6.1.1 Aromatic compounds Flashcards

1
Q

molecular formualar of benzene

A

C6H6

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2
Q

what mechanism does benzene undergo

A

electrophillic substitution

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3
Q

how many bond lengths would benzene have to fit with kekule

A

2 different bond lengths due to double and single bonds

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4
Q

how many bond lengths does benzene actually have

A

one

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5
Q

what explains the anomalous properties of benzene

A

a ring structure where the spare pairs of electrons are delocalised around all 6 carbon atoms
- delocalised electrons above and below the plane of atoms

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6
Q

bonding in benzene

A

each C has 4 outer electrons
1 used to bond to H
2 used to bond to adjacent carbons
remaining 6 are delocalised in a cloud above and below the plane of the ring

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7
Q

what do the delocalised electrons in benzene cause

A

rise to extra stability called delocalisation energy

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8
Q

isomer of arene compound for benzene

A

if had 3 double bonds it should have 2 isomers but benzene only has one

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9
Q

enthalpy of hydrogenation for kekule structure to prove its wrong

A

it should undergo similar reactions to cyclohexene and cyclodihexene howeveer it doesnt as the enthalpy is lower

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10
Q

Halogenation of benzene

A

halogen carrier must be present - FeCl3,AlBr3,FeBr3

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11
Q

nitration of benzene

A

concentrated nitric acid with concentrated sulphuric acid - warm

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12
Q

alkylation of benzene

A

reacting benzene with haloalkane with presence of AlCl3

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13
Q

acylation of benzene

A

presence of AlCl3

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14
Q

Directing effect

A

presence of substituted groups on a benzene ring will have an effect on the substitution of further groups

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15
Q

what increase the electron density

A

releasing electrons

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16
Q

what decreases the electron density

A

withdrawing electrons

17
Q

electron donating groups

A

-OH phenol
-NH2 amine

18
Q

electron withdrawing groups

A
  • NO2 nitro
19
Q

activating groups

A

side chains that increase electron density allow electrophiles to react faster than with benzene

20
Q

what directing numbers are electron donating groups

A

2,4

21
Q

oxygen as a donating group and how it happens

A

O is very electronegative
has effect of pushing electrons forcing areas of charge over the 2,4,6 position causing negative dipoles that attract electrophiles more effectively

22
Q

deactivating groups

A

side chains that decrease electron density slow electrophile reactions compared to benzene

23
Q

NO2 directing numbers

A

3,5