1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) with ionic modification supported on magnetic nanoparticles was prepared and characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TG), vibrating sample magnetometer (VSM) and elemental analysis. The supported ionic specie was certified as a highly active and magnetically recoverable catalyst for the synthesis of various substituted ureas and structurally diverse N-heterocyclic compounds. The catalyst can be readily recovered by external magnetie and be reused for 6 times without significant loss in catalytic activity. Ionic tagged catalyst performs much better than its ionic-free counterpart in organic transformations.Keywords: Immobilization; Ionic moiety; Magnetic nanoparticles; Recyclability; TBD;

Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane (DABCO) have been synthesized to catalyze the aza-Michael addition of secondary amines to α,β-unsaturated compounds. Among the catalysts tested, [DABCO-PDO][OAc] was found to be most suitable for the reaction of a wide range of cyclic substrates without any solvent at room temperature, and afford the products in good to excellent yields within an appropriate amount of time. The proposed mechanism for the dual activation of the catalyst was supported by experimental results as well as the DFT calculation. In addition, the ionic liquids used can be regenerated and recycled several times without any loss of activity.Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane (DABCO) have been synthesized to catalyze the aza-Michael addition of secondary amines to α,β-unsaturated compounds.

Ionic tagged 1,4-Diazabicyclo[2.2.2]octane (DABCO) grafted on magnetic nanoparticles (MNPs) was prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) and thermal gravimetric analysis (TGA). The resulting magnetic solid supported DABCO catalyst with an ionic moiety was efficient for aza-Michael addition of aliphatic amines to various α,β-unsaturated amides in water at room temperature, affording the desired products in good to excellent yields. Gratifyingly, the catalyst could be readily recovered by an external magnet and reused ten times without any significant loss of activity.

Four novel basic ionic liquids (ILs), based on 1,4-diazobicyclo[2.2.2]octane (DABCO) and 3-chloro-1,2-propanediol, have been introduced as catalysts for Knoevenagel condensation. These catalysts are applicable to a wide range of aromatic/heteroaromatic aldehydes with α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water at room temperature, and they afford the products in excellent yields within short times. These reactions are operationally simple, and the desired products can be separated directly from the reaction mixture without further purification. A possible reaction mechanism was proposed, and the relevant evidence was given. In addition, the ionic liquids used can be regenerated and recycled several times without significant loss of activity. Furthermore, the novel ILs could be efficiently used in a step of atorvastatin synthesis.

Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synthesized and fully characterized. The novel catalyst (MNPs@PA-IL) was applied in phospha-Michael addition and gave the desired β-phosphonomalonates in good yields. The MNPs supported catalyst with ionic tag could be readily recovered from the reaction mixture using an external magnet. Compared with ionic-free counterpart (MNPs@PA), MNPs@PA-IL present better catalytic activity. The proposed mechanism regarding the MNPs@PA-IL catalyzed phospha-Michael reaction was also discussed.

An array of novel 1,4-diazobicyclo[2.2.2]octane (DABCO) based ionic liquids were developed and used as recyclable catalysts for the aza-Michael addition at room temperature without any organic solvent. [DABCO–PDO][OAc] was found to be the most efficient catalyst, and the amount of catalyst was only 10 mol %. Various amines reacted with a wide range of α,β-unsaturated amides, smoothly affording target products in good to excellent yields within hours. Moreover, the catalyst could be reused up to eight times, still maintaining a high catalytic activity. Finally, a plausible mechanism was proposed. FTIR and computational chemistry were used to verify the catalytic mechanism.

The objective of this study is to investigate numerically the flow characteristics of falling film on horizontal circular tubes. Numerical simulations are performed using FLUENT for 2D configurations with one and two cylinders. The volume of fluid method is used to track the motion of liquid falling film and the gas-liquid interface. The effect of flow characteristics on heat and transfer coefficient may be remarkable, although it has been neglected in previous studies. The velocity distribution and the film thickness characteristics on the top tube, some special flow characteristics on the bottom tube, intertube flow modes and effect of liquid feeder height on flow characteristics have been studied. Our simulations indicate that 1) the velocity distributions of the upper and lower parts of the tube are not strictly symmetric and nonuniform, 2) the film thickness depends on flow rate and angular distributions, 3) the flow characteristics of the top tube are different from those of the bottom tube, 4) three principal and two intermediate transition modes are distinguished, and 5) the liquid feed height plays an important role on the formation of falling film. The numerical results are in a good agreement with the theoretical values by the Nusselt model and the reported results.

Surface wave dynamics of falling film on the surface of periodic rectangular wall under monochromatic-frequency flowrate forcing disturbances is studied via numerical simulation. Waveforms formed on the periodic rectangular wall are different from those on the flat plate. At low frequency, the perturbation introduced at the inlet first undergoes a steady flow region and then develops into solitary waves. When the frequency becomes higher, solitary waves disappear. Film deformations in the steady flow region and characteristics of solitary waves are studied as the film travels down. There are circulations at the depression of periodic wall which are dependent on the local film characteristics and geometry of the corrugation. Moreover, the flow rate and geometry of the corrugations can also affect the evolvement of the monochromatic perturbation.

•High purity ethylene glycol diacetate was gotten in a single reactive distillation.•As an auxiliary reaction, the hydration of ethylene oxide (EO) was proposed.•Energy consumption was saved more than 48% achieved by the dynamic state simulation.In this paper, an innovative ethylene glycol diacetate (EGDA) synthesis process in a single reactive distillation column has been investigated. The consecutive, reversible second-order esterification of ethylene glycol (EG) with acetic acid (HAC) to ethylene glycol monoacetate (EGMA) and ethylene glycol diacetate (EGDA) were intensified by the hydration of. As an auxiliary reaction, the hydration of EO greatly promoted the esterification reaction equilibrium to the right, not only consuming water, but also generate the ethylene glycol in situ. Fixing the feed rate of EG, EO, and HAC at 21.6, 68.4 and 180 kmol/h, respectively, impacts of four important parameters, i.e., number of theoretical stage, feed position, reflux ratio, rate of distillation and operating pressure on the purity of EGDA, energy consumption, conversion, selectivity and yield were investigated to achieve an optimal process design in the steady state simulation by Aspen Plus. On the basis of steady state, the dynamic state simulation by Aspen Plus Dynamics has achieved an innovative process to produce EGDA without EG feed.Download high-res image (225KB)Download full-size image

Ionic tagged 1,4-Diazabicyclo[2.2.2]octane (DABCO) grafted on magnetic nanoparticles (MNPs) was prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) and thermal gravimetric analysis (TGA). The resulting magnetic solid supported DABCO catalyst with an ionic moiety was efficient for aza-Michael addition of aliphatic amines to various α,β-unsaturated amides in water at room temperature, affording the desired products in good to excellent yields. Gratifyingly, the catalyst could be readily recovered by an external magnet and reused ten times without any significant loss of activity.