Hello. I remember a problem I had with drawing a splitting tree for nitrotoluene. The coupling constants varied, you know, para, meta, ortho, they were all different. My teacher told us to assume certain values for each. What I don't understand is how a proton in nitrotoluene (or even toluene, whatever) is split by these substituents that are so far away. I read that protons can only be split by a neighbouring carbon, or, (if there's a double bond) the neighbouring carbon's neighbour, mr. carbon 3! (mr. carbon 1 is the carbon whose proton is being split). I hope you're not too confused. And so what's the point of having a coupling constant for something that's ortho, something that's more than 3 bonds away (2 sigma bonds for pi and a sigma bond)? There's something obviously wrong with the way I'm looking at this, someone PLEASE enlighten me.