Bond Scission Research Articles

Synthesis of Tetrahydro‐β‐carbolines via Cascade Sigmatropic Rearrangements

We have developed a synthesis for tetrahydro‐β‐carbolines involving cascade sigmatropic rearrangements. The substrates were conveniently prepared from parent anilines via a [2,3]‐sigmatropic rearrangement and cyanomethylation. Silver‐mediated decyanation afforded the corresponding iminium cation, which underwent a cascade consisting of an aza‐Cope rearrangement, an aza‐oxa‐Cope rearrangement, an aromatization, and a Pictet–Spengler reaction, and tetrahydro‐β‐carbolines were obtained as the single product. The reaction involved seven bond scissions and four bond formations and was triggered by a single reagent.

Accelerated Mechanochemical Bond Scission and Stabilization against Heat and Light in Carbamoyloxime Mechanophores.

Current approaches to the discovery of mechanochemical reactions in polymers are limited by the interconnection of the zero-force and force-modified potential energy surfaces since most mechanochemical reactions are force-biased thermal reactions. Here, carbamoyloximes are developed as a mechanophore class in which the mechanochemical reaction rates counterintuitively increase together with the thermal stability. All carbamoyloxime mechanophores undergo force-induced homolytic bond scission at the N-O bond, and their mechanochemical scission rate increases with the degree of substitution on the α-substituent. Yet, carbamoylaldoximes react to both heat and light with a pericyclic syn elimination, while carbamoylketoximes undergo thermal decomposition at high temperature and photochemical homolytic scission only from the triplet state. Thereby, the mechanochemical and thermal reaction trajectories are separated, and the thermal stability increases alongside the mechanochemical reaction kinetics. This approach may play an important role in the future of systematic mechanochemical reaction discovery.

Mechanistic studies on the oxidation reaction of n-pentane

The oxidation reaction mechanism of n-pentane is investigated using density functional theory and transition state theory as a case study to elucidate the combustion characteristics of liquids with low boiling points. This study divides the oxidation reaction of n-pentane into four steps. First, n-pentane decomposes to form n-pentyl radicals C5H11 and H, CH3 and C4H9, and C2H5 and C3H7 radicals. Second, n-pentane primarily undergoes H-abstraction reactions with H, CH3, C2H5, and C3H7 radicals to form the C5H11 radicals. Subsequently, C5H11 radicals react with O2 in an addition reaction to form n-pentyl peroxy radicals ROO. Finally, ROO radical undergoes internal H-atom transfer to form hydroperoxy pentyl radicals QOOH, which then undergoes cyclization and bond scission to produce cyclic ethers, alkenes, aldehydes, OH radicals, and HO2 radicals. Results indicate that n-pentane readily decomposes into C2H5 and C3H7 radicals, with a bond dissociation energy of 367.1 KJ/mol. The H-abstraction reactions involving H and CH3 radicals have the fastest rates, which require the lowest energy barriers of 21.6 and 41.9 KJ/mol, respectively. The reaction between C5H11 and O2 is a barrierless addition reaction. The oxidation of n-pentane, which leads to the formation of 2-methyloxirane and OH radicals, exhibits the fastest reaction rate.

Selective monodeuteration enabled by bisphosphonium catalyzed ring opening processes

The selective incorporation of a deuterium atom into small molecules with high selectivity is highly valuable for medical and chemical research. Unfortunately, this remains challenging due to the complete deuteration caused by commonly used hydrogen isotope exchange strategies. We report the development of a photocatalytic selective monodeuteration protocol utilizing C–C bond as the unconventional functional handle. The synergistic combination of radical-mediated C–C bond scission and deuterium atom transfer processes enables the effective constructions of benzylic CDH moieties with high selectivity for monodeuteration. The combinational use of a bisphosphonium photocatalyst, thiol catalyst, and CH3OD deuteration agent provides operationally simple conditions for photocatalytic monodeuteration. Moreover, the photoinduced electron transfer process of the bisphosphonium photocatalyst is elucidated through a series of spectroscopy experiments, identifying a peculiar back electron transfer process that can be regulated by subsequent nucleophilic additions.

Strain learning in protein-based mechanical metamaterials

Mechanical deformation of polymer networks causes molecular-level motion and bond scission that ultimately lead to material failure. Mitigating this strain-induced loss in mechanical integrity is a significant challenge, especially in the development of active and shape-memory materials. We report the additive manufacturing of mechanical metamaterials made with a protein-based polymer that undergo a unique stiffening and strengthening behavior after shape recovery cycles. We utilize a bovine serum albumin-based polymer and show that cyclic tension and recovery experiments on the neat resin lead to a ~60% increase in the strength and stiffness of the material. This is attributed to the release of stored length in the protein mechanophores during plastic deformation that is preserved after the recovery cycle, thereby leading to a "strain learning" behavior. We perform compression experiments on three-dimensionally printed lattice metamaterials made from this protein-based polymer and find that, in certain lattices, the strain learning effect is not only preserved but amplified, causing up to a 2.5× increase in the stiffness of the recovered metamaterial. These protein-polymer strain learning metamaterials offer a unique platform for materials that can autonomously remodel after being deformed, mimicking the remodeling processes that occur in natural materials.

Stereochemical Impacts on Acyclic Mechanochemical Carbon-Carbon Bond Activation.

The influence of stereochemistry on the mechanochemistry rate is studied using a new mechanophore based on a benzopinacol (BP) skeleton. Two sets of BP diastereomers, the meso R,S and the R,R/S,S were isolated, incorporated into the center of a poly(methyl acrylate), and their mechanical activation rate was measured in solution. Under mechanical stress, the central C-C bond in BP is cleaved, providing two independent benzophenone molecules with higher UV-absorption coefficient at 254 nm. Monitoring the reaction rate spectroscopically indicates that the chiral R,R/S,S enantiomers react ~1.4 fold faster compared to the meso R,S diastereomer. In-silico modeling indicates that a hydrogen bond between the syn hydroxyls in the R,R diastereomer becomes shorter with stress, reducing the maximal force required for C-C bond scission, while this bond is inexistent in the meso diastereomer, as the hydroxyl are anti to each other. Our results indicate that in polymer where free rotation around bonds is possible, non-covalent interactions between backbone substituents, which are affected by relative stereochemistry, can play a fundamental role in the mechanochemical stability of the polymer.

Stereochemical Impacts on Acyclic Mechanochemical Carbon‐Carbon Bond Activation

The influence of stereochemistry on the mechanochemistry rate is studied using a new mechanophore based on a benzopinacol (BP) skeleton. Two sets of BP diastereomers, the meso R,S and the R,R/S,S were isolated, incorporated into the center of a poly(methyl acrylate), and their mechanical activation rate was measured in solution. Under mechanical stress, the central C‐C bond in BP is cleaved, providing two independent benzophenone molecules with higher UV‐absorption coefficient at 254 nm. Monitoring the reaction rate spectroscopically indicates that the chiral R,R/S,S enantiomers react ~1.4 fold faster compared to the meso R,S diastereomer. In‐silico modeling indicates that a hydrogen bond between the syn hydroxyls in the R,R diastereomer becomes shorter with stress, reducing the maximal force required for C‐C bond scission, while this bond is inexistent in the meso diastereomer, as the hydroxyl are anti to each other. Our results indicate that in polymer where free rotation around bonds is possible, non‐covalent interactions between backbone substituents, which are affected by relative stereochemistry, can play a fundamental role in the mechanochemical stability of the polymer.

Promoting role of Ru species on Ir-Fe/BN catalyst in 1,2-diols hydrogenolysis to secondary alcohols

Noble metal-based-bimetallic catalysts have been highly investigated and applied in wide applications including biomass transformation via regioselective C−O hydrogenolysis while further modification especially with noble metal is highly promising yet still under investigation. Herein, Ru was found as an effective modifier among the screened noble metals (Ru, Pt, Rh, Pd, Au, and Ag) for Ir-Fe/BN (Ir = 5 wt%, Fe/Ir = 0.25) catalyst in terminal C−O hydrogenolysis of 1,2-butanediol (1,2-BuD) to 2-butanol (2-BuOH). Only trace amount of Ru (up to 0.5 wt%) was effective in terms of high 2-BuOH selectivity (> 60%) and activity (about twice). Larger amount of Ru species (3 wt%) highly enhanced the activity but gave low selectivity to 2-BuOH with by-products of terminal C−C bond scission. Optimized catalyst (Ru(0.5)-Ir-Fe/BN) was reusable at least 4 times and gave moderate 2-BuOH yield (47%) in hydrogenolysis of 1,2-BuD. The promoting effect of Ru addition (0.5 wt%) to Ir-Fe/BN on hydrogenolysis of various alcohols was also confirmed. Combining catalytic tests with various characterizations, the promotion mechanism of Ru species in trimetallic catalysts was clarified. The Ru species in Ru(0.5)-Ir-Fe/BN form alloy with Ir and are enriched at the interface with BN surface, and direct interaction between Ru and Fe was not necessary in Ru-Ir-Fe alloy. The interface of Ir and Fe on the surface of Ir-Fe alloy may work as active sites for 1,2-diols to secondary alcohols via direct C−O hydrogenolysis, in which Ru-modified Ir activates H2 to form hydride-like species. The activity of Ru species in C−C bond cleavage was highly suppressed due to the direct interaction with Ir species and less exposed to substrate. Larger loading amount of Ru species (3 wt%) led to the formation Ru-rich trimetallic alloy, which further works as active sites for C−C bond scission.

Synthesis and Mass Spectrometry Structural Assessment of Polyesteramides Based on ε-Caprolactone and L-Phenylalanine.

L-Phenylalanine-ε-caprolactone-based polyesteramides (PCPs) were synthesized via melt polycondensation across a diverse range of molar compositions. The copolymer structure was extensively characterized using nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). NMR analysis confirmed the intercalation of the L-Phenylalanine comonomer units within the polyester backbone. MALDI MS characterization further demonstrated the formation of linear PCP chains with carboxyl end groups. A detailed structural analysis through MALDI MS/MS fragmentation indicated that ester bond scission was the predominant fragmentation mechanism, depicting the polyesteramide sequence in the copolymers. The resulting copolymers were primarily amorphous, except for those with molar compositions of 90/10 and 80/20, which exhibited semi-crystalline structures. Additionally, these PCPs showed an increase in glass transition temperatures with higher amino acid contents and demonstrated good thermal stabilities, as evidenced by a 10% mass loss at elevated temperatures.

Trimetallic Alloys as an Electrocatalyst for Fuel Cells: The Case of Methyl Formate on Pt3Pd3Sn2.

The shift toward renewable energy sources plays a central role in the quest for a circular economy. In this context, methyl formate (MF) has garnered attention as a compelling hydrogen carrier and alternative fuel, because of its remarkable characteristics (energy density, ease of storage and transport, and low boiling point). In this study, DFT calculations supported by online electrochemical mass spectroscopy (OE-MS) were performed to investigate the MF electro-oxidation (MFEO) on Pt3Pd3Sn2 (111). The DFT calculations provide insight into the role of Pt, Pd, and Sn atoms in MFEO. Pt and Pd together provide a preferred active site for initiating MFEO through the O-H bond scission, and Sn plays an essential role in the mitigation of CO through oxygenation or water activation. By comparing the reaction energies and activation barriers for all possible reactions in MFEO, the suggested path necessitates a minimum energy of 0.14 eV to initiate the MFEO. This value was supported by the experimental results, showing that the oxidation wave of MF starts at 0.15 V (70 °C). Density functional theory (DFT) results, supported by OE-MS, indicate that the hydrolysis of MF prior to MFEO is not preferred on Pt3Pd3Sn2 (111) surfaces, although the formation of methanol is plausible via a CH3O intermediate. Among the three small organic molecules (SOMs) studied─MF, methanol, and formic acid─MF has the lowest activation energy for the initial bond breaking that starts the whole oxidation process (0.13 eV), compared to formic acid (0.45 eV) and methanol (0.61 eV); thus, MF is the preferred fuel on Pt3Pd3Sn2 (111).

Understanding Selectivity in Product Distributions from Laser Ablation of Organic Liquids.

Pulsed laser ablation in organic solvents is widely used to produce oxide-free metal and metal carbide nanoparticles, often with carbon coatings resulting from laser-induced reactions in the organic solvent. To gain insight into how the molecular structure of the solvent affects these reaction pathways, this work investigates ablation of the C6H14 isomers n-hexane, 2-methylpentane, and 3-methylpentane through characterization of the gas and liquid products with mass spectrometry. Ablation of each C6H14 isomer produces a distinct distribution of product molecular weights and isomers. 2-methylpentane preferentially produces C3 and C9, whereas 3-methylpentane produces C2, C4, C8, and C10 products. These preferential product distributions, along with the lack of such selectivity in n-hexane, arise from differences in the most favorable C-C bond scission pathways in each C6H14 isomer. Moreover, the particular isomers of C8H18, C9H20, C10H22, and C12H26 produced by ablation of each C6H14 isomer indicate that the vast majority of reaction pathways involve addition reactions between a fragment radical and parent C6H14 or between two C6H14 molecules, without molecular rearrangement. This propensity toward direct addition suggests that the chemical reactions induced by ultrashort pulsed laser ablation proceed on faster time scales than those of radical rearrangements.

Recycling Valuable Phenol from Polycarbonate Plastic Waste Via Direct Depolymerization and Csp2-Csp3 Bond Cleavage Under Mild Conditions.

Upcycling plastic waste into commodity chemicals is recognized as an environmentally benign solution and beneficial for the sustained growth of humanity. Nevertheless, transition metal-free catalysts and energy-efficient conditions pose significant challenges due to the robust mechanical properties of plastics. Here, a strategy for selective production of phenol by upcycling polycarbonate waste via direct depolymerization and Csp2-Csp3 bond cleavage in an aqueous medium under mild conditions is reported. The commercial zeolites efficiently catalyze the depolymerization, Csp2-Csp3 bond hydrolysis, and direct Csp2-Csp3 bond scission at Cα of PC. Among all evaluated zeolites, HY (Si/Al=15) showed excellent catalytic performance, attributed to the ~75 % yield of phenol and ~15 % of acetone. The approach also employs different municipal waste PC for upcycling. Studies reveal that HY (15) exhibits high catalytic efficiency and phenol yield due to its optimum acid sites and textual properties. A scale-up experiment demonstrated that 3.1 g of phenol was produced from 5.0 g of PC, and the mass balance was 90 %. A combination of control experiments, NMR analysis, and DFT studies proposed the reaction pathway. Our findings present a sustainable avenue for upcycling PC waste and offer a new way to produce phenol, contributing to the advancement of a circular economy.

New Insights into the Understanding of High-Pressure Air Injection (HPAI): The Role of the Different Chemical Reactions

High-pressure air injection (HPAI) is an enhanced oil recovery process in which compressed air is injected into deep, light oil reservoirs, with the expectation that the oxygen in the injected air will react with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide. The different chemical reactions taking place can be grouped into oxygen addition, thermal cracking, oxygen-induced cracking, and bond scission reactions. The latter reactions involve the combustion of a flammable vapor as well as the combustion of solid fuel, commonly known as “coke”. Since stable peak temperatures observed during HPAI experiments are typically below 300 °C, it has been suggested that thermal cracking and combustion of solid fuel may not be important reaction mechanisms for the process. The objective of this work is to assess the validity of that hypothesis. Therefore, this study makes use of different oxidation and combustion HPAI experiments, which were performed on two different light oil reservoir samples. Modeling of those tests indicate that thermal cracking is not an important reaction mechanism during HPAI and can potentially be ignored. The work also suggests that the main fuel consumed by the process is a flammable vapor generated by the chemical reactions. This represents a shift from the original in situ combustion paradigm, which is based on the combustion of coke.

UV-Induced Reaction Pathways in Bromoform Probed with Ultrafast Electron Diffraction.

For many chemical reactions, it remains notoriously difficult to predict and experimentally determine the rates and branching ratios between different reaction channels. This is particularly the case for reactions involving short-lived intermediates, whose observation requires ultrafast methods. The UV photochemistry of bromoform (CHBr3) is among the most intensely studied photoreactions. Yet, a detailed understanding of the chemical pathways leading to the production of atomic Br and molecular Br2 fragments has proven challenging. In particular, the role of isomerization and/or roaming and their competition with direct C-Br bond scission has been a matter of continued debate. Here, gas-phase ultrafast megaelectronvolt electron diffraction (MeV-UED) is used to directly study structural dynamics in bromoform after single 267 nm photon excitation with femtosecond temporal resolution. The results show unambiguously that isomerization contributes significantly to the early stages of the UV photochemistry of bromoform. In addition to direct C-Br bond breaking within <200 fs, formation of iso-CHBr3 (Br-CH-Br-Br) is observed on the same time scale and with an isomer lifetime of >1.1 ps. The branching ratio between direct dissociation and isomerization is determined to be 0.4 ± 0.2:0.6 ± 0.2, i.e., approximately 60% of molecules undergo isomerization within the first few hundred femtoseconds after UV excitation. The structure and time of formation of iso-CHBr3 compare favorably with the results of an ab initio molecular dynamics simulation. The lifetime and interatomic distances of the isomer are consistent with the involvement of a roaming reaction mechanism.

Can ZnO/Cu catalyst provide promising activity for glycerol direct dehydrogenation? A combined density functional theory and coverage-dependent microkinetics study

Non-oxidative dehydrogenation (NODH) reaction of glycerol is a perfect atom economical technical route to produce higher-value 1,3-dihydroxyacetone (DHA). Cu-based catalyst (especially ZnO/Cu system), is known as active species for alcohol dehydrogenation, which may be also promising one for glycerol NODH. In this study, we combine coverage-dependent free energy profile using first-principle calculation, and microkinetic model, to investigate the NODH of glycerol on the ZnO/Cu(111) surface, and a detailed comparison is made with Cu (111) surface. The coverage-dependent microkinetic model takes into account the lateral adsorbate–adsorbate self-interactions and cross-interactions, and their effect on binding energy of both intermediate and transition state. Besides, it guarantees the reaction kinetics is based on the coverage self-consistent between surface model and microkinetic result under practically reaction conditions. Compared with coverage-dependent kinetics simulation (20 %–30 %), coverage-independent model overestimates the DHA selectivity on Cu (111) (over 90 %). Our coverage-dependent kinetics simulation illustrates that both glycerol conversion and DHA selectivity are most determined by the first dehydrogenation step (OH bond scission) of glycerol on Cu (111). However, when ZnO cluster adsorbed on the Cu (111) surface, ZnO cluster promotes the electron transferring between glycerol and Cu sites, which accelerates OH bond scission process of glycerol. Under coverage-dependent microkinetic model, the turnover frequency and selectivity of DHA on ZnO/Cu(111) get much improvement compared with Cu (111). Finally, the superior of ZnO/Cu(111) is further proved by continuous stirred tank reactor simulation, where NODH of glycerol need shorter residence times or lower temperature to reach 100 % conversion, as well as keep higher DHA selectivity.

CO2 utilization and on-purpose ethylene production: a chemical looping approach

CO2-assisted ethane dehydrogenation (CO2-ODHE) is a promising carbon atom economy process for upgrading CO2 to CO in tandem with C2H6 to C2H4 conversion. Iron oxide-based materials are selective for on purpose ethylene production through CO2-ODHE. The feed admission mode was found to play an important role on catalytic performance. Alternating C2H6 (reduction step) and CO2 (oxidation step) feedstock to a fixed bed reactor (chemical looping concept, CO2-ODHE-CL) attained constant ethane and CO2 conversion per step at 600oC, equal to ~17.6%, while C2H4 selectivity during the reduction step was ~75%. The lattice oxygen mobility is a descriptor for the materials used during the CO2-ODHE-CL, since low mobility resulted in an increased C-H bond scission selectivity, i.e., C2H4 production, during the reduction step. Temperature programmed 18O2 isotope exchange experiments, along with temperature programmed H2 – reduction, were employed to exemplify the latter statement, investigating the lattice oxygen reactivity of the examined materials and the mechanism through which the lattice oxygen is reacting. X-ray techniques (X-ray Diffraction, X-ray Raman Scattering Spectrometry, X-ray Absorption Spectrometry) along with structural modeling demonstrated that the formation of a spinel like arrangement between Mg and Fe, stabilized lattice oxygen and thus minimized the undesired C-C bond scission during the C2H6 step of CO2-ODHE-CL.

Inverse ceria-nickel catalyst for enhanced C-O bond hydrogenolysis of biomass and polyether.

Regulating interfacial electronic structure of oxide-metal composite catalyst for the selective transformation of biomass or plastic waste into high-value chemicals through specific C-O bond scission is still challenging due to the presence of multiple reducible bonds and low catalytic activity. Herein, we find that the inverse catalyst of 4CeOx/Ni can efficiently transform various lignocellulose derivatives and polyether into the corresponding value-added hydroxyl-containing chemicals with activity enhancement (up to 36.5-fold increase in rate) compared to the conventional metal/oxide supported catalyst. In situ experiments and theoretical calculations reveal the electron-rich interfacial Ce and Ni species are responsible for the selective adsorption of C-O bond and efficient generation of Hδ- species, respectively, which synergistic facilitate cleavage of C-O bond and subsequent hydrogenation. This work advances the fundamental understanding of interfacial electronic interaction over inverse catalyst and provides a promising catalyst design strategy for efficient transformation of C-O bond.

Synthesis of the double spiked µ5-sulfide pentanuclear clusters using thermic reactions of Ru3-mercaptopyridine complexes

The treatment of [Ru3(CO)10(μ-dppm)] with 6-methyl-2-mercaptopyridine (1) or 5-trifluoromethyl-2-mercaptopyridine (2) in refluxing THF for 10 h results in the formation of μ5 sulfide-capped pentanuclear clusters [Ru5(CO)11(μ-H)(μ5-S){μ-κ2N,C-NC5H3(R)})(μ-κ2P2-dppm)2] (R = CH3, 3a, 3a'; R=CF3, 3b,3b') respectively. These compounds exhibit unique structural features, with a μ5-S capped binding trinuclear and dinuclear fragments. The mercaptopyridine ligands undergo S-C bond scission, forming an orthometalated pyridine ligand coordinated to a Ru-Ru bond with a concomitant μ-hydride ligand formation. The structures also feature two dppm ligands, one in the Ru-Ru, which bears the μ-H, and the other bridging the Ru-Ru bond with the orthometallated pyridine. In solution, linkage isomers were observed; they differ in the coordination position of the orthometallated pyridine bonded to the same Ru-Ru bond. A single-crystal X-ray diffraction study confirmed the molecular structures of compounds 3a and 3b. NMR, IR, and HRMS were also carried out.

Breaking Strong Alkynyl-Phenyl Bonds: Poly(para-phenylene ethynylene)s under Mechanical Stress.

Stronger chemical bonds withstand higher mechanical forces; thus, the rupture of single bonds is preferred over the rupture of double or triple bonds or aromatic rings. We investigated bond scission in poly(dialkyl-p-phenylene ethynylene)s (PPEs), a fully conjugated polymer. In a scale-bridging approach using electron-paramagnetic resonance spectroscopy and gel permeation chromatography of cryomilled samples, in combination with density functional theory calculations and coarse-grained simulations, we conclude that mechanical force cleaves the sp-sp2 bond of PPEs (bond dissociation energy as high as 600 kJ mol-1). Bond scission primarily occurs in shear bands with locally increased shear stresses. The scission occurs in the middle of the PPE chains. Breaking sp-sp2 bonds into free radicals thus is feasible but requires significant mechanical force and an efficient stress concentration.

Bioelectricity drives transformation of nitrogen and perfluorooctanoic acid in constructed wetlands: Performances and mechanisms

In this study, constructed wetland-microbial fuel cell (CW-MFC) filled with modified basalt fiber (MBF) via iron modification was utilized for treating perfluorooctanoic acid (PFOA) containing sewage. Results showed the significant promotion by bioelectricity on ammonium and total nitrogen by 7.80–8.14 %. Although such enhancement was suppressed by PFOA, higher removal was still observed with closed circuit, and PFOA removal also increased by 9.05 %. Bioelectricity contributed to enrichment of bacteria involved in nitrifying (Nitrospira and Ellin6067), denitrifying (like Thauera and Dechloromonas), iron redox (Geobacter), and sulfate-reducing (Desulfobacter), aligned with up-regulated of functional genes, including amoA, narG , napA, narK, narS, nrfA, sulp and sqr. Enrichment of autohydrogenotrophic and sulfide-oxidizing autotrophic denitrifiers, and nitrate dependent iron oxidation bacteria by bioelectricity all promoted denitrification. Moreover, bioelectricity boosted relative abundance of organic compounds degradation enzymes, such as dehydrogenase, decarboxylase, and dehalogenase, supporting the enhancement on PFOA removal. Generally, PFOA was converted to short-chain perfluorocarboxylic acids (PFCAs) via decarboxylation, hydroxylation, HF elimination, hydrolysis, F- elimination, C-C bond scission, and dehydration in CW-MFC. The final PFCAs-products determined was perfluorobutyric acid. This work estimated feasibility of treating PFOA containing sewage by CM-MFC, and offered new insights on enhancing mechanisms of nitrogen and PFOA conversion.