Abstract: | An equation has been developed which relates ortho or C-β 13C substituent chemical shifts (SCS) to the ortho proton–proton coupling constant in the unsubstituted member of a conjugated series. This method is an extension of previous equations which have been used to predict ortho 1H SCS values, and has its origin in a relationship between bond order and SCS values. The equation was derived from ortho 13C data in 2-naphthalenes and monosubstituted benzenes and its application to other unsaturated series is discussed. |