The Reaction between Styrene and Triisobutylaluminum

Natta, G.; Pino, P.; Mazzanti, G.; Longi, P.; Bernardini, Fabio

doi:10.1021/ja01519a065

Cited by 36 publications

(10 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It seems the initial temperature rise within the first few seconds is faster than the formation of dormant sites. Afterwards, when the quasisteady-state is reached, the rate curve from the calorimetric and MFM methods coincides and documents the wellestablished fact that the presence of hydrogen as a chain transfer agent enhances the polymerization rate, probably because of the well-known dormant-site re-activation with hydrogen (see, for example, Natta et al, [14] Chadwick et al, [15] and Mori et al [16] ). Under the present polymerization conditions, this phenomenon is apparently obeyed, the quasi-steady-state polymerization rate in the presence of hydrogen is higher.…”

Section: Resultssupporting

confidence: 60%

Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

Pimplapure

Zheng

Loos

et al. 2005

Macromol. Rapid Commun.

View full text Add to dashboard Cite

Summary: “True” initial polymerization rates can be calculated from the adiabatic temperature rise under isoperibolic conditions. They are much higher than initial polymerization rates measured by standard mass flow meter methods under quasi‐steady‐state conditions. These high initial rates are followed by a fast apparent deactivation (“attenuation”) until a constant (“plateau”) activity is reached at low polymerization yields of 2–3 g PP · (g catalyst)−1 caused by an “increasing degree of encapsulation” of active sites. Mass transfer limitations are not observed. Cross sectional SEM images of the polymer samples support these kinetic findings.Rate of polymerization (g of PP · (g catalyst)−1 · h−1) and yield of polymerization (g of PP · (g catalyst)−1) as function of time.magnified imageRate of polymerization (g of PP · (g catalyst)−1 · h−1) and yield of polymerization (g of PP · (g catalyst)−1) as function of time.

show abstract

Section: Resultssupporting

confidence: 60%

Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

Pimplapure

Zheng

Loos

et al. 2005

Macromol. Rapid Commun.

View full text Add to dashboard Cite

show abstract

“…As a result of styrene hydroalumination, generation of isomeric complexes responsible for the formation of corresponding OACs (10a) and (10b) occurs. Structures (9a) and (9b) indicate these two regioisomeric product intermediates (Scheme 18.8 ) [33,34] . In contrast to styrene, α -methylstyrene and α -phenylstyrene react with DIBAL regioselectively giving OAC (11) (Scheme 18.9 ) [35] .…”

Section: Alkenesmentioning

confidence: 99%

Hydrometallation of Unsaturated Compounds

Джемилев

Ибрагимов

2008

Modern Reduction Methods

View full text Add to dashboard Cite

18 IntroductionTo the number of signifi cant hydrometallating reagents that have been introduced into organic synthesis should be added the stable hydrides of transition metals (Zr) and nontransition metals (B, Al, Mg).Today, hydrides of the these metals and their derivatives are widely used in the reduction of alkenes, dienes, alkynes, allenes, heteroolefi ns and carbonyl compounds as well as for the production of the corresponding organometallic compounds and selective alkene functionalization via the synthesis of compounds containing polar metal -carbon (M − C) bonds. These may be involved in reactions with electrophilic or nucleophilic reagents affording functional derivatives.Generally, the thermal additions of the above hydrides to alkenes proceed via the four -center transition state (1) , with subsequent cleavage of the M − H bond and metal addition. In this case the corresponding organometallic compounds are formed according to Scheme 18.1 .The use of metal complex catalysts in organic and metalloorganic chemistry allows the chemo -, regio -and stereoselective hydroalumination of unsaturated compounds under mild conditions with high yields.The role of a transition metal catalyst in these reactions is determined by its ability to activate the starting substrate by coordination to the metal center forming the intermediate hydride complex (2) . The latter, being a more active hydrometallating reagent, attacks alkenes under mild conditions with subsequent transmetallation of the starting hydride affording the target organic compound (3) according to Scheme 18.2 .To date, a large number of reports have appeared in the literature on the application of hydride reagents in both thermal and catalytic hydrometallation of unsaturated compounds. Hydroboration, hydroalumination, hydrozirconation and hydromagnesiation of unsaturated compounds such as alkenes, dienes or alkynes are considered the most effective reactions for producing the related metalloorganic compounds. It is not possible to consider all these reactions within the

show abstract

“…Among these, the most important are H2 proposed by Vandenberg [166] and Bua and Luciani [167,168] and Zn alkyls proposed by Natta, Pasquon and Giachetti [169,170]. There are some doubts that such substances should only be considered as true chain transfers in that they cause also a reduction of the propylene polymerization rate [168][169][170].…”

Section: D) Modified Ziegler-natta Catalystsmentioning

confidence: 99%

“…VA3-AI(C2Hs)2CI) [218], the molecular weight of the resulting copolymer is higher with aged catalysts. The molecular weight may be controlled by transfer agents such as H2 [168] or ZnR 2 [169,170]. The copolymers used for the synthesis of elastomers contain 25 to 55 % by weight propylene and 2 to 5 % by weight termonomer [232].…”

Section: Random Copolymersmentioning

confidence: 99%