Reaction of the trivacant heteropolyanions α A PW9O349- with CH3SiCl3 leads to the formation of the organosilyl derivative (TBA)3[α A PW9O34(CH3SiO)3(CH3Si)]. The crystal X ray diffraction analysis shows that the cr...Reaction of the trivacant heteropolyanions α A PW9O349- with CH3SiCl3 leads to the formation of the organosilyl derivative (TBA)3[α A PW9O34(CH3SiO)3(CH3Si)]. The crystal X ray diffraction analysis shows that the crystalbelongs to orthorhombic with space group Pca21, M=3177.09 and the unit cell parameters: a=25.761(5)?,b=14.519(3)?,c=24.396(5)?.V=9124(3)?3,Z=4,Dc=2.225g·cm-3,μ(MoKα)=11.438mm-1,F(000)=5464,R=0.0561,Rw=0.0866. The anion consists of one α A PW9O349- anion linked by three CH3SiO+ groups, whichattached to the fourth CH3Si through three Si O Si bridges.展开更多
Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstat...Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstate anion [PW11O39]7-or the complete Keggin-type heteropolyanion [PW12O40]3-,under two-phase conditions using ethyl acetate as the solvent. It was found that the lacunary-type catalyst showed higher activity and better recyclability than the complete Keggin-type catalyst under the same reaction conditions. 31P NMR spectroscopy and solubility measurements for the two catalysts revealed that the [PW11O39]7-anion had a much faster degradation rate than the [PW12O40]3-anion in an excess of H2O2,which resulted in the formation of more catalytically active species. As a result,the lacunary-type phosphotungstate anion-based catalyst gave a better catalytic performance than the complete Keggin-type anion in ethyl acetate.展开更多
文摘Reaction of the trivacant heteropolyanions α A PW9O349- with CH3SiCl3 leads to the formation of the organosilyl derivative (TBA)3[α A PW9O34(CH3SiO)3(CH3Si)]. The crystal X ray diffraction analysis shows that the crystalbelongs to orthorhombic with space group Pca21, M=3177.09 and the unit cell parameters: a=25.761(5)?,b=14.519(3)?,c=24.396(5)?.V=9124(3)?3,Z=4,Dc=2.225g·cm-3,μ(MoKα)=11.438mm-1,F(000)=5464,R=0.0561,Rw=0.0866. The anion consists of one α A PW9O349- anion linked by three CH3SiO+ groups, whichattached to the fourth CH3Si through three Si O Si bridges.
基金supported by the National Natural Science Foundation of China (20773037, 21073058)
文摘Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstate anion [PW11O39]7-or the complete Keggin-type heteropolyanion [PW12O40]3-,under two-phase conditions using ethyl acetate as the solvent. It was found that the lacunary-type catalyst showed higher activity and better recyclability than the complete Keggin-type catalyst under the same reaction conditions. 31P NMR spectroscopy and solubility measurements for the two catalysts revealed that the [PW11O39]7-anion had a much faster degradation rate than the [PW12O40]3-anion in an excess of H2O2,which resulted in the formation of more catalytically active species. As a result,the lacunary-type phosphotungstate anion-based catalyst gave a better catalytic performance than the complete Keggin-type anion in ethyl acetate.
