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Problem. Review from Monday. C. H. 3. C. H. C. H. 3. 3. C. H. C. l. C. H. 3. 3. A. l. C. l. 3. O. C. H. 3. Multiple Additions may be a problem You may get lots of ortho to throw away. C. l. A. l. C. l. 3. Problem. C. H. 3.

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Problem

Review from Monday

C

H

3

C

H

C

H

3

3

C

H

C

l

C

H

3

3

A

l

C

l

3

O

C

H

3

Multiple Additions

may be a problem

You may get lots of

ortho to throw

away

C

l

A

l

C

l

3

Problem

C

H

3

C

H

C

H

O

3

3

H

H

Zn(Hg)

+

H

H

Would it help

to change the

order?

HCl

O


O

O

O

O

C

H

C

H

C

l

3

C

l

3

+

A

l

C

l

3

A

l

C

l

3

C

H

3

Deactivating

group. No

Friedel Crafts

Z

n

(

H

g

)

H

C

l

C

H

C

l

3

A

l

C

l

3

O

Z

n

(

H

g

)

C

H

H

C

l

3

C

H

3

C

H

3


O

O

H

C

l

O

O

A

l

C

l

3

Predict the main product

O

O

O

O

O

O

A B C

D E F

O

O

O

O

O

O


O

O

H

C

l

O

O

A

l

C

l

3

O

H

O

O

O


O

O

H

C

l

O

O

A

l

C

l

3

Predict the main product

O

O

O

O

O

O

A B C

D E F

O

O

O

O

O

O


H

+

H

-

F

F

Draw a mechanism and predict the product

F

F

A B C D

E F G

F

F


Review from Monday

Electrophilic Aromatic Substitution Reactions

C

H

C

H

C

H

C

H

3

3

B

r

3

3

B

r

B

r

-

B

r

B

r

H

B

r

/

F

e

B

r

2

3

+

+

+

B

r

-

F

e

B

r

3

B

r

B

r

F

e

B

r

3

60% 39% <1%


Review from Monday

C

H

C

H

C

H

3

3

3

B

r

B

r

B

r

H

H

H

C

H

C

H

C

H

C

H

3

3

3

3

B

r

B

r

/

F

e

B

r

Methyl does not help meta

2

3

+

+

Methyl

helps stabilize

ortho

H

B

r

C

H

2

B

r

B

r

H

(and para)

para

60% 39% <1%


Electron Donating Groups

d-

d-

Most basic sites

d-

C

H

3

Electron Withdrawing Groups

d+

d+

Most basic sites

d+


para

ortho

d-

d-

O

C

H

d+

3

d+

O

C

H

C

Bad

3

C

B

r

/

F

e

B

r

2

3

slower

B

r

m

a

i

n

p

r

o

d

u

c

t

Avoids putting

d+ near

d-

d+

Meta wins


Electrophilic Aromatic Substitution Reactions

B

r

B

r

B

r

-

B

r /

H

+

B

r

-

F

e

B

r

3

Two more

C

l

-

C

l

/

A

l

C

l

3

F

e

B

r

3

C

l

N

O

S

O

H

2

3

O

C

H

-

C

l

/

A

l

C

l

3

3

C

H

C

l

3

A

l

C

l

3

C

H

3

O

Friedel Crafts Alkylation

C

C

H

3

Friedel Crafts Acylation


O

O

N

O

O

/

H

S

O

H

N

O

H

N

O

2

4

3

no reaction

N

-

H

O

Electrophilic Aromatic Subsitution

How can you make HNO3 a stronger acid?

Add another acid.

O

H

N

O

O

O

O

O

O

N

H

H

N

S

H

S

O

O

O

O

O

O

O

O

O

N

i

t

r

o

n

i

u

m

i

o

n

H

H


O

O

S

O

H

3

O

Fuming

S

H

S

O

H

2

4

no reaction

O

S

O

O

Electrophilic Aromatic Subsitution

How can you make H2SO4 a stronger acid?

Add another acid.

O

O

O

+

-

H

O

+

H

S

O

+

H

S

S

H

S

3

4

O

O

O

O

O

O

O

H

O

H


Now that we have all our reactions, lets summarize

activation and deactivation

Electron Donating Groups activate the ring

Best

O

H

C

C

H

3

3

C

H

N

H

N

H

N

3

2

Which

one is

not

a

EDG?

A B C D

C

H

O

3

H

H

C

O

O

3

O

O

H

C

O

3

Direct

substitution

ortho/para

E F G H


Now that we have all our reactions, lets summarize

activation and deactivation

Electron Withdrawing Groups deactivate the ring

Best

H

N

O

O

O

O

N

H

N

H

3

2

C

S

O

H

N

3

+

H

anilinium

aniline

C

H

C

H

3

3

H

O

R

O

O

O

H

N

O

  • EDG or

  • EWG

?

Direct substitution meta


O

O

O

H

O

O

O

O

O

H

O

p

k

=

9

.

9

9

a

O

H

N

N

O

O

O

O

O

O

H

C

H

C

3

3

p

k

=

7

.

1

5

p

k

=

1

0

.

2

1

a

a

Predict pKa

N

O

O

A. less than 10 B. greater than 10


-X pKa

-H

-NO2

-OCH3

-CH3

-CN

-COCH3

-CF3

-F

-Cl

9.99

7.15

10.21

X

X

O

H

O

10.26

8.61

8.05

d-

8.68

inductive

effect

resonance

effect

9.89

9.41


C

l

What about a halide? Does a Cl

activate or deactivate the ring?

d-

C

l

C

l

C

l

C

l

d+

inductive

effect

resonance

effect

Cl poor at

p bonding

Deactivates,but directs ortho-para


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