Solvents
have an enormous impact on yield and turnover of chemical
reactions in complex media. There is, however, a lack of consistent
model-based tools to a priori identify the appropriate
solvent for homogeneously catalyzed reactions. Here, a thermodynamically
consistent approach for a reductive amination reaction is presented.
It combines solvent screening using a thermodynamic-activity model
and quantum chemical calculations. The optimization of activity coefficient-based
predicted kinetics gives a suitable list of candidate solvents. The
results were confirmed by batch experiments in selected solvents.
This approach allows reducing time and lab resources for solvent selection
to a minimum.
The transformation of chemical production processes to a sustainable feedstock from renewable sources requires a careful assessment of current thermodynamic data, reaction mechanisms and kinetics. The Pd-catalyzed alkoxycarbonylation of the long chain olefin methyl 10-undecenoate (10-UME) from castor oil with methanol yields the building blocks for a renewable polyamide. The mechanism for the complex multi-step reaction cycle including active catalyst formation was elucidated. The experimental catalyst selectivity with 1,2-bis(di-tert-butylphos-phino-methyl)benzene (1,2-DTBPMB) as a ligand towards the desired linear diester product can be reproduced and rationalized. The mechanisms of possible side reactions and well as catalyst inhibition by carbon monoxide were also investigated. Solvent effects have an influence on reaction equilibria and transition barriers. These were considered in polar (methanol) and nonpolar (dodecane) media using implicit or mixed cluster/ continuum solvation models when explicit solvent coordination was critical.
Transition-metal substituted Keggin-type polyoxometalates (POMs) are of great interest for applications in biomedicine, material science and catalysis. The synthesis of transition metal-substituted Keggin-type polytungstates via the formation of a lacunary...
For a comprehensive understanding of catalyst stability, knowledge of deactivation processes is an important keystone in addition to activity and selectivity. The underlying mechanisms and kinetics of deactivation help to...
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