
%0 Journal Article
%A Rottendorf, H 
%A Sternhell, S 
%T Spin-spin coupling between side-chain and ring protons and the effect of electron delocalization on allylic coupling
%J Australian Journal of Chemistry
%D 1964/12/01
%V 17
%N 12
%P 1315-1328
%K 
%R https://doi.org/10.1071/CH9641315
%U https://www.publish.csiro.au/paper/CH9641315 
%X The side-chain-ring coupling constants3 in the three isomeric tetrachlorotoluenes are Jortho 0.63±0.02 c/s, Jmeta 0.36±0.02 c/s, and Jpara 0.63±0.01 c/s. The magnitudes of side-chain coupling constants in benzene derivatives are discussed. In symmetrical six-membered aromatic and heterocyclic compounds the magnitude of the ortho side-chain coupling constants is approximately 0.6 c/s but varies from less than 0.3 cis to 1.1 c/s in molecules where some bond localization occurs. Ortho side-chain coupling constants in five-membered heterocyclic compounds also appear to be affected by electron localization. It is therefore likely that the magnitude of the ortho side-chain coupling constants may be a direct measure of bond order. Long-range coupling data on indole derivatives are reported. In two &#946;,&#946;-dimethylstyrenes the stronger side-chain to ring coupling is to the ortho position. The relation between allylic coupling and electron delocalization is explored and a new criterion for electron delocalization proposed. 
