TY - JOUR
T1 - Highly efficient isocyanate-free microwave-assisted synthesis of [6]-oligourea
AU - Qaroush, Abdussalam K.
AU - Al-Hamayda, Asmaa S.
AU - Khashman, Yasmeen K.
AU - Vagin, Sergei I.
AU - Troll, Carsten
AU - Rieger, Bernhard
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): UK-C0020/KSA-C0069
Acknowledgements: A. K. Q. is grateful to King Abdullah University for Science and Technology, KAUST for the financial support of the scholarship of his PhD for the project UK-C0020/KSA-C0069. In addition, we thank Dr Wolfgang Eisenreich and Dr Timo Anselment for their help with the NMR experiments.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
PY - 2013
Y1 - 2013
N2 - A new eco-friendly, isocyanate-free, energy-saving method for the production of [6]-oligourea, utilizing a green carbonylating agent, viz. propylene carbonate, is reported. It comprises an organocatalyzed, microwave-assisted, solvent-free synthesis. Two modes of microwave-assisted synthesis, viz. dynamic and fixed energy modes, were applied. Upon optimization, the dynamic mode gave 79% yields of [6]-oligourea. On the other hand, almost quantitative yields were obtained using the fixed mode, within 20 min, at 10 W and with the same catalyst loading. Combination of both organocatalysis and microwave energy input appears to be a key issue for the efficiency of the reaction, with the fixed energy mode being best suited. It should be noted that all data reported are reproducible (due to the homogeneous microwave technology used by CEM Discover S-Class of microwave reactors). To the best of our knowledge, this is the best eco-friendly synthetic approach for the preparation of the title oligomers. It paves the way for using more of the biorenewable and sustainable chemicals as a feedstock for the production of polyureas. The oligomer produced was analyzed by EA, ATR-FTIR, XRD, 1H and 13CNMR. Furthermore, thermal properties of the resulting [6]-oligourea were analyzed using TGA and DSC. © The Royal Society of Chemistry 2013.
AB - A new eco-friendly, isocyanate-free, energy-saving method for the production of [6]-oligourea, utilizing a green carbonylating agent, viz. propylene carbonate, is reported. It comprises an organocatalyzed, microwave-assisted, solvent-free synthesis. Two modes of microwave-assisted synthesis, viz. dynamic and fixed energy modes, were applied. Upon optimization, the dynamic mode gave 79% yields of [6]-oligourea. On the other hand, almost quantitative yields were obtained using the fixed mode, within 20 min, at 10 W and with the same catalyst loading. Combination of both organocatalysis and microwave energy input appears to be a key issue for the efficiency of the reaction, with the fixed energy mode being best suited. It should be noted that all data reported are reproducible (due to the homogeneous microwave technology used by CEM Discover S-Class of microwave reactors). To the best of our knowledge, this is the best eco-friendly synthetic approach for the preparation of the title oligomers. It paves the way for using more of the biorenewable and sustainable chemicals as a feedstock for the production of polyureas. The oligomer produced was analyzed by EA, ATR-FTIR, XRD, 1H and 13CNMR. Furthermore, thermal properties of the resulting [6]-oligourea were analyzed using TGA and DSC. © The Royal Society of Chemistry 2013.
UR - http://hdl.handle.net/10754/598503
UR - http://xlink.rsc.org/?DOI=c3cy00117b
UR - http://www.scopus.com/inward/record.url?scp=84881414478&partnerID=8YFLogxK
U2 - 10.1039/c3cy00117b
DO - 10.1039/c3cy00117b
M3 - Article
SN - 2044-4753
VL - 3
SP - 2221
JO - Catalysis Science & Technology
JF - Catalysis Science & Technology
IS - 9
ER -