Urea‐ and Thiourea‐Catalyzed Aminolysis of Carbonates

Abstract

The aminolysis of (poly)carbonates by (poly)amines provides access to non-isocyanate polyurethanes (NIPUs) that are toxic-reagent-free analogues of polyurethanes (PUs). Owing to their low reactivity, the ring opening of cyclic carbonates requires the use of a catalyst. Herein, we report that the more available and cheaper ureas could advantageously be used for catalyzing the formation of NIPUs at the expense of the thiourea analogues. In addition, we demonstrate a medium-range pKa of the (thio)urea and an unqeual substitution pattern is critical for controlling the efficiency of the carbonate opening.

Hydrogen bonds prevent obtaining high molar mass PHUs

“…The aminolysis of cyclic carbonates is one of the most promising alternatives for the synthesis of isocyanate‐free PUs, which leads to Polyhydroxyurethanes (PHUs). Endo et al ., Figosky et al ., and some of us have greatly contributed to the PHUs chemistry. In the literature five‐membered (C5), six‐membered (C6), seven‐membered (C7) 27 and eight‐membered (C8) cyclocarbonates were investigated.…”

“…Numerous amines and cyclic carbonates have been proposed in order to improve the reactivity of cyclocarbonate aminolysis . Moreover, catalytic studies have been conducted to improve the reactivity as well . Interesting results were observed at the beginning of the reaction but the final conversions generally remain close to 80%.…”

Synthesis and Application of Nonisocyanate Polyurethanes

“…The joint work of several universities (France, Germany) urea-and thiourea-catalyzed aminolysis of carbonates has been studied [18]. This study demonstrates that readily available and affordable urea derivatives may advantageously replace thiourea derivatives or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in the aminolysis of carbonate reactions.…”

Base‐Promoted Oxidative C(sp3)–S Bond Cross‐Coupling of Inactive Fluorenes and Thiols for the Synthesis of 9‐Monothiolated Fluorenes

“…To the best of our knowledge, synthesis of 9‐monothiolated fluorenes through directly C‐H functionalization is less reported. Traditional methods for 9‐monothiolated fluorenes mainly involve the cross‐coupling of thiols with 9‐halofluorenes, which suffer from prehalogenation and harsh conditions. Herein, we would like to communicate the first cross‐coupling reaction of fluorenes and thiols to synthesize 9‐monothiolated fluorenes through base‐promoted C(sp 3 )–S bond cross‐coupling under mild conditions.…”