Catalytic Systems Adapted to Glycerol Medium. Applications in Selective Processes

Solvents are used in huge amounts in the chemical industry and this is one of the biggest problems to be solved not only from an environmental point of view, but also for economic reasons. The solvents commonly used in the industry are volatile, toxic, inflammable and/or corrosive; then, their replacement by others less harmful represents a crucial objective. Glycerol appears as a promising candidate to substitute the conventional organic solvents. It is produced in huge amounts as a waste in biodiesel industry. Consequently, the valorisation of glycerol becomes an important concern. This compound possesses very interesting properties to be used as solvent such as its non-toxicity, the wide range of temperature for its liquid state, negligible vapour pressure, capacity for solubilising organic and inorganic compounds, low miscibility with other organic solvents and also its low price.

This Thesis deals with the development of new catalytic systems in glycerol medium. In particular, in this work we show how glycerol can facilitate the stabilisation of copper(I) nanoparticles that are able to catalyse the 1,3-dipolar Huisgen cycloaddition between terminal alkynes and organic azides (known as click reaction). The reaction proceeds at room temperature and it is very efficient. Moreover, this reaction can be carried out in the absence of copper using non-activated internal alkynes, working under microwave irradiation. Glycerol favours the process in comparison with other solvents (including protic ones), probably due to its ability to form hydrogen bonds, which favours the interaction with the microwave irradiation (accelerating the process). With the aim of studying stereoselective transformations in this medium, we have conceived new enantiopure ligands derived from PTA (1,3,5-triaza-7-phosphaadamantane). These innovative phosphines have been applied in enantioselective processes, such as pinacolboryl addition to N-Boc-imines (Cu) or α-amination (Cu), among others, or as organocatalyst (Morita-Baylis-Hillman reaction).