Dicyclopentadienyltitanium dichloride

Titanium-containing polyethers have been prepared by the reaction of dicyclopentadienyltitanium dichloride with aromatic and ahphatic diols via an interfacial and/or aqueous solution polycondensation technique (273). 

Dicyclopentadienyltitanium dichloride is possibly superior to titanium tetrachloride as a catalyst. Nickel(ll) compounds are also active, but with these catalysts concurrent addition of the organomagnesium compounds to carbon-carbon multiple bonds (see Section 4.1) causes complications. Examples of hydromagnesiation by Grignard reagents are listed in Table 3.8. As will be seen from entries in Table 3.8, the stereochemistry of addition to alkynes is syn. The regiochemistry is also usually predictable in the relevant examples in Table 3.8, one regioisomer is obtained mainly or exclusively. In other cases, however, mixtures are formed [54]. 

A 500 ml three-necked flask is fitted with a pressure-equalizing dropping funnel and a stopper, and furnished with a magnetic stirrer bar and an inert atmosphere. Isobutylmagnesium chloride (0.75 M in ether, 320 mol, 240 mmol) is placed in the flask and cooled by means of an ice-water bath. Dicyclopentadienyltitanium dichloride (1.3 g, 5.2 mmol) is added, and the solution is stirred at 0° for 10 min. A solution of oct-2-yn-l-ol (13.2 g, 105 mmol) is added to the cooled solution dropwise from the dropping funnel during 20 min, and the resulting solution is stirred at room temperature for 4 h. 

A useful alternative to phosphorus ylids are the titanium reagents, such as, 71, prepared from dicyclopentadienyltitanium dichloride and trimethylaluminum. Treatment of a carbonyl compound with the titanium cyclopentadienide complex 71 Tebbe s reagent) in toluene-THF containing a small amount of pyridine " leads to the alkene. Dimethyltitanocene (Me2TiCp2), called the Petasis reagent, is a convenient and highly useful alternative to The mechanism of Petasis... 

If dicyclopentadienyltitanium dichlorides (CsHs Men TiCb (n = 0, 2-5) are reduced with magnesium in the presence of bis(trimethylstannyl)acetylene, rc-complexes are formed with structures such as those shown in 8-5 and 8-6 115 similar complexes are known for silylacetylenes. 

Dicyclopentadienyltitanium dichloride (Titanocene dichloride), CpaTiClj. Mol. wt. 249.00. Suppliers Alfa, ROC/RIC. 

The new compound l,r-methylenetitanocene dichloride (25) is as effective as its well-known analogue dicyclopentadienyltitanium dichloride in catalysing olefin polymerisation. Further evidence for binuclear... 

Dicyclopentadienyl iron Di-2,4-cyclopentadien-1-yl iron. See Ferrocene Dicyclopentadienyinickel. SeeNickelocene Dicyclopentadienyltitanium dichloride. See Tltanocene dichloride... 

Synonyms Bis (cyclopentadienyl) dichIorotitaniurn Biscyclopentadienyltitanium dichloride Biscyclopentadienyltitanium (IV) dichloride Dichlorobis (1,3-cyclopentadiene) titanium Dichlorobiscyclopentadienyl titanium Dichlorodicyclopentadienyltitanium (Dichlorodi-pi-cyclopentadienyltitanium Dichlorotitanocene Dicyclopentadienyidichlorotitanium Dicyclopentadienyltitanium dichloride Titanium, dichloro-di-pi-cyclopentadienyl- Titanium ferrocene Titanocene Titanocene dichloride... 

Breslow, D. S. Newburg, N. R. Dicyclopentadienyltitanium dichloride-aUcylaluminum complexes as soluble catalysts for the polymerization of ethylene. J. Am. Chem. Soc. 1959, 81, 81-86. 

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