A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m2 g -1) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 °C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH3-TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Bro?nsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.
Sinhamahapatra, Apurba,Sutradhar, Narottom,Ghosh, Malay,Bajaj, Hari C.,Panda, Asit B.
experimental part
p. 87 - 93
(2012/04/10)
(1S,2S,3R,6R)-6-aminocyclohex-4-ene-1,2,3-triol (=(-)-conduramine B-1) is a selective inhibitor of α-mannosidases. Its inhibitory activity is enhanced by N-benzylation
(-)- and (+)-Conduramine B-1 ((-)- and (+)-5, resp.) have been derived from (+)- and (-)-7-oxabicyclo[2.2.1]hept-5-en-2-one ('naked sugars' of the first generation). Although (-)-5 imitates the structure of β-glucosides, it does not inhibit β-glucosidases
Lysek, Robert,Schuetz, Catherine,Vogel, Pierre
p. 2788 - 2811
(2007/10/03)
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