Anhydrous lanthanide chlorides LnCl 3 (Ln=Sc, Y, La to Lu except for Pm), which are difficult to prepare in other ways, were prepared by chemical vapor transport (CVT) process. Rare earth oxide reacted with Al 2Cl ...Anhydrous lanthanide chlorides LnCl 3 (Ln=Sc, Y, La to Lu except for Pm), which are difficult to prepare in other ways, were prepared by chemical vapor transport (CVT) process. Rare earth oxide reacted with Al 2Cl 6 at 300℃ to produce LnCl 3, which was then separated from other solids by means of CVT at a temperature gradient from 400 to 180℃. Residual Al 2Cl 6 (g) was removed by carrier of dry N 2 gas at 200℃. The yielding rates were >90%, and the purity of products was >99.5%.展开更多
It is known that the first lanthanide （Ln） catalyst used for stereospecific polymeriza-tion of conjugated diene is composed of LnCl3 and R3Al.It initiates stereospecific polymeri-zation of butadiene with a very high...It is known that the first lanthanide （Ln） catalyst used for stereospecific polymeriza-tion of conjugated diene is composed of LnCl3 and R3Al.It initiates stereospecific polymeri-zation of butadiene with a very high cis-1, 4 content（98%）, yet owns poor activity. This paper presents the new results obtained in our laboratory. By adding alcohol tothis binary system （LnCl3-R3Al）, the catalytic activity is greatly enhanced without any losson its high stereospecificity. It is shown that the catalytic activity is dependent on the ratioof its components and their order of addition. Furthermore, we have ascertained that itis the alcohol complex of LnCl3 with a definite composition LnCl3.R3OH, that turns out tobe an active catalyst when treated with R3Al.展开更多
Copolymerization of styrene (St) and isoprene (IP) was carried out with a catalyst system composed of anhydrous lanthanide chloride hexamethyl phosphoramide complex (LnCl3HMPA) and aluminum organic compound (AOC). Amo...Copolymerization of styrene (St) and isoprene (IP) was carried out with a catalyst system composed of anhydrous lanthanide chloride hexamethyl phosphoramide complex (LnCl3HMPA) and aluminum organic compound (AOC). Among the catalysts examined, catalyst NdCl3HMPA/Al(i-Bu)3 showed a high activity in the copolymerization under certain conditions giving copolymers (5%15% St content) with high cis-1,4 microstructure in IP units (>95%). The effects of HMPA/Nd molar ratio, Al/Nd molar ratio, monomer/Nd molar ratio, St feed ratio, and the reaction time on copolymerization were examined with this catalytic system. The obtained copolymers were characterized by 1H and 13C NMR spectroscopies and gel-permeation chromatography (GPC).展开更多
文摘Anhydrous lanthanide chlorides LnCl 3 (Ln=Sc, Y, La to Lu except for Pm), which are difficult to prepare in other ways, were prepared by chemical vapor transport (CVT) process. Rare earth oxide reacted with Al 2Cl 6 at 300℃ to produce LnCl 3, which was then separated from other solids by means of CVT at a temperature gradient from 400 to 180℃. Residual Al 2Cl 6 (g) was removed by carrier of dry N 2 gas at 200℃. The yielding rates were >90%, and the purity of products was >99.5%.
文摘It is known that the first lanthanide （Ln） catalyst used for stereospecific polymeriza-tion of conjugated diene is composed of LnCl3 and R3Al.It initiates stereospecific polymeri-zation of butadiene with a very high cis-1, 4 content（98%）, yet owns poor activity. This paper presents the new results obtained in our laboratory. By adding alcohol tothis binary system （LnCl3-R3Al）, the catalytic activity is greatly enhanced without any losson its high stereospecificity. It is shown that the catalytic activity is dependent on the ratioof its components and their order of addition. Furthermore, we have ascertained that itis the alcohol complex of LnCl3 with a definite composition LnCl3.R3OH, that turns out tobe an active catalyst when treated with R3Al.
基金Project supported by the Major State Basic Research Development Program (No. 1999064801) the National Natural Science Foundation of China (No. 20254001) and Zhejiang Provincial Natural Science Foundation.
文摘Copolymerization of styrene (St) and isoprene (IP) was carried out with a catalyst system composed of anhydrous lanthanide chloride hexamethyl phosphoramide complex (LnCl3HMPA) and aluminum organic compound (AOC). Among the catalysts examined, catalyst NdCl3HMPA/Al(i-Bu)3 showed a high activity in the copolymerization under certain conditions giving copolymers (5%15% St content) with high cis-1,4 microstructure in IP units (>95%). The effects of HMPA/Nd molar ratio, Al/Nd molar ratio, monomer/Nd molar ratio, St feed ratio, and the reaction time on copolymerization were examined with this catalytic system. The obtained copolymers were characterized by 1H and 13C NMR spectroscopies and gel-permeation chromatography (GPC).
