Bifunctional silanol-based HBD catalysts for CO2 fixation into cyclic carbonates. (12th November 2019)

• Record Type: Journal Article
• Authors: Pérez-Pérez, Jovana; Hernández-Balderas, Uvaldo; Martínez-Otero, Diego; Jancik, Vojtech
• Is Part Of: New journal of chemistry. Volume 43:Number 47(2019)
• Page Start: 18525
• Page End: 18533
• Publication Date: 2019-11-12
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c9nj04840e
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Unprecedented silanol-based bifunctional HBD catalysts with tetraalkylammonium units directly incorporated into their structures were prepared from tailor-made silanols and used in the preparation of cyclic carbonates. Abstract : First examples of unprecedented silanol-based bifunctional HBD catalysts [( t BuO)2 {(N(CH2 CH2 )3 N)CH2 CH2 O}Si(OH)] + I − and ( Rac )- and ( R )-[( t BuO)2 {(N(CH2 CH2 )3 N)CH2 (Et)CHO)}Si(OH)] + I − with tetraalkylammonium units directly incorporated into their structures were prepared from tailor-made silanols. These bifunctional silanols were used together with other mixed alkoxysilanols of general formula ( t BuO)2 (RO)SiOH (R = Me, Et, i Pr, –CH2 CH2 I and –CH(Et)CH2 I) in a systematic study of their catalytic properties for the preparation of cyclic carbonates using a library of epoxides and industrial-grade carbon dioxide. With 4 mol% catalyst loading in the absence of a solvent and an external nucleophile source, the bifunctional catalysts showed good to very good conversion of epoxides to the corresponding cyclic carbonates within 10 h at 70 °C and 75 psi of CO2 . Furthermore, the developed synthetic approach used in the preparation of these mixed alkyl silanols via the hydrolysis of the corresponding acetoxysilyl alkoxides ( t BuO)2 (RO)Si(OAc) (R = organic moiety) allowed a straightforward route to the modification of the steric bulk around the silicon atom and the introduction of functional groups for further derivatization.