Use of 13C isotope shifts to assign carbon atoms α and β (and para) to a hydroxy group in alkyl substituted phenols and alcohols

Doublets can be observed for carbons α and β to the hydroxyl in aliphatic alcohols containing equimolar amounts of OH and OD dissolved in (CH3)2SO containing CaSO4 desiccant. Isotopic doublets are also observed for the ipso and ortho carbons in alkyl substituted phenols. Para isotopic doublets are observable in para‐substituted phenols containing a large 2‐substituent. The isotope shift is positive (low field) for the para carbon, opposite to the negative shifts usually observed.