1. Mei-Yan Wang, Xin Jin, Xiaofei Wang, Shumei Xia, Yue Wang, Shouying Huang, Ying Li, Liang-Nian He*, Xinbin Ma*, Copper‐Catalyzed and Proton‐Directed Selective Hydroxymethylation of Alkynes with CO2, Angew. Chem. Int. Ed., 202110.1002/anie.202012768. [link]

    Abstract:  An intriguing strategy for copper‐catalyzed hydroxymethylation of alkynes with CO2 and hydrosilane was developed. Switched on/off a proton source, e.g. tBuOH, direct hydroxymethylation and reductive hydroxymethylation could be triggered selectively, delivering a series of allylic alcohols and homobenzylic alcohols respectively, with high levels of Z/E, regio‐ and enantioselectivity. Such a selective synthesis is attributed to the differences in response of vinylcopper intermediate to proton and CO2. The protonation of vinylcopper species is demonstrated to be prior to hydroxymethylation, thus allowing a diversion from direct alkyne hydroxymethylation to reductive hydroxymethylation in the presence of suitable proton.
  2. Xiao Zhang, Hong-Ru Li, Feng-Ge Zhao, Xiao-Ying Cui, Feng Ye, Liang-Nian He*, Green Process for Hydrogenation of Methyl Ricinoleate to Methyl 12-Hydroxystearate Over Diatomite Supported Cu-Ni Bimetallic CatalystGreen Chemical Engineering2021, DOI: 10.1016/j.gce.2020.09.011. [link]

    Abstract: A series of diatomite supported Cu–Ni bimetallic catalysts were prepared using the co-impregnation method to improve the efficiency and selectivity toward methyl 12-hydroxystearate in the hydrogenation of methyl ricinoleate. The catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (H2-TPR). All the characterization results verified the formation of highly dispersed Ni–Cu alloy on support. Moreover, by subtly regulating the Ni/Cu molar ratio as well as the reaction parameters, the hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate proceeded efficiently and selectively, affording 97% yield of methyl 12-hydroxystearate and nearly equivalent conversion of methyl ricinoleate under 2 MPa H2 pressure and at 130 °C in 4 h with only 1 wt% of the catalyst Ni7Cu1/diatomite (based on methyl ricinoleate). Besides, the supported Cu–Ni bimetallic catalyst is stable during recycle and reuse. After five cycles of reuse, much catalytic activity is still preserved. Therefore, this low-cost and stable bimetallic catalyst would be promising for the hydrogenation of methyl ricinoleate to methyl 12-hydroxystearate, representing an example of green catalysis for efficiently conversion of biomass to value-added chemicals and materials.
  1. Wen-Bin Huang, Fang-Yu Ren, Ming-Wei Wang, Li-Qi Qiu, Kai-Hong Chen, and Liang-Nian He*, Cu(II)-Catalyzed Phosphonocarboxylative Cyclization Reaction of Propargylic Amines and Phosphine Oxide with CO2. J. Org. Chem. 2020, 85, 14109−14120. [link]
    Abstract: Compounds bearing organophosphorus motifs and 2-oxazolidinone have found numerous applications in pharmaceut- ical chemistry, homogeneous catalysis, and organic materials. Here, we describe an efficient and selective protocol for straightforward access to a series of 5-((diarylphosphoryl)methyl)oxazolidin-2- ones via the copper-catalyzed difunctionalization of the C≡C bond of propargylic amines with CO2 and phosphine oxide. Notably, copper catalysis is a sustainable and benign catalytic mode. This reaction proceeds under mild reaction conditions, which is operationally simple and scalable with a broad scope, exclusive selectivity, and good functional group compatibility. Mechanistic studies suggest a one-pot tandem cyclization/radical addition sequence, along with the phosphorylation/cyclization scheme.
  2. Zhi-Hua Zhou, Kai-Hong Chen, Song Gao, Zhi-Wen Yang, and Liang-Nian He*, Ionic Liquid-Modified Porous Organometallic Polymers as Efficient and Selective Photocatalysts for Visible-Light-Driven CO2 Reduction. Research, 2020, DOI: 10.34133/2020/9398285. [link]

    Abstract: In the photoreduction of CO2 to CO, the competitive H2 evolution is always inevitable due to the approximate reduction potentials of H+/H2 and CO2/CO, which results in poor selectivity for CO production. Herein, imidazolium-type ionic liquid- (IL-) modified rhenium bipyridine-based porous organometallic polymers (Re-POMP-IL) were designed as efficient and selective photocatalysts for visible-light CO 2 photoreduction to CO based on the affinity of IL with CO2 . Photoreduction studies demonstrated that CO2 photoreduction promoted by Re -POMP-IL functioning as the catalyst exhibits excellent CO selectivity up to 95.5% and generate 40.1mmol CO/g of Re-POMP-IL1.0 (obtained by providing equivalent [(5,5 ′ -divinyl-2,2 ′ -bipyridine)Re(CO)3Cl] and 3-ethyl-1- vinyl-1H-imidazol-3-ium bromide) at 12 h, outperforming that attained with the corresponding Re-POMP analogue without IL, which highlights the crucial role of IL. Notably, CO2 adsorption, light harvesting, and transfer of photogenerated charges as key steps for CO2RR were studied by employing POMPs modified with different amounts of IL as photocatalysts, among which the CO2 affinity as an important factor for POMPs catalyzed CO2 reduction is revealed. Overall, this work provides a practical pathway to improve the CO2 photoreduction efficiency and CO selectivity by employing IL as a regulator.
  3. Kai-Hong Chen, Hong-Ru Li, Liang-Nian He*, Advance and Prospective on CO2 Activation and Transformation Strategy. Chin. J. Org. Chem., 2020, DOI: 10.6023/cjoc202004030. [link]
  4. Xiao Zhang, Kai-Hong Chen, Zhi-Hua Zhou, Liang-Nian He*, Reduced Graphene Oxide Supported Ag Nanoparticles: An Efficient Catalyst for CO2 Conversion at Ambient Conditions. ChemCatChem2020, DOI: 10.1002/cctc.202000738. [link]

    Abstract: A highly efficient carboxylative cyclization of propargylic alcohols with CO2 under atmospheric pressure catalyzed by silver (0) nanoparticles decorated reduced graphene oxide (Ag-rGO) is reported. Ag-rGO was fully characterized by scanning electron microscope spectra (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectra, Raman spectra and X-ray photoelectron spectroscopy (XPS). Notably, Ag-rGO can be also applied to the construction of other value-added chemicals (β-oxopropylcarbamates and 2-oxazolidi-nones) from CO2 at ambient conditions. In addition, Ag-rGO is stable and reusable, which shows the potential for the practical application for CO2 capture and utilization (CCU).
  5. Chun-Shuai Cao, Shu-Mei Xia, Zhen-Jun Song, Hang Xu, Ying Shi, Liang-Nian He*, Peng Cheng, and Bin Zhao* Highly Efficient Conversion and Reaction Mechanism of Propargylic Amines and CO2 Catalyzed by Eco-Friendly Noble-Metal-Free [Zn116] Nanocages. Angew. Chem. Int. Ed., 2020, DOI: 10.1002/anie.201914596. [link]

    Abstract: The reaction of propargylic amines and CO2 can provide high‐value‐added chemical products. However, most of catalysts in such reactions employ noble metals to obtain high yield, and it is important to seek eco‐friendly noble‐metal‐free MOFs catalysts. Here, a giant and lantern‐like [Zn116] nanocage in zinc‐tetrazole 3D framework [Zn22(Trz)8(OH)12(H2O)9·8 H2O]n Trz=(C4N12O)4− (1) was obtained and structurally characterized. It consists of six [Zn14O21] clusters and eight [Zn4O4] clusters. To our knowledge, this is the highest‐nuclearity nanocages constructed by Zn‐clusters as building blocks to date. Importantly, catalytic investigations reveal that can efficiently catalyze the cycloaddition of propargylic amines with CO2, exclusively affording various 2‐oxazolidinones under mild conditions. It is the first eco‐friendly noble‐metal‐free MOFs catalyst for the cyclization of propargylic amines with CO2. DFT calculations uncover that ZnII ions can efficiently activate both C≡C bonds of propargylic amines and CO2 by coordination interaction. NMR and FTIR spectroscopy further prove that Zn‐clusters play an important role in activating C≡C bonds of propargylic amines. Furthermore, the electronic properties of related reactants, intermediates and products can help to understand the basic reaction mechanism and crucial role of catalyst 1.
  6. Hong-Ru Li and Liang-Nian He*, Construction of C–Cu Bond: A Useful Strategy in CO2 Conversion. Organometallics, 2020, DOI: 10.1021/acs.organomet.9b00642. [link]
    Abstract: Carbon dioxide is not only one of the greenhouse gases but also an appealing renewable C1 source. To reconcile the environmental benefit with chemical industry development, conversion of CO₂ into valuable chemicals is proposed, and tremendous effort has been devoted to developing new synthetic protocols and highly efficient catalytic systems, wherein copper catalysis is attractive and features effective, inexpensive, and diverse transformation of CO₂. Considering the ubiquity of the C–Cu bond in organic chemistry and the wide application of the resulting carbocuprate species in reductive coupling with electrophiles, C–Cu formation and subsequent CO₂ insertion has been developed as an important strategy for CO₂ chemical fixation, thereby resulting in the preparation of a variety of valuable chemicals. To arouse broad interest in this strategy, we summarize recent advances and give an overview on CO₂ transformations via the carbocuprate species on the basis of the C–Cu bond formation mechanism, including copper⁻promoted alkyne and halide activation, transmetalation of some specific chemicals with copper, and hydrocupration, borocupration, and silylcupration of unsaturated substrates. It is hoped that this review can provide some clues for further exploration in this field.                                                                                                                                                                                                  
  7. Yu Song, Xing He, Bing Yu, Hong-Ru Li* and Liang-Nian He*, Protic ionic liquid-promoted synthesis of dimethyl carbonate from ethylene carbonate and methanol. Chin. Chem. Lett., 2020, 31(3), 667-672. [link]
  8. Xiao-Ya Li, Hong-Chen Fu, Xiao-Fang Liu, Shu-Han Yang, Kai-Hong Chen* and Liang-Nian He*, Design of Lewis base functionalized ionic liquids for the N-formylation of amines with CO2 and hydrosilane: The cation effects. Catalysis Today, 2020, DOI: 10.1016/j.cattod.2020.01.030. [link]

    Abstract: A series of functionalized ionic liquids (ILs) were developed for the reductive functionalization of CO2 with amine and hydrosilane to afford formamides under mild conditions. It was found that 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-based IL i.e. [DBUC12]Br showed high efficiency for the N-formylation reaction of amines without using any organic solvents or additives. Furthermore, control experiments suggested the cations with active hydrogen may weaken the nucleophilicity of anions through ion pairing interactions, thereby affecting the activation of hydrosilane. The reaction mechanism was then investigated by Density Functional Theory (DFT) calculations. This protocol represents a highly efficient and environmentally friendly example for catalytic conversion of CO2 into value-added chemicals such as formamide derivatives by employing DBU functionalized ILs.
  9. Lili Tang, Kejie Du, Bing Yu*, Liangnian He*, Oxidation of aromatic sulfides with molecular oxygen: Controllable synthesis of sulfoxides or sulfones. Chin. Chem. Lett.2020, 31, DOI: 10.1016/j.cclet.2020.03.030. [link]
  10. Wenlong Xiang, Zeyu Sun, Yurong Wu, Liang-Nian He, Chang-jun Liu*, Enhanced cycloaddition of CO2 to epichlorohydrin over zeolitic imidazolate frameworks with mixed linkers under solventless and co-catalyst-free condition, Catalysis Today, 2020, 339, 337-343. [link]

    Abstract: An efficient dual-ligand zeolitic imidazolate framework ZIF-8-90 was fabricated for the synthesis of five-membered cyclic carbonate from CO2 and epichlorohydrin (ECH) in the absence of co-catalysts and solvents. The effects of various reaction parameters were studied. The dual-ligand ZIF-8-90 showed very high selectivity (up to 99%). ZIF-8-90 exhibited better catalytic ability with lower cost than ZIF-90 and enhanced framework stability with significantly improved selectivity compared to ZIF-8. Moreover, the catalyst has been successfully reused for three cycles with negligible decrease in the catalytic activity. A plausible mechanism for the ZIF-8-90 catalyzed ECH−CO2 cycloaddition under solvent-free and co-catalyst-free has been proposed.

  11. Fei You, Xing He, Song Gao, Hong-Ru Li* and Liangnian He*Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid. Beilstein J. Org. Chem.2020, 16, 351-361. [link]

    : Raw material from biomass and green preparation processes are the two key features for the development of green products. As a bio-lubricant in metalworking fluids, estolides of ricinoleic acid are considered as the promising substitute to mineral oil with a favorable viscosity and viscosity index. Thus, an efficient and sustainable synthesis protocol is urgently needed to make the product really green. In this work, an environment-friendly Brønsted acidic ionic liquid (IL) 1-butanesulfonic acid diazabicyclo[5.4.0]undec-7-ene dihydrogen phosphate ([HSO3-BDBU]H2PO4) was developed as the efficient catalyst for the production of oligomeric ricinoleic acid from ricinoleic acid under solvent-free conditions. The reaction parameters containing reaction temperature, vacuum degree, amount of catalyst and reaction time were optimized and it was found that the reaction under the conditions of 190 °C and 50 kPa with 15 wt % of the [HSO3-BDBU]H2PO4 related to ricinoleic acid can afford a qualified product with an acid value of 51 mg KOH/g (which corresponds to the oligomerization degree of 4) after 6 h. Furthermore, the acid value of the product can be adjusted by regulating the reaction time, implying this protocol can serve as a versatile method to prepare the products with different oligomerization degree and different applications. The other merit of this protocol is the facile product separation by stratification and decantation ascribed to the immiscibility of the product and catalyst at room temperature. It is also worth mentioning that the IL catalyst can be used at least for five cycles with high catalytic activity. As a result, the protocol based on the IL catalyst, i.e. [HSO3-BDBU]H2PO4 shows great potential in industrial production of oligomeric ricinoleic acid from ricinoleic acid.
  12. Liang-Nian He (Editor-in-Chief), Preface for Current Organic Synthesis2020, 17(1), 2. [link]
  13. Kai-Hong Chen, Ning Wang, Zhi-Wen Yang, Shu-Mei Xia and Liangnian He*Tuning of Ionic Second Coordination Sphere in Evolved Rhenium Catalyst for Efficient Visible Light-Driven CO2 Reduction. ChemSusChem2020, DOI: 10.1002/cssc.202000698. [link]

    Abstract: Developing an efficient and easy-to-handle strategy in designing catalysts for CO2 reduction into CO by harnessing sunlight is a promising project. Here, a facile strategy was developed to design a Re catalyst modified with an ionic secondary coordination sphere for photoreduction of CO2 to CO by visible light. By adding ionic liquids or tuning a different ionic secondary coordination sphere, it was discovered that an outstanding optical property, other than CO2 absorption ability or the ability to dissociation of chloride anion, is the prerequisite for catalyst design. Accordingly, a novel Re catalyst, {Re[BpyMe(tris(2-hydroxyethyl)amine)](CO)3Cl}Br (Re-THEA), was designed, screened, and resulted in a relative high quantum yield (up to 34 %) for visible-light-induced CO2 reduction with a single-molecule system. DFT calculations, combined with experimental outcomes, suggested the pendant ionic tris(2-hydroxyethyl)amino (THEA) group on Re-THEA can enhance visible-light absorption, stabilize reaction intermediates, and suppress the Re-Re dimer formation.
  1.  Yu-Nong Li*, Xiao-Fang Liu and Liang-Nian He*An alternative route of CO2 conversion: Pd/C-catalyzed oxazolidinone hydrogenation to HCOOH and secondary alkyl-(2-arylethyl)amines with one stone two bird strategy. J. CO2 Util., 2019, 29, 74-81. [link]

Abstract: The oxazolidinone as one kind of annular CO2 derivatives has been hydrogenated by a new catalytic system Pd/C-TMGPEG150Me, affording formic acid and the corresponding alkyl-(2-arylethyl)amines under mild conditions in the high yields of 89% and 98%, respectively. This one stone two bird strategy validates a potential alternative route of approach for indirect conversion of CO2 to energy-related products, and opens up a novel way of synthesizing linear secondary amines without selectivity issues.

  1. Shuai Zhang*, Feng Han, Shaorui Yan, Mingyue He, Chengxia Miao and Liang-Nian He*Efficient Catalysts In Situ Generated from Zinc, Amide and Benzyl Bromide for Epoxide/CO2 Coupling Reaction at Atmospheric Pressure. EurJ. Org. Chem., 2019, 2019, 1311-1316. [link]

Abstract: Active catalysts in situ generated from Zn powder, dimethyl formamide and benzyl bromide were designed for fixation of CO2 to cyclic carbonates at 80 oC and atmospheric pressure of CO2. Zinc bromide and N,N-dibenzyl-N,N-dimethylammonium bromide, being proved as active catalyst species, were in situ generated and immediately converted various terminal epoxides to the corresponding carbonates efficiently.

  1. Xian-Dong Lang, Zheng-Ming Li*, andLiang-Nian He*, Protic ionic liquid-catalyzed synthesis of oxazolidinones using cyclic carbonates as both CO2 surrogate and sustainable solvent. CatalToday2019, 324, 167-173. [link]

Abstract: The thermodynamic stability and kinetic inertness represent substantial obstacles for direct chemical transformation of CO2. Consequently, conversion of the CO2 equivalent in an efficient and energy-saving manner has gained much attention being viewed as an indirect pathway to chemical utilization of CO2. In this article, we would like to report the synthesis of oxazolidinones via the carboxylative cyclization of anilines with cyclic carbonate using protic ionic liquid 1,8-diazabicyclo[5.4.0]-7-undecenium imidazolide [HDBU][Im] as the bifunctional catalyst under mild conditions without addition of conventional organic solvents. The distinguished features of this protocol include low catalyst loading, wide functionality tolerance and convenient recycling of the catalyst. A series of functional groups such as Cl, Br, CH3, OCH3 and NO2 can be well tolerated under the reaction conditions, providing the corresponding products in moderate to good yields (61–92%). In addition, to shed light on the cooperative interactions of [HDBU][Im]/EC and [HDBU][Im]/aniline, NMR technique and DFT study were also performed, respectively.

  1. Xian-Dong Lang, Fei You, Xing He, Yi-Chen Yu andLiang-Nian He*, Rhodium(I)-catalyzed Pauson–Khand-type reaction using formic acid as a CO surrogate: an alternative approach for indirect CO2 utilization. Green Chem., 2019, 21(3), 509-514.[link]

Abstract: Formic acid is found to be an ideal CO surrogate for the rhodium(I)-catalyzed Pauson–Khand-type (PK-type) reaction of various substituted 1,6-enynes to afford bicyclic cyclopentenones in moderate to good yields. High TON value of up to 263 and good results in the gram-scale experiment were also obtained, demonstrating the efficacy of this methodology. In addition, heterocyclic molecules of pharmaceutical importance were also furnished via inter- or intra-molecular hetero-PK-type reactions, further broadening the application of current strategy. In this protocol, formic acid was utilized as a bridging molecule for the conversion of CO2 to CO, since formic acid is manufactured via catalytic hydrogenation of CO2 and releases CO in the presence of acetic anhydride readily. Therefore, this methodology represents a green and indirect approach for chemical valorization of CO2 in the preparation of value-added compounds.

  1. Xiaoya Li andLiang-Nian He*, Ionic Liquid-Promoted CO2 Reductive Functionalization. In Encyclopedia of Ionic Liquids, Zhang, S., Ed. Springer Singapore: Singapore, 2019; pp 1-7. [link]


  1. Shumei Xia andLiang-Nian He*, Ionic Liquids in Nucleophilic Substitution. In Encyclopedia of Ionic Liquids, Zhang, S., Ed. Springer Singapore: Singapore, 2019; pp 1-8. [link]


  1. Xiao-Fang Liu, Xiao-Ya Li andLiang-Nian He*, Transition Metal-Catalyzed Reductive Functionalization of CO2Eur. J. Org. Chem.2019, 2019(14), 2437-2447. (VIP Paper) [link]

Abstract: Reductive functionalization of CO2 combining both the formation of the new bonds and CO2 reduction in the presence of reductant, such as molecular hydrogen, hydrosilane, or hydroborane has become increasingly attractive, which enlarges the spectra of compounds directly available from CO2 thus provides fresh idea for CO2 chemistry. This microreview briefly summarizes recent advances in new bond construction using CO2 as formyl, methylene, and methyl source with transition‐metal catalyst, which are divided into sections according to C–N, C–C, and C–O bonds formation in the presence of nitrogen‐, carbon‐, and oxygen‐nucleophiles respectively. The challenges and opportunities with future trends of the reductive functionalization of CO2 are discussed as well.

  1. Zhi-Hua Zhou, Xiao Zhang, Yong-Fu Huang, Kai-Hong Chen* andLiang-Nian He*, Synthesis of α-hydroxy ketones by copper(I)-catalyzed hydration of propargylic alcohols: CO2 as a cocatalyst under atmospheric pressure. Chin. J. Catal.2019,40(9), 1345-1351. [link]

Abstract: Inexpensive and efficient Cu(I) catalysis is reported for the synthesis of α-hydroxy ketones from propargylic alcohols, CO2, and water via tandem carboxylative cyclization and nucleophilic addition reaction. Notably, hydration of propargylic alcohols can be carried out smoothly under atmospheric CO2 pressure, generating a series of α-hydroxy ketones efficiently and selectively. This strategy shows great potential for the preparation of valuable α-hydroxy ketones by using CO2as a crucial cocatalyst under mild conditions.

  1. Yu Song, Xing He, Bing Yu, Hong-Ru Li* andLiang-Nian He*, Protic ionic liquid-promoted synthesis of dimethyl carbonate from ethylene carbonate and methanol. Chin. Chem. Lett.2019, DOI: 10.1016/j.cclet.2019.07.053. [link]

Abstract: In this work, the protic ionic liquid [DBUH][Im] (1,8-diazabicyclo[5.4.0]-7-undeceniumimidazolide) was developed as an efficient catalyst for the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate. At 70 °C, up to 97% conversion of ethylene carbonate and 91% yield of dimethyl carbonate were obtained with 1 mol% [DBUH][Im] (relative to ethylene carbonate) as catalyst in 2 h. Even at room temperature, the conversion of ethylene carbonate can reach 94% and the yield of dimethyl carbonate can approach 81% for 6 h. Catalytic mechanism investigation showed the high catalytic efficiency of this ionic liquid results from the synergistic activation effect, where in the cation can activate ethylene carbonate and the anion can activate methanol through hydrogen bond formation. Although the reusability of the ionic liquid need to be further improved, high efficiency and commercial availability of [DBUH][Im] render it a promising catalyst for the preparation of dimethyl carbonate.

  1. Liang-Nian He(Editor-in-Chief), Preface for Current Organic Synthesis2019, 16(1), 2. [link]


  1. Liang-Nian He*,Response to Commentary by T. Mita on Transition Metal-Catalyzed Carboxylation of Terminal Alkynes with CO2Mini-Reviews in Organic Chemistry2019, 16(5), 409. [link]
  1. Hong-Chen Fu, Fei You, Hong-Ru Li* andLiang-Nian He*, CO2 Capture and in situ Catalytic Transformation. Front. Chem.2019, 7(525), doi: 10.3389/fchem.2019.00525. [link]

Abstract: The escalating rate of fossil fuel combustion contributes to excessive CO2 emission and the resulting global climate change has drawn considerable attention. Therefore, tremendous efforts have been devoted to mitigate the CO2 accumulation in the atmosphere. Carbon capture and storage (CCS) strategy has been regarded as one of the promising options for controlling CO2 build-up. However, desorption and compression of CO2 need extra energy input. To circumvent this energy issue, carbon capture and utilization (CCU) strategy has been proposed whereby CO2 can be captured and in situ activated simultaneously to participate in the subsequent conversion under mild conditions, offering valuable compounds. As an alternative to CCS, the CCU has attracted much concern. Although various absorbents have been developed for the CCU strategy, the direct, in situ chemical conversion of the captured CO2 into valuable chemicals remains in its infancies compared with the gaseous CO2 conversion. This review summarizes the recent progress on CO2 capture and in situ catalytic transformation. The contents are introduced according to the absorbent types, in which different reaction type is involved and the transformation mechanism of the captured CO2 and the role of the absorbent in the conversion are especially elucidated. We hope this review can shed light on the transformation of the captured CO2 and arouse broad concern on the CCU strategy.

  1. Zhi-Hua Zhou, Shu-Mei Xia, Si-Yuan Huang, Yu-Zhong Huang, Kai-Hong Chen* andLiang-Nian He*, Cobalt-based catalysis for carboxylative cyclization of propargylic amines with CO2 at atmospheric pressure. J. CO2 Util.2019, 34, 404-410. [link]

Abstract: A cobalt-bicyclic guanidine catalytic system consisting of CoBr2 and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) for the carboxylative cyclization of terminal propargylic amines with CO2 was firstly developed in this work to produce 2-oxazolinones efficiently. The existence of induction period urged us to understand the reaction mechanism of cobalt catalysis. Investigation on the roles of CoBr2 and TBD was conducted using control experiments and density functional theory (DFT) calculation. TBD presumably acts as a base to activate propargylic amine for favorable CO2 capture, and a ligand to coordinate with CoBr2 via forming bulkier CoBr2(TBD) in the same time. This bulkier complex can enhance the O-nucleophility of the in situ formed carbamate intermediate and then promote subsequent intramolecular cyclization to generate 2-oxazolinone, accounting for the high activity of cobalt catalysis. This protocol enables the synthesis of various 2-oxazolinones from propargylic amines and CO2 under atmospheric pressure in good to excellent yields, representing a simple, cost-effective and practical route for CO2 fixation to 2-oxazolinones under mild conditions.

  1. Zhi-Hua Zhou, Kai-Hong Chen,* and Liang-Nian He*, Efficient and Recyclable Cobalt(II)/Ionic Liquid Catalytic System for CO2 Conversion to Prepare 2-Oxazolinones at Atmospheric Pressure, Chin. J. Chem. 201937, 1223-1228. [link]

Abstract: Converting CO2 into value-added chemicals represents a promising way to alleviate the CO2 derived environmental issues, for which the development of catalysts with high efficiency and recyclability is very desirable. Herein, the catalytic system by combining cobalt source and ionic liquid (IL) has been developed as the efficacious and recyclable catalyst for the carboxylative cyclization of propargylic amine and CO2 to prepare 2-oxazolinones. In this protocol, various propargylic amines were successfully transformed into the corresponding 2-oxazolinones with CoBr2 and diethylimidazolium acetate ([EEIM][OAc]) as the catalyst under atmospheric CO2 pressure. It is worth noting that the turnover number (TON) of this transformation can be up to 1740, presumably being attributed to the cooperative effect of the cobalt and IL. Furthermore, the existence of IL enables the catalytic system to be easily recycled to 10 times without losing its activity.

  1. Wenlong Xiang, Zeyu Sun, Yurong Wu,Liang-Nian He, Chang-jun Liu*, Enhanced cycloaddition of CO2 to epichlorohydrin over zeolitic imidazolate frameworks with mixed linkers under solventless and co-catalyst-free condition, Catalysis Today2020, 339, 337-343. [link]

Abstract: An efficient dual-ligand zeolitic imidazolate framework ZIF-8-90 was fabricated for the synthesis of five-membered cyclic carbonate from CO2 and epichlorohydrin (ECH) in the absence of co-catalysts and solvents. The effects of various reaction parameters were studied. The dual-ligand ZIF-8-90 showed very high selectivity (up to 99%). ZIF-8-90 exhibited better catalytic ability with lower cost than ZIF-90 and enhanced framework stability with significantly improved selectivity compared to ZIF-8. Moreover, the catalyst has been successfully reused for three cycles with negligible decrease in the catalytic activity. A plausible mechanism for the ZIF-8-90 catalyzed ECH−CO2 cycloaddition under solvent-free and co-catalyst-free has been proposed.