Silver (I) activated quaternization of tertiary amines by alkyl iodides: Overall analysis coupling homogeneous and heterogeneous processes

Kinetic data for the silver (I) activated homogeneous and heterogeneous quaternization of tributylamine by alkyl iodides in toluene is presented. Silver iodide was used as a solid catalyst. Solution and surface parameters were obtained applying the multistep kinetic model, previously proposed by Santos and Barbosa. A scrutiny of the derived quantities evidences competing structural and electronic effects. The solution reaction is dominated by structural factors while electronic effects govern the surface process. An overall analysis considering data from triethylamine systems, earlier investigated, allowed the establishment of a parallelism between the homogeneous and heterogeneous processes. A molecular level study involving size, shape and orientation of the chemical species on the surface, lead to estimates of interfacial layer thicknesses. A combination of surface parameters superficial reacting monolayer thicknesses and, the parallelism between homogeneous and heterogeneous catalysis consented the evaluation of “volumetric surface rate constants” which are directly comparable with their solution counterparts.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (237 K)Download as PowerPoint slideHighlights► Experimental data for new systems substantiated model previously proposed. ► Stereochemical and electronic effects governing solution and surface processes were scrutinized. ► Molecular level analysis afforded the definition of unitary superficial reaction compartments. ► “Volumetric surface rate constants” allowed the direct comparison of solution and surface rates.