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Organic Chemistry > Ch. 16 – Reactions of Aromatic Compounds > Flashcards

Ch. 16 – Reactions of Aromatic Compounds Flashcards

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1
Q

Does benzene act as an electrophile or a nucleophile?

A

nucleophile (has lose pi electrons that are delocalized)

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2
Q

What type of general reactions are favored for benzenes? Hint: aromaticity

A

those that keep the aromatic ring intact

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3
Q

What is electrophilic aromatic substitution?

A

H atom on benzene is replaced by an electrophile (+E)

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4
Q

How many steps does the general mechanism for electrophilic aromatic sub have? What are they?

A

2 steps

1) add E+ to benzene (forms carbocation)
2) base deprotonates to reform aromatic molecule

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5
Q

How many resonance structures are given when C+ is formed by the addition of E+ to benzene?

A

3 res structures where carbon w/ E is sp3 hybridized

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6
Q

What is a sigma complex?

A

resulting carbocation structure after adding E to benzene ring

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7
Q

What is the RDS is EA sub?

A

addition of E+ because molecule loses aromaticity

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8
Q

Where is positive charge on EA resonance structures always located?

A

either in ortho or peta positions

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9
Q

How do groups on ortho/peta carbons affect Ea in formation of carbocation intermediate in EA sub?

A

groups that stabilize positive charge will drop Ea

groups that destabilize positive charge will increase Ea

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10
Q

What is the active electrophile in halogenation of benzene?

A

Lewis acid-base complex

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11
Q

What product does FC alkylation of benzene give?

A

alkyl benzene

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12
Q

What product does FC acylation of benzene give?

A

ketone

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13
Q

In FC alkylation of benzene, which R-Cl types give carbocations?

A

2º and 3º only

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14
Q

What type of electrophile does acylation produce?

A

acylium ion

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15
Q

Do vinyl and aryl halides react with FC alkylation?

A

No because their carbocations are highly unstable

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16
Q

Can carbocation RAR occur for FC alkylation?

A

yep, hydride shift

17
Q

What forms from intramolecular FC reactions?

A

forms new ring (will be double ring)

18
Q

Can carbocation RAR occur for FC acylation?

A

no RAR

19
Q

What causes inductive effects?

A

electronegativity of atoms in the sub and polarizability

20
Q

If an atom is more EN than carbon (inductive), what happens to electron density?

A

pulled out of benzene

21
Q

If a polarizable alkyl group (X is in a pi system) is on benzene (inductive), what happens to electron density?

A

donated to benzene

22
Q

How does p character effect electronegativity?

A

more p character = more EN

23
Q

What are resonance effects?

A

donation or withdrawal of electrons depending on if they put positive or negative charges on benzene

24
Q

How can you tell if res structures donate or withdraw electron density?

A

donate if neg charges result on benzene

withdraw if pos charges result on benzene

25
Q

What groups are always electron donating?

A

alkyl (R) groups, O, N groups

26
Q

What groups are always electron withdrawing?

A

halogens (X), double bond, Y with full or partial pos charge

27
Q

What groups are ortho/para directors and activators?

A

alkyl and O/N groups

28
Q

What group is ortho/para deactivators?

A

halogens

29
Q

What groups are meta directors and deactivators?

A

Y with double bond or partial/full pos charge

30
Q

What are activators?

A

subs on benzene that make it react faster

31
Q

What are deactivators?

A

subs on benzene that make it react slower

32
Q

What makes an activator/deactivator?

A

RDS accounting for formation of carbocation
activators = electron donating groups because they stabilize carbocation
deactivators = electron withdrawing groups because they destabilize carbocation

33
Q

What is the one group that follows inductive effects over resonance effects?

A

halogens

Organic Chemistry (26 decks)

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