81669-47-8Relevant academic research and scientific papers
Addition of Anilines to the BF4 Complex, and the 'Ordered Transition State Mechanism'
Odiaka, Timothy I.
, p. 561 - 566 (2007/10/02)
Kinetic studies of the reversible addition of anilines to the complex BF4 (1;dienyl=C7H9) have demonstrated the dependence of rate on the electronic and steric nature of the attacking nucleophile.A plot of ΔHa versus ΔSa for the reaction of aniline with the complexes BF4 (1; dienyl=C6H7, 2-MeOC6H6, or C7H9) is linear,the slope of which gives an isokinetic temperature of 369 +/- 23 K, indicating enthalpy control over the associative process.The reaction of aniline and other substituted anilines with complexes (1) clearly reveals the predominance of negative entropies of activation for the dissociative processes in these systems, thus providing strong support for the recently proposed 'Ordered Transition State Mechanism'.
Kinetics of Nucleophilic Attack on Co-ordinated Organic Moieties. Part 19. Addition of Anilines to Tricarbonyl(1-5-η-dienyl)iron Cations
Kane-Maguire, Leon A. P.,Odiaka, Timothy I.,Turgoose, Steve,Williams, Peter A.
, p. 2489 - 2495 (2007/10/02)
Spectroscopic and kinetic studies of the reactions below (X=H, 2-Me, 3-Me, 4-Me, 2-Cl, 3-Cl, 4-Cl, 4-OMe, or 4-NO2) in CH3CN have provided quantitative information on the importance of basicity and steric factors in controlling amine nucleophilicity towards co-ordinated ?-hydrocarbons.Similar reactions with cations (+) (1a) and (+) (1c) have also been investigated.For the reactions of 4-methoxy- and 4-methyl-aniline with (1b), which proceed to completion, kobs.=k1.However, for the equilibrium reactions of the other less basic amines with cations (1a)-(1c) the two-term expression kobs.=k1 + k-1/(+K2Ka) is indicated.The general rate trend C6H7 > 2-MeOC6H6 > C7H9 and the low ΔH%1 and large negetive ΔS%1 values are consistent with direct addition to the dienyl rings.For attack by non-sterically crowded anilines on (1b), a Broensted plot of log k1 versus pKa of the amine conjugate acid (in H2O) has a high slope of 1.0, indicating a very strong dependence of k1 on amine basicity.A Hammett plot for this reaction gives a slope of -2.7, indicating significant bond formation and build-up of positive charge on the aniline nitrogen atom in the transition state.The steric retardation of k1 caused by blocking substituents in the 2-position of the anilines is considerably smaller than that previously found for the related additions of pyridines to cations (1a)-(1c).
