1-Hexene rhodium-catalyzed hydroformylation at partial substrate conversion: influence of reaction parameters on the chemoselectivtty and regioselectivity

Autor: Raffaello Lazzaroni, Sergio Bertozzi, Paolo Pertici, Giovanni Fabrizi
Rok vydání: 1990
Předmět:
Zdroj: Journal of Molecular Catalysis. 58:75-85
ISSN: 0304-5102
Popis: The influence of the reaction parameters (temperature, gas pressure) on the chemo- and regioselectivity of 1-hexene hydroformylation in the presence of Rh4(CO)12 as catalytic precursor has been investigated at partial and complete conversion. Both chemo- and regioselectivity are independent of the substrate conversion until 1-hexene is present in the reaction mixture. Chemoselectivity to aldehydes is complete at room temperature, while at higher temperatures it decreases with decreasing pressure and increasing temperature as a consequence of 1-hexene isomerization to (E)- and (Z)-2-hexenes. Similar amounts of heptanal and 2-methylhexanal are obtained at room temperature. At higher temperature and partial substrate conversion, only 1-hexene is converted to aldehydes; the regioselectivity towards the linear isomer increases from 4% at room temperature to 48% at 120 °C and is not affected by the gas pressure. Differing behaviours of the linear and branched alkyl metal intermediates towards the β-hydride elimination under the reaction conditions account for the influence of the reaction parameters on the chemo- and regioselectivity in 1-alkene hydroformylation.
Databáze: OpenAIRE