Dipartimento di Chimica e Tecnologie Chimiche - Tesi di Dottorato
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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Chimica e Tecnologie Chimiche dell'Università della Calabria.
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Item New Catalyzed Approaches For The One-Step Synthesis Of High Value-Added Products(Università della Calabria, 2021-10-28) Amuso, Roberta; Critelli, Salvatore; Gabrele, Bartolo; Veltri, LuciaHeterocyclic compounds play an important role in synthetic and bioorganic chemistry, as they represent a structural motif in a large number of biologically active natural and non-natural compounds. The synthesis of new heterocycles possessing biological activity and the development of innovative and accessible synthetic pathways are currently a very widespread research area. In the present PhD thesis is reported the development of new synthetic, simple and innovative methodologies in one step for the direct formation of high value-added compounds by the catalytic activation of simple building blocks, CO and CO2. CO is a simplest and most available C-1 unit, which meets the requirements of “atom economy”, step economy and “green chemistry”; the possibility to synthesize molecules of important pharmacological interest by a direct carbonylation procedure involving the use of carbon monoxide represent a very attractive alternative synthetic approach. CO2 is the main component of greenhouse gases, responsible for the increase in the earth's temperature and anomalous climate changes. Thus, post-combustion COIn fact, carbon dioxide can be considered as a ubiquitous, cheap, abundant, non-toxic, non-flammable and renewable C1 source, which has great importance from the viewpoint of both environmental protection and resource utilization. In the first chapter is reported a new example of an additive cyclocarbonylation process leading to 1-thia-4a,9-diazafluoren-4-ones, an important class of polyheterocyclic compounds known to possess important pharmacological activities. Part of this PhD was spent at Leibniz Institute for Catalysis in Rostock University. Here, ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. The advantages of the new catalysts are demonstrated in the general green α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Furthermore, other cyclometalated ruthenium complexes bearing bidentate ligand were obtained for methylation of anilines with methanol to selectively give N-methylanilines. The hydrogen autotransfer procedure has been applied under mild conditions (60 °C) in a practical manner (NaOH as base).2 capture and its conversion into high value-added chemicals are integral parts of today’s green energy industry.Item Synthesis of high value added molecules by catalytic and heterocyclization approaches(2018-05-11) Mancuso, Raffaella; Critelli, Salvatore; Gabriele, BartoloIn the present PhD thesis is reported the development of new sustainable catalytic processes for the production of high value added molecules starting from simple and readily available building blocks, under safer and low-intensive energy conditions, by iodocyclization, carbonylation and cycloisomerization reactions in non-conventionl solvents such as Deep Eutectic Solvents (DES) and Ionic Liquids (ILs). Catalytic processes, in which several different units can be assembled in one step in ordered sequence under the promoting action of a suitable catalyst, are destined to play a central role in current synthesis. Of particular importance is the development of novel catalytic processes for the reconversion of CO and CO2 into organic molecules. CO is an inexpensive and readily available C-1 source, and its incorporation into an organic substrate (carbonylation) is now widely recognized as a very important tool in synthesis. Nowadays, carbonylations are at the basis of important industrial technologies for the conversion of easily available feedstocks into useful products of our daily life, and find increasing application in organic synthesis for the production of fine chemicals. CO2 is another very attractive C-1 feedstock for organic synthesis. It is ubiquitously available, low toxic, and abundant. Since the industrial revolution, CO2 has been continuously released in huge amounts in the atmosphere from all combustion processes of organic carbon for the production of energy. Therefore, the efficient reconversion of CO2 (“spent” carbon) into high value added products (“working”-carbon; chemicals, fuels, materials) is one of the current most important strategic goals in chemical research, which will allow to make a step forward toward a more sustainable economy. Non-conventional solvents, such as polyethylene glycols, ionic liquids (ILs), Deep Eutectic Solvents, or supercritical CO2 are less toxic and more eco-friendly than traditional organic solvents. Their use in the processes studied in this thesis allowed an easier separation and purification of the products and, in the case of catalytic reactions, the recycling of the catalyst as well. The direct syntheses of ureas, oxamides, 2-oxazolidinones, and benzoxazolones by oxidative carbonylation of amines, β-amino alcohols, and 2-aminophenols allows obtaining high value added molecules, with a large number of important applications in several fields, starting from very simple building blocks. In chapter two is reported the possibility to carry out these transformations using the PdI2/KI catalytic system in an ionic liquid (IL), such as BmimBF4, as the solvent. The catalyst-solvent system can be recycled several times with only a slight loss of activity, while the product can be easily recovered by crystallization. In the some chapter the reactivity of 2-(2-alkynylphenoxy)anilines under PdI2/KI-catalyzed oxidative carbonylation conditions has been studied. 8-endo-dig cyclization preferentially occurred when the triple bond was terminal, leading to the formation of carbonylated β-lactam derivatives. These novel medium-sized heterocyclic compounds showed anti-tumor activity against both estrogen receptor-positive (MCF-7) and triple negative (MDA-MB-231) breast cancer cell lines. In chapter three is showed that the heterocyclodehydration and iodocyclization of readily available 1-mercapto-3-yn-2-ols has been performed in a deep eutectic solvent (DES), that is, ChCl/Gly, as a non-conventional green solvent. The DES/catalytic system could be easily recycled several times without appreciable loss of activity, after extraction of the thiophene product with hexane or Et2O. In chapter three the first example of a tandem thionation/S-cyclization process leading to benzo[c]thiophene-1(3H)-thione and 1H-isothiochromene-1-thione derivatives, starting from 2-alkynylbenzoic acids, is also reported. Depending on the nature of the substituent at the distal β carbon of the triple bond, either benzothiophenethiones or isothiochromenethiones were obtained selectively, in high to excellent yields. In chapter four a novel methodology to easily access imidazolidin-2-ones from propargylamines, primary amine and CO2 with guanidine bases as catalysts under solvent-free conditions is reported. Bicyclic guanidines, able to catalyze the formation of oxazolidinones from propargylamines and CO2, are presented for the first time as effective organocatalysts for the chemical fixation of CO2 into linear and cyclic ureas.Item Innovative composite membranes for advanced applications(2019-05-10) Grasso, Giuseppe; Critelli, Salvatore; Gabriele, BartoloPresented thesis work is mainly focused on coatings preparation, their potentiality and applications in membrane science: from water desalination to antibiofouling membranes, to gas separation. In fact, coating preparation represents an useful and versatile technique which allows a fine control of membrane properties and performance such as chemical or physical resistance, durability, etc. One of major drawbacks is represented by production costs, which can become important in scale-up operations. Therefore, although several type and methodologies for coating preparation are known and reported in literature, a lack of cheap, efficient and scale-up adaptable coating methods made their different preparation methods of particular interest. The results presented herein, concern the preparation of three different coating methods whose applications are briefly summarized below: Chapter 2: Development of PVDF-f-Graphene Thin Film Composite Membrane for Membrane Distillation Chapter 2 reports a novel method for TFC membrane fabrication, using graphene layer coated on chemically-functionalized PVDF. PVDF is hydrophobic polymer whose properties are well suited for those applications in which hydrophobicity is needed such as Membrane Distillation. In order to increase adhesion between PVDF and graphene, we co-polymerized PVDF with a suitable monomer bearing aromatic part, using a procedure which involves 2 steps reaction: introduction of double bonds on polymer backbone by basic treatment followed by its reaction with monomer through radical reaction. Membranes have been prepared using functionalized PVDF polymer (PVDF-f) and tested on Direct Contact Membrane Distillation (DCMD) apparatus at first. Subsequently tests were conducted using PVDF-f-Graphene composite membrane, using graphene synthetized using Chemical Vapor Deposition ( CVD) method. Created membranes were analyzed and their chemical, physical and morphological properties were investigated. Membranes made using PVDF-f polymer exhibited good flux and salt rejection (up to 99.9 %), whereas graphene association to PVDF-f membranes leads to lower water flux but higher rejection and durability (up to 99.99 %). In chapter 3 a simple and innovative synthetic strategy for Acryloyloxyalkiltriethyl ammonium salts surfactants (AATEABs) starting from cheap and easily available chemicals is discussed. Herein reported surfactants can be used as coating for membranes to whom they confer high anti biofouling properties. Synthetic procedure was first optimized in order to work avoiding prohibitive conditions such as Inert atmosphere or high temperature and then applied to the synthesis of surfactants bearing a different alkyl-chain length. Antibacterial activity evaluation, has been done performing several tests against Gram +\- and yeast strains; results confirmed that AATEABs bearing C11 (AUTEAB) and C12 (ADTEAB) alkyl chain possess highest activity which is remarkable high for ADTEAB. AATEABs may find applications as polymerizable coatings for watr-treatment membranes ( commercial or not) to be used in Pressure-Driven Membrane Processes or in any other membrane-based system in which antifouling properties may play an important role. Chapter 4: Thin Film Composite Membrane fabrication for gas separation: Defect control and bench-scale demonstration Fourth chapter of this thesis work, concerns the preparation of TFC membranes to be used for CO2/N2 separation, on the relationship between TFC membrane material and membrane properties and the role of the protective layer in determining the amount of defects, which is a crucial aspect for all the gas separation-related processes. We report a simple and efficient procedure which can also be applied to for defect controlling during scale-up process and which is not valid for CO2 separation membranes only. Results demonstrate a correlation between the properties of protective layer and separation performances: in particular, the possibility to apply a coating film on commercial membrane permits the creation of membranes in which the amount of defect is dramatically reduced. Another crucial aspect discussed in chapter 4 concerns the thickness of protective layer used for defect control: in fact, whereas the presence of protective layer plays an important role defect-free membrane creation process, its thickness impacts on separation operation. With our method, the preparation of membranes with very thin protective layer ( 0.1 μm or below) is possible.