Alkylation Reactions Research Articles

CONVERSION OF PROPANE TO FORMALDEHYDE ON IRON PHOSPHATE

Phosphates represent diverse complex systems, whose basic structural unit is tetrahedron. They are widely applied as catalysts, carriers of catalytic active substances, adsorbents and ion exchangers. Phosphoric acid and phosphates act as catalyst for reactions of alkylation, cracking, izomerization, polymerization, hydrogenation and dehydrogenation. Phosphates of some metals promote oxidation of normal alkanes with derivation of aldehydes, acids, spirits and maleic anhydride.
 The process of propane and propylene oxidation on iron phosphate is investigated, as well as the influence of such factors as temperature, contact time of the reacting mixture with the catalyst t, the ratio of oxygen and hydrocarbon concentration in a mixture, and the influence of hydrogen concentration on the given process is shown.
 It is demonstrated that the optimum conditions for the realization of propane oxidation process is the temperature of 973 K and t = 0.17 s. It is established that with excess propane in the reaction mixture propylene is the predecessor of formaldehyde. On the contrary, at small concentration of propane in the mixture formaldehyde will be derived immediately from propane. The schemes of propane and propylene oxidation in formaldehyde are offered.
 Keywords: catalyst; oxidatio; рhosphates; propane; propylene; formaldehyde.

Built in electric-field active 2D β-BN/ZIS coated water-fed photoelectrode for methane conversion into hydrogen gas and VAPs through non-oxidative coupling

The photocatalytic conversion of methane into value added products with an add on power generation offers new sustainable solution for the GHG and commercial methane reforming. In present study photo-electrochemical conversion of CH4 gas into H2 gas and other value-added products like C2H6, C3H8, and C4H10 gas under ambient conditions through non-oxidative coupling of CH3* radicals at chain termination were investigated. Interfaces between two photocenters hinder the charge mobility therefore, built-in electric field induced VDW heterojunction of 2D/2D β-BiNbO4/ZnIn2S4 is constructed to enhance the spatial separation of excitons. Additionally, to remove the bubble diffusion challenge of gas to liquid phase 2D β-BiNbO4/ZnIn2S4 coated PES Air-photoanode is adopted. It presented gas phase photocatalysis redox reaction of alkylation and significant hydrogen generation. Presence of porous morphology and polar group in PES increased the ECSA and performance of photoanode by reducing the Rs, Rct and accumulation layer impedances. Electrochemical analysis also proven the potency of VDW 2D β-BN/ZIS for substantial hydrogen generation. 14.2% light-to-hydrogen efficiency with 61% selectivity was observed which is much higher than most of the reported LTH efficiency of photo fuel cell. The light-to fuel (LTF) efficiency is more than 17.3% and 49.7 mW/m2 of power production providing an opportunity to oxidise the methane under the ambient environment into energy-rich derivatives along with electricity generation.

Amino modified nanofibers anchored to Prussian blue nanoparticles selectively remove Cs+ from water

To improve the selective separation performance of silica nanofibers (SiO2 NFs) for cesium ions (Cs+) and overcome the defects of Prussian blue nanoparticles (PB NPs), PB/SiO2-NH2 NFs were prepared to remove Cs+ from water. Among them, 3-aminopropyltriethoxysilane (APTES) underwent an alkylation reaction with SiO2, resulting in the formation of a dense Si-O-Si network structure that decorated the surface of SiO2 NFs. Meanwhile, the amino functional groups in APTES combined with Fe3+ and then reacted with Fe2+ to form PB NPs, which anchored firmly on the aminoated SiO2 NFs surface. In our experiment, the maximum adsorption capacity of PB/SiO2-NH2 NFs was 111.38 mg/g, which was 31.5 mg/g higher than that of SiO2 NFs. At the same time, after the fifth cycle, the removal rate of Cs+ by PB/SiO2-NH2 NFs adsorbent was 75.36% ± 3.69%. In addition, the adsorption isotherms and adsorption kinetics of PB/SiO2-NH2 NFs were combined with the Freundlich model and the quasi-two-stage fitting model, respectively. Further mechanism analysis showed that the bond between PB/SiO2-NH2 NFs and Cs+ was mainly a synergistic action of ion exchange, electrostatic adsorption and membrane separation.

Synthesis, NMR, IR, Raman spectra and DFT calculations of 1‐octyl‐1,4‐diazabicyclo [2.2.2] octan‐1‐ium bis(trifluoromethylsulfonyl)imide

In this study, a novel [C8DABCO+] [(CF3SO2)2N−] ionic liquid (IL) was prepared by an alkylation reaction and then characterized it by experimental 1H-, 13C-, and 19F-NMR, IR and Raman spectroscopies together with B3LYP/6-311G** calculations in gas phase and aqueous solution to confirm its structure. DSC and TGA measurements show that it can be classified as a thermally stable ionic liquid. Three different structures (I), (II) and (III) were proposed for the IL with Cis and Trans positions of CF3 groups of anion evidencing better correlations among experimental and predicted spectra for structure (III). Strong S-O···H interactions were predicted in the gas phase while in solution the C-F···H distance is shorter (2.654 Å) than the S-O···H ones (2.827 Å). The analysis of MK charges reveals the presence of positive charges on quaternary N23 atoms both in vaccum and in solution; conversely positive Mulliken charges reside on O49 and O50 in the gas phase, while negative ones are found in solution. Molecular Electrostatic potential (MEP) surfaces support the electrophilic sites on quaternary N23 while the nucleophilic sites are observed on O, N and F atoms of the anion. NBO and AIM calculations reveal the characteristics of cation-anion interactions in the two media, as supported by the different f(νN-C), f(νSO2), f(δSO2) and f(δCH2) force constants values. Gap values suggest that [C8DABCO+] [(CF3SO2)2N−] is less reactive than [C8DABCO+] [Br−] while the characteristics of frontier orbitals justify the cation-anion interactions and support the important role of 1,4-diazabicyclo [2.2.2] octane (DABCO) in the properties of [C8DABCO+] [(CF3SO2)2N−] IL in both media. The complete assignments of 174 vibration modes expected for [C8DABCO+] [(CF3SO2)2N−] IL are reported together with the scaled force constants.

Synthesis and biological evaluation of bis-chalcone conjugates containing lysine linker as potential anticancer agents

Eight bis-chalcone conjugates with lysine linker were synthesized by alkylation reaction and evaluated for the antiproliferative potential. All the newly synthesized derivatives were first screened against Liver cancer (MHCC-97H), Colorectal cancer (HCT116), and Gastric cancer (TMK1) using CCK-8 assay under the concentrations from 0 to 100 μM, suggesting that gastric cancer cell TMK1 is more sensitive to these derivatives except 3d and 3f. Further, these compounds were tested in more gastric cancer-related cells including MKN45, AGS, IM95 and a normal gastric epithelial (GES1) cell line. Results indicated that the derivative 3a exhibited the most potent activity against TMK1 (IC50 = 22.29 µM, near to the reference drug 5-FU) and AGS(IC50 = 22.14 µM). In vivo anti-tumor study showed that compound 3a effectively inhibited tumor growth in TMK1-induced xenograft model without visible side effects. The mechanism of action on 3a on tumor growth inhibition was further investigated by RNA-Seq analysis in TMK1 cells, which indicates a positive regulation of apoptotic signaling pathway. Finally, cancer cell apoptosis after treated with 3a was confirmed with the expression of Annexin V, cleaved caspase 3 and Bax in TMK1 cells. Our results suggest that the bis-chalcone conjugate compound 3a is a promising tumor inhibitory agent for some gastric cancer.

Synthesis of Secondary Trifluoromethyl Boronic Esters through Visible Light Induced Decarboxylative Alkylation Reactions

AbstractWe demonstrated a practical and general methodology for the synthesis of secondary trifluoromethyl boronic esters through visible light induced decarboxylative alkylation reaction. This reaction was driven by the photochemical activity of electron donor‐acceptor (EDA) complex. Except for wide group tolerance, moderate to high yields and simple reaction conditions, the practicality of this protocol was further demonstrated by direct modification of bioactive molecules and further derivations.magnified image

Highly Efficient and Regioselective Synthesis of N‐Acyl Protected 2‐Aminoacrylates through a PPh3‐Catalyzed Reaction of Alkyl Propiolates with Amides

AbstractA simple and convenient strategy for the synthesis of N‐acyl protected 2‐aminoacrylates via PPh3‐catalyzed reaction of alkyl propiolates with amides has been developed. This protocol is rapid and highly regioselective to provide various N‐acyl protected 2‐aminoacrylates in high yields (up to 95 %). The chemical structure of the product was determined by X‐ray single‐crystal structure analysis. In contrast, 3‐sulfonamidoacrylates were obtained by Cs2CO3‐catalyzed reactions of alkyl propiolates with secondary sulfamides. Moreover, synthetic utility of this method was further highlighted in the late‐stage modification of drug molecules.

Chemoselective α-Alkylation of Nitriles with Primary Alcohols by Manganese(I)-Catalysis.

A sustainable and easy-to-use protocol for the alkylation of aryl nitriles with the earth-abundant manganese(I) catalyst is presented. The alkylation reaction employs readily available nitriles and naturally abundant alcohols as the coupling partners. The reaction proceeds chemoselectively and encompasses a broad substrate scope with good to excellent yields. The catalytic reaction yields selectively α-branched nitriles and water as the sole byproduct. Experimental studies were executed to understand the mechanism of the catalytic reaction.

Cyano-functionalized ionic porous polymer: A novel adsorbent for effectively enriching trace estrogens in water and milk

Estrogens have been recognized as a class of endocrine disruptors. It is of utmost significance to develop a sensitive analytical method for the reliable determination of estrogen in environmental and food samples. Herein, a series of cyano-functionalized ionic porous organic polymers (CN-iPOPs) were successfully prepared for the first time using (1-imidazolyl)acetonitrile and biphenyl dichlorobenzene as building blocks via Friedel-Crafts alkylation reaction. The optimized CN-iPOPs (CN-iPOP3) displayed exceptional sorption capacity for estrogens, making it an advanced adsorbent for solid phase extraction (SPE) of estrogens. In combination, CN-iPOP3 based SPE with high performance liquid chromatography, a sensitive and reliable method was developed for determination of four estrogens in lake water and milk samples. Under optimal conditions, good linear response was obtained to be 0.09–100.0 ng mL−1 for lake water and 0.90–1000.0 ng mL−1 for milk, with detection limits (S/N = 3) of 0.03–0.05 ng mL−1 and 0.30–0.70 ng mL−1 respectively. The method recoveries were in the range of 85.0%-119.0% with the relative standard deviations lower than 7.8%. The synergistic effect of electrostatic force, hydrogen bond, π-π stacking interaction and hydrophobic interaction was proved to be the main adsorption mechanism. This research provides a promising approach to design iPOP-based adsorbents for effectively enriching or removing organic pollutants.

A theoretical study of the mechanisms, regio- and enantioselectivities associated with rhodium-catalyzed allylic alkylation reactions using hard benzylzinc nucleophiles

A systematic theoretical study of rhodium-catalyzed allylic alkylation reactions using hard benzylzinc nucleophiles was performed. The mechanisms were investigated in detail together with the regioselectivity associated with the branched and linear pathways and the intriguing anti- (as opposed to syn-) diastereoselectivity of this process. The preferred mechanism was found to be initiated by the oxidative addition of the rhodium(I) complex followed by migration of the benzyl nucleophile to the Rh center. The subsequent nucleophilic addition of a benzyl group to the η3-allyl moiety takes place via the formation of a new C–C bond to afford the final allylic benzylation product. This proposed mechanism readily explains the experimental observation that the products obtained from such reactions are branched (as opposed to linear) with an anti-configuration (as opposed to a syn-configuration). This work also provides reasons for the lower regioselectivity observed for a OCO2tBu leaving group or cyanophenyl/secondary amide substituents at the 4-position of the substrate. The present study is expected to assist in the rational design of potential substrates for analogous reactions.

Enhanced Brønsted acid strength of HCl-promoted SO42−/TiO2 solid composite superacid: Synergetic effect of hydrogen chloride with induced titanium site

Development of the strategy to regulate the acidic properties of solid superacids had been attracting widespread attention in the acidic catalysis-related fields. In the present work, an HCl-promoted SO42−/TiO2 solid composite superacid was synthesized by incorporation of hydrogen chloride into sulfated titania (SO42−/TiO2). The Brønsted acid strength of HCl-promoted SO42−/TiO2 was significantly increased compared with that of SO42−/TiO2. Friedel-Crafts alkylation reaction results of HCl-promoted SO42−/TiO2 showed an increase by 27% in reaction rate and decreased byproduct selectivity (1% versus 10% for HCl-promoted SO42−/TiO2 and SO42−/TiO2, respectively). Structural characterizations demonstrated that HCl had the synergetic effect with induced titanium ion of HCl-promoted SO42−/TiO2 to form a new type of Brønsted acidic site. The configuration of enhanced Brønsted acidic site verified by DFT calculations was more liable to release the proton than that of conventional Brønsted acidic site, consequently increasing the Brønsted acid strength of HCl-promoted SO42−/TiO2.

Light, metal‐free regioselectiveC6‐Halkylation of purines and purine nucleosides with alcohols

AbstractA metal‐, light‐free radical alkylation reaction of purines and nucleosides has been achieved with readily available alcohols (1°, 2°, 3°) as the alkyl radical sources enabled by oxalates, which does not need any catalysts, N2protection, and protecting groups. Although there are three potential active C(sp2)H bonds and four interferential nitrogen atoms in the purine motif, the reaction still shows excellent regioselectivity at C6H position and does not face multialkylation problem. Besides, this approach shows broad functional groups tolerance and is scalable to the gram level, which can be applied to late‐stage CH alkylation of purine to synthesize 6‐cyclopentyl nebularine with anti‐CEM activity, thus demonstrating its utility.

Martin Silicates as Versatile Radical Precursors in Photoredox/ Nickel Dual Catalysis

AbstractA cross-coupling methodology is described based on the nickel-catalyzed connection of an aryl moiety to an alkyl radical generated by photoinduced single-electron oxidation of a silicate formed from a Martin spirosilane. Complementary to the other anionic radical precursors in photoredox catalysis, Martin silicates permit access to highly reactive alkyl radicals directly engageable in smooth C(sp2)–C(sp3) bond-formation reactions.

Synthesis, non-covalent interactions and chemical reactivity of 1-pentyl-3-phenylquinoxalin-2(1H)-one — Structural and computational studies

This contribution presents the synthesis of a new quinoxaline derivative, 1-pentyl-3-phenylquinoxalin-2(1H)-one with formula C19H20N2O, through an alkylation reaction, followed by a thorough structural characterization. X-ray crystallography revealed that π-stacking and unconventional CH…O/π hydrogen bonding play a significant role in the supramolecular solid-state framework. These interactions are further assisted by infrequent CO…π interactions and CH…HC dispersive contacts. These non-covalent interactions (NCIs) are analyzed in terms of geometrical criteria, and Hirshfeld surface analysis is used to demonstrate their individual contributions. The nature and strength of prevalent NCIs are thoroughly discussed via computational tools NCI, NBO, and QTAIM. Moreover, the application of Density Functional Theory (DFT) at the wB97X-D/cc-pVTZ level yields valuable insights into both the global and local chemical reactivity of studied compound, thereby enhancing our understanding of the chemistry involved in the synthesis of quinoxaline and its derivatives.

Fundamental and Development of Microreaction Technology for the Application of Fine Chemicals Synthesis

The fine chemical process has many environmental and safety problems related to the unavoidable use of various organic reactions which are highly involved with exothermic reactions, explosive intermediates, corrosive reagents, toxic or reactive gases, flammable and pyrophoric compounds, and extreme conditions. Limited by the traditional batch process, the efficiency of these reactions should be manually lowered to keep the reaction from going out of control. Benefiting from its rapid transfer of reaction heat, efficient micro-mixing of ingredients, and minimal hold-up of hazardous reagents, continuous-flow microreaction synthesis has emerged as a new technology for producing fine chemicals efficiently and safely in the last two decades. Here, we will introduce some recent progress on the fundamentals and developments of efficient, green, and safe processes for fine chemical synthesis using microreaction technology mainly by our group, including rearrangement reaction, cycloaddition reaction, diazotization reaction, coupling reaction, alkylation reaction, and sulfonation reaction. Based on our research progress, the development of microreaction technology in fine chemical synthesis was discussed here, including applying online analysis and intelligent algorithms to improve the efficiency of the development of microreaction systems from lab scale to commercial production, extending the application of microreaction technology to solid or particle treatment, studying the behaviors of heterogeneous reactions, revealing principles for scaling up heterogeneous reactions in specialized microreactors, and decision toolbox considering both the characteristic of the microreaction system and the overall goal of the industry.

Converting waste expanded polystyrene into higher-value-added hyper-crosslinked porous polymer for rapid and high-efficient adsorption of aflatoxins

White pollution caused by the massive discharges of waste expanded polystyrene (WEPS) has become a critical global issue, so the effective conversion of WEPS is of great significance to reduce white pollution. Herein, adopting WEPS as raw material, three high-value-added hyper-crosslinked polymers (WEPS-HCPs) with high surface areas and abundant micro/mesoporous structures were synthesized via Friedel-Crafts alkylation reaction using dimethoxymethane, dichloroxylene and 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCB) as cross-linker, respectively. The WEPS-HCPs were used as sorbent to extract aflatoxins (AFs) and all the HCPs exhibited high adsorption capacity. For the fast separation and recovery of the sorbent, WEPS-BCB was chosen as a model HCP to be magnetically functionalized to obtain a magnetic HCP (mWEPS-BCB) for the first time. Based on magnetic solid phase extraction with the mWEPS-BCB as sorbent, a fast and sensitive method was developed to determine trace level of AFs in grain food. Under the optimal conditions, the proposed method presented wide linear range (0.008–10.0 ng g−1), low detection limit (0.002–0.015 ng g−1) and satisfactory precision (relative standard deviation < 7%). Converting WEPS into a high-value-added sorbent not only provided a facile strategy for effective recycling of WEPS, but also developed a sensitive method for accurate determination of AFs in grain food, achieving significant economic and environmental benefits.

Enantioselective Synthesis of an All-Carbon Quaternary Stereocenter by Chiral Brønsted Acid-Catalyzed Friedel-Crafts-Type Reaction between Pyrroles and 3-Indolylmethanols.

We have developed a chiral phosphoric acid-catalyzed enantioselective Friedel-Crafts alkylation reaction between pyrroles and indolylmethanols. Wide substrate scope was observed, and a chiral all-carbon quaternary center was constructed at the 3 position of indoles in high yields with high to excellent enantioselectivities (up to 99% ee).

Application of functional metal anionic Lewis acid ionic liquids in the alkylation of chlorobenzene/SOCl2.

4,4'-Dichlorodiphenyl sulfoxide is the main raw material for the manufacture of polysulfone, polyether sulfone and other engineering plastics. It is also an intermediate for medicines, dyes and pesticides, which has been widely utilized in engineering plastics, fine chemicals and other fields. The alkylation of chlorobenzene with thionyl chloride can give 4,4'-dichlorodiphenyl sulfoxide as a product using Lewis acidic ionic liquids. In this work, metal-based methylimidazolium ionic liquids were synthesized, which were found to be efficient catalysts for alkylation reactions. The molar ratio of different metal chlorides to 1-butyl-3-methyl imidazole chloride and the influence of different metal chlorine additives on the catalytic Lewis acid center were investigated. The fissionable species of AlCl3 in ionic liquids will enhance the acidity of ionic liquids and, thus, promote the catalytic performance of ionic liquids. Under the optimized reaction conditions, the conversion rate of excess chlorobenzene was 45.3% and the selectivity of 4,4'-dichlorodiphenyl sulfoxide was 31.9%.

Preparation of monocyclic aromatic hydrocarbons from chlorine-containing mixed waste plastics via tandem catalysis coupled with hydrothermal pretreatment

Pyrolytic conversion of chlorine-containing mixed plastic (CMP) wastes into monocyclic aromatic hydrocarbons (MAHs) suffered the chlorinated pollutants and low product yield, making it difficult for continuous industrial operation. Herein, a novel method of tandem catalytic pyrolysis of CMP coupled with hydrothermal pretreatment (HY) for the clean production of high-yield MAHs was investigated. The pyrolytic kinetics of the feedstocks obtained after HY was analyzed, and the synergistic mechanism of HY and tandem catalysis over carbon-based catalyst (Fe/Ni/Mo@N/C) and zeolite (HZSM-5) was established. The results showed that the homogenization effect of HY on CMP was the key to improving its catalytic activity. High pretreatment temperature effectively weakened the branch-chain bond of the polyolefin molecules and dramatically reduced the pyrolytic activation energy of CMP. Additionally, the β-scission and alkylation reactions in the catalytic process were significantly promoted by HY, and subsequently improved the yields of toluene and xylene in HY-tandem catalysis, the selectivity of MAHs and benzene, toluene, ethylbenzene, and xylene (BTEX) reached 84.09% and 71.29%, respectively. The increased yield of BTEX favoured by the synergistic effect of pretreatment and catalysis was promoted to 351.97 mg/g in HY-tandem catalysis, whose yield was 9.52 times that of thermal pyrolysis. After the catalytic reaction of 360 min and transforming 18 times of the mixed plastic wastes, the coke amount of the microporous catalyst was still lower than 4 wt%. This work provides a potentially transformative solution to the challenge of upcycling unsorted plastic waste.

Removal of large class of organic pollutants and gold using Phloroglucinol/Resorcinol coupled Triazine-based porous organic polymer

Due to the various anthropogenic activities, the continuous release of organic pollutants is a serious global threat. Thus, developing effective removal and remediation technologies for hazardous pollutants is essential to minimize the adverse effects on human health and the environment. Herein, we developed hyper-crosslinked polymers (HCPs) via catalyst-free solvothermal Friedel-Crafts alkylation reaction using tris-phloroglucinol/tris-resorcinol substituted triazine and dimethoxymethane. The obtained HCPs (HCP-CPF, HCP-CRF) exhibit variation in the surface area, pore size and morphology. The cross-linking of Phloroglucinol-triazine-based planar monomers via methylene spacer leads to porous coral-like morphology with a high surface area (Sarea = 480 m2/g) in HCP-CPF. In contrast, the cross-linking of Resorcinol-substituted triazine-based monomers displayed a fibre network with comparatively low surface area (Sarea = 35.7 m2/g) in HCP-CRF. The presence of densely functionalized multiple hydroxyl groups, good surface area and aqueous dispersibility in HCPs facilitate the fast and efficient removal capacity of various cationic dyes and paraquat herbicide in water. The HCP-CPF displayed fast removal capacity towards the large class of different organic dyes, and it removed 100% of most of the dyes within 10 min from the aqueous solution. Furthermore, the recovery of gold from an aqueous solution is one of the essential and crucial tasks. HCP-CPF and HCP-CRF exhibited a good removal capacity towards Au3+ via in-situ reduction (Qmax = 497.5 mg/g for HCP-CPF and Qmax = 463.33 mg/g for HCP-CRF).