# Concentration of minor products in the nitration of nitrobenzene

I was baffled by the concentration of minor products in the nitration of nitrobenzene.

This is the picture from Solomon Frhyle's book, page $695$:

Since nitro is electron withdrawing and meta directing, the high concentration of meta isomer is justified. However, I had predicted the order to be $m>p>o$ because both nitro groups are electron withdrawing and if they are close together they will cause destabilisation by increasing charge density at adjacent places. On the other hand in the para isomer, the nitro groups are far away so development of partial positivity at opposite ends shouldn't be a big problem.

Could someone explain why the para isomer is less in concentration and how my reasoning is incorrect?

• I wouldn't be too concerned about small differences in the yield of the minor products. If these are isolated yields, then they have been scaled to 100%. How easy is it to isolate ortho vs. para isomer? There is a 2:1 statistical factor in favor of the ortho isomer. – user55119 Mar 2 '18 at 19:22
• These are only values given for example, possibly even from single experiment; you seem to be trusting simple rationalisation way too much. – Mithoron Mar 2 '18 at 19:57
• Maybe some intramolecular attraction that we are unaware of? Was anything mentioned in the book about that? @Mithoron – dr.drizzy Mar 2 '18 at 20:35
• @user55119 Could you please explain what you meant by "If these are isolated yields, then they have been scaled to 100%" and "There is a 2:1 statistical factor in favor of the ortho isomer."? – Gaurang Tandon Mar 3 '18 at 3:29
• @Gaurang there are two ortho positions and only one para. – Avnish Kabaj Mar 3 '18 at 9:33