First successful correlation of the UV spectra of three kinds of styrenes with spin‐delocalization substituent constants σ.

UV spectra of 17 para‐Y‐substituted styrenes, 8 para‐Y‐substituted α‐methylstyrenes and 20 para‐Y‐substituted α,β,β‐trifluorostyrenes were measured and correlated against spin‐delocalization substituent constants (σ.) with confidence levels above 99·9%.