Sidearm effect in (thio)urea/alkoxide-mediated ring-opening polymerization of cyclic esters was written by Zhu, Ningning;Behzadi, Shabnam;Si, Guifu;Tan, Chen. And the article was included in Polymer International in 2021.Electric Literature of C4H7NS The following contents are mentioned in the article:
Thiourea and urea catalysts have received much attention in the field of ring-opening polymerization In the (thio)urea/alkoxide catalytic system, sidearm groups can influence the catalytic performance of the organocatalyst moiety. In this work, a series of (thio)ureas bearing 2-, 3- and 4-pyridyl moieties were designed and synthesized. The (thio)ureas bearing a 2-pyridyl group exhibited much higher catalytic activities than the (thio)ureas bearing 3- or 4-pyridyl groups, suggesting a sidearm effect. Both crystal data and computational studies indicated that 2-pyridyl can form an intramol. hydrogen bond with the NH moiety, resulting in a Broensted base/Lewis acid bifunctional catalytic system. Furthermore, the catalyst was stimuli-responsive in Lewis acid/base-modulated ring-opening polymerization Coordination between the Lewis acid BEt3 and the catalyst was found to terminate the polymerization Subsequently, the coordinated species was cleaved using the Lewis base bicyclo[2.2.2]-1,4-diazaoctane, resulting in the reactivation of the catalyst. 2020 Society of Chem. Industry. This study involved multiple reactions and reactants, such as Isopropylisothiocyanate (cas: 2253-73-8Electric Literature of C4H7NS).
Isopropylisothiocyanate (cas: 2253-73-8) belongs to esters. Esters are widespread in nature and are widely used in industry. In nature, fats are in general triesters derived from glycerol and fatty acids. Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries. Liquid esters of low volatility serve as softening agents for resins and plastics. Esters also include many industrially important polymers. Polymethyl methacrylate is a glass substitute sold under the names Lucite and Plexiglas; polyethylene terephthalate is used as a film (Mylar) and as textile fibres sold as Terylene, Fortrel, and Dacron.Electric Literature of C4H7NS
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics