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2. SYNTHESIS OF CONDENSATION POLYMERS DERIVED FROM SILYLATED MONOMERS UNDER PHASE TRANSFER CATALYSIS

Author

Tagle, L. H., Claudio Terraza, Ahlers, W., and Vera, C.

Abstract

The synthesis of the poly(carbonate) and poly(thiocarbonate) derived from the diphenol bis(4-hydroxyphenyl)-phenylmethylsilane and the poly(ester) derived from the same diphenol and the acid dichloride bis(4-chloroformylphenyl)-phenylmethylsilane are described. Polymers were synthesized under phase transfer conditions and the results were evaluated by the yields and inherent viscosity values. The phase transfer process was effective, but the results were affected by the increase of the NaOH concentration in the aqueous phase, in the sense that it was possible to see hydrolytic processes that decrease the yields and the inherent viscosity values. Also there was an influence of the nature of the catalysts, with BTEAC being efficient due to it hydrophilic nature

Published
2005

3. Hydroformylation catalyst comprising a complex with ligands having a structure derived from bisphenol A

Author

Ahlers, W., Paciello, R., Vogt, D., Vlugt, van der, J.I., Ahlers, W., Paciello, R., Vogt, D., and Vlugt, van der, J.I.

Abstract

Ethylenically unsaturated compounds are hydroformylated in the presence of a hydroformylation catalyst comprising at least one complex of a metal of transition group VIII with at least one phosphorus-containing compound as ligand, where this compound contains two groups which contain P atoms and are bound to a molecular skeleton derived from bisphenol A.

Published
2002

4. Method for hydroformylation, xanthene-bridged ligands and catalyst comprising a complex of said ligands

Author

Ahlers, W., Wiebelhaus, D., Paciello, R., Bartsch, M., Baumann, R., Vogt, D., Hewat, A.C., Ahlers, W., Wiebelhaus, D., Paciello, R., Bartsch, M., Baumann, R., Vogt, D., and Hewat, A.C.

Abstract

The invention relates to a method for the hydroformylation of ethylenically unsaturated compounds, whereby at least one complex of a metal of subgroup VIII is used as the hydroformylation catalyst, having at least one compound containing phosphorus, arsenic, or antimony as a ligand. Each compound comprises two groups having a P, As, or Sb atom and at least two other heteroatoms, said groups being bound to a xanthene-type molecular structure. The invention also relates to novel compounds of this type and catalysts comprising at least one complex of a metal of subgroup VIII having at least one such compound as a ligand.

Published
2002

5. Ligands for pnicogen chelate complexes with a metal of subroup VIII and use of the complexes of catalysts for hydroformylation, carbonylation, hydrocyanation or hydrogenation

Author

Ahlers, W., Paciello, R., Vogt, D., Hofmann, P., Ahlers, W., Paciello, R., Vogt, D., and Hofmann, P.

Abstract

The invention relates to pnicogen chelate compounds that have two groups, which contain pnicogen atoms, and are bound to one another via an xanthene-like or triptycene-like molecular skeleton. At least one pyrrole group is covalently bound via its nitrogen atom to each pnicogen atom. The invention also relates to catalysts consisting of a complex of a metal from subgroup VIII with at least one pnicogen compound serving as a ligand, and to a method for hydroformylating olefins

Published
2002

9. Formation, Structure, and Dynamic Behavior of a Novel Dinuclear Cationic μ-2,4-Hexadiyne Bis(zirconocene) Complex

Author

Ahlers, W., Temme, B., Erker, G., Frohlich, R., and Zippel, F.

Abstract

Bis(propynyl)zirconocene (1b) reacts with 0.5 molar equiv of trityl tetraphenylborate by a propynyl group transfer to form Ph3CC&tbd1;CCH3 and Cp2ZrC&tbd1;CCH3+. The in-situ-generated (propynyl)zirconocene cation is not stable under the reaction conditions but instantaneously reacts with the neutral starting material 1b to form the [(μ-C&tbd1;CCH3)(μ-CH3C&tbd1;CC&tbd1;CCH3)(ZrCp2)2+][BPh4-] salt, 9. Complex 9 was characterized by an X-ray crystal structure analysis. It contains an unsymmetrically bridging hexadiyne ligand and exhibits a planar-tetracoordinate carbon center that is stabilized by a three-center two-electron interaction with the two adjacent zirconocene moieties. In solution, complex 9 exhibits dynamic NMR spectra that indicate a symmetrizing exchange of the bonding situations between the two ends of the μ-hexadiyne ligand. The Gibbs activation energy of the automerization reaction of 9 is ΔG&thermod;(190 K) ≈ 9.5 kcal mol-1.

Published
1997

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