Effect of tert-Butyl Chloride on the Isoprene Polymerization with Neodymium Isopropoxide/Diisobutylaluminum Hydride and Neodymium Isopropoxide/Methylaluminoxane Catalysts

✍ Scribed by Weimin Dong; Kiyoshi Endo; Toshio Masuda

• Book ID: 102485575
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 123 KB
• Volume: 204
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200290062

✦ Synopsis

Abstract

The effect of tert‐butyl chloride (__t__BuCl) as a third catalyst component on the isoprene polymerization with neodymium isopropoxide (Nd(O__i__Pr)~3~)/diisobutylaluminum hydride (Al(__i__Bu)~2~H) and Nd(O__i__Pr)~3~/methylaluminoxane(MAO) catalysts was examined in heptane at a fixed [Al]/[Nd] ratio of 30 and reaction temperatures of 30 and 60 °C. The Nd(O__i__Pr)~3~/Al(__i__Bu)~2~H catalyst was inactive without __t__BuCl, i.e., at [Cl]/[Nd] = 0, while it showed the highest activity under the conditions of [Cl]/[Nd] = 3.0 and an addition order of {Al(__i__Bu)~2~H + __t__BuCl} + Nd(O__i__Pr)~3~ to yield polyisoprene with relatively low molecular weight (M~n~ ca. 5 × 10^4^), broad MWD (M~w~/M~n~ ca. 5.4), and high cis‐1,4 content (ca. 96%) at 30 °C. On the other hand, the Nd(O__i__Pr)~3~/MAO catalyst was effective at [Cl]/[Nd] = 0, and the most active at [Cl]/[Nd] = 1.0–1.5 with an addition order of {Nd(O__i__Pr)~3~ + MAO} + __t__BuCl to afford polymer with high molecular weight (M~n~ ca. 8 × 10^5^), fairly narrow MWD (M~w~/M~n~ ca. 1.6) and high cis‐1,4 content (ca. 94%) at 30 °C. Thus, the novel Nd(O__i__Pr)~3~/MAO/__t__BuCl system features high activity, high molecular weight, narrow MWD, and high cis‐1,4 stereospecificity, as compared with the conventional Nd(O__i__Pr)~3~/Al(__i__Bu)~2~H/__t__BuCl system.

Effect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(O__i__Pr)~3~/Al(__i__Bu)~2~H/__t__BuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.

magnified imageEffect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(O__i__Pr)~3~/Al(__i__Bu)~2~H/__t__BuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.