Catalytic interconversion reactions between C1 compounds: CO₂, CO, formic acid, methanol, methane and derivatives

Our society has grown considerably thanks to the use of fossil resources. The use of these resources, in the field of energy or the chemical industry, leads to a disruption of the natural carbon cycle caused by the accumulation of an anthropogenic CO₂ in the atmosphere. To overcome this issue, one of the conceivable solutions is to gradually abandon fossil hydrocarbons in favor of renewable carbon resources such as CO₂ for the storage of renewable energies and/or as a source of chemical products. The first building blocks obtained from CO₂ are one carbon atom containing molecules, known as C1 compounds. It includes methane (CH₄), carbon monoxide (CO), methanol (CH₃OH), formic acid (HCOOH). These reactions are limited by their practicality, their yield or by their selectivity. Therefore, they are not an ideal solution to the initial problem. In this context, this doctoral work has explored alternative ways of inter-converting these compounds to offer CO₂ recovery pathways. In the first place, the use of HCOOH was proposed as a CO vector. This topic is born of the growing interest for the organic chemistry sector to obtain liquid or solid sources of CO. In a second step, a new disproportionation strategy was developed to access CH₃OH from HCOOH derivatives, the silicon formates. These reagents allow to avoid the thermodynamic limitation related to the disproportionation of HCOOH. The control of the silylated by-products recycling enabled the success of this transformation. A new CH₄ production route was also developed from CH₃OH using HCOOH as a reducing agent. Finally, the knowledge acquired on CO₂ activation and reactivity enabled a transposition by analogy to other iso-electronic molecules, including carbodiimides in order to form the isoureas under organo-catalytic conditions. (author)