628-68-2Relevant articles and documents
Self-assembled orthoester cryptands: Orthoester scope, post-functionalization, kinetic locking and tunable degradation kinetics
L?w, Henrik,Mena-Osteritz, Elena,Von Delius, Max
, p. 4785 - 4793 (2018/06/07)
Dynamic adaptability and biodegradability are key features of functional, 21st century host-guest systems. We have recently discovered a class of tripodal supramolecular hosts, in which two orthoesters act as constitutionally dynamic bridgeheads. Having previously demonstrated the adaptive nature of these hosts, we now report the synthesis and characterization-including eight solid state structures-of a diverse set of orthoester cages, which provides evidence for the broad scope of this new host class. With the same set of compounds, we demonstrated that the rates of orthoester exchange and hydrolysis can be tuned over a remarkably wide range, from rapid hydrolysis at pH 8 to nearly inert at pH 1, and that the Taft parameter of the orthoester substituent allows an adequate prediction of the reaction kinetics. Moreover, the synthesis of an alkyne-capped cryptand enabled the post-functionalization of orthoester cryptands by Sonogashira and CuAAC "click" reactions. The methylation of the resulting triazole furnished a cryptate that was kinetically inert towards orthoester exchange and hydrolysis at pH > 1, which is equivalent to the "turnoff" of constitutionally dynamic imines by means of reduction. These findings indicate that orthoester cages may be more broadly useful than anticipated, e.g. as drug delivery agents with precisely tunable biodegradability or, thanks to the kinetic locking strategy, as ion sensors.
Method of Synthesizing Polyol Acetate by Using Catalyst of Ionic Liquid Heteropoly Acid
-
Paragraph [0032]; [0039], (2013/05/09)
The present invention uses a nitrogen-containing organic compound to be reacted with an alkyl sultone to obtain a zwitterion compound. The zwitterion compound is reacted with a heteropoly acid (HPA) to obtain an ionic liquid HPA (IL-HPA). The IL-HPA is used for acetylation of polyol and HOAc for obtaining polyol acetate. The IL used in the reaction can be recycled. Thus, problems of product separation, waste acid handling, and corrosion of facilities are solved and production through esterification is improved with a green catalysis.
SYNTHESIS OF SEVERELY STERICALLY HINDERED SECONDARY AMINOETHER ALCOHOLS FROM A KETENE AND/OR CARBOXYLIC ACID HALIDE AND/OR CARBOXYLIC ACID ANHYDRIDE
-
Page/Page column 19-20, (2008/06/13)
Severely sterically hindered secondary aminoether alcohols are prepared by a process comprising reacting a ketene with sulfuric acid to produce an anhydride which is then reacted with, to cleave the ring of, a dioxane to yield a cleavage product which is then aminated using an amine, followed by hydrolysis with a base to yield the desired severely sterically hindered secondary aminoether alcohol.
