Organic Chemistry> How to easily find which is +m and-m grou...

How to easily find which is +m and-m group and what is way
to find it

Prem , 5 Years ago

Grade 11

5 Answers

Arun

Last Activity: 5 Years ago

+M effect- groups which have lone pairs (also incld functional groups with lone pairs) , all methyl grps (due to hyperconjugation), groups with a negative charge

-M groups- groups with positive charge, functional groups with no lone pair(eg NO2)

Remember - halogens show +m effect and -I effect but their -i effect is more dominating while in other functional groups +M is more dominating if they show +M and -I ( -OCH3)

Vikas TU

Last Activity: 5 Years ago

Dear student

-M Effect is shown by groups which decreases the electron density on benzene.

+M Effect is shown by groups which increases the electron density on benzene ring.

Good Luck

ANKIT DHAKAD

Last Activity: 5 Years ago

+M Group has lone pair or - ve charge and - M group has +ve charge or conjugate system which has more EN than other conjugate system example is ph-cho, Cho is a - M group bcz it has more EN than C=C bond in benzene

Srinivasan S

Last Activity: 5 Years ago

All answers mentioned earlier are correct. I suggest an easier solution. If you know your periodic table well enough.

Consider Ar – X-Y (where Ar is aryl ring, X is an atom (not group) attached directly to Ar and Y is an atom attached directly to X). Here, when:

X belongs to a higher group in the periodic table than Y (e.g. -OH, -CH3, -NH2 etc.), then XY is o-/p- directing.
X belongs to a lower group in the periodic table than Y (e.g. NO2, COCH3, CN etc) then XY is m-directin

Hope this helps