Two
new U(VI)-containing silicotungstates with similar sandwiched
polyanions but different space structures, two-dimensional Na10.5H3.5(H2O)36[Na(UO2)(α-SiW9O34)]2·2.5H2O (1) and three-dimensional Na14(H2O)36[Na(UO2)(α-SiW9O34)]2·4H2O (2), have been synthesized by the reactions of UO2(OAc)2 and Na10[α-SiW9O34]·18H2O in aqueous solution at different pH values.
Structure analyses demonstrated that different reaction conditions
may provide different self-assembly conditions and result in the different
coordination environments of Na(I)-H2O clusters with different
disorders, which are the keys to the differences between 1 and 2. Compound 2 was demonstrated to
show excellent catalytic activity for the synthesis of 3H-benzo[b][1,4]diazepines and pyrazoles via the intermolecular
cyclization reactions, and the yields of the desired products reached
99%. This work illustrates the catalytic properties for U(VI)-containing
POMs.
As the solvent system ethanol + cyclohexane is selected for the purification of clopidogrel hydrogen sulfate (Form II) [CHS(II)], the solubilities of CHS(II) in the binary solvent mixtures were measured at the temperatures ranging from (283.35 to 333.75) K. The solubility increased with both the rising temperature and mole fraction of ethanol in the binary solvent. The experimental data were well-fitted by the Jouyban−Acree model, and the thermodynamic parameters were calculated correspondingly. The result demonstrated that the dissolution process of CHS(II) in the ethanol + cyclohexane mixture was endothermic and entropy-driven.
A simple and practical O2 oxidized scission of monosubstituted, gem- and 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins to aldehydes and ketones in PEGDME has been developed.
An efficient heterogeneous and green catalyst [HEMTH]H2[PMo12O40] was prepared to catalysis the oxa-Pictet–Spengler cyclization of arylethanols and aldehydes to afford isochromans with excellent yields using dimethyl carbonate as a green solvent.
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