Thermodynamics of Aliphatic Cyclic Urethanes, of Their Ring-Opening Polymerization, and of Corresponding Polyurethanes

Polymerization of Cyclic Carbamates: A Practical Route to Aliphatic Polyurethanes

“…We have initially synthesized the cyclic carbamate monomers a−d (Figure 2) and investigated the use of these monomers in the presence of different anionic initiators (e.g., sodium hydride and yttrium tris(isopropoxide)). In accordance with previous observations, 17 we found them to be unreactive. By analogy with cyclic carbonates, we then hypothesized that cyclohexyl carbamate derivatives would have a better potential for ROP due to a more significant ring strain.…”

“…, sodium hydride and yttrium tris­(isopropoxide)). In accordance with previous observations, we found them to be unreactive. By analogy with cyclic carbonates, we then hypothesized that cyclohexyl carbamate derivatives would have a better potential for ROP due to a more significant ring strain.…”

Direct Assembly of 2‐Oxazolidinones by Chemical Fixation of Carbon Dioxide

“…Therefore, the selectivity of the reaction in the presence or absence of K + is directly related to the thermodynamic stability of five‐ and six‐membered cyclic carbamates 4 and 5 . Thus, the latter species lies 1.8 kcal mol −1 (1.5 kcal mol −1 in the presence of K + ) over the former, which is in nice agreement with the experimentally observed favored formation of 4 over 5 (see Table 1) and previously published thermodynamic studies 24…”

“…Thus, the latter species lies 1.8 kcal mol À1 (1.5 kcal mol À1 in the presence of K + ) over the former, which is in nice agreement with the experimentally observed favored formation of 4 over 5 (see Table 1) and previously published thermodynamic studies. [24] At variance, the barrier energy difference significantly increases when Cs + is involved in the process. The computed DDG°value of 1.7 kcal mol À1 for the reactions involving TS2 c and TS3 c is translated into a Boltzmann's ratio of 92:8 (at 65 8C), which nearly matches the experimentally observed 81:17 ratio of 4 and 5 (see Table 1).…”

Novel green fatty acid-based bis-cyclic carbonates for the synthesis of isocyanate-free poly(hydroxyurethane amide)s

“…[5][6][7][8] Therefore, the need to nd alternative routes for the synthesis of PUs which avoid the use of isocyanate is of high importance. Several ways are considered to produce more sustainable non isocyanate polyurethanes (NIPU) from vegetable oil derivatives, such as: (i) the ring-opening of cyclic carbonates by amines, [9][10][11] (ii) the transurethane process [12][13][14][15] and (iii) the self-condensation method based on the Curtius rearrangement in which the AB-type monomer contains both hydroxyl and acyl azide groups. 16,17 The reaction of cyclic carbonates with amines has emerged as the most promising non-isocyanate route leading to poly(hydroxyurethane)s (PHUs).…”