I have been learning about nmr and I am confused about how to identify whether two hydrogen on different carbon atoms are homotopic, diastereotopic or emantiotopic. I can do identify this when two hydrogens are attached to same carbon atoms, but when it is different I am lost.I have searched lot on web, but they only include examples of two hydrogens on same atom, not on different ones. So can anyone help determine what the two hydrogen are in these compounds and why ? Thanks.
You determine by labeling. Take the two hydrogens in question and label them one at a time to get two molecules. What's the relationship between these two molecules? If the molecules are the same, then the hydrogens were homotopic. If they are enantiomers, the hydrogens are enantiotopic. Otherwise, if they are diastereomeric molecules, the hydrogens are diastereomeric.