نتایج جستجو برای: lewis acid
تعداد نتایج: 761908 فیلتر نتایج به سال:
Framework-associated aluminum is demonstrated to facilitate a reversible switch between Lewis and Brønsted acidity in zeolites with the acid sites preferentially populating side-pockets case of mordenite.
The selective transformation of hexose and pentose sugars to intermediate platform chemicals, such as furans, is an essential step in the conversion of cellulosic and hemicellulosic biomass to biofuels and biochemicals. Yet, many challenges in achieving commercially viable processes remain. In this feature article, we outline challenges that need to be overcome to enable these transformations. ...
The methods of thermal analysis – thermogravimetry, differential were used to study the catalytic system phosphor-molybdenum heteropoly acid–aluminum oxide. It is shown that modification aluminum oxide has a direct effect on state acid. On surface ƞ-Al2O3, phosphomolybdic acid destroyed by interaction with strong Lewis’s sites carrier, while γ-Al2O3 it retains individuality, probably due multi...
Expression of sialyl Lewis is known to be increased in cancers of the digestive organs. The determinant serves as a ligand for E-selectin and mediates hematogenous metastasis of cancers. In contrast, disialyl Lewis, which has an extra sialic acid attached at the C6-position of penultimate GlcNAc in sialyl Lewis, is expressed preferentially on nonmalignant colonic epithelial cells, and its expre...
efficient and chemoselective protection of aldehydes to the corresponding dimethyl acetals have been carried out by mixture of trimethyl orthoformate and methanol in the presence of a catalytic amount of tmscl or alcl3 under microwave irradiation. under these conditions, acetalization of ketones does not take place and they remain intact under reaction conditions. the results are compared with ...
We report a detailed synthetic and mechanistic study of an unusual bifunctional, sequential hetero-Diels-Alder/ring-opening reaction in which chiral, metal complexed ketene enolates react with o-quinones to afford highly enantioenriched, alpha-hydroxylated carbonyl derivatives in excellent yield. A number of Lewis acids were screened in tandem with cinchona alkaloid derivatives; surprisingly, t...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید