Hello,
Background: In the labs, we were nitrating bromobenzene, separating isomers (the first fraction of crystals obtained after recrystallisation should have been a completely pure 1-nitro-4-bromobenzene; the remaining liquid was separated by rotary evaporation to obtain the less pure second product) and doing an NMR of the second fraction, the less pure. Little to say, my lab skills failed yet again and I got a (relatively to other classmates) horrendous spectrum, adding to it my limited confidence in reading NMR spectra I would appreciate if someone could take a look at my workings and say if and where I'm wrong. //
(See pic of spectrum: [green peaks (B, C, E, F) belonging to meta-nitro bromobenzene; purple peaks (D, I) belonging to para-nitro bromobenzene; and blue peaks (G, H, J) belonging to ortho-nitro bromobenzene] and see table for my analysis).
My main point of worry is the meta isomer (is it even meta? It shouldn't be there if I haven't let the emperature reach too high). Why (in what I have labelled) is hydrogen 9 less deshielded than hydrogen 10? Hydrogen 9 should be deshielded by both NO2 and Br in ortho position, so very strongly. I was trying to follow guidance from this video: https://youtu.be/94D_gy0lG_0?t=756
