AbstractAs one of important raw materials for fine chemical industry, propionaldehyde is used to produce some intermediates, such as propionate, propanol and trimethylolethane. These intermediates are further used to produce alkyd resin, ethiazide, and the fine chemicals as the additives for foods, paints, fodders, textiles, rubber and so on. Ethylene hydroformylation is the main industrial production route for propionaldehyde.In this research, homogeneous ethylene hydroformylation in toluene solvent had been carried on, and tubular reactor was firstly used for this reaction. Compared with tank reactor, the tubular reactor has simpler structure, easier sealing technology and better continuous running ability.The influences of concentration of catalyst and ligand, reaction temperature, reaction time and reaction pressure on this reaction were studied using a batch tank reactor. The optimum reaction conditions were that the molar ratio of H2, C2H4 and CO is 1:1:1; the amounts of catalyst, triphenylphosphineand and toluene were 0.0135 g, 0.0387 g and 10 mL respectively; the reaction temperature was 100 ℃; the reaction pressure was 2 MPa. Under the optimum reaction for 2 h, both ethylene conversion and propionaldehyde selectivity were over 99 %, and the TOF was as high as 11000 h-1.Fixing the amount of catalyst, ligand and toluene, the kinetics of the reaction was further studied. The reaction orders of CO, C2H4 and H2 were -0.93, 0.96 and 0.63 ,respectively. The activation energy of the reaction was 55 kJ/mol.Based on the results of the reaction rule, the tubular reactor was designed and built. The stable continuous operation was realized on the tubular reactor. Under the optimum reaction conditions, the average conversion of ethylene and selectivity to propionaldehyde was 77 % and 99 % respectively, and the collection amounts of the liquid products reached 300 g/h.
In this dissertation, we discover for the first time that N-alkoxyphthalimides can produce alkoxy radical through blue LED light irradiation with fac-Ir(ppy)3 catalysis. The alkoxy radical undergoes 1,5-hydrogen transfer so that non-activated C-H bond can be cleaved to generate carbon radical, which is further captured by the allyl sulfone to realize intermolecular C-C bond coupling reaction. This reaction has excellent chemoselectivity, and different types of N-alkoxyphthalimides are compatible to give moderate to good yields of desired products. Mechanistic studies suggested the existence of alkoxy radicals and the intramolecular 1,5-hydrogen transfer, and the possibility of intermolecular hydrogen transfer was ruled out. We further discovered that this reaction can be carried out in neutral aqueous conditions. From a chemical point of view, in contrast to traditional methods using n-Bu3SnH/AIBN for radical initiations, our reaction conditions is milder and intermolecular C-C bond coupling reaction is achieved. From the biological point of view, this visible-light-induced reaction offers potential for a biomolecular- compatible reaction.
Catalytic conversions from methane to value-added chemicals via non-syngas route are of great significance to the utilization of natural gas. The oxidative bromination of methane (OBM) is a newly developing technology, which is extremely appropriate for use in small- and medium-scale natural gas fields due to less steps and avoiding the production of syngas. In the present work, we try to develop the catalysts for the OBM reaction and investigate possible reaction mechanism. In this thesis, oxidative bromination of methane over Rh-based catalysts supported on different carriers was studied. It was found that inert supports such as SiC and SiO2 were in favor of the selectivity for bromomethanes, whereas deep oxidation occurred over ZrO2 and TiO2 oxides. H2-temperature-programmed reduction experiments confirmed that inert carrier-supported Rh catalysts were more difficult to be reduced than the metal oxide-supported catalysts. Thermodynamic analysis revealed that the steam reforming of bromomethanes was promoted at higher reaction temperatures. It was concluded that the superior performance of the inert carrier-supported catalysts could be ascribed to the medium redox ability, which suppressed the steam reforming reaction. Besides, Rh/SiC shew good stability performance, while Rh/SiO2 suffered severe coke deposition. Various supported-non precious metal oxide catalysts were employed for the OBM reaction. BaO/SiO2 showed good reactivity at the initial stage, however, it deactivated quickly due to the leaching of active components. It was found that BaO/SiO2 functioned mainly in two aspects: (1) Converting HBr to Br2 through the metathesis of BaO/BaBr2; (2) Preventing the leaching of Br2 to the gaseous and limiting the free-radical reactions. A new FePO4/SiO2 catalyst was developed and used for the OBM reaction for the first time in this thesis, which showd efficient and stable performance even at relatively lower reaction temperatures. The characterization results confirmed that the stable active components in the FePO4/SiO2 catalyst were comprised of near-equimolar Fe2P2O7 and α-Fe3(P2O7)2, and the two components were in a dynamic transformation during the reaction. Based on these observations, a redox route was proposed for the OBM reaction catalyzed by FePO4/SiO2. The deactivation of the FePO4/SiO2 catalysts was also studied. Coke deposition, resulting directly from the accumulation of CH2Br2 during the reaction, was found to be the main reason for the deactivation.
As an important organic intermediate, 3-methy-3-buten-1-ol (MBOH) is widely used in synthesis of perfume, medicine, pesticide and polymer materials and so on. At present, the Ene reaction and Prins reaction in acidic conditions are two main routes to synthesize MBOH. Both of them use formaldehyde and isobutylene as raw materials. But the Ene reaction needs high temperature and high pressure. In order to overcome these problems, immobilized ZnCl2 catalysts were prepared and the synthesis of 3-methy-3-buten-1-ol (MBOH) from isobutylene and formaldehyde over the as-prepared catalysts via Prins reaction were studied in this paper. First, the thermodynamic of the reaction was calculated using Benson Group Contribution methods and the change of Gibbs free energy (△rG) and equilibrium constants (K) for the Prins reaction were obtained. The result indicated the reaction was exothermic reaction. Thus, relative low reaction temperature was more favorable. Then, the effect of the reaction parameters, such as temperature, molar ratio of isobutene to formaldehyde, reaction time and catalyst content on the reaction were investigated. The results showed that the formaldehyde conversion was more than 99% under different conditions. Reaction temperature and the acidity as well as the amount of the acid sites over the catalyst played an important role on the selectivity of MBOH. Under the optimum reaction conditions, the selectivity and the yield of MBOH could reach 93.8% and 93.4%, respectively. After reuse of the catalyst 5 times, yield of MBOH still reached 85.2%．
The potential energy surface (PES) is the most basic and important factor from the perspective of dynamics calculations. In the present thesis, the PESs of the Ne + H2+ ground state and S + H2 triplet states are constructed. Based on the new PESs, we carry out the corresponding adiabatic and nonadiabatic dynamics calculations. In S(1D,3P) + H2 reaction system, the spin-orbital-induced intersystem crossing effects are investigated, which permit the reaction to occur without surmounting the triplet barrier when the initial wave packet is on the triplet state. The clear resonance structures of the integral cross sections are found in the low collision energy region. When the initial wave packet is on the singlet state, intersystem crossing leads to a electronic–state quenching to S(3P) + H2 state. So the adiabatic cross section based on the single PES is larger than the nonadiabatic reaction cross sections.We carry out the high–lever ab initio single-point energy calculations for the Ne + H2+ ground state, and build the new three–dimension PES using the many-body expansion. The analysis of the reaction path indicates that the interaction region of the PES has been greatly improved. Quantum dynamics calculations show that the reaction probability presents rich resonance structures for a fixed total angular momentum J. The vibrational excitation enhances the reactivity more greatly than the collision energy. Exact quantum calculation shows that the Coriolis effects are very important for the integral cross section of the Ne + H2+ reaction system.We present an exact quantum dynamical study and quasi-classical trajectory(QCT) calculations for the exchange and abstraction processes for the H + HS reaction. A good agreement is found between QCT and TDWP reaction probabilities at the total momentum J = 0 .The lower reaction barrier for the abstraction reaction makes it easier to occur in the low-collision-energy region, which reveals a preference of the abstraction channel over the exchange channel at low and moderate collision energies. Once the collision energy exceeds the exchange reaction barrier, the exchange process quickly becomes dominant, presumably due to the fact that the exchange reaction has a larger acceptance cone than that of the abstraction reaction.
Potential energy surface(PES) plays an irreplaceable role in molecular reaction dynamics. It has always been a popular topic in the chemical physics field. In this thesis, the accurate PESs for two reaction systems H(2S)+NH and O(3P)+H2 are constructed. The time-dependent wave packet and quasi-classical trajectory methods are employed for the tri-atomic reaction system. The ground state hydrogen abstraction reaction H(2S)+NH→N(4S)+H2 plays an important role in the decay of imidogen(NH) in the pyrolysis of ammonia and gas-phase combustion reactions of nitrogen compounds. The many body expansion and neural network methods have been used to ﬁt the accurate ab initio energy points, which were computed using MRCI/aug-cc-pV5Z level. We have taken the Coriolis coupling (CC) and centrifugal sudden (CS) approximation into the calculations, respectively. The calculated rate constants agree with the available experimental results very well and are better than previous theoretical calculations. The reaction of O(3P)+H2 has been widely studied due to its importance in combustion processes and atmospheric reaction. Various studies were reported including the adiabatic and non-adiabatic potential energy surfaces construction and dynamical investigation. We used the AP function to fit the ab initio energy points. And the lowest state 13A″ was constructed by extrapolation to the complete basis set limit. The quantum wave packet calculations were carried out on the new potential energy surfaces. The influence of the basis set extrapolation method on the potential energy surface is studied.The extensive investigations on the neutral and ionic of LiH are due to its potential importance in the primordial universe chemistry. We applied the time-dependent wave packet and the quasi-classical trajectory methods for this reaction system. The reaction probabilities are significantly different from the previous ones on the DMJ PES. One interesting fact is that our results for the title reaction are similar to the calculation of H+LiH+. In order to better understand the reaction mechanism, the variation of internuclear distances are presented as a function of propagation time. The effect of Coriolis coupling in the reaction H+LiH is performed.
The Study of Organocatalytic Asymmetric Michael Reaction The Michael reaction is an important reaction to produce C-C bond. The Michael reaction of β, β-disubstituted nitroalkene is a useful way to construct synthetically useful quaternary chiral center. But because of its large hindrance and low activity, there are few reports on it. In this work, we used more active malononitrile to react with α-substituted-β-nitro acrylate and we found that this reaction could proceed well with the catalyst derived from Cinchonidine. Then, we studied organocatalytic asymmetric Michael reaction of malononitrile to β, β-disubstituted nitroalkenes in detail. Through straightforward one-step reaction, we obtained a synthetically valuable intermediate with high yield and enantioselectivity. More importantly, the product bears an all-carbon quaternary chiral center. This intermediate could be used to synthesize derivativies of dihydropyrrole and some other compounds which have bioactivity. At the same time, the derivative of the product can be β-amino acid ester. After that, A highly enantioselective aza-Michael reaction of benzotriazole to β, β-disubstituted nitroalkenes has been developed with moderate to high yields. The products bear quaternary chiral centers. Through simple reduction of the nitro section in adducts, we could got the derivatives of α, β-two amino acid. The derivatives can have significant applications in bio- pharmaceutical industry. Key words: asymmetric Michael reaction, malononitrile, aza-Michael reaction, benzotriazole, quaternary chiral centers
Currently，shortage of recourses and environmental pollution is an important issue. CO2 is a greenhouse gas. It is also a cheap and abundant C1 resource. Conversion of CO2 into useful chemicals is of great importance from both theoretical and practical viewpoints. In this thesis, the transformation and utilization of CO2 is reviewed and the hydrogenation of CO2 to produce N,N-dimethylformamide (DMF) and methyl formate(MF) is studied. The contents and main results are summarized as follows: 1. A series of Cu-based catalysts were prepared and characterized by different techniques. The catalytic performance of the catalysts for the synthesis of DMF from CO2, H2, and dimethylamine were investigated. It was demonstrated that Cu/ZnO and Cu/ZnO/Al2O3 had very high activity and selectivity for the reaction. Cu and ZnO had excellent synergistic effect to catalyze the reaction and the possible mechanism of synergistic effect is proposed. The effects of reaction temperature, time, pressure, amount of catalyst used and the composition of the catalysts on the reaction were investigated systematically. The yield of DMF could be as high as 97% at the optimized condition.2. The commercial Ru/C catalyst was used for the synthesis of DMF from CO2, H2, and dimethylamine for the first time. The effects of reaction temperature, time, pressure, amount of catalyst used on the reaction were investigated. It was found that maximum yield of DMF occurred at 150 oC. The pressure of H2 affected the yield of DMF significantly, but the effect of CO2 pressure on the yield was much smaller. The yield of DMF could reach 91% at the optimized condition. In the reaction, CO2 and H2 reacted to form formic acid, which was then reacted with dimethylamine to form DMF. The route has some obvious advantages, such as very small amount of catalyst was used in the reaction.3. In order to solve the problem that the reaction of CO2, H2, and methanol is limited thermodynamically, the reaction was coupled with the hydrolysis of propylene oxide (PO) to produce propylene glycol (PG), and RuCl3 and Ru/C were used as the catalysts for the coupled reaction. The effects of reaction temperature, time, pressure, amounts of catalyst and co-catalyst used on the reaction were investigated. It was shown that both of the catalysts were very active for the reaction. The hydrolysis shifted the chemical equilibrium of the reaction to synthesize MF. At optimized condition, high yields of MF and PG were obtained. This provides a new route to produce value-added chemicals using CO2 as a reactant. Key Words：carbon dioxide, hydrogenation, N,N-dimethylformamide, methyl formate