Q2. What is the ultimate goal of the research?
The ultimate goal is to design a catalytic system with a high activity and selectivity, an efficient catalyst recycling and which possesses a high stability.
Q3. What is the main advantage of homogeneous catalysts?
catalytic properties such as chemo-, regio-, and stereoselectivity can be tuned easily because of the well-defined nature of the homogeneous catalysts.
Q4. What is the common method of separation of the catalyst from the product?
The commonly used method, separation by distillation, requires elevated temperatures that are not compatible with most homogeneous catalysts, which in general are thermally sensitive in nature.
Q5. What is the retention rate of the tris(pincer) complexes?
The two-dimensional phenylene-extended tris(pincer) 4a had a retention rate of 98.7%, while for the tris(pincer) complex 3 retention dropped below the 94%.
Q6. What is the effect of the palladium centres on the catalytic activity of dode?
dodecakis(NCN-Pd) 6b showed an almost threefold increase in catalytic activity per PdII centre which is proposed to be due to cooperative effects between different catalytic sites, since the palladium centres aremuch closer together than in the other shape-persistent compounds [17,20].
Q7. What membrane was used for the nanofiltration experiments?
The nanofiltration experiments were performed in a continuously operating high-pressure-membranereactor equipped with the MPF-60 or MPF-50 nanofiltration membrane.
Q8. How stable was the complex 6b under the continuous reaction conditions?
Complex 6b was found to be stable under the continuous reaction conditions as a constant activity was obtained at prolonged reaction times (26 h, 65 exchanged reactor volumes).
Q9. What is the effect of the shape-persistent complexes on the catalytic?
Comparison between shape-persistent complexes and flexible carbosilane dendrimers of similar nanosize dimensions (according to molecular modelling), resulted in higher retentions for the shape-persistent complexes.
Q10. What is the retention rate of the multi(NCN-Pt) complexes?
Themononuclear NCN-pincer complex showed a retention rate of 82.4% only; the catalyst is completely washed out of the reactor within 30 cycles, which is far from being sufficient for continuous catalysis.
Q11. What is the effect of the shape-persistence on the catalytic activity of the multi?
by relating the molecular volumes of the various complexes to the retention rates, it became clear that shape-persistence is advantageous for obtaining optimal retentions by nanofiltration membranes.
Q12. What is the significance of the Lewis acid catalytic activity?
This implies an efficient use of all catalytic sites during catalysis and once again underlines that the Lewis acid catalytic activity is almost independent of the para functionality of the pincer moiety.
Q13. What is the effect of the MVK catalyst on the catalytic activity of the NC?
Dodecakis(NCN-Pd) complex 6b was applied as a homogeneous catalyst in the double Michael reaction between MVK and ethyl a-cyanoacetate under continuous reaction conditions in a nanofiltration membrane reactor [20].
Q14. What is the role of the para substituent in the pincer moiety?
the pincer moiety possesses all desired properties to be incorporated into a recyclable macromolecular homogeneous catalyst and which also is stable under continuous operating conditions thereby retaining thecatalytic activity of the non-supported pincer-metal complex.
Q15. What is the way to approach the challenge of recycling homogeneous catalysts?
One way of approaching this challenge is by anchoring the homogeneous catalyst on a large, soluble organic support that can be separated from the product mixture by nano- or ultrafiltration.
Q16. What are the main conditions for the use of membrane technology?
with a number of important conditions fulfilled, i.e. high rates of retention, high catalyst stability and solvent resistant membranes, membrane technology is very promising for extended application of homogeneous catalysts in industrial processes.
Q17. What is the effect of the para substituent on the Lewis-acidic palladium centres?
a series of mononuclear parasubstituted [PdIIX(NCN)] complexes was synthesized to study the electronic influence of the para substituent, the anchoring point for immobilization, on the Lewis-acidic palladium centres by means of catalysis and DFT calculations [17].