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Compared with the traditional catalytic hydrogenation, catalytic transferhydrogenation, as a more environmental friendly reaction, has easier requirements onequipment due to its numerous advantages, such as mild reaction conditions and lowdangerousness. Aiming at the present disadvantages of transfer hydrogenation, thisresearch initially prepares some ruthenium nanoparticles, which are adaptable in bothaqueous phase and organic phase, in the method of microwave radiation heating withPVP being as stabilizer. Then, the research conducts TEM characterization on thoseruthenium nanoparticles and observes the impacts of different preparation conditionson them. Secondly, those ruthenium nanoparticles are used for catalyzing theacetophenone in transfer hydrogenation reaction by one-pot method. This researchmainly investigates the impacts of reaction temperature, PVP dosage, the categoriesand concentrations of base used in the system and reaction time on catalytic system’sefficiency in order to make sure the best reaction parameters. In the end, this researchinvestigates the reuse effect of this system. Through this research, some conclusionsbelow are obtained.Because PVP, the stabilizer, disperses and stabilizes ruthenium nanoparticlesproperly, so the particle size of nanoparticles is very tine and the distribution isuniform. Also, the reducing agent to reduce the precursor, RuCl3, is the mixedsolution of hydrazine hydrate and KOH and its reducing capability is appropriate withthe dosage ratio of reduction capability to KOH being around6:1. Moreover, in theprocess of preparing ruthenium nanoparticles, feeding sequence can affect rutheniumnanoparticles’ certain performances, for instance, the size. It is the most appropriatesequence that adding the mixed solution of PVP and precursor dropwise into reducingagent solution, which is under fast stirring so that the ruthenium nanoparticlesprepared distribute uniformly and stabilize in shape.With the different dosage of PVP and rising temperature, the reaction efficiency of ruthenium nanoparticles catalyzing acetophenone transfer hydrogenation presents atrend, which is increasing rapidly at first and then continuing rising at a low rate.Therefore, the best temperature of this catalyzing transfer hydrogenation reaction isabout95℃.It is not proper for the ruthenium nanoparticles’ normal catalysis that addingeither too much PVP or too little PVP into the system. With the rising dosage of PVP,the yield of this reaction increases initially and then begins to drop after the peak. At95℃, the best dosage ratio ofPVP to RuCl3is65:1.The changing trends of the reaction yield with base concentration are similar,while using KOH, NaOH or LiOH as synergist respectively. More specifically, theyield keeps increaseing with the base concentration’s rising in the reaction system tillthe peak, where the base concentration gets a certain amount and the yield is thehighest. After this point, the yield is rarely affected by the base concentration.Comparing these three different bases, KOH as synergist supplies the best results andthe best concentration is0.5000mol/L.With reaction time extending, the yield also increases. However, after120minutes, the yield stops rising and keeps stable from then on. Therefore, it can beregarded that the highest reaction yield is59.7%whilst the reaction temperature being95℃, the ratio of PVP to RuCl3being65:1, the concentration of KOH being0.5000mol/L and the best reaction time being120minutes.It is not only simple but mild as well to separate products and catalyzing systemin the method of extracting, still standing and layering, which also has higherfeasibility. Under the best reaction condition (the reaction temperature being95℃, theratio of PVP to RuCl3being65:1, the concentration of KOH being0.5000mol/L andthe best reaction time being120minutes), this catalyzing system can be usedefficiently by twice to three times. With the increasing of reusing times, the rutheniumnanoparticles begin to aggregate seriously. Especially after being used twice, thereaction yield decreases rapidly.
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