Grade 12th passOrganic Chemistry

According to huckel's rule,n=1 in benzene but n indicates no. of pi bonds and benzene has 3 pi bonds,so how is n=1??
P.S.-Please do tell me if I went wrong somewhere and the reason too!

Aishwarya Byreddy

9 Years agoGrade 12th pass

5 Answers

Arnab Saha

Approved Tutor Answer9 Years ago

Huckels rule states that a planar yclic compound is aromatic if the number of electrons involved in resonance is 4n+2. In benzene there are 3 pi bonds and each pi bond is composed of 2 electrons. Now all pi bonds and hence 3×2=6 ( I.e. 4×(1)+2) electrons are involved in resonance. Therefore it is aromatic.

Aishwarya Byreddy

9 Years ago

Yeah but how are you taking n=1 for benzene?????? By what means are you estimating the n value?????????

Arnab Saha

9 Years ago

I`m not exactly taking n=1 for benzene. But instead, I`m simply saying that the total number of electrons involved in the resonance of benzene is 6 and when we put n=1 in 4n+2 we get 6 which satisfies the condition for aromatic its according to heckles rule.

Aishwarya Byreddy

9 Years ago

I just wanna know what exactly “n” means! I understood what you said but I just wanna know what the letter indicates.!

Arnab Saha

9 Years ago

N is just a random variable. It doesn`t signify anything alone. If you put different integral values of n from 0 onwards in 4n+2 you get the number of electrons needed for aromaticity which in the afore mentioned case is 1. For example...if 4 pi bonds are involved in resonance then 8 electrons are involved. But 8 doesn`t satisfy 4n+2 for any integral value of n. So the compound isn`t aromatic