[jayana]

Hello,

This is regarding NMR. I am not sure of "apprearance of proton NMR in achiral and chiral solvent" and about homotopic, enentiotopic, diastereotopic in methylenes and methyls. 

Can anybody help me understanding the difference between methylene and methyls under the context of NMR???

Can u give any webste links regading these???

Thanks in advance

Jay

[movies]

enantiotopic with respect to a methylene group would refer to a situation where if you changed either one of those protons to a different group then you would get enantiomers.  The most common thing to see in NMR is diastereotopic protons.  The idea is the same, but these occur when you have a chiral center in your molecule already, then if you were to change either of the two protons of a methylene to something else you would have diastereomers.