Per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants used in industrial applications and are globally distributed in the environment. A group of PFASs that are difficult to measure with today’s method are perfluoroalkyl acid precursors (PFAA precursors) that, when degraded, serves as indirect sources of PFAAs. This study has optimized a previously developed method for quantification of PFAA precursors in soil; through total oxidizable precursor assay (TOP assay) under alkaline conditions, to be applicable on sewage sludge. To achieve and maintain an alkaline environment during the entire oxidative treatment, several parameters were tested: concentrations of NaOH, persulfate and sample; additional clean-up with graphitized non-porous carbon and reaction time. Solid phase extraction-weak anion exchange (SPE-WAX) was used for clean-up and separation of analytes, and LC-MS/MS was used for quantification. The optimal conditions with the highest levels of PFAAs detected was obtained with 1.33 M NaOH, 60 mM persulfate, 3.57 g/L sludge with a reaction time of 6 hours. The use of graphitized non-porous carbon reduced matrix effects on oxidative conversion resulting in a higher pH as well as a higher degree of oxidation, but with some analyte loss.

Ce projet concerne la synthèse et caractérisation de nouveaux matériaux composites à base de nanoclusteurs de thiolates d’or Au25(SR)18 (tGNCs), supportés sur divers polymères de coordination (MOFs), ainsi que sur ZrO2. L’activité catalytique de ces matériaux a été évaluée sur la transformation de différents substrats. Les tGNCs sont des matériaux atomiquement bien définis et connus pour être actifs dans des réactions d’oxydation. Les nanoparticules de MOFs sont des matériaux pouvant servir de support pour des tGNCs avec de bonnes dispersions. Certains MOFs sont connus pour avoir des propriétés acides et peuvent être actifs en catalyse. Parmi eux, MIL-101 (Cr), UiO-66 (Zr) et ZIF-8 (Zn) on été choisis en raison de leur propriétés acides et/ou de stabilité thermique. La synergie entre les tGNCs et les MOFs a été évaluée à travers la conversion catalytique de différents substrats tels le glucose, le fructose, l’alcool benzylique et le furfural, impliquant des étapes nécessitant un caractère acide et/ou oxydant. Globalement, il n’a pas été observé d’impact de la présence d’or sur la réactivité de ces substrats, et les tendences catalytiques sont celles obtenues avec les MOFs seuls. Cela est certainement dû à la stabilité thermique non suffisante des MOFs qui prévient une calcination efficace des tNGCs. Lorsque ces clusters sont déposés sur ZrO2, il a été possible de les calciner à différentes températures pour étudier l’effet du ligand et de la taille de particules, pour des réactions d’oxydation en phase liquide. Ainsi, il a été montré par exemple que la température de calcination a un impact significatif sur le comportement catalytique de ces composites, qui ont donné de bonnes activités pour l’oxydation de l’alcool benzylique en benzaldéhyde dans le toluène et en conditions douces, et pour l’esterification oxydante du furfural en furoate de méthyle / This research project reports the synthesis and characterization of new composite materials based on Au25(SR)18 thiolate gold nanoclusters (tGNCs), supported over a range of metal organic frameworks (MOFs), and ZrO2. The synthesized composite materials were tested for catalytic transformations of various substrates. tGNCs are atomically well defined materials known to be active in oxidation reactions. MOFs nanoparticles are materials suitable for high dispersion of tGNCs. Some MOFs are known to have acidity and can be active as catalysts. Among them, MIL-101 (Cr), UiO-66 (Zr) and ZIF-8 (Zn) were chosen due to their acidic and/or thermal stability properties. The synergy between tGNCs and MOFs has been tested through catalytic conversions of different substrates like glucose, fructose, benzylalcohol and furfural, involving steps requiring acidic and oxidative features. Globally, no impact of the presence of Au clusters was observed, and the composite materials showed the same catalytic trends as those obtained with the MOFs alone. This is mainly due to the not sufficient thermal stability of the MOFs that prevents efficient calcination of the tGNCs. In contrast, when deposited on ZrO2 it was possible to calcine Au25(SG)18 nanoclusters at different temperatures to study the ligand and particle size effects in liquid phase oxidation reactions. For example, the calcination temperature had a significant impact on the catalytic behaviour of this composite materials, which showed good activity for the oxidation of benzyl alcohol into benzaldehyde in toluene under mild conditions, and of furfural oxidative esterification into methyl-2-furoate

The thesis entitled “Copper-Catalyzed Novel Oxidative Transformations: Construction of Carbon-Hetero Bonds” is divided into two main sections. Section A deals with the utility of azide as a nitrogen source for C-N bond formation, which is further divided into 4 chapters, and section B presents decarboxylative radical coupling reaction for C-heteroatom bond formation which is further divided in to two chapters. Section A Chapter 1 describes an approach for the direct synthesis of nitrile from the corresponding alcohols using azide as a nitrogen source. Nitrile functionality is a versatile and ubiquitous which occurs in a variety of natural products. Nitrile functionality can be easily transformed into a variety of functional groups and products such as aldehydes, ketones, acids, amines, amides and nitrogen-containing heterocycles, such as tetrazoles and oxazoles. In this chapter a successful attempt for developing a novel methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been described. This strategy uses DDQ as an oxidant and TMSN3 as a source of nitrogen in the presence of a catalytic amount of Cu(ClO4)2·6H2O. A few representative examples are highlighted in Scheme 1.1 Scheme 1. Oxidative conversion of alcohols to nitriles Second chapter represents a protocol for the synthesis of 1,5-disubstituted tetrazoles from the corresponding secondary alcohols. Among heterocyles, tetrazole and its derivatives are important class of nitrogen containing molecules. Due to their well-known biological activities as well as vast applications in pharmaceuticals and material science, they are potential targets for synthetic organic chemists. Therefore, a simple and user-friendly method for the synthesis of tetrazole is desirable. In this chapter, a mild and convenient method to synthesize 1,5-disubstituted tetrazoles using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 2).2 Scheme 2. Oxidative conversion of secondary alcohols to tetrazoles Third chapter presents a method for synthesizing amides from their corresponding secondary alcohols. Amide functionality is a crucial backbone in peptide chemistry, it also serve as an important precursor or intermediate for variety of organic transformations. In this contention, a mild and convenient method to synthesize amides using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 3).3 Scheme 3. Oxidative conversion of secondary alcohols to amides Additionally, the application of this methodology has also been revealed for the synthesis azides directly from their alcohols. Some of the representative examples are shown in the Scheme 4.3 Scheme 4. Direct conversion of alcohols to their azides. Fourth chapter describes highly chemoselective Schmidt reaction. The classical Schmidt reaction involves the formation of new carbon-nitrogen bonds in a reaction of a carbon-centred electrophile with hydrazoic acid followed by loss of nitrogen, which usually occurs via a rearrangement. It is well known that under the Schmidt reaction conditions, ketones and carboxylic acids are converted into their corresponding amides and amines respectively, whereas aldehydes furnish a mixture of formanilides and nitriles. In this chapter, Schmidt reaction of aldehydes to obtain their nitriles without formation of the corresponding formanilide is presented (Scheme 5).4 It was also observed that aromatic ketones and acids functionalities were intact under the reaction condition, unlike the conventional Schmidt reaction. Scheme 5. Highly chemoselective Schmidt reaction Section B It is divided into two chapters, describes a copper catalyzed decarboxylative radical coupling for the synthesis of vinyl sulfones and nitroolefins (Scheme 6). Scheme 6. General strategy for the second part First chapter narrates a strategy for synthesizing nitroolefins from the α,β-unsaturated carboxylic acids. Nitroolefins represent a unique class of nitro compounds, which have multifaceted utility in organic synthesis. They possess antibacterial, rodent-repelling, and antitumor activities. They serve as important intermediates in organic synthesis. Nitroolefins also react with a variety of nucleophiles, and their electron-deficient character renders them as a powerful dienophiles in Diels-Alder reactions. In our attempt to use the decarboxylative strategy, this chapter describes a method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their corresponding nitroolefins. This nitrodecarboxylation reaction is performed using catalytic amount of CuCl in the presence of air using TBN as a nitrating source (Scheme 7).5 Besides, the reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives which are generally difficult to access from other conventional methods. Scheme 7. Decarboxylative nitration Second chapter presents a new protocol for the synthesis of vinyl sulfones from the α,β-unsaturated carboxylic acid. Vinyl sulfones are versatile building blocks, which find their utility as Michael acceptors and used in cycloaddition reactions. This functional group has also been shown to potently inhibit a variety of enzymatic processes, and thus provides unique properties for drug design and medicinal chemistry. Vinyl sulfones are prominent in medicinal chemistry owing to their wide presence in pharmaceutically active molecules, such as enzyme inhibitors and biological activity. In this chapter, we report a method for the construction of C-S bonds via ligand promoted decarboxylative radical sulfonylation of ,-unsaturated carboxylic acids to synthesize vinyl sulfones using Cu catalysis (Scheme 8).6 This is the first report for this particular conversion. Scheme 8. Decarboxylative sulfonation