanisol: a metoxila orienta mais que o flúorDesenhe a formação do íon nitrônio a partir do ácido nítrico, o ataque do 4-fluoroanisol em orto à metoxila e a rearomatização a 4-fluoro-2-nitroanisol.
- Nitration of anisole to 2-nitroanisoleDraw nitronium formation, ortho attack by anisole with the methoxy oxygen stabilising the arenium ion, and deprotonation to 2-nitroanisole.
- Nitration of 1,3-dimethoxybenzene to 2,4-dimethoxy-1-nitrobenzeneDraw nitronium formation from nitric acid, attack at C4 of 1,3-dimethoxybenzene with methoxy stabilisation, and loss of the ring proton.
- Nitração do 4-metilbenzoato de metila ao éster 3-nitroDesenhe a formação do íon nitrônio, o ataque do 4-metilbenzoato de metila pelo carbono em orto à metila e em meta ao éster, e a rearomatização a 4-metil-3-nitrobenzoato de metila.
- Nitration of naphthalene to 1-nitronaphthaleneDraw nitronium formation, attack at C1 of naphthalene with a benzenoid-preserving arenium ion, and deprotonation to 1-nitronaphthalene.
- SNAr do 1-cloro-2,4-dinitrobenzeno com anilinaDesenhe a adição da anilina ao 1-cloro-2,4-dinitrobenzeno formando o complexo de Meisenheimer, a perda de cloreto e a desprotonação que formam a 2,4-dinitrodifenilamina.
- SNAr da 4-fluorobenzonitrila com fenóxidoDesenhe a desprotonação do fenol pelo carbonato, a adição do fenóxido à 4-fluorobenzonitrila e a perda de fluoreto que formam a 4-fenoxibenzonitrila.
- SNAr of 1-fluoro-4-nitrobenzene with piperidineDraw piperidine adding to 1-fluoro-4-nitrobenzene to give the Meisenheimer complex, loss of fluoride, and deprotonation to 1-(4-nitrophenyl)piperidine.
- Sulfonation of nitrobenzene to 3-nitrobenzenesulfonic acidDraw meta attack of nitrobenzene on sulfur trioxide, deprotonation by hydrogen sulfate and protonation of the sulfonate.
Preveja o produto 7
- Amination of 2-bromoanisole with NaNH₂Predict the regiochemistry of nucleophilic addition to an unsymmetrical benzyne bearing an inductively withdrawing group.
- Amination of 4-chlorotoluene with NaNH₂Predict the cine-substitution products of an unactivated aryl halide reacting through benzyne.
- Brominate 4-nitrotoluenePredict the position of substitution when two ring substituents reinforce each other's directing effects.
- Trapping benzyne with furanPredict the Diels–Alder adduct when benzyne is generated in the presence of furan.
- Friedel–Crafts with 2-chlorobutanePredict the alkylbenzene from Friedel–Crafts alkylation of benzene with 2-chlorobutane.
- Nitrating 4-chloroanisolePredict nitration regiochemistry when two ortho/para directors compete on 4-chloroanisole.
- Sanger's reagent with an aminePredict the SNAr product of 1-fluoro-2,4-dinitrobenzene with a primary amine.
Classificar 6
- Which arene will not undergo Friedel–Crafts acylation?Identify a ring too deactivated for Friedel–Crafts acylation.
- Which species is aromatic?Apply Hückel's 4n + 2 rule to cyclic ions and neutral polyenes, including the effect of charge on the π count.
- Which nitrogen lone pair is in the aromatic sextet?Decide whether a heteroatom lone pair belongs to the aromatic π system in pyrrole and pyridine and connect it to basicity.
- Which aryl chloride undergoes SNAr?Recognise the substrate requirement for nucleophilic aromatic substitution by addition–elimination.
- Is azulene aromatic?Apply Hückel criteria to the fused 5–7 bicyclic hydrocarbon azulene.
- Find the meta directorIdentify the meta-directing group among common benzene substituents.
Comparar 4
- Rank three ring hydrocarbons by acidityRank hydrocarbon acidity from the delocalisation and aromaticity of the conjugate-base anions.
- Rank five arenes by rate of nitrationOrder monosubstituted benzenes by EAS rate from the activating or deactivating character of the substituent.
- Rank aryl chlorides for SNArRank aryl chlorides in SNAr reactivity by counting ortho/para nitro groups.
- Rank arenes for brominationRank five arenes by rate of electrophilic bromination from substituent donor strength.
Calcular 3
- π electrons in the cyclooctatetraene dianionCount the π electrons of a reduced annulene and use the count to explain a change in shape.
- Partial rate factor for para nitration of tolueneCalculate a partial rate factor from a relative rate and an isomer distribution.
- Count π electrons in the tropylium ionCount the π electrons of a cyclic carbocation to decide whether it is aromatic.
Encontre o erro 1
- A Friedel–Crafts plan for an aminoketoneFind the flaw in a Friedel–Crafts acylation planned on a free arylamine.
Interprete as evidências 4
- Where did the ¹⁴C label go?Interpret an isotope-labelling result as evidence for a benzyne intermediate.
- What a missing isotope effect meansInterpret the absence of a kinetic isotope effect in EAS nitration as evidence that attack, not deprotonation, is rate-determining.
- Um multipleto de 5H em 7,2 ppm: identifique o areno C9H12Use um multipleto aromático de cinco prótons para identificar um benzeno monossubstituído e atribuir sua cadeia lateral.
- Dois dubletos aromáticos de 2H: qual padrão de substituição?Reconheça o padrão aromático de dois dubletos no RMN de ¹H de um benzeno para-dissubstituído.
Trabalhe de trás para frente 1
- Which intermediate leads to 3-nitrobenzoic acid?Work backwards from a meta-disubstituted target to the intermediate that sets up the correct directing effect.
Planeje uma síntese 9
- Turn a meta director into an ortho/para directorChoose a reagent that converts an aromatic nitro group into an amino group.
- Make 1-chloro-3-propylbenzene from benzenePlan a three-step arene synthesis that uses an acyl group as a temporary meta director and avoids carbocation rearrangement.
- Make 2-bromotoluene free of the para isomerUse a reversible sulfonic acid blocking group to direct a substitution ortho to an alkyl group.
- Make 1-bromo-3-nitrobenzene from benzeneChoose the order of two electrophilic substitutions from the relationship of the substituents in the target.
- Make 4-bromobenzoic acid from tolueneOrder a ring substitution and a side-chain oxidation so that the directing effect of the side chain is used before it changes.
- Which sequence gives butylbenzene?Plan a route to butylbenzene that avoids carbocation rearrangement.
- Ácido 3-aminobenzoico a partir do toluenoOrdene a oxidação da cadeia lateral, a nitração e a redução do grupo nitro para preparar o ácido 3-aminobenzoico a partir do tolueno.
- Ácido 4-clorobenzenossulfônico a partir do benzeno em duas etapasEscolha a ordem de cloração e sulfonação que coloca os dois grupos em para no benzeno.
- Ordene a rota do tolueno ao ácido 4-nitrobenzoicoOrdene a nitração, a separação dos isômeros e a oxidação da cadeia lateral para preparar o ácido 4-nitrobenzoico a partir do tolueno.
Explique por quê 5
- Why does aniline give meta product in mixed acid?Explain how protonation of an amino group in strong acid converts an ortho/para director into a meta director.
- Why alkylation over-reacts and acylation does notExplain the difference in over-reaction between Friedel–Crafts alkylation and acylation from the effect of the group introduced.
- One bromide is a salt, the other is notExplain a difference in ionisation between two cyclic allylic bromides from the aromaticity of the cations they would form.
- Why acylation stops after oneExplain why Friedel–Crafts acylation gives monosubstitution while alkylation over-reacts.
- Why cyclopropenone is so polarExplain the large dipole of cyclopropenone with an aromatic charge-separated contributor.
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