On Sustainability Aspects of the Synthesis of Five-Membered Cyclic Carbonates

Abstract

The synthesis of cyclic carbonates, substrates gaining growing interest due to their broad spectrum of applications, is analyzed from a Green Chemistry perspective. Extensive research has been carried out on the synthesis of these substances, which are of interest especially for the preparation of so-called non-isocyanate polyurethanes (NIPUs). Often, the renewability of the raw materials, derived for instance from carbon dioxide, diols, urea, or alkyl carbonates, is taken into account, without considering sustainability aspects of their synthesis protocols. In this review, we employ E-factors and discuss basic toxicity information to compare numerous approaches and data reported in the literature for synthesizing the most common cyclic carbonates to provide a useful, although not exhaustive, first sustainability evaluation. This study highlights that to achieve a more sustainable manufacture of cyclic carbonates, the renewability of the starting materials has to be matched with safer chemicals and mild and efficient reaction protocols in order to limit the environmental impact of their synthesis.

Valorization of waste biomass for the fabrication of isocyanate-free polyurethane foams

“…E factor) due to the CO 2 -based synthetic pathway for the cyclic carbonate monomer (5CC), which has recently been identified as more sustainable than the dimethylcarbonate pathway. 57 Moreover, the bio-based content was still higher than previously reported water-induced self-blown NIPU obtained from CO 2 -based 5CC. 28 Therefore, our work represents a significant step toward sustainable biomass-rich self-blown isocyanate-free polyurethane foams.…”

Green Synthesis of Stable Lignin Nanoparticles with Reversible Swelling Behavior and Enhanced Multifunctional Features

“…Ultrasonication can promote cavitation phenomena, thus causing hot spots in the solution media featuring high local temperature and pressure, causing the formation of free radical species, which can trigger chemical reactions . Notably, it appears that hydroxide (•OH) and superoxide (HO 2 –•) radicals produced during the acoustic cavitation process in lignin suspensions can promote lignin oxidation, leading to its chemical cross-linking and subsequent polymerization. ,, Indeed, extensive oxidation occurs for long sonication times or in a strong oxidizing agent during the ultrasound treatment. , From NMR analysis and the experiments of chemical degradation (Figure S-2B), it can be shown that no significant cross-linking is achieved due to ultrasonication in the hybrid synthesis. As reported by previous studies, this might be due to the short sonication time as well as the low lignin concentration because of its progressive addition to the batch.…”