Jiayin Hu

Transformation of Atmospheric CO2 Catalyzed by Protic Ionic Liquids: Efficient Synthesis of 2‐Oxazolidinones

Protic ionic liquids (PILs), such as 1,8-diazabicyclo[5.4.0]-7-undecenium 2-methylimidazolide [DBUH][MIm], can catalyze the reaction of atmospheric CO2 with a broad range of propargylic amines to form the corresponding 2-oxazolidinones. The products are formed in high yields under mild, metal-free conditions. The cheaper and greener PILs can be easily recycled and reused at least five times without a decrease in the catalytic activity and selectivity. A reaction mechanism was proposed on the basis of a detailed DFT study which indicates that both the cation and anion of the PIL play key synergistic roles in accelerating the reaction.

Efficient synthesis of quinazoline-2,4(1H,3H)-diones from CO2 using ionic liquids as a dual solvent–catalyst at atmospheric pressure

The highly efficient transformation of CO2 into value-added chemicals is an interesting topic in green chemistry. In this work, we studied the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and 2-aminobenzonitriles in a series of ionic liquids (ILs). It was found that 1-butyl-3-methylimidazolium acetate ([Bmim]Ac), a simple and easily prepared IL, could act as both solvent and catalyst, the reactions could be carried out very efficiently at atmospheric pressure of CO2, and a high yield of the products was obtained. Further study indicated that the IL was also very efficient for converting other 2-aminobenzonitriles into their corresponding quinazoline-2,4(1H,3H)-diones in high yields at atmospheric pressure. Moreover, the separation of the products from the IL was very easy, and the IL could be reused at least five times without considerable loss in catalytic activity.

Cobalt catalysts: very efficient for hydrogenation of biomass-derived ethyl levulinate to gamma-valerolactone under mild conditions

Hydrogenation of ester levulinate to gamma-valerolactone (GVL) is an interesting reaction in biomass conversion to produce value-added chemicals. Exploration of efficient and robust catalysts is crucial for large-scale application. In this work, we conducted the reaction catalyzed by a Co catalyst, and it was found that commercially available Co3O4 was very efficient for this reaction under mild conditions after reduction by H2. The effects of temperature, hydrogen pressure, amount of the catalyst used, and reaction time on the yield of GVL were studied. Under optimized conditions, the yield of GVL could reach 98%. The catalyst could be reused at least 10 times without notable loss of the activity and selectivity. The catalyst was characterized by scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). It was demonstrated that the metallic Co0 was the active species for the hydrogenation reaction. As far as we know, this is the first work conducting the reaction using Co as the catalyst.

Efficient synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and 2-aminobenzonitriles in water without any catalyst

We discovered that the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and 2-aminobenzonitriles could proceed efficiently in water without any catalyst and excellent yields were obtained, while the reaction did not occur in organic solvents. This green and simple route to synthesize quinazoline-2,4(1H,3H)-diones has great potential for application.

Zinc(II)-catalyzed reactions of carbon dioxide and propargylic alcohols to carbonates at room temperature

Carbon dioxide (CO2) is an abundant and renewable feedstock for the production of value-added chemicals. Herein, we carried out the first work to use ZnI2/NEt3 as the catalyst for the reactions of CO2 and propargylic alcohols to form α-alkylidene cyclic carbonates. It was discovered that the catalyst system could efficiently promote the reaction at room temperature under solvent-free conditions, and the yields of the target products could reach 99%. The zinc(II) and NEt3 play excellent synergistic roles in activating both CO2 and propargylic alcohols.

Efficient Reduction of CO2 into Formic Acid on a Lead or Tin Electrode using an Ionic Liquid Catholyte Mixture

Highly efficient electrochemical reduction of CO2 into value-added chemicals using cheap and easily prepared electrodes is environmentally and economically compelling. The first work on the electrocatalytic reduction of CO2 in ternary electrolytes containing ionic liquid, organic solvent, and H2 O is described. Addition of a small amount of H2 O to an ionic liquid/acetonitrile electrolyte mixture significantly enhanced the efficiency of the electrochemical reduction of CO2 into formic acid (HCOOH) on a Pb or Sn electrode, and the efficiency was extremely high using an ionic liquid/acetonitrile/H2 O ternary mixture. The partial current density for HCOOH reached 37.6 mA cm(-2) at a Faradaic efficiency of 91.6 %, which is much higher than all values reported to date for this reaction, including those using homogeneous and noble metal electrocatalysts. The reasons for such high efficiency were investigated using controlled experiments.

Synthesizing Ag Nanoparticles of Small Size on a Hierarchical Porosity Support for the Carboxylative Cyclization of Propargyl Alcohols with CO2 under Ambient Conditions

Both immobilization of Ag nanoparticles (AgNPs) of very small size on hierarchical porosity supports and carboxylative cyclization of propargyl alcohols with CO2 under ambient conditions are very interesting. In this work, we synthesized AgNPs supported on sulfonated macroreticular resin (SMR) with hierarchical pores in water/alcohol solutions. It was shown that the size of the AgNPs on the SMR could be tailored easily by altering the synthetic solutions, and very small AgNPs with narrow size distribution (1-3 nm) could be obtained in water/methanol solution. It was found that the AgNPs/SMR with small AgNPs was highly efficient and an easily recyclable catalyst for the synthesis of α-alkylidene cyclic carbonates by carboxylative cyclization of propargyl alcohols with CO2 at ambient pressure and temperature, which was the first work to use metal nanoparticles as the catalysts for the reaction.

A route to convert CO2: synthesis of 3,4,5-trisubstituted oxazolones

Production of value-added chemicals using carbon dioxide (CO2) as a feedstock is favorable to the sustainable development of the chemical industry. In this work, we have discovered for the first time that CO2 can react with propargylic amines to produce 3,4,5-trisubstituted oxazolones, a class of very useful chemicals. It was found that the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) can catalyze the reactions efficiently at atmospheric pressure under metal-free conditions. It was also found that [Bmim][OAc] and IL 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([Bmim][Tf2N]) have an excellent synergistic effect for promoting the reactions. The [Bmim][OAc]/[Bmim][Tf2N] catalytic system can be reused at least five times without loss in catalytic activity and selectivity. The reaction mechanism was proposed on the basis of density functional theory (DFT) calculation and the experimental results.

One-pot conversion of carbohydrates into gamma-valerolactone catalyzed by highly cross-linked ionic liquid polymer and Co/TiO2

The acid catalytic conversion of carbohydrates into levulinate esters followed by metal catalytic hydrogenation is an important approach to obtain gamma-valerolactone (GVL) from biomass. In this work, we prepared the highly cross-linked polymer of divinylbenzene with acid ionic liquid (PDVB-IL) and supported Co on TiO2 (Co/TiO2), which were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental analysis. It was demonstrated that the PDVB-IL polymer could efficiently catalyze the esterification reaction of furfuryl alcohol (FAL), 5-hydroxymethylfurfural (HMF), and fructose with ethanol to produce the intermediate ethyl levulinate (EL), and the EL in the reaction mixture was directly hydrogenated to GVL over the Co/TiO2 without requiring purification and with high yields.

Theoretical study on the reaction of CO2 and 2-aminobenzonitrile to form quinazoline-2,4(1H,3H)-dione in water without any catalyst

Development of efficient and green routes to convert CO2 into value-added products is of great importance. Recently, we found that quinazoline-2,4(1H,3H)-diones and their derivatives could be synthesized from CO2 and 2-aminobenzonitriles in water efficiently without a catalyst and excellent yields were obtained, while the reactions did not occur in organic solvents. In this work, using density functional theory (DFT) we conduct the first theoretical work to study the mechanism of the reactions in water. It is revealed that CO2 reacts via carbonic acid (H2CO3) with 2-aminobenzonitrile to form the product. Formation of H2CO3 from CO2 and water is the key for the reactions to proceed smoothly in water without a catalyst because of two reasons. First, H2CO3 reacts with 2-aminobenzonitriles more easily than CO2 itself; second, H2CO3 can effectively promote the reaction by the synergistic action of its carbonyl O atom and one of the hydroxyl O atoms.