The New Revolutionary Development Of Catalysis As The Driving Force For The Commercial Dynamic Success Of Polyolefins

Galli, Paolo; Vecellio, G.

doi:10.1007/978-3-642-59465-6_15

Cited by 6 publications

(2 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, it cannot be denied that the detailed logical study during the evolutionary period provides the setting upon which revolution becomes inevitable. Such is surely the case in the development of polyolefins, − and it seems the same will hold true for polycarbonates. − …”

Section: Introductionmentioning

confidence: 90%

Concerning the Mechanism of the Ring Opening of Propylene Oxide in the Copolymerization of Propylene Oxide and Carbon Dioxide To Give Poly(propylene carbonate)

2004

View full text Add to dashboard Cite

The reactions between (TPP)AlX, where TPP = tetraphenylporphyrin and X = Cl, O(CH(2))(9)CH(3), and O(2)C(CH(2))(6)CH(3), and propylene oxide, PO, have been studied in CDCl(3) and have been shown to give (TPP)AlOCHMeCH(2)X and (TPP)AlOCH(2)CHMeX compounds. The relative rates of ring opening of PO follow the order Cl > OR > O(2)CR, but in the presence of added 4-(dimethylamino)pyridine, DMAP (1 equiv), the order is changed to O(2)CR > OR. From studies of kinetics, the ring opening of PO is shown to be first order in [Al]. Carbon dioxide inserts reversibly into the Al-OR bond to give the compound (TPP)AlO(2)COR, and this reaction is promoted by the addition of DMAP. The coordination of DMAP to (TPP)AlX is favored in the order O(2)C(CH(2))(6)CH(3) > O(2)CO(CH(2))(9)CH(3) >> O(CH(2))(9)CH(3). The microstructure of the poly(propylene carbonate), PPC, formed in the reactions between (TPP)AlCl/DMAP and (R,R-salen)CrCl and rac-PO/S-PO/R-PO and CO(2), has been investigated by (13)C [(1)H] NMR spectroscopy. The ring opening of PO is shown to proceed via competitive attack on the methine and methylene carbon atoms, and furthermore attack at the methine carbon occurs with both retention and inversion of stereochemistry. On the basis of these results, the reaction pathway leading to ring opening of PO can be traced to an interchange associative mechanism, wherein coordination of PO to the electrophilic aluminum atom occurs within the vicinity of the Al-X bond (X = Cl, OR, O(2)CR, or O(2)COR). The role of DMAP is two-fold: (i) to labilize the trans Al-X bond toward heterolytic behavior, and (ii) to promote the insertion of CO(2) into the Al-OR bond.

show abstract

Section: Introductionmentioning

confidence: 90%

Concerning the Mechanism of the Ring Opening of Propylene Oxide in the Copolymerization of Propylene Oxide and Carbon Dioxide To Give Poly(propylene carbonate)

2004

View full text Add to dashboard Cite

show abstract

“…One of the truly great successes in organometallic chemistry during the second half of the twentieth century was the elucidation of the mechanism of olefin polymerization by well-defined metal complexes. , From the time of the discoveries of Ziegler and Natta to the understanding of stereocontrol at single-site metallocene catalysts took some 50 years, but then, with this knowledge, the production of poly-α-olefins with a designed microstructure was possible. – In contrast, the control of microstructure in polyoxygenates is much less well-understood and has as of yet been relatively little studied. For example, in the polymerization of propylene oxide (PO) ( rac ) by base catalysis to give regioregular head-to-tail (HT) triads, stereocontrol is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Complexities in the Ring-Opening Polymerization of Lactide by Chiral Salen Aluminum Initiators

et al. 2008

View full text Add to dashboard Cite

The preparation of (R, R)- and (S, S)-salen Al(OR) complexes, where R = Et, CH2(i)Pr, CH2(t)Bu, and CH2CH(S)MeCl, are reported, along with their reactions with rac-lactide (salen = N, N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamino). Rapid, reversible coordination of LA to the salen metal complex is observed, and it is shown that the relative rates of alcohol/alkoxide exchange are comparable to the NMR time scale while the rate of chain transfer involving (R, R)-salenAl(O-R-R) and (S, S)-salenAl(O-S-R) is much faster than the initial rate of ring opening of the LA monomer. For a primary [Al-OR] moiety, the ring opening of rac-LA is much faster than the ring-opening polymerization/enchainment of LA, and in the initial ring-opening event, the diastereoselectivity is dependent on the solvent, the chirality of the salen ligand, and the OR group. Irrespective of the initiator group OR or the solvent, the system moves to a pseudostatic equilibrium concentration of L- and D-LA which is dependent on the nature of the chirality of the salen ligand. Further studies show that the relative rate of trans-esterification is slower than the rate of LA enchainment and that the rate of epimerization is the slowest reaction in the system. Adventitious water leads to loss of catalytic activity and formation of the inert oxo-bridged compound [(salen)Al]2(mu-O) which has been structurally characterized.

show abstract

The discovery of isotactic polypropylene and its impact on pure and applied science

Corradini

2003

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

This article recalls some aspects of the fascinating history of the discovery by Giulio Natta and his research group of the stereoselective polymerization of propylene and the understanding of the relationships between structure and properties of semicrystalline polymers. The impact of the discovery of isotactic polypropylene and stereoregular polymers on pure and applied science is briefly outlined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 391–395, 2004

show abstract

The New Revolutionary Development Of Catalysis As The Driving Force For The Commercial Dynamic Success Of Polyolefins

Cited by 6 publications

References 5 publications

Concerning the Mechanism of the Ring Opening of Propylene Oxide in the Copolymerization of Propylene Oxide and Carbon Dioxide To Give Poly(propylene carbonate)

Concerning the Mechanism of the Ring Opening of Propylene Oxide in the Copolymerization of Propylene Oxide and Carbon Dioxide To Give Poly(propylene carbonate)

Complexities in the Ring-Opening Polymerization of Lactide by Chiral Salen Aluminum Initiators

The discovery of isotactic polypropylene and its impact on pure and applied science

Contact Info

Product

Resources

About