6795-79-5

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• 74-85-1 ethene 

Downstream Products

• 502-56-7 nonanone-5 
• 215957-73-6 3,3-Dibutylcyclobutanone toluene-p-sulfonylhydrazone 
• 2768-15-2 2-butylhexan-1-ol 
• 1616882-76-8 C₁₇H₂₅NO₃ 

Relevant academic research and scientific papers

Lewis acid promoted titanium alkylidene formation: Off-cycle intermediates relevant to olefin trimerization catalysis

Two new precatalysts for ethylene and α-olefin trimerization, (FI)Ti(CH2SiMe3)2Me and (FI)Ti(CH2CMe3)2Me (FI = phenoxy-imine), have been synthesized and structurally characterized by X-ray diffraction. (FI)Ti(CH2SiMe3)2Me can be activated with 1 equiv of B(C6F5)3 at room temperature to give the solvent-separated ion pair [(FI)Ti(CH2SiMe3)2][MeB(C6F5)3], which catalytically trimerizes ethylene or 1-pentene to produce 1-hexene or C15 olefins, respectively. The neopentyl analogue (FI)Ti(CH2CMe3)2Me is unstable toward activation with B(C6F5)3 at room temperature, giving no discernible diamagnetic titanium complexes, but at -30 °C the following can be observed by NMR spectroscopy: (i) formation of the bis-neopentyl cation [(FI)Ti(CH2CMe3)2]+, (ii) α-elimination of neopentane to give the neopentylidene complex [(FI)Ti(=CHCMe3)]+, and (iii) subsequent conversion to the imido-olefin complex [(MeOAr2N=)Ti(OArHC=CHCMe3)]+ via an intramolecular metathesis reaction with the imine fragment of the (FI) ligand. If the reaction is carried out at low temperature in the presence of ethylene, catalytic production of 1-hexene is observed, in addition to the titanacyclobutane complex [(FI)Ti(CH(CMe3)CH2CH2)]+, resulting from addition of ethylene to the neopentylidene [(FI)Ti(=CHCMe3)]+. None of the complexes observed spectroscopically subsequent to [(FI)Ti(CH2CMe3)2]+ is an intermediate or precursor for ethylene trimerization, but notwithstanding these off-cycle pathways, [(FI)Ti(CH2CMe3)2]+ is a precatalyst that undergoes rapid initiation to generate a catalyst for trimerizing ethylene or 1-pentene.

Selective ethylene trimerization by titanium complexes bearing phenoxy-imine ligands: NMR and EPR Spectroscopic studies of the reaction intermediates

The catalyst systems (FI)TiCl3/MAO (FI = phenoxyimine ligand with an additional aryl-O-CH3 donor) display exceptionally high activity in selective ethylene trimerization. By means of NMR and EPR spectroscopy, the nature of the Ti species formed in the catalyst systems (FI)TiCl3/MAO, (FI)TiCl3/MMAO, and (FI)TiCl 3/AlR3/[Ph3C]+[B(C6F 5)4]- (R = Me, Et, iBu) has been studied. It was shown that outer-sphere ion pairs of the type [(FI)Ti IVMe2]+[A]- ([A]- = [MeMAO]-, [MeMMAO]-, [B(C6F5) 4]-) are formed at the initial stage of the reaction of (FI)TiCl3 with MAO, MMAO, and AlMe3/[Ph3C] +[B(C6F5)4]-. These ion pairs further partially convert into TiIII and TiII species. In the systems (FI)TiCl3/MAO and (FI)TiCl 3/AlMe3/[Ph3C]+[B(C 6F5)4]-, complexes with the proposed structures (FI)TiIIIMe2, (FI)TiIICl, and [(FI)TiII(S)]+[A]- ([A]- = [MeMAO]-, [B(C6F5)4)]-, S = solvent, vacancy) were observed (concentrations of TiIII species was lower than those of the TiII congeners). In contrast, in the system (FI)TiCl3/MMAO, the concentrations of TiIII species (ion pairs of the type [(FI)TiIII(μ-H)(μ-Cl)Al iBu2]+[MeMMAO]-) were higher than those of the TiII counterparts (ion pairs [(FI)TiII(S)] +[MeMMAO]-). The system (FI)TiCl3/MMAO displays lower activity and selectivity in 1-hexene formation, in comparison to (FI)TiCl3/MAO, due to undesirable PE generation. Probably, Ti II and TiIV ion pairs are those participating in ethylene trimerization.

Decene formation in ethylene trimerization reaction catalyzed by Cr-pyrrole system

Decene formation in the ethylene trimerization reaction was studied using a chromium(III) 2-ethylhexanoate/2,5-dimethylpyrrole/triethylaluminum/ diethylaluminum chloride catalyst system. Kinetic investigations revealed that some decene formation reactions did not depend on 1-hexene concentration, because 1-hexene and catalyst may react with ethylene before dissociation of 1-hexene-catalyst complex after 1-hexene formation. The results demonstrated that decene formation is an intrinsic part of the trimerization reaction mechanism. It was also shown that a stepwise elimination mechanism for the decomposition of the chromacycloheptane intermediate cannot explain the observed product distribution. The dependencies found allow selection of appropriate conditions for low or high decene formation in the ethylene trimerization reaction.

Highly selective olefin trimerization catalysis by a borane-activated titanium trimethyl complex

Reaction of a trimethyl titanium complex, (FI)TiMe3 (FI = phenoxy-imine), with 1 equiv of B(C6F5)3 gives [(FI)TiMe2][MeB(C6F5)3], an effective precatalyst for the selective trimerization of ethylene. Mechanistic studies indicate that catalyst initiation involves generation of an active TiII species by olefin insertion into a Ti-Me bond, followed by β-H elimination and reductive elimination of methane, and that initiation is slow relative to trimerization. (FI)TiMe3/B(C6F 5)3 also leads to a competent catalyst for the oligomerization of α-olefins, displaying high selectivity for trimers (>95%), approximately 85% of which are one regioisomer. This catalyst system thus shows promise for selectively converting light α-olefins into transportation fuels and lubricants.

Trimerization of ethylene to 1-hexene with titanium complexes bearing phenoxy-imine ligands with pendant donors combined with MAO

New Ti complexes bearing phenoxy-imine ligands with pendant aryl-OMe donors have been developed for ethylene trimerization to produce 1-hexene. These Ti complexes combined with methylaluminoxane selectively trimerize ethylene to form 1-hexene with exceptionally high activity (e.g., 6.59 tons of 1-hexene/((g of Ti) h)).