טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentPorat Alexander
SubjectNew Halogenation Methods
DepartmentDepartment of Chemistry
Supervisor Professor Mark Gandelman
Full Thesis textFull thesis text - English Version


Abstract

This research is focused on development of new, practical and metal free halogenation methods by use of N-Haloamides. In the first part chloro- and bromodecarboxylation reactions of primary, secondary, tertiary alkanoic and aromatic carboxylic acids are described. Good yields and functional groups compatibility is demonstrated on more than hundred examples. Recovery and recycling process for all reagents was developed. It was found that halogenated cyanuric acid derivatives are the most appropriate N-haloamides for this transformation. The mechanism investigation shows that under various conditions the isocyanurate action could differ, however its high oxidation potential plays the key role in these transformations.

The second part of this work is dedicated to radical C-H bond iodination. Contrary to C-H chlorination and bromination, the direct iodination of alkanes represents a great challenge. We reveal a new N-iodoamide that is capable of a direct and efficient C-H bond iodination of various cyclic and acyclic alkanes providing iodoalkanes in good yields. This is the first use of N-iodoamide for C-H bond iodination. The method also works well for benzylic C-H bonds, thereby constituting the missing version of the Wohl-Ziegler iodination reaction. Mechanistic details were elucidated by DFT computations. The N-centered radical, derived from the used N-iodoamide, which is the key intermediate in this process, was matrix-isolated in a solid argon matrix and characterized by UV-vis as well as IR spectroscopy.