[goldy]

Hello everybody,
What main information do we get from the coupling constant?
Thank you very much.

[jmendoza]

you mean coupling reagents?

[goldy]

you mean coupling reagents?

I mean coupling constant (j value)

[helenn]

Which protons are coupled (next to each other).

[macman104]

Coupling constants can also provide information about the dihedral angle between the two protons in most systems, relating them to the Karplus Equation.  In general this rule applies nicely, however, some systems may not behave exactly as expected.

They can also be applied to many other rigid systems, such as hydrogens on an alkene, and aromatic hydrogens.  Various coupling patterns all have characteristic coupling constants associated with them.