10- Aromatic Compounds

What are the rules for aromaticy?

must be a ring, sp2-sp hybrodized, pi electrons must be 4N+2, the ring must be planar

Carbocations count as ___ pi electrons and lone pairs/negative charges sometimes count as ____ pi electrons.

0, 2

Double and triple bonds count as ____ pi electrons.

two

How do we know when to count lone pairs?

When the lone pairs are able to be resonance delocalized

What is the aromatic system equation?

4n+2

Do we count the lone pair if there is a double bond to it?

NO

Do we count carbanions in a ring system?

yes, if they are within the ring

What is the anti-aromatic equation?

4n

To be aromatic, the ring must be ______, which means flat.

planar

What are examples of non-planar molecules?

stop sign, 5 pi bonds (two stop signs),

In an Sn1 reaction, we form a ______ intermediate then an incoming nucleophile attacks the positive charge to give us a racemic product.

carbocation

The more stable the carbocation intermediate in the SN1 reaction, what does this lead to?

faster reaction

How does aromaticity affect acidity?

-if an acid forms an aromatic conjugate base, then that acid will be more acidic because the aromaticity makes its conjugate base more stable

The carbon that immediately comes off the benzene ring is known as the?

benzene carbon

As long as the benzene carbon is bonded to at least one H, then you can do what reactions?

KMnO4, OH-/H3O+, heat or Na2Cr2O7, H2SO4

Ketone with Zn(Hg), HCl, heat

Alkane Chain

Ketone with H2NNH2, HO-, Heat

alkane

How to add NO2 to aromatic ring?

HNO3, H2SO4 (nitration)

How do we add SO3H to the benzene ring for sulfonation?

SO3, H2SO4

How do we add Br to benzene ring?

Br2, FeBr3

How do we add Cl2 to benzene ring?

Cl2/ AlCl3

How do we add an alkyl chain to the benzene ring?

R-Cl/AlCl3 (friedel-crafts alkylation)

What is friedel-crafts acylation?

Cl-COR/AlCl3

What is formylation on the benzene ring?

CO, HCl, AlCl3, CuCl which adds aldehyde

The substituent already on the ring determine where the new ___ will go.

addition

Substituents that suck electron density out of benzene ring are called _____ directors and substituents that donate electron density into the benzene ring are called ______ directors.

meta; ortho/para

Are are moderate deactivating groups?

aldehydes, ketones, carboxylic acids, esters, carbonyl-containing functional groups

What are the strong deactivating groups?

NO2, SO3H, CN, NR3+, CX3

What are the weak deactivating groups?

-X

What are the weak activating groups?

R=Alkyl or -aromatic groups

What are the moderate activating groups?

OR, -NH-OR, -OOR

What are the strong activating groups?

O-, OH, NR2, NRH, NH2

What is the way to remember that withdrawers go meta?

W goes M

What is the intermediate for electron aromatic substitution

pi bond attacks electron and form carbocation intermediate

Where are the negative charges when we have donating groups?

on the ortho and para positions (more electron density)

Where are the positive charges in the ring on the withdrawing groups?

On the ortho and para sucking the density away from these areas

If you have more than one substituent on the ring, the one with the ____ ___ will determine where it goes.

highest energy

What are the Friedel-Craft limitations?

they do not work with strong/moderate meta directors, This can be overcome with strong ortho/para directer.

What is a diazonium salt?

formed when you react NH2 with NaNO2, HCl (HONO)

Can you directly form phenol from a benzene?

NO

NO2 with H2, Pd/C or Sn, HCl

NH2

Aniline (NH2)

This is formed from NO2 and H2/PdC or Sn, HCl

What can you react a diazonium salt with to form a phenol?

H3O+ or EtOH

What is the only way of going from benzene to phenol?

forming the diazonium salt

What are reactions we can do we diazonium salt?

CuBR or CuCl, CuCN, KI, H3O+ / EtOH, HBF3, H3PO2

What do we count carboanions as?

2

Fridel craft alkylation is able to undergo ______

rearrangement to form the most stable carbocation intermediate

What does H2NNH2, KOH, Heat do?

reduces ketone to alkane

When you have CN on the benzene ring, how can we make that a carboxylic acid?

H3O+, heat

If a lone pair is invloved in pi bonding through resonance, it resies in a ____ orbital. If it does not participate in resonance, it resides in the atom's ____ state.

p; hybridized