Kinetics of the Reaction of Benzoyl Halides with Toluene in Non-polar Solvents under the Influence of Aluminum Halides^1,2

Lanthanide Triflate-Catalyzed Arene Acylation. Relation to Classical Friedel–Crafts Acylation

“…Variable-temperature kinetic characterization of Yb(OTf) 3 -catalyzed anisole acylation with acetic anhydride yields the following activation parameters: Δ H ‡ = 12.9 (4) kcal·mol −1 , Δ S ‡ = −44.8 (1.3) e.u., and E a = 13.1 (4) kcal·mol −1 . These values are comparable to those found in classical AlCl 3 -catalyzed FC acylation reactions that exhibit overall second-order kinetics of type ν = k 2 [AlCl 3 ·RCOCl] 1 [ArH] 1 . , As shown in Table , AlCl 3 -catalyzed benzene acetylation in ethylenedichloride proceeds with Δ H ‡ = 12.7 kcal·mol −1 , Δ S ‡ = −27.6 e.u., and E a = 13.3 kcal·mol −1 . Similar parameters were reported for both acetylation and benzoylation of benzene in either ethylene dichloride or benzoyl chloride as the solvent .…”

“…The magnitude of the present KIE suggests C−H scission is either partial or complete in the transition state. , These results are consistent with the overall rate law and the multistep mechanism of eqs , , and . In classical FC AlCl 3 -catalyzed benzene and toluene acetylations in polar nitro solvents, comparable values are: k H / k D = 2.45 and 2.68, respectively. ,, L n 3 + A c 2 O ⇌ k − 1 k 1 Ln ( normalA normalc 2 normalO ) 3 + Ln false( A c 2 O false) 3 + ⁢ + a nisole ⇌ k − 2 k 2 Ln ( normalA normalc 2 normalO ) ( anisole ) 3 + Ln false( A c 2 …”

The Friedel Crafts Acylation Reaction. VIII. Elucidation of Reaction Intermediates by a Kinetic Study of the Behaviour of the Aromatic Reacting Hydrocarbon and an Analysis of Solvent Effects

“…However it must be noted that there is some ambiguity in the previous experiments as the polarity of the medium is changed by substituting the solvent ortho-dichlorobenzene (dielectric constant = DC 10) by the less polar toluene (DC g 2). However only a small amount of solvent is substituted and the solvent polarity has but little influence on the rate in benzoylation reactions [ 3 ] ; furthermore the polarity does not change in the reac-tion of mesitylene with p .methoxy-benzoyl chloride as benzene, toluene, and mesitylene have nearly the same dielectric strength.…”

Thiopyrylium Scaffolds from the Lewis/Brønsted-Acid-Promoted Cyclization of Thioethers

“…The Eyring–Polanyi equation affords an activation enthalpy of 12.9 ± 0.5 kcal/mol and an activation entropy of −22.6 ± 0.9 cal/(mol·K), which leads to Δ G ‡ = 19.6 ± 0.8 kcal/mol at 298.15 K (Figure S1). These experimental data are comparable to those of previously reported Lewis-acid-induced Friedel–Crafts acylations and acetylations . Deuterated 3b- d 5 was subjected to identical reaction conditions, and a rate constant of k obs ( 3b- d 5 , 298 K) = 2.45 ± 0.12 × 10 –2 (mol –2 L 2 s –1 ) was observed.…”