Ortho-Para & Meta Directors

Give 2 charcteristics all ortho-para directors share

1. all are activating groups

2. all electron donating

O – 

NR

NH2 

OH 

.tell whether these are:

 1.strongly ,moderate, weakly activating OR deactivating

include why


 


 

2.ortho- para OR meta  directors

 STRONGLY activating ortho- para  directors

 

why:  they all contain lone pairs , i.e. unshared electron pairs that exist outside the ring

the most activating ortho- para f directors tend to have
electron pairs that exist outside the ring

which is more activating?

 

 

OH vs OCH3

OH b/c:

 

it has an unshared electron pair

1.amides, OCOR, CH3O-

vs 

2.R (alkyl), C6H5

 

Both of these grps are activating but which set is stronger?

amides, carboxylic acid, CH3O-

are moderatly activating

 

while R (alkyl), C6Hare the weakest activating grps 

(these have no lone pairs, which can make resonance structures)

put these in order from most deactivating  to least deactivating

Cl-

I-

Br-

F-

Most deactivating= most electronegative

F-

Cl-

Br-

I-

 

-X

halogens

Tell whether:

1.stong/moderate/weak

activating 

2. o/p or meta directors

Halogens are weakly deactivating

& ortho para directors

 

they can donate an unshared pair of electrons (as shown by resoance structures) by indutive effect.

what is the inductive effect?

if ‘G’ is an electronegative atom(a substitute on the benzene ring) than Carbon then the:

ring: + charge

 

 G : -charge

ring will have postive charge

electron contribution to benzene is greater by resoance or the indutive effect.

resonance

 

(structures allow the posotive charge to go on the substitute , aka NOT IN THE RING)

order these grps from most electron donating to least electron donating

OR, -NH2, OH, -NR2

most e donating= more lone pairs

-NH2,-NR2

OH

OR

X (weakly deactating=electronegative)

N02, NR3+,CF3,-CCl3

.tell whether these are:

 1.strongly ,moderate, weakly activating OR deactivating

2.ortho- para OR meta  directors

 why?

strongly deactivating/meta directors

the combined electonegativities of these atoms, has an inductive effect,causes positive charge to be in the ring.

which is more deactivating

tell whether these are:

CN or CF3 why?

CF3 

(F is more electronegative than N)

which is more deactivating

                        -CCl3 or -SO3H?

 -CCl3 

more electronegative

COOH

COOR

COHR

COR2

tell whether these are:

 

 1.strongly ,moderate, weak activating OR deactivating

2.ortho- para OR meta  directors

 why?

moderatly deactivating

 

b/c carbonyl grp provides resonace structures in which electrons are taken away from ring (giving it a positive charge)

Tagged In :

Get help with your homework


image
Haven't found the Essay You Want? Get your custom essay sample For Only $13.90/page

Sarah from studyhippoHi there, would you like to get such a paper? How about receiving a customized one?

Check it out