Selective formation of the rctt chair stereoisomers of octa-O-alkyl resorcin[4]arenes using Brønsted acid catalysis
作者:Deborah Moore、Graeme W. Watson、Thorfinnur Gunnlaugsson、Susan E. Matthews
DOI:10.1039/b714735j
日期:——
New synthetic conditions are described for the fully selective formation of the rctt chair stereoisomers of octa-O-alkyl resorcin[4]arenes; these offer a clean route into the chair conformer of these interesting receptor molecules. Brønsted acid catalysis in acetic acid solutions results in the formation of the single isomer when 1,3-dimethoxybenzene is heated at 80 °C with a range of aldehydes, straight-
CROSS-LINKED RUBBERY POLYURETHANE-ETHER MEMBRANES FOR SEPARATIONS
申请人:UOP LLC
公开号:US20150114224A1
公开(公告)日:2015-04-30
Cross-linked rubbery polyurethane-ether polymeric membranes are made from cross-linked rubbery polyurethane-ether polymers that are synthesized from a diisocyanate-terminated polyether and a tetrol with four hydroxyl functional groups. The hydroxyl groups on the tetrol react with the isocyanate groups on the diisocyanate-terminated polyether to form urethane bonds. The cross-linked rubbery polyurethane-ether polymeric membrane selectively permeate condensable vapors such as C
3
to C
35
hydrocarbons, aromatics, water vapor, carbon dioxide, and hydrogen sulfide and rejects methane and ethane. The cross-linked rubbery polyurethane-ether polymeric membrane have high permeance for condensable vapors, high selectivity for condensable vapors over methane and ethane, and high resistance to liquid chemicals.