benzene + phenol

Question 1

who created the first model of benzene

Answer 1

August Kekule

Question 2

describe benzenes reactivity

Answer 2

Benzene has a low reactivity as it does not take part in electrophilic addition reactions since:
the 2 forms were in a rapid equilibrium so an approaching Br2 molecule could not get attracted to a π bond before the structure changed

Question 3

how did kekule solve the bond length discrepancy for benzene

Answer 3

he discovered that all carbon - carbon bonds in benzene are the same length
so a C=C bond length was the same as a C-C bond length

Question 4

what does the circle represent in the second model of benzene

Answer 4

it represents the multiple π bonds in benzene which are alternating rapidly and in a rapid equilibrium so cannot be in a fixed position is represented simply as a circle

Question 5

what is the EXPECTED enthalpy change of hydrogenation of benzene, explain

Answer 5

expected to be -357 kJ mol^-1 since the enthalpy change of cyclohexene is -119 so it WAS safe to assume that it should be -119 x 3 since benzene has three more π bonds than cyclohexene

Question 6

what is the ACTUAL enthalpy change of hydrogenation of benzene

Answer 6

the actual enthalpy change of hydrogenation of benzene is -208 kJ mol^-1

Question 7

what does the enthalpy change of hydrogenation of benzene prove

Answer 7

the enthalpy change of hydrogenation proves that benzene is more stable than expected since -208 < -357. Also this shows that the enthalpy change is less exothermic than expected

Question 8

what are the reagents and conditions for the alkylation of benzene

Answer 8

reagents: halogenalkane & ANHYDROUS AlCl3
conditions: room temp

Question 9

complete the equation _ _ _ _ + C2H5Cl -> _ _ _ _ _ _ _ _ + HCl
and name the electrophile

Answer 9

C6H6 & C6H5C2H5
electrophile is C2H5

Question 10

what are the reagents and conditions for the nitration of benzene

Answer 10

reagents: conc. nitric acid & conc sulphuric acid
conditions: reflux at 55°C

Question 11

what are the reagents and conditions for the halogenation of benzene

Answer 11

reagents: Cl & a halogen carrier (catalyst)
conditions: reflux with a halogen carrier (feCl3, AlCl3)

Question 12

what are the reagents and conditions of the acylation of benzene

Answer 12

Acyl chloride & anhydrous AlCl3 and reflux at 50°C

Question 13

what are the reagents and conditions for the bromination of benzene

Answer 13

halogen carrier (AlBr3) and room temp