Effect of the basic property of reactants (tertiary amine catalysts, a substrate amine, and acid neutralizers) on catalytic dehydrocondensation between a carboxylic acid and an amine by using 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) was studied. The reaction yield was affected by the acid-base equilibrium among reactants. In dichloromethane, a representative aprotic solvent, a strongly basi...

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. ...

Three novel compounds, named the aselacins, which inhibit the binding of endothelin to its receptor have been isolated from two related Acremonium species of fungi grown in stationary culture. These compounds are cyclic pentapeptolides with a ring formed by cyclo[Gly-D-Ser-D-Trp-beta-Ala-L-Thr] and an additional exocyclic D-Gln to which is attached a functionalized long chain fatty acid. The as...

Icosahedral carborane anions such as CHB11Cl11- are amongst the least coordinating, most chemically inert anions known. They are also amongst the least basic, so their conjugate acids, H(carborane), are superacids (i.e. stronger than 100% H2SO4). Acidity scale measurements indicate that H(CHB11Cl11) is the strongest pure Brønsted acid presently known, surpassing triflic and fluorosulfuric acid....

This work presents the pH sensing ability of a fluorescent indolin‐3‐imine derivative. Protonation weakly basic imine (pKa = 8.3 its conjugate acid) results in significant redshift absorption band. The fluorophore acts as photobase, with basicity increase approximately 6 units upon photoexcitation. behavior promotes excited state proton transfer from weak acids such protic solvents. characteris...

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 ...