Renewable Monomer Feedstocks via Olefin Metathesis:  Fundamental Mechanistic Studies of Methyl Oleate Ethenolysis with the First-Generation Grubbs Catalyst

Abstract

The conversion of seed oil based feedstocks such as methyl oleate into useful commercial raw materials via olefin metathesis has been a research focus for decades, due to their low cost and renewable supply, but technical success has been limited due to poor catalyst activities and turnovers. We report here recent studies on the cross-metathesis of methyl oleate with ethylene (ethenolysis) catalyzed by bis(tricyclohexylphosphine)benzylideneruthenium dichloride (1). At 25 °C/60 psig of ethylene, catalysis by 1 results in the highly selective formation of 1-decene and methyl 9-decenoate. However, reactivity losses limit the catalyst turnovers well below commercial viability in batch reactor operation. In an attempt to address the limitations of this chemistry, a combination of an experimental evaluation of the impact of process parameters, a detailed analysis of the fundamental reaction steps, kinetic modeling, and molecular modeling has been applied to develop a more detailed understanding of this complex catalytic pathway. These fundamental studies have led to a more complete understanding of the factors impacting catalyst performance and the identification of approaches necessary to achieve an economically viable process.

Alkene Metathesis Catalysis: A Key for Transformations of Unsaturated Plant Oils and Renewable Derivatives

“…Initial catalysts used for this ethenolysis were WCl 6 /SnMe 4 [21], and the heterogeneous Re 2 O 7 /Al 2 O 3 /SnMe 4 [22,23] catalysts, as well as the first well-defined ruthenium catalysts such as I, II, IV ( Fig. 1) [24][25][26][27]. These studies revealed that double bond isomerization easily takes place, is favoured by high temperature, and produces many products.…”

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

“…However, any CM is in equilibrium with the back reaction, ethenolysis, which is the cleavage of an internal olefin to generate two terminal olefins. Furthermore, ethenolysis of internal olefins has received attention as a method to access materials and fuels from renewable sources such as seed oil derivatives [50][51][52][53][54][55]. It was postulated that 6 could be employed in a Z-selective ethenolysis as a method to purify E-olefins.…”

Transformação de triglicerídeos em combustíveis, materiais poliméricos e insumos químicos: algumas aplicações da catálise na oleoquímica

“…Por intermédio da reação de metátese de substratos oleaginosos, é possível a obtenção de olefinas estruturalmente simples com diferentes comprimentos de cadeia e graus de insaturação, além de compostos como mono e diésteres 76,77 , demonstrando um alto potencial para a síntese de compostos com interesse em áreas como a farmacológica 78 . Por ex., a metátese do oleato de etila resulta na formação do 9-octadeceno-1,18-diato de dietila, conforme ilustrado na Figura 7, que é empregado como matéria-prima na obtenção de perfumes 79,80 .…”