Carbon2Polymer: A CO₂‐based Route to Polyurethanes via Oxidative Carbonylation of TDA with Methyl Formate

Abstract

The Carbon2Polymer project involves a multistep reaction sequence for the non‐phosgene synthesis of the high‐value polymer precursor toluene‐2,4‐diisocyanate (TDI) starting from carbon dioxide. The present study of the oxidative carbonylation revealed that for the intermediate toluene‐2,4‐dicarbamate (TDC) the productivity is highest with Pd@ZrO2, followed by Pd@CeO2. As one of the side products which are formed in parallel and consecutive reactions the methylene‐bridged dimer “TDCCH2TDC” (5) has a promising potential for industrial application.

Supporting-Electrolyte-Free Anodic Oxidation of Oxamic Acids into Isocyanates: An Expedient Way to Access Ureas, Carbamates, and Thiocarbamates

“…As an alternative, the Lossen rearrangement provides access to isocyanates under relatively mild conditions but still requires the synthesis of a potentially unstable hydroxamic acid. , Some recent developments using dehydrating agents, such as carbonyldiimidazole (CDI), and activating reagents, such as dimethyl carbonate (DMC), have received particular attention (Figure ). Additional developments, such as amine carboxylation using CO 2 as the carbon source, − reductive carboxylation of nitroaromatics, and carbamate metathesis, have emerged. − However, these methods still suffer from the limited availability and stability of the commercial starting materials, metal catalysts, and toxic gas reagents, which could be disfavored by industries.…”

A green route to polyurethanes: oxidative carbonylation of industrially relevant aromatic diamines by CO2-based methyl formate

“…Their origin can be associated with the presence of dimethyl carbonate (DMC) that is known to be formed under the conditions of oxidative carbonylation with MF. 15 The presence of DMC in the reaction mixture was confirmed together with dimethyl oxalate (DMO) by GC-MS. Reaction of DMO with sodium methanolate can also lead to DMC formation.…”

“…11,16a MF and the methanolic sodium methanolate solution together with the catalyst system were pre-equilibrated in a stainless-steel reactor to generate the desired CO/methanol mixture. [11][12][13][14][15] After heating to 140°C for one hour, a constant CO pressure of 74 bar was formed and the reactor was pressurized with 29 bar of synthetic air. Using a HPLC pump the oxidative carbonylation was started by adding a methanolic TDA solution.…”

“…14a Thus, CO 2 -derived MF can be regarded as liquid, easily transportable and safe source for CO/ methanol mixtures. [11][12][13][14][15] The idea of using MF for the synthesis of aromatic carbamates was demonstrated previously only for the monofunctional model substrate aniline. [11][12][13] Here, we present the first detailed investigations on the oxidative carbonylation of actual polyurethane precursors TDA, 4,4′methylenedianiline (MDA) and 2,4-diaminomesitylene employing MF as CO 2 -based CO/MeOH source in combination with several Pd based catalysts.…”

A dual-functional catalyst for selective dicarbamate synthesis via oxidative carbonylation: enhanced methoxylation for suppressing urea polymer formation

“…Non-phosgene diisocyanates can be practically obtained through the thermal decomposition of dicarbamates, indicating that the efficient and sustainable synthesis of dicarbamates is important. 6,7 Dicarbamates can be synthesized by reacting nitro-or amino compounds with carbonyl sources, such as dimethyl carbonate (DMC), CO 2 , and CO. [8][9][10][11][12] The syn-thesis route using DMC is advantageous due to its mild reaction conditions and high carbamate yields. However, this method requires additional processes for DMC synthesis, such as transesterification of cyclic carbonates with methanol and oxidative carbonylation of methanol.…”