KINETICS AND MECHANISM OF DIELS-ALDER ADDITIONS OF TETRACYANOETHYLENE TO ANTHRACENE DERIVATIVES-III EFFECT OF SUBSTITUENTS ON RATES AND INTERMEDIATE COMPLEX FORMATION

Article abstract of DOI:10.1016/S0040-4020(01)98972-0

In Diels-Alder additions of tetracyanoethylene to 1,2-, and 9-substituted anthracenes, formation constants (K) for the intermediate complexes have been separated from the global rate constant (K₂^obs).The relatively small range of values of K indicates a very small charge transfer in the complexes.The transition state for conversion of complex into adduct showed a marked degree of charge development, particularly for the 9-substituted derivatives (ρ=-7).Substituents in the outer rings gave good rate correlations with composite constants (?_m⁺ + ?_p⁺) with a ρ value of -3.The substituent effects are discussed in terms of these and other parameters.Values for equilibrium constants for the overall addition (K_eq) are reported.