Catalytic Hydrogenation of Urea Derivatives and Polyureas

Abstract

We present herein the catalytic hydrogenation of various urea derivatives to amines and methanol. The reaction is catalyzed by a ruthenium or an iridium Macho pincer complex and produces amine and methanol in very good to excellent yields. Moreover, we also expand this concept to demonstrate the first example of the hydrogenative depolymerization of polyureas to produce diamines and methanol in moderate yields.

Hydrogenative depolymerization of silicon-modified polyureas

“…Pioneering advances in this reaction have been made by the group of Kumar using ruthenium and iridium Macho-pincer catalysts. 28 Having identified the need for selective depolymerization catalysts for silicon-modified polyurea derivatives, we initially studied the catalytic performance of various transition metal catalysts bearing pincer-type ligands. These complexes have only been very recently introduced as active catalysts for the hydrogenative depolymerization of polycarbonate, 29-35 polyurethane, [36][37][38][39][40] and polyurea, 28 however the hydrogenative depolymerization of SMPs has not yet been reported.…”

“…Pioneering advances in this reaction have been made by the group of Kumar using ruthenium and iridium Macho-pincer catalysts. 28…”

Homogeneous Hydrogenation of CO2 and CO to Methanol: The Renaissance of Low‐Temperature Catalysis in the Context of the Methanol Economy

“…While molecular catalysts were majorly instrumental in the discovery of these small molecule transformations, the catalytic systems further inspired the development of several hydrogenative depolymerization of polycarbonates, polyurethanes and polyurea derivatives to methanol and the co-monomers, demonstrating a green chemical process for waste upcycling. [8,148,150,[157][158][159][160] Figure 26. Indirect methanol synthesis from various derivatives and capture products of CO 2 .…”

Polyureas as SEI-forming Additives for Li Metal Anodes

“…Interestingly, these polyureas can also be depolymerised back to diamines and methanol via the catalytic hydrogenation process. 37 Of all the polyureas reported by us using this method, only PU0 (Table 1) was found to be soluble in bis(2methoxyethyl) ether (diglyme) which is a common solvent of choice for the electrolyte for Li-O2 batteries. We started our studies by measuring coulombic efficiency using PU0 as an SEI forming additive in 1 M LiTFSI in diglyme electrolyte (1 mAh Li plating on Cu, Li stripping).…”

“…Although the coulombic efficiency and the number of plating/stripping cycling can be improved, this report demonstrates the first proof of concept that polyureas can potentially be used as a new class of material, for SEI-forming additives in the case of Li-O2 batteries as well as other next-generation batteries with a metal anode. The potentially renewable and recyclable nature of polyureas [35][36][37] present added benefits for the design of a sustainable battery.…”