I am studying NMR and the concept of chemical equivalence is confusing. What does it mean exactly? Does it involve having different atoms to the left, right, up and down of a particular hydrogen in question? Please explain. Also I don't understand diastereotopic hydrogen give two shift? Like wouldn't rotating the bonds give same chemical environment to the two hydrogen giving them one signal. I am confused.

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    $\begingroup$ Homotopic, Enantiotopic, Diastereotopic - masterorganicchemistry.com/2012/04/17/… $\endgroup$ – MaxW Feb 11 '17 at 20:07
  • $\begingroup$ In reference to NMR, chemical environment would be something that causes H peak to shift or split. $\endgroup$ – MaxW Feb 11 '17 at 20:08
  • $\begingroup$ Chemical and Magnetic Equivalence - u-of-o-nmr-facility.blogspot.com/2008/08/… $\endgroup$ – MaxW Feb 11 '17 at 20:11
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    $\begingroup$ The two questions are only mildly related; you should separate them into two different questions. Incidentally, I’m sure the diastereotopic-hydrogens-two-signals-question has been asked before on here. $\endgroup$ – Jan Feb 12 '17 at 20:55