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Hydrogenolysis of biomass-derived lignin sources is highly important for the conversion of renewable biomass resources to biofuels. However, lots of developed catalysts suffer from the drawbacks of expensive precious metal catalysts and/or operation under harsh conditions. In the present work, Co–Ni bimetallic catalysts were prepared and applied in catalyzing hydrogenolysis of Caryl–O aromatic ethers with high activities under the promotion of Nb2C MXene additive. Especially, the hydrogenolysis of diphenyl ether (DPE), a 4–O–5 model compound, to cyclohexane (cy) and cyclohexyl alcohol (cy-ol) could be achieved over the Co2Ni1Ox–Nb2C MXene catalytic system at 120 °C and under 5 bar of H2, which are mild conditions in comparison with those for the developed heterogeneous precious-metal-free catalysts. The excellent catalytic performances stemmed from the strong interaction between Co and Ni species and the promotion of Lewis acidic sites offered by Nb2C MXene. The proposed reaction pathway involved the direct hydrogenolysis of DPE route, in which DPE was initially hydrogenolyzed to benzene and phenol. They were further hydrogenated to cy and cy-ol. The present work not only develops a noble-metal-free bimetallic catalyst for utilization of biomass-derived lignin sources, but also provides a novel strategy for using the Nb2C MXene material.

By using N,N-dimethylformamide (DMF) as a methylenating reagent, the copper-catalyzed CH activation of indole was demonstrated as an efficient and facile protocol for synthesizing 3,3′-diindolylmethane (DIM) and its derivatives. The results indicate that copper chloride was the best catalyst among the investigated transition metal salts, which affords an excellent regioselectivity and good yield when tert-butyl hydroperoxide (TBHP) was used as an oxidant.

The strong desire for developing promising candidates of insensitive nitro energetic materials has spurred numerous attempts to discern the nitration details. The nitration mechanism of 2-methyl-4,6-dihydroxypyrimidine (MDP) with nitronium (NO2+) to form 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione is studied via DFT-B3LYP/6-311G(d,p) method. The possible nitration pathways are excavated and illustrated. Herein, a unique/incredible induction/enhancement of the co-existing acidic group of HSO4− to the targeted nitration is definitively proposed. The impact of the introduction order of four nitro groups (–NO2) on the title nitration is systematically demonstrated. It is suggested that the proposed induction of HSO4− may effectively promote/catalyze not only the NO2+ attack, but the H-transfer and H-abstraction as well, and thus dramatically decreases the activation free energy of the nitration system. Moreover, the NO2+ attack may be dynamically affected by the pre-introduced –NO2 and the resulted fluctuation of charge distribution in the pre-intermediates, which has been primarily supported via the calculated atomic charge, Coulomb attraction and Fukui function. It is indicated that the preferential dinitration on –CH3 with the induction of HSO4− (path A) is the most likely pathway. It is optimistically expected that the present study may provide a theoretical basis to the research and engineering tests of the title nitration, and promote the exploration of related insensitive energetic materials.

Cost-effective adsorbents for volatile organic compounds elimination were synthesized at room temperature. New kinds of external cross-linkers were developed and used in the one-step Friedel–Crafts reaction. The synthesized polymers exhibit a high surface area (BET surface area up to 1345 m2 g−1), large pore volume, superhydrophobic nature and excellent adsorption capacity for benzene, which is one of the highest to date among the reported adsorbents. It also possesses super preferential selectivity towards benzene in a high humid gas stream. Therefore, this kind of material is a promising adsorbent for air purification and environmental protection.

A new kind of hydrophobic hyper-cross-linked polymers (HCPs) with high surface area, large pore volume, and controllable average pore size was prepared. The synthesized HCP-0.5 sample, having the biggest BET specific surface area (1394 m(2)/g), pore volume (1.55 m(3)/g) and micro-mesopore structure (average pore diameter of 4.4 nm), was used as a novel adsorbent for removing benzene. The results of the static adsorption/desorption experiment at 298,308 and 318 K showed that HCP-0.5 has a very large adsorption capability of 19.16 mmol g(-1) at 298 K for benzene. Dynamic adsorption experiments of benzene on HCP-0.5 under dry and humid condition (RH = 80%) revealed that the existence of water vapor had little effect on dynamic adsorption capacity of benzene on HCP-0.5 and almost did not change the breakthrough time. Therefore, these synthesized polymers can be used as efficient and competitive adsorbents for removing VOCs, especially under humid conditions. (C) 2015 Elsevier B.V. All rights reserved.

Sustainable reactive dyeing of cotton in green non-nucleophilic solvents was investigated. Dye fixation in the new medium was modeled using DFT calculations with the aim of understanding the role of organic bases. The novel procedure uses non-nucleophilic green solvents instead of water to eliminate the dye hydrolysis. All residuals in the spent dye bath could be conveniently recycled and reused. The three major stages in cotton reactive dyeing, cellulose swelling, dye adsorption and dye fixation were optimized respectively. Two organic bases and potassium carbonate were studied for dye fixation. The mechanisms of the amine-promoted dye fixation were modeled using density function theory (DFT) calculations. The formation of the amine-dye intermediate was elucidated and analyzed using high performance liquid chromatography (HPLC) analysis. The quaternary ammonium catalysis effect on intermediates forming was observed. A 10-cycle repeated dyeing sequence was demonstrated using Reactive orange 5 to give consistently high shade buildup, excellent colorfastness and dramatic reduction in resource consumption. The results have implications for better understanding the new hydrolysis-free and recyclable solvent dyeing process.

A novel fluorinated reversible addition-fragmentation chain transfer agent, S,S-di-pentaflourobenzyl trithiocarbonate (DPFBTTC), was designed and synthesized. DPFBTTC and dibenzyl trithiocarbonate (DBTTC) were applied in the polymerization of dodecafluoroheptyl methacrylate (DFHMA), hexafluorobutyl methacrylate (HFBMA), and trifluoroethyl methacrylate (TFEMA) in scCO2. The polymerization processes were monitored using a high-pressure in-situ NIR, through which the polymerization kinetics was investigated and the controllability of DPFBTTC was evaluated. It is found that the controllability of DPFBTTC presented in the order of DFHMA > HFBMA > TFEMA, indicating that DPFBTTC may fit for the controlled polymerization of the highly fluorinated methacrylates. Moreover, the controllability of DPFBTTC is verified to be better than that of DBTTC, possibly resulting from the enhanced accessibility/miscibility of DPFBTTC to the fluorinated monomer used. We believe that the employment of DPFBTTC and the resulted introduction of stable pentafluorobenzyl end groups to the polymer are expected to distinctly improve performances of the polymer, and thus will meet the special application requirements. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

A prominent enhancement in solubility of epoxide oligomers in supercritical CO2 (scCO2) was definitively accomplished via fluorination. The fluorinated epoxide oligomers (FEO) exhibited incredibly low transition pressure (PT) as compared with a library of other epoxide oligomers. For determining the nature of the observed special affinity of the FEO to CO2, the detailed solvation behaviors of 14 epoxide oligomers in gaseous and supercritical CO2 were investigated using a high-pressure in situ ATR FTIR system as the pressure increased from 0.1 to 40.0 MPa. The key role of the intermolecular interactions on the enhanced solubility of the FEO in scCO2 was established and the major factors impacting the molecular interplay between the epoxide oligomers and CO2 were systematically evaluated. We attribute the uniquely enhanced solubility of the FEO in scCO2 to the synergistic effects of the increased special attraction between the FEO and CO2, the decreased self-interaction among the FEO and the excellent accessibility of the FEO to CO2. Since the FEO are suggested to be the most soluble species in scCO2, we optimistically believe that the FEO may act as the ideal solubilizing chain after being transplanted or grafted into other targeted molecules and thus can be employed in developing a series of novel fluorinated monomers, ligands/complexes/catalysts and surfactants in a scCO2 system.

The hydrolysis mechanism and the kinetics of using 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione (NMP) to prepare the representative insensitive energetic material 1,1-diamino-2,2-dinitroethylene (FOX-7) in a nitric–sulfuric acid system are systematically investigated via a density functional theory (DFT) method. The impact of the co-existing acidic group of HSO4− as well as the solvent effects of the mixed acids on the hydrolysis of NMP are elucidated and discerned, and the proposed catalysis and promotion of the hydrolysis of NMP with HSO4− are verified. The HSO4−-catalyzed hydrolysis pathway is more favorable than the direct pathway as well as the H2O-catalyzed hydrolysis, indicating that HSO4− may be a promising catalyst for the preparation of FOX-7 in a mixed acid system. The present study is expected to provide a better understanding of the hydrolysis of NMP, and will significantly help with better preparation of FOX-7 and other nitro-energetic materials.

A novel, high-efficiency and high-selectivity construction of β-trifluoromethyl enol ether via base-induced/promoted C–O coupling of trifluoromethylated vinyl chloride and phenols is presented with a broad substrate scope. The reaction mechanism, especially the significantly high selectivity, was excavated and understood via DFT calculation and is well supported by the experimental observation.

A triple-sensitive polymer of poly(ethylene glycol)-iminoboronate nitrobenzyl ethanediol chelate (PEG-INEC) is efficiently fabricated via the convenient aqueous iminoboronate multi-component reaction (MCR) of methoxypolyethylene glycol amine (mPEG-NH2 ), 2-formylphenylboronic acid (FPBA), and bis(2-nitrophenyl) ethanediol (BNPE, a photo-cleavable nitrobenzyl alcohol derivate). The aqueous MCR synthetic procedure is followed using 1 H NMR and turbidity analysis. It is shown that polymer nano-aggregates of PEG-INEC in aqueous solution can be dissociated through the stimuli responsive reactions of the hydrophobic iminoboronate nitrobenzyl ethanediol chelates (INECs) when exposed to UV light, acid, and H2 O2 , respectively. Furthermore, upon the stimulation of combined triggers, the dissociation of polymer nano-aggregates can be accelerated to different extents, resulting in the synergistic release of encapsulated hydrophobic molecules in water. The proposed facile and general method is quite desirable and of great importance in practical applications like drug and gene delivery.

A one-step, continuous flow-phase, highly catalytic hydrogenation–isomerization of dicyclopentadiene (DCPD) directly into exo-tetrahydrodicyclopentadiene (exo-THDCPD) has been successfully performed over a fixed-bed reactor. This method is a greener and more cost-effective single-step route than the use of AlCl3 and noble metals (Pd, Pt, and Au) and, instead, employs a combination of Ni/γ-Al2O3 for hydrogenation and Ni/Hβ for isomerization. The bifunctional catalysts provided 100% DCPD conversion and 70% selectivity for exo-THDCPD and displayed a high stability without obvious deactivation over 200 h of testing. The synergistic effect of Ni hydrogenation activity and the isomerization activity of the supports is a key factor for the catalytic hydrogenation–isomerization of DCPD. A series of supports (ReY, USY, USReY, HY, HReY, Hβ, MCM-41, γ-Al2O3, SiO2, and NaY) were initially investigated as the Ni-supported catalysts. Surprisingly, we found that Hβ had a high activity for the isomerization of endo-THDCP...

Pt/MWCNT and Pd/MWCNT nanocatalysts were prepared via a liquid reduction method. The selective hydrogenation of cinnamaldehyde (CAL) was investigated over 5.0 wt.% Pt/MWCNT and 5.0 wt.% Pd/MWCNT catalysts in a CO2-expanded alcoholic medium at different reaction conditions. The hydrogenation selectivities over these two catalyst types were shown to be entirely different. It was found that the Pt/MWCNT catalysts are highly selective for C=O bonds, giving the unsaturated alcohol a selectivity for cinnamyl alcohol (COL) of 97.3% and a conversion rate for cinnamaldehyde of 99.3%. Conversely, the Pd/MWCNT catalyst is highly selective for C=C bonds, producing a saturated aldehyde with a selectivity for hydrocinnamaldehyde (HCAL) of 91.3% and a conversion rate for cinnamaldehyde of 98.6%. The small diameter of the Pt or Pd granules over the multiwalled carbon nanotubes (MWCNTs) leads to a high catalyst activity, and an increase of CO2 pressure results in a better hydrogenation performance for C=O bonds than that for C=C bonds.

The strong desire for the extensive application of supercritical carbon dioxide (scCO2) as an environmentally benign solvent in polymers synthesis and processing has spurred numerous attempts to discern and improve its solvability toward monomers as well as polymers. The detailed solvation processes along with the phase behaviors of a fluorinated liquid monomer (LM) of 2,2,2-trifluoroethyl methacrylate (TFEMA), as well as another 13 non-fluorinated LMs in gaseous and supercritical CO2, were respectively investigated by using a newly built high-pressure ATR-FTIR in situ monitoring system as CO2 pressure stepwise increased from 0 to 38.0 MPa. Interestingly, an unexpected vibrational absorption variation, especially a distinct blue-shift in the in situ FTIR spectra of the functional groups in each LM + CO2 binary system, was generally observed during the solvation process as CO2 pressure increased. A similar variation trend of the vibrational absorption of the C–F bond in the TFEMA + CO2 system was also obta...

The typical polymerization process in supercritical fluids (SCFs) was improved through modifying the reaction system and designing and using sampling tubes. The efficacy of the newly developed procedure was demonstrated by the free radical homopolymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) and coplymerization of TFEMA and N-vinylpyrrolidone (NVP) in supercritical carbon dioxide (scCO2). Results indicate that the newly developed procedure has the characteristics of minimum loss of reactants and polymerization starting at the desired temperature and pressure. Furthermore, the polymerization process can be well tracked by analyzing the reaction mixtures online sampled from the reactor at certain reaction times by FT-IR, 1H NMR, and GPC. The reaction time and the product properties can be optimized based on the tracking results. For the first time, block copolymers by free radical polymerization in scCO2 was successfully synthesized by sequential addition of TFEMA and methyl methacrylate (MMA) in...

Fluorescent photolabile groups undergoing convenient synthesis and fast cleavage are being explored because of their increasing utility in both synthetic and biological chemistry. Herein, a model photosensitive poly(ethylene glycol)-lipid of NP-B-PEG with a 2-nitrobenzyl 2-pyridinylmethyl borate hydrophobic tail is synthesized. The (1) H-NMR and absorption spectra analysis of NP-B-PEG upon 365 nm irradiation in water supports a rapid photocleavage of nitrobenzyl borate with the concomitant hydrolysis of 2-pyridinylmethyl borate. It is also shown that the borate tail hydrolyzes slowly in water. Fortunately, when the polymer aqueous solution is loaded with the hydrophobic doxorubicin (DOX), the borate hydrolysis can be much retarded. The phototriggered experiment shows a two-stage DOX release: first, the slow leakage as a result of the photocleavage of 2-nitrobenzyl borate before the vesicle disintegration; second, the quick DOX precipitation from the disintegrated vesicles induced by the speeding up hydrolysis of 2-pyridinylmethyl borate.

Preparative methods of obtaining bicycloalkapyrazines (2) by the low-valent titanium induced reductive cyclization of dinitriles (1), and for obtaining bi(azacycloalka)pyrazines (5) from N,N-bis(2-cyanoethyl)-aromatics amines (4) are presented.

The intermolecular and intramolecular coupling reaction of carboxylic derivaties with aromatic ketones induced by titanium tetrachloride and zinc powder was studied.

The first examples of a Pd-catalyzed carbonylation of aryl boronic acids with sp(3) carbon partners are presented. Various boronic acids were shown to react with 1,3-diesters and 1,3-diketones to afford structurally unique carbonyl compounds. By employing 2-substituted 1,3-diesters, synthetically-challenging quaternary carbon centres were accessed. In total, 42 examples of aryl carbonyl compounds were prepared in moderate to good yields. The catalytic system features the use of a bidentated phosphine ligand and a relatively low CO pressure (5 atm), providing an easy, alternative method for the preparation of triketones.

The intermolecular and intramolecular coupling reaction of carboxylic derivaties with aromatic ketones induced by titanium tetrachloride and zinc powder was studied.

Preparative methods of obtaining bicycloalkapyrazines (2) by the low-valent titanium induced reductive cyclization of dinitriles (1), and for obtaining bi(azacycloalka)pyrazines (5) from N,N-bis(2-cyanoethyl)-aromatics amines (4) are presented.