ACS Structure and Reactivity of Aromatic Compounds

How many isomeric tribromobenzenes exist?

A) none! (such a compound cannot exist)

B) 1

C) 2

D) 3

D) 3

A C8H10 hydrocarbon is nitrated by HNO3 and sulfuric acid. Two, and only two, C8H9NO2 isomers are obtained. Which of the following fits this evidence?

A) ethylbenzene

B) ortho-xylene

C) meta-xylene

D) para-xylene

B) ortho-xylene

Which of the following is an important reactive electrophile in aromatic ring nitration?

A) NO2(+)

B) NO(+)

C) N2(+)

D) N2O(+)

A) NO2(+)

Bromination of meta-chloronitrobenzene may produce how many C6H3ClBrNO2 isomers?

A) 1

B) 2

C) 3

D) 4

D) 4

How many isomeric dinitrobenzoic acids can exist? C6H3(NO2)2CO2H

A) 3

B) 4

C) 5

D) 6

D) 6

Which of the following is phenol?

A) C6H5OH

B) C6H5CH2OH

C) C6H5COCH3

D) C6H5OCH3

A) C6H5OH

What is the order of reactivity of the following compounds in electrophilic substitution? (more reactive > less reactive) I toluene II nitrobenzene III benzene IV phenol

A) I > II > III > IV

B) IV > III > II > I

C) I > III > IV > II

D) IV > I > III > II

D) IV > I > III > II

What is the order of reactivity of the following compounds in electrophilic substitution? (more reactive > less reactive) I chlorobenzene II aniline III ethylbenzene IV benzoic acid

A) I > II > III > IV

B) II > III > I > IV

C) I > III > IV > II

D) II > I > IV > III

B) II > III > I > IV

What is the order of increased meta electrophilic substitution for the following compounds? ( more meta product > less meta product) I C6H5N(CH3)3(+) II C6H5CH2Cl III C6H5CHCl2 IV C6H5CCl3

A) I > II > III > IV

B) III > II > IV > I

C) I > II > IV > III

D) I > IV > III > II

D) I > IV > III > II

Which of the following benzene ring substituents is deactivating but ortho-para directing?

A) -N=O

B) -OCH3

C) -COCH3

D) -NO2

A) -N=O

Which of the following organic chlorides will not give a Friedel-Craft alkylation product when heated with benzene and AlCl3.

A) (CH3)3CCl

B) CH2=CHCH2Cl

C) CH3CH2Cl

D) CH2=CHCl

D) CH2=CHCl

Which of the following substituents on a benzene ring is ortho-para directing?

A) -OCOCH3

B) -COCH3

C) -CO2H

D) -CN

A) -OCOCH3

Which of the following compounds reacts rapidly with Br2 in the dark?

A) benzene

B) anisole C6H5OCH3

C) acetophenone C6H5COCH3

D) none of the above

B) anisole C6H5OCH3

Which of the following reaction sequences would be best for converting para-bromoanisole to ortho-ethylanisole?

A) (i) H2 & Pt catalyst (ii) C2H5Cl & AlCl3

B) (i) Mg in ether (ii) aqueous alcohol (iii) C2H5Cl & AlCl3

C) (i) Mg in ether (ii) C2H5Cl & AlCl3

D) (i) C2H5Cl & AlCl3 (ii) Mg in ether (iii) aqueous alcohol

D) (i) C2H5Cl & AlCl3 (ii) Mg in ether (iii) aqueous alcohol

When Friedel-Craft alkylation of benzene is carried out with 1 equiv. of tert-butyl chloride, a large amount of para-di-tert-butylbenzene is formed, along with the mono-substitution product.Why doesn't all the benzene react to give tert-butylbenzene (the mono-substitution product)?

A) the tert-butyl substituent activates the benzene ring to further substitution.

B) the reaction is bimolecular, so two tert-butyl chloride molecules combine with one benzene molecule.

C) the tert-butyl substituent is large and favors reaction at the para-position.

D) the disubstituted product is favored in equilibrium with the mono-substituted ring..

A) the tert-butyl substituent activates the benzene ring to further substitution.

When para-bromotoluene is treated with NaNH2 in ether, the bromine is lost and a mixture of para & meta-CH3C6H4NH2 products is obtained. What kind of intermediate would account for this?

A) a charge delocalized anion formed by nucleophilic addition of NH2(-) to the benzene ring..

B) a charge delocalized anion formed by abstraction of a methyl proton by the base NH2(-).

C) an aryl cation formed by loss of bromide anion.

D) a benzyne species formed by elimination of HBr.

D) a benzyne species formed by elimination of HBr.

Sulfonation of naphthalene by conc. sulfuric acid produces the 1-sulfonic acid at 120 ºC and the 2-sulfonic acid at 160 ºC.Which of the following statements is not true?

A) the 2- sulfonic acid is kinetically favored

B) sulfonation is a reversible reaction

C) the 2- sulfonic acid is thermodynamically favored (more stable)

D) electrophilic attack at C-1 is favored over attack at C-2

A) the 2- sulfonic acid is kinetically favored

6H5OCH2CH2Br is heated with Mg in ether and then quenched in cold 10% HCl.What organic product will be obtained by ether extraction of the aqueous acid?

A) C6H5OCH2CH3

B) C6H5OCH2CH2OH

C) C6H5OH

D) C6H6

C) C6H5OH

A C9H12O compound is reacted with a solution of lithium in liquid ammonia.After evaporation of the ammonia, the residue is warmed with 10% HCl and extracted with ether.The product is identified as 2-cyclohexenone. Which of the following might be the starting compound?

A) C6H5OC3H7

B) C6H5CH2CH2CH2OH

C) C6H5CH2CH2OCH3

D) C6H5CH2CH(OH)CH3

A) C6H5OC3H7

Which of the following procedures would be best for the preparation of phenyl benzyl ether? C6H5OCH2C6H5

A) C6H5Cl + C6H5CH2O(-) Na(+)

B) C6H5O(-) Na(+) + C6H5CH2Cl

C) 2 C6H5Cl + Na2O

D) 2 C6H5MgBr + CH2O

B) C6H5O(-) Na(+) + C6H5CH2Cl

Which reaction sequence would be best for preparing 3,5-dibromoaniline from nitrobenzene?

A) (i) 3 H2 & Pt or Ni catalyst (ii) 2 Br2 in ether

B) (i) excess Br2 + FeBr3 & heat (ii) 3 H2 & Pt or Ni catalyst

C) (i) 3 H2 & Pt or Ni catalyst (ii) H2SO4 & heat (iii) excess HBr

D) (i) H2SO4 & heat (ii) excess Br2 + FeBr3 & heat (iii) 3 H2 & Pt or Ni catalyst

B) (i) excess Br2 + FeBr3 & heat (ii) 3 H2 & Pt or Ni catalyst

How could one prepare 3,4,5-tribromoaniline from para-nitroaniline? note: HNO2 = NaNO2 + 10% H2SO4

A) (i) 3 H2 & Pt or Ni catalyst (ii) 2 Br2 in ether (iii) HNO2 0 ºC (iv) H3PO2

B) (i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii) excess Cu2Br2 + HBr C) (i) 2 Br2 in ether (ii) 3 H2 & Pt or Ni catalyst (iii) HNO2 0 ºC (iv) H3PO2

D) (i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3 H2 & Pt or Ni catalyst

D) (i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3 H2 & Pt or Ni catalyst

How could one prepare 3,5-dibromophenol from para-nitroaniline? note: HNO2 = NaNO2 + 10% H2SO4

A) (i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) H3PO2 (iv) 3 H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat

B) (i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii) excess Cu2Br2 + HBr (iv) KOH & heat

C) (i) HNO2 0 ºC, then heat (ii) 2 Br2 in ether (iii) 3 H2 & Pt or Ni catalyst (iv) HNO2 0 ºC (v) Cu2Br2 + HBr

D) (i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3 H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat

A) (i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) H3PO2 (iv) 3 H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat

Iodination of benzene is not easily carried out. How can one prepare para-iodobenzoic acid from para-nitrotoluene? note: HNO2 = NaNO2 + 10% H2SO4

A) (i) Br2 + FeBr2 (ii) Mg in ether, then CO2 (iii) 3 H2 & Pt or Ni catalyst (iv) HNO2 0 ºC (v) KI solution

B) (i) NBS in CCl4 & heat (ii) NaI in acetone (iii) 3 H2 & Pt or Ni catalyst (iv) HNO2 0 ºC (v) H3PO2

C) (i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii) Cu2Br2 + HBr (iv) KMnO4 & heat (v) KI solution

D) (i) KMnO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii) HNO2 0 ºC (iv) KI solution

D) (i) KMnO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii) HNO2 0 ºC (iv) KI solution

An important group of commercial dyes, known as azo dyes, are prepared by a diazo coupling reaction. What functional group characterizes an azo dye?

A) -N=O

B) -N3

C) -N=N-

D) -NO2

C) -N=N-

Which sequence of reactions would be best for preparing meta-propylaniline from benzene?

A) (i) HNO3 & H2SO4 & heat (ii) C3H7COCl + AlCl3 (iii) 5 H2 & Pt or Ni catalyst

B) (i) C3H7COCl + AlCl3 (ii) HNO3 & H2SO4 & heat (iii) 5 H2 & Pt or Ni catalyst

C) (i) C3H7COCl + AlCl3 (ii) 2 H2 & Pt or Ni catalyst (iii) HNO3 & H2SO4 & heat (iv) 3 H2 & Pt or Ni catalyst

D) (i) HNO3 & H2SO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii) C3H7COCl (iv) 2 H2 & Pt or Ni catalyst

B) (i) C3H7COCl + AlCl3 (ii) HNO3 & H2SO4 & heat (iii) 5 H2 & Pt or Ni catalyst

The aromatic heterocyclic base pyridine is sulfonated by heating with conc. sulfuric acid Which of the following statements about this reaction is correct? (note that in numbering the ring nitogen is #1)

A) pyridine reacts more rapidly than benzene and is sulfonated at C-3

B) pyridine reacts more rapidly than benzene and is sulfonated at C-2 & C-4

C) pyridine reacts more slowly than benzene and is sulfonated at C-3

D) pyridine reacts more slowly than benzene and is sulfonated at C-2 & C-4

C) pyridine reacts more slowly than benzene and is sulfonated at C-3

Heating benzene in a large excess of 80% D2SO4 in D2O results in what product?

A) C6H5SO3D

B) C6H5OD

C) C6H5D

D) C6D6

D) C6D6

A solution of cyclohexene in benzene is stirred at 0 ºC while concentrated sulfuric acid is added. After washing away the acid and removing the excess benzene, what product is isolated?

A) cyclohexylbenzene

B) 1-cyclohexylcyclohexene

C) trans-1,2-diphenylcyclohexane

D) 1,1-diphenylcyclohexane

A) cyclohexylbenzene

Devise a series of reactions to convert benzene into meta-chlorobromobenzene. Select reagents and conditions from the following table, listing them in the order of use.

1 sulfuric acid (conc.)heat

2 Cl2 + FeCl3 & heat

3 NaNO2 + H3O(+)0 ºC4 H2Pt catalyst

5 Mg in ether

6 PBr37 H3PO28 HNO3 (conc.) +H2SO4 (conc.) & heat

9 Cu2Br2 + HBr10 (CH3CO)2O+ pyridine

A) 1 then 2 then 6

B) 2 then 8 then 4 then 3 then 9

C) 8 then 4 then 10 then 2 then 3 then 9

D) 8 then 2 then 4 then 3 then 9

D) 8 then 2 then 4 then 3 then 9