Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, ...Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, 2,2i-bisphenol, and 2,2'-bisnaphthol,respectively. In the presence of a moderate amount of methylaluminoxane (MAO), the complexesexhibited catalytic activities for ethylene polymerization. Complex Ⅰ showed the highest activityat Al/Ti molar ratio of 500 at the temperature of 30℃. With increasing of polymerizationtemperature, catalytic activities and molecular weight of the obtained polyethylene tended todecrease, and molecular weight distribution of polyethylene became narrower. With the molecularsimulation method, the charges on titanium atoms of complexes Ⅰ, Ⅱ, and Ⅲ, and the bond anglesformed by Ti and bisphenoxy ligands were calculated. It was concluded that the smaller the netcharge on Ti and the smaller the angle of O1―Ti―O2, the higher the activity of the complex.展开更多
3,5-Diaryl-1,2,4-oxadiazoles were synthesized by homocoupling of chloroarylaldoxime from arylaldoxime and N-chlorosuccinimide(NCS)in the presence of Cs_(2)CO_(3) in one pot.The method is suitable for thiophene-3-carba...3,5-Diaryl-1,2,4-oxadiazoles were synthesized by homocoupling of chloroarylaldoxime from arylaldoxime and N-chlorosuccinimide(NCS)in the presence of Cs_(2)CO_(3) in one pot.The method is suitable for thiophene-3-carbaldehyde,ison-icotinaldehyde and arylaldehyde without active substituent with a yield from 19%to 78%.However,it was not suitable for aliphatic aldehydes,other heteroaromatic aldehydes and benzaldehydes carrying active groups(hydroxyl,amino and carbox-ylic acid).Compared to reported methods,this method uses only aromatic aldoxime as a single substrate.The process is sim-ple,convenient,and green,making it a reliable way to synthesize 3,5-(homo-substituted)-1,2,4-oxadiazoles.展开更多
基金The work is supported by Special Funds for State Major Basic Research Projects of China(No.G1999064801)
文摘Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, 2,2i-bisphenol, and 2,2'-bisnaphthol,respectively. In the presence of a moderate amount of methylaluminoxane (MAO), the complexesexhibited catalytic activities for ethylene polymerization. Complex Ⅰ showed the highest activityat Al/Ti molar ratio of 500 at the temperature of 30℃. With increasing of polymerizationtemperature, catalytic activities and molecular weight of the obtained polyethylene tended todecrease, and molecular weight distribution of polyethylene became narrower. With the molecularsimulation method, the charges on titanium atoms of complexes Ⅰ, Ⅱ, and Ⅲ, and the bond anglesformed by Ti and bisphenoxy ligands were calculated. It was concluded that the smaller the netcharge on Ti and the smaller the angle of O1―Ti―O2, the higher the activity of the complex.
文摘3,5-Diaryl-1,2,4-oxadiazoles were synthesized by homocoupling of chloroarylaldoxime from arylaldoxime and N-chlorosuccinimide(NCS)in the presence of Cs_(2)CO_(3) in one pot.The method is suitable for thiophene-3-carbaldehyde,ison-icotinaldehyde and arylaldehyde without active substituent with a yield from 19%to 78%.However,it was not suitable for aliphatic aldehydes,other heteroaromatic aldehydes and benzaldehydes carrying active groups(hydroxyl,amino and carbox-ylic acid).Compared to reported methods,this method uses only aromatic aldoxime as a single substrate.The process is sim-ple,convenient,and green,making it a reliable way to synthesize 3,5-(homo-substituted)-1,2,4-oxadiazoles.
