ZUSAMMENFASSUNG: N,N,N',N'-Tetramethylathylendiamin (TMD) ruft in den Systemen Organolithium (RLi)/Isopren schon beim Molverhaltnis [TMD]/[RLi] z 1 eine betrachtliche Zunahme der Polymerisationsgeschwindigkeit und bevorzugte Bildung von 3,4-Kettengliedern in den Polymeren hervor. Um die Natur dieser Effekte zu klaren, wurden Fraktionen der Polymeren untersucht, die sich beim parallelen Verlauf der Wachstumsreaktion an RLi-Agenzien und deren Komplexen mit TMD bilden, was durch die Wahl des Verhaltnisses [TMD]/[RLi] = 0,Ol erreicht wurde. Der hochste Gehalt an 3,4-Gliedern in dem unter dieser Bedingung erhaltenen Polyisopren wurde fur die Fraktion mit dem kleinsten Molekulargewicht festgestellt. Es wird ein moglicher Mechanismus fur diese Erscheinung vorgeschlagen. SUMMARY: N,N,N',N'-Tetramethylethylenediamine (TMD) causes a significant increase of the polymerization rate and of the content of 3,4-links in the polymers formed in the systems organolithium (RLi)/isoprene already at a mole-ratio [TMD]/[RLi] r 1. In order to clear the nature of these effects fractions of the polymers formed at a ratio [TMD]/[RLi] = 0,Ol which secured parallel propagation reactions by the RLi-speciesand their complexes with TMD were investigated. The highest content of 3,4-links was found in the polyisoprene fraction with the lowest molecular weight. A possible mechanism of this phenomenon is discussed.

Molecular weights and structural characteristics of the polymers formed in the system isoprene/oligoisoprenyllithium (OILi)/N,N,N',N'-tetramethylethylenediamine (TMD)/hexane (mole ratio TMD/ OILi=O,Ol) at various conversions at -30°C were determined. The applied conditions made it possible to judge the relative activity of various types of growing chains. The results obtained suggest an opposite influence of the complex formation with respect to the associated and non-associated organolithium compounds. It was found that the former are activated (in comparison to the non-complexed associates), whereas the latter (in comparison to the non-complexed monomeric forms M,Li) become less active by complex formation. The possible causes of this different behaviour are considered. Einleitung

Molecular weights and structural characteristics of the polymers formed in the system isoprene/oligoisoprenyllithium (OILi)/I ,2-dimethoxyethane (DME)/hexane (mole ratio DME/ OILi = 0.01) for various conversions at -30°C were determined. The results obtained corroborate the former conclusion that the complexation of an electron donor with the monomeric form of the growing chain reduces the reactivity of the latter.

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