Carla Kern

A study of a new catalytic system for the metathesis of funcionalized olefins

Efetuou-se o estudo sobre um novo sistema catalítico WCI6.PMHS. Curvas de conversão, números de rotação e freqüências de rotação foram comparados àqueles para os sistemas já conhecidos na literatura. Os resultados mostram que o novo sistema tem atividades análogas nas reações de metátese do 1 0-undecenoato de meti la e 1 0-undecenonitrila que os sistemas conhecidos para esse tipo de reações, com a vantagem de utilizar como catalisador um composto menos tóxico e de menor custo que SnMe4 e Ph2SiH2.

Reactivity of Tungsten-aryloxides with Hydrosilane Cocatalysts in Olefin Metathesis

The reactivity of the [WCl4(OAr)2] (OAr = O-2,6-C3H3Cl2, O-2,6-C6H3F2 and O-C6H3Me2) systems, plus the silicon compounds Ph2SiH2 and polymethylhydrosiloxane (PMHS), were studied in metathesis reactions. The olefins used were methyl-10-undecenoate and 1-hexene. The results showed that the [WCl4(OAr)2]-silicon compound systems are active and selective when the aryloxide ligand contain electronegative groups. The silicon compound PMHS proved to be the best cocatalyst for metathesis, even with the [WCl4(O-2,6-C6H3Me 2)2] compound, which has no electronegative substituents. Because it is non-toxic, non-volatile, easy to handle and cheap, PMHS is a good alternative cocatalyst in metathesis reactions.

A comparative study of hydrosilane compounds as cocatalysts in the metathesis of 1-hexene

Abstract The selectivity of 1-hexene metathesis using WCl6 as catalyst was evaluated with a series of hydrosilane-compounds as cocatalysts: Ph3SiH, Ph2SiH2, PhSiH3 and polymethylhydrosiloxane (PMHS). The metathesis reaction is favored by the addition of promoters. When in the presence of WCl4(OAr)2, OAr=2,6-dichlorophenoxide, 2,6-difluorophenoxide, olefin metathesis occurs with good selectivity without the use of promoters.