amounts of TDA-urea could not be determined quantitatively due to formation of oligomeric ureas with different end groups. No base is required. Solid diphenylphosphino-polystyrene (PS-PPh2) was purchased from Novabiochem® (Cas-No: 39319-11-4, loading ca. Register and get informed about new articles. In. Accepted 17 Oct 2013, Our further analysis shows that EDA–isocyanate is less prone to cyclization than MEA–isocyanate, which in turn allows for more facile urea formation. aReactions were carried out in a MW reactor: azido derivative, PS-PPh2 (1.5 equiv), CO2 (14.5 bar), 50 °C, 1.5 h, then 3 (2 equiv) 70 °C, 3 h. bIsolated yield. between the hydrogen of the secondary amine and the carbonyl oxygen whereas the Synthesis of benzyl isocyanate. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (http://www.beilstein-journals.org/bjoc). aReactions were carried out in a MW reactor: alkyl bromide, NaN3 (2 equiv), MeCN, 95 °C, 3 h ; then PS-PPh2 (1.5 equiv), CO2 (14.5 bar), amine (2 equiv), at 50 °C 1.5 h then 70 °C 3 h. bIsolated yield. tin compounds like dibutyltin dilaurate (DBTL). This may take some time to load. This is particularly true for diisocyanates in para position whereas diisocyanates in ortho position have somewhat lower reactivity due to steric hindrance The mixture was then filtered on paper and the solvent was evaporated under vacuum. Figure 3.12 The reaction of isocyanate and water forming an amine. Since CO2 requires a large energy input to be transformed , we have studied a synthetic procedure which uses a MW reactor (SynthWave by Milestone) and is well suited for parallel syntheses at any reaction temperature and gas pressure (up to 300 °C and 200 bar). The robustness of this MW-promoted sequential one-pot procedure was established by synthesizing a set of 13 different urea derivatives. The optimized procedure benefited from the use of a quasi-stoichiometric amount of PS-PPh2 and can be applied for the efficient, safe, rapid, and cost-effective production of urea derivative libraries. Our work highlights the importance of kinetic effects associated with the local structure and dynamics of solvent molecules around the intermediates that may significantly alter the degradation process of amine solvents. The reconfiguration dynamics of isocyanate is found to be governed by the dynamic nature of the interaction between its terminal group and surrounding solvent molecules. The mixture was stirred at rt for 15 min. If you are the author of this article you do not need to formally request permission MW-promoted reactions were carried out in a SynthWave (Milestone, Italy). Certainly, the insolubility of most isocyanates with water will have significant effect on the observed rate of reaction and can conceivably account for much disparity of the measured rates found in the literature . Physical and mechanical properties of polymers. polyisocyanates (N-substituted 1-nylons). Kyndra B. Sluiter, ; He, H. S.; Shi, M.; Toy, P. H. Friant-Michel, P.; Marsura, A.; Kovacs, J.; Pintér, I.; Rivail, J.-L. Delebecq, E.; Pascault, J.-P.; Boutevin, B.; Ganachaud, F. Decicco, C. S.; Seng, J. L.; Kennedy, K. E.; Covington, M. B.; Welch, P. K.; Arner, E. C.; Magolda, R. L.; Nelson, D. J. Nowick, J. S.; Powell, N. A.; Nguyen, T. M.; Noronha, G. Nowick, J. S.; Holmes, D. L.; Noronha, G.; Smith, E. M.; Nguyen, T. M.; Huang, S.-L. Marinescu, L.; Thinggaard, J.; Thomsen, I. Benjamin J. Pollock, However, the byproduct of this reaction is triphenylphosphine oxide, which is difficult to remove.
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