טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentKhateep Soleeman
SubjectMolecular and Environmental Effects in Tautomerization
and Protonation Processes in Crystals and other
Organized Systems
DepartmentDepartment of Chemistry
Supervisor Professor Yoav Eichen


Abstract

Tautomerization and proton-transfer (PT) processes have been studied extensively in recent years due to their fundamental importance in many chemical and biological processes. Evidence for site dependence in tautomerization processes in solids as well as in other solid-state chemical transformations can be found in numerous systems where a slight variation in the environment of the reactants results in a significant change in activity or in mechanism path selection. In most cases, a straightforward structure-reactivity correlation could not be drawn for reactions in the solid state. Therefore, rationalization of the experimental results was mostly restricted to effects at the isolated reacting-molecule level, ignoring its close packing within a “solvation shell” or, at most, regarding the environment as simple restriction to the molecular motion (“reaction in a cage” approach). For modeling the reaction site effect in crystalline systems an experimental investigation of a tautomerization process in different derivatives of 2(2,4-dinitrobenzyl) pyridine in the crystalline state was performed, and a theoretical approach was presented. The novel approach is applied in the study of tautomerization processes in the different polymorphs of 2(2,4-dinitrobenzyl)-3-methyl pyridine, and other DNBP derivatives, Scheme 1.


  Scheme 1