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## Design, synthesis and characterization of magnesium catalytic systems

### Karolina Jachimczuk

#### Abstract

Organometallic chemistry is very interesting and very important branch of chemistry that combines features of both organic and inorganic chemistry. Due to its unique properties, organometallic compounds are widely used in catalysis and chemical synthesis. One of the most important and most commonly used groups of organometallics are organomagnesium complexes. The siginificance of this fact was confirmed by The Nobel Prize for the discovery of organomagnesium halides, which was received by Victor Grignard in 1912. Grignard’s studies contributed to the development of many new synthesis of organic compounds, in particulary alcohols. Organomagnesium compounds are currently enjoying something of a renaissance. Many research groups in the world are working on the utilization of the magnesium complexes in catalytic reactions e.g. polymerization of lactide or epoxidation of enones.The aim of this study was the design and synthesis of new magnesium systems based on the tert-butylmagnesium complexes stabilized by α-diimine ligands, investigation of their reactivity with molecular oxygen and then utilization as initiators of the polymerization of rac-lactide. Result and discussion In the first step of the study, the synthesis of commercially unavailable di-tertbutylmagnesium was conducted. The resulting tBu2Mg solution was used in the reactions with the two α-diimine ligands: 1,4-di-tert-butyl-1,3-diazabutadiene (tBu-DAB) and 1,4-bi(2,6- diisopropylphenyl)-1,3-diazabutadiene (dipp-DAB). The structures of all products in solution, were confirmed by 1H NMR spectroscopy. Additionally molecular structure of the complex stabilized by tBu-DAB ligand was determined by single crystal X-ray diffraction studies In the next part of the study, the oxygenation of the resulting tert-butylmagnesium complexes by dry air were investigated. The structure of all products in solution were characterized by 1H NMR spectroscopy and, furthermore, the molecular structure of the alkoxymagnesium complex stabilized by tBu-DAB ligand was determined by single crystal X-ray diffraction studies. In the last step both tert-butoxymagnesium complexes was used as initiators in the polymerization of rac-lactide. The molar ratio of both initiators to lactide was 1:50. As results, the slight catalytic activity was observed for the complexes stabilized by dipp-DAB ligand after 24 h of reactions at room temperature. Under the same conditions, the magnesium complex stabilized by tBu-DAB ligand showed no activity as initiators for the polymerization of rac-lactide. In conclusion, two new magnesium complexes stabilized by tBu-DAB ligand were obtained and structurally characterized. Additionally, the presence of the Schlenk equilibrium between alkyl and bischelant complexes in the solutions of tert-butylmagnesium complexes was proved. Unfortunately both tert-butoxymagnesium complexes show insignificant activity as the initiators in the rac-lactide polymerization, however further studies on the catalytic activity of the resulting complexes, e. g. in the epoxidation of enones, are planned.
Diploma type
Engineer's / Bachelor of Science
Diploma type
Engineer's thesis
Author
Karolina Jachimczuk Karolina Jachimczuk,, Undefined Affiliation
Title in Polish
Projektowanie, synteza i charakteryzacja magnezowych układów katalitycznych
Supervisor
Karolina Zelga (FC/DCOC) Karolina Zelga,, Department Of Catalysis And Organometallic Chemistry (FC/DCOC)Faculty of Chemistry (FC)
Certifying unit
Faculty of Chemistry (FC)
Affiliation unit
Department Of Catalysis And Organometallic Chemistry (FC/DCOC)
Study subject / specialization
Technologia Chemiczna
Language
(pl) Polish
Status
Finished
Defense Date
04-02-2016
Issue date (year)
2016
Keywords in Polish
x
Keywords in English
x
Abstract in Polish
urn:pw-repo:WUTffbb6a35bec3413d81d78bb747a11a89