Periodic Reporting for period 2 - ReNewHydrides (Renewable Hydride Donors and Their Utilization in Catalytic Reduction and Deoxygenation Reactions)
Période du rapport: 2021-04-01 au 2022-09-30
The production of chemicals, plastics, solvents, etc., contributes to 20 % of the Gross Value Added in the EU, where sales have doubled over the last 20 years. Despite this dynamism, the chemical industry is energy intensive and 95 % of organic chemicals derive from fossil oil and natural gas. To sustain the growth of this industry, the replacement of fossil feedstocks with renewable carbon, phosphorus and silicon sources should be encouraged. Nonetheless, such a sourcing shift represents a paradigm shift: while the development of petrochemistry has relied on the selective oxidation of hydrocarbons, the conversion of renewable feedstocks (e.g. CO2, phosphates, silicates or biomass) requires efficient reduction methods and catalysts to overcome their oxidized nature.
Today, no reduction method meets the criteria for a versatile and energy efficient reduction of oxidized feedstocks and the aim of the ReNewHydrides project is to design novel reductants and catalytic reactions to achieve this important aim. At the crossroads of main group element chemistry, organometallic chemistry, electrochemistry and homogenous catalysis, the teams develops innovative and recyclable reductants based on silicon and boron compounds, which are further utilized to tackle catalytic challenges in the reduction of C–O, N–O
P–O and Si–O bonds. The overarching principle is to build a balanced synthetic cycle, where the electrochemical reduction of functionalized and oxidized substrates is ensured by silicon and boron based hydride donors, with a high energy efficiency and selectivity.
The project is divided is two complementary strands: while Strand 1 focuses on the development of renewable hydride donors based on silicon and boron, Strand 2 will explores the uses of these new reductants in the reduction of C–O, N–O
P–O and Si–O bonds where H2 utilization fails.
Today, no reduction method meets the criteria for a versatile and energy efficient reduction of oxidized feedstocks and the aim of the ReNewHydrides project is to design novel reductants and catalytic reactions to achieve this important aim. At the crossroads of main group element chemistry, organometallic chemistry, electrochemistry and homogenous catalysis, the teams develops innovative and recyclable reductants based on silicon and boron compounds, which are further utilized to tackle catalytic challenges in the reduction of C–O, N–O
P–O and Si–O bonds. The overarching principle is to build a balanced synthetic cycle, where the electrochemical reduction of functionalized and oxidized substrates is ensured by silicon and boron based hydride donors, with a high energy efficiency and selectivity.
The project is divided is two complementary strands: while Strand 1 focuses on the development of renewable hydride donors based on silicon and boron, Strand 2 will explores the uses of these new reductants in the reduction of C–O, N–O
P–O and Si–O bonds where H2 utilization fails.
The plan work has been set up in the two strands of the project. In the first strand, the preparation of silicon hydrides, namely hydrosilanes, has been thought after using electrochemical procedures. Although this challenging task has been inconclusive so far, hydrosilanes have been successfully synthesized using hydrogen (H2) as an energy vector. In addition, a new class of silicon and boron based hydrides has been explored: silyl and boryl formates, which act as surrogates for hydrosilanes and hydroboranes. In the second strand of the project, the utilization of the reductants developed in Strand 1 has been carried out. In particular, the project has shown that hydroboranes could be used in the reductive depolymerization of polyester and polycarbonates for the first time. The upcycling of household wastes has been demonstrated to chemicals and fuels.
The main progresses targeted until the end of the project, concern the following disruptive transformations:
- A proof-of-concept for the electrochemical generation of hydrosilanes and hydroboranes, with the design of a suitable cell and cathodic catalysts
- The demonstration that amines can be homologated using cascade reductive carbonylation, in order to generate long chain aliphatic amines which are useful molecules in the formulation of detergents
- Opening the reactivity of silyl and boryl formates through catalysis for the transfer- hydrosilylation and hydroboration of esters and phosphine oxides.
- A proof-of-concept for the electrochemical generation of hydrosilanes and hydroboranes, with the design of a suitable cell and cathodic catalysts
- The demonstration that amines can be homologated using cascade reductive carbonylation, in order to generate long chain aliphatic amines which are useful molecules in the formulation of detergents
- Opening the reactivity of silyl and boryl formates through catalysis for the transfer- hydrosilylation and hydroboration of esters and phosphine oxides.