Oligomerization of 1‐hexene initiated by Zr(OnPr)₄‐AlEt₂Cl, 1. Influences of reaction parameters on kinetics and products' distribution

Abstract

As part of our investigation of high a-olefin oligomerization initiated by the complexation of a transition metal (Ti and Zr) compound with an organoaluminium derivative, the oligomerization of 1-hexene initiated by Zr(OnPr),AlEt,Cl was studied in detail at 20°C. It was found that a high mole ratio of [Al]/[Zr] (> 5) was necessary in order to observe activity for 1 -hexene oligomerization. The highest activity was obtained for ratios ranging from 12 to 15. The products formed were mainly dimers, addition products of the ethyl group to 1-hexene, and isomers of 1 -hexene. The corresponding saturated alkanes were also formed in large amount. Their relative percentage is proportional to the mole ratio of [Al]/[l-hexene].

The C-terminal sterile alpha motif (SAM) domain of human p73 is a highly dynamic protein, which acquires high thermal stability through a decrease in backbone flexibility

“…Both regions regulate the transcriptional activity of p73a; in fact, the isolated SAM domain represses the function of the p73 activation domain. 15 Furthermore, p73a (and also p63a) has its p53-like function dramatically reduced in comparison with other non-SAM-containing isoforms, suggesting that the SAM domain could be responsible for those functional differences. 16 SAM domains are involved in expanding or regulating protein functions via self-association, association with other SAM domains, lipids, or nucleic acids.…”

“…34,35 The relaxation rates of each spin are functions of the spectral density function, J(o); this function accounts for: (i) the physical form of the magnetic interactions; and (ii) the frequency-dependence of the thermal motions of the system. The amide 15 N-spin in proteins is a particularly useful probe to monitor dynamics. Its relaxation mechanisms come from the local time-varying magnetic fields generated at the 1 H and 15 N nuclei due to the global tumbling of the molecule and the internal mobility of various N-H bond vectors.…”

“…The amide 15 N-spin in proteins is a particularly useful probe to monitor dynamics. Its relaxation mechanisms come from the local time-varying magnetic fields generated at the 1 H and 15 N nuclei due to the global tumbling of the molecule and the internal mobility of various N-H bond vectors. These movements control its experimental NMR observables (the 15 N T 1 -and T 2 -relaxation times, and the 15 N- 1 H NOE acquired at one or more magnetic fields).…”

Synthesis and characterization of bis(indenyl) zirconium aryloxide derivatives and their use in α‐olefin polymerization

“…Its tacticity was deduced from clean 13 C NMR resonances, whose values are very similar for all the polymers obtained by using all the catalysts analysed. By comparing our 13 C NMR resonances with those reported in the literature 18,[20][21][22] it can be determined whether the polymers are isotactic or syndiotactic; in our case, the chemical shifts always correspond to those typical of isotactic polyhexene.…”

Silyl‐functionalized polyolefins via co‐polymerization of vinylsilanes with ethylene or propylene catalyzed by group IV metallocene complexes

“…All these observations are consistent with termination E (either cis or trans). Although the 2,1‐insertion of propylene has been noted in a few cases, the internal double bond termination has never been reported in metallocene‐catalyzed propylene polymerization . The formation of internal double may have resulted from a β‐H elimination after the last insertion of propylene in a 2,1‐fashion.…”