Production Of Carboxylic Acids Research Articles

Optimisation of the Production of Bio-Based Basic Chemicals from Biogenic Secondary Waste Through Dispersion

Biogenic waste from waste treatment plants, also known as secondary waste, can be used to produce bio-based carboxylic acids. Conventionally, these are produced by chemically synthesis of petroleum-based raw materials or synthesis of natural oils (e.g. coconut or palm kernel oil). Using organic residues and waste materials in a cascade to produce bio-based products can contribute to the circular bioeconomy. In the biological treatment process for production of bio-based carboxylic acids, microorganisms that are already present in the secondary waste use ethanol to convert short-chain carboxylic acids (with one to three carbon atoms) into medium-chain carboxylic acids (with four to ten carbon atoms). During the treatment process, medium-chain carboxylic acids are separated from the secondary waste by using in-situ extraction (liquid-liquid extraction). In previous studies, bioreactors without a dispersing function were used on a laboratory scale. In order to optimise the production and extraction of the formed medium-chain carboxylic acids, the bioreactors should be upgraded with a device for dispersing the extraction solvent in the secondary waste. Dispersing can increase the surface area between the extraction solvent and the secondary waste and therefore also the ability to extract the medium-chain carboxylic acids. To evaluate the effects of dispersing on the production of bio-based carboxylic acids, the production and extraction rates of static bioreactors without dispersing are compared with those of dynamic bioreactors with dispersing on a laboratory scale. Leachate from a composting plant was used as secondary waste. According to the results of the current study, it can be confirmed that dispersion has a positive effect on the biological treatment process. In addition to the increased degradation of the nutrient ethanol, the production of medium-chain carboxylic acids in the secondary waste as well as the extracted medium-chain carboxylic acids could be increased by dispersing.

Selective Oxidations of Toluenes and Benzyl Alcohols by an Unspecific Peroxygenase (UPO)

Unspecific Peroxygenases (UPOs) have emerged as robust biocatalysts for selective oxygenation reactions, as they are easily produced at scale and require only hydrogen peroxide as the external oxidant. UPOs can catalyze the oxygenation of the primary benzylic carbons of toluenes to give alcohol, aldehyde and carboxylic acid products. They can also catalyze hydroxylation at the benzylic position of ethylbenzenes, and the subsequent oxidation of the secondary alcohols to ketones. In this study, we have investigated factors that affect the balance of products in UPO‐catalyzed benzylic oxygenations using a range of functionalised toluenes and ethyl benzenes, and a UPO from Agrocybe aegerita (rAaeUPO‐PaDa‐I‐H variant). The product distribution is dependent upon a mixture of steric and electronic effects and, in selected cases, controlling the reaction conditions permits products from each product series to be generated chemoselectively. In this way, electron poor toluenes were converted directly into carboxylic acids in isolated yields of 36–99% on preparative scale.

Real-Time Identification of Aerosol-Phase Carboxylic Acid Production Using Extractive Electrospray Ionization Mass Spectrometry.

Comprehensive identification of aerosol sources and their constituent organic compounds requires aerosol-phase molecular-level characterization with a high time resolution. While real-time chemical characterization of aerosols is becoming increasingly common, information about functionalization and structure is typically obtained from offline methods. This study presents a method for determining the presence of carboxylic acid functional groups in real time using extractive electrospray ionization mass spectrometry based on measurements of [M - H + 2Na]+ adducts. The method is validated and characterized using standard compounds. A proof-of-concept application to α-pinene secondary organic aerosol (SOA) shows the ability to identify carboxylic acids even in complex mixtures. The real-time capability of the method allows for the observation of the production of carboxylic acids, likely formed in the particle phase on short time scales (<120 min). Our research explains previous findings of carboxylic acids being a significant component of SOA and a quick decrease in peroxide functionalization following SOA formation. We show that the formation of these acids is commensurate with the increase of dimers in the particle phase. Our results imply that SOA is in constant evolution through condensed-phase processes, which lower the volatility of the aerosol components and increase the available condensed mass for SOA growth and, therefore, aerosol mass loading in the atmosphere. Further work could aim to quantify the effect of particle-phase acid formation on the aerosol volatility distributions.

Oxygenolytic cleavage of 1,2-diols with dioxygen by a mononuclear nonheme iron complex: Mimicking the reaction of myo-inositol oxygenase

A mononuclear iron(II) complex, [(TpPh2)FeII(OTf)(CH3CN)] (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate, OTf = triflate) has been isolated and its efficiency toward the aliphatic CC bond cleavage reaction of 1,2-diols with dioxygen has been investigated. Separate reactions between the iron(II)-triflate complex and different 1,2-diolates form the corresponding iron(II)-diolate complexes in solution. While the iron(II) complex of the tetradentate TPA (tris(2-pyridylmethyl)amine) ligand is not efficient in affecting the CC cleavage of 1,2-diol with dioxygen, complex 1 displays catalytic activity to afford carboxylic acid and aldehyde. Isotope labeling studies with 18O2 reveal that one oxygen atom from dioxygen is incorporated into the carboxylic acid product. The oxygenative CC cleavage reactions occur on the 1,2-diols containing at least one α-H atom. The kinetic isotope effect value of 5.7 supports the abstraction of an α-H by an iron(III)-superoxo species to propagate the CC cleavage reactions. The oxidative cleavage of 1,2-diolates by the iron(II) complex mimics the reaction catalyzed by the nonheme diiron enzyme, myo-inositol oxygenase.

Lactate-mediated medium-chain fatty acid production from expired dairy and beverage waste

Fruits, vegetables, and dairy products are typically the primary sources of household food waste. Currently, anaerobic digestion is the most used bioprocess for the treatment of food waste with concomitant generation of biogas. However, to achieve a circular carbon economy, the organics in food waste should be converted to new chemicals with higher value than energy. Here we demonstrate the feasibility of medium-chain carboxylic acid (MCCA) production from expired dairy and beverage waste via a chain elongation platform mediated by lactate. In a two-stage fermentation process, the first stage with optimized operational conditions, including varying temperatures and organic loading rates, transformed expired dairy and beverage waste into lactate at a concentration higher than 900 mM C at 43 °C. This lactate was then used to produce >500 mM C caproate and >300 mM C butyrate via microbial chain elongation. Predominantly, lactate-producing microbes such as Lactobacillus and Lacticaseibacillus were regulated by temperature and could be highly enriched under mesophilic conditions in the first-stage reactor. In the second-stage chain elongation reactor, the dominating microbes were primarily from the genera Megasphaera and Caproiciproducens, shaped by varying feed and inoculum sources. Co-occurrence network analysis revealed positive correlations among species from the genera Caproiciproducens, Ruminococcus, and CAG-352, as well as Megasphaera, Bacteroides, and Solobacterium, indicating strong microbial interactions that enhance caproate production. These findings suggest that producing MCCAs from expired dairy and beverage waste via lactate-mediated chain elongation is a viable method for sustainable waste management and could serve as a chemical production platform in the context of building a circular bioeconomy.

Catalyst‐Green Solvent System for Highly Efficient Production of Carboxylic Acids from Light Oxygenates, CO2 and H2

AbstractCatalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1‐ethyl‐3‐methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C−C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value‐added carboxylic acids, and therefore is promising for commercial application.

Selective Stereoretention of Carbohydrates upon C-C Cleavage Enabling D-Glyceric Acid Production with High Optical Purity over a Ag/γ-Al2O3 Catalyst.

Chiral carboxylic acid production from renewable biomass by chemocatalysis is vitally important for reducing our carbon footprint, but remains underdeveloped. We herein establish a strategy that make use of a stereogenic center of biomass to achieve a rare example of D-glyceric acid production with the highest yield (86.8 %) reported to date as well as an excellent ee value (>99 %). Unlike traditional asymmetric catalysis, chiral catalysts/additives are not required. Ample experiments combined with quantum chemical calculations established the origins of the stereogenic center and catalyst performance. The chirality at C4 in D-xylose was proved to be retained and successfully delivered to C2 in D-glyceric acid during C-C cleavage. The remarkable cooperative-roles of Ag+ and Ag0 in the constructed Ag/γ-Al2O3 catalyst are disclosed as the crucial contributors. Ag+ was responsible for low-temperature activation of D-xylose, while Ag0 facilitated the generation of active O* from O2. Ag+ and active O* cooperatively promoted the precise cleavage of the C2-C3 bond, and more importantly O* allowed the immediate fast oxidization of the D-glyceraldehyde intermediate to stabilize D-glyceric acid, thereby inhibiting the side reaction that induced racemization. This strategy makes a significant breakthrough in overcoming the limitation of poor enantioselectivity in current chemocatalytic conversion of biomass.

Selective Stereoretention of Carbohydrates upon C−C Cleavage Enabling D‐Glyceric Acid Production with High Optical Purity over a Ag/γ‐Al2O3 Catalyst

AbstractChiral carboxylic acid production from renewable biomass by chemocatalysis is vitally important for reducing our carbon footprint, but remains underdeveloped. We herein establish a strategy that make use of a stereogenic center of biomass to achieve a rare example of D‐glyceric acid production with the highest yield (86.8 %) reported to date as well as an excellent ee value (&gt;99 %). Unlike traditional asymmetric catalysis, chiral catalysts/additives are not required. Ample experiments combined with quantum chemical calculations established the origins of the stereogenic center and catalyst performance. The chirality at C4 in D‐xylose was proved to be retained and successfully delivered to C2 in D‐glyceric acid during C−C cleavage. The remarkable cooperative‐roles of Ag+ and Ag0 in the constructed Ag/γ‐Al2O3 catalyst are disclosed as the crucial contributors. Ag+ was responsible for low‐temperature activation of D‐xylose, while Ag0 facilitated the generation of active O* from O2. Ag+ and active O* cooperatively promoted the precise cleavage of the C2−C3 bond, and more importantly O* allowed the immediate fast oxidization of the D‐glyceraldehyde intermediate to stabilize D‐glyceric acid, thereby inhibiting the side reaction that induced racemization. This strategy makes a significant breakthrough in overcoming the limitation of poor enantioselectivity in current chemocatalytic conversion of biomass.

Pulsed‐Laser‐Driven CO2 Reduction Reaction for the Control of the Photoluminescence Quantum Yield of Organometallic Gold Nanocomposites

Over the last decade, the CO2 reduction reaction (CO2RR) has been increasingly exploited for the synthesis of high‐value raw materials in gaseous or liquid form, although no examples of CO2 fixation in nanoparticle systems have been demonstrated. Herein, CO2 fixation into solid nanomaterials by laser synthesis and processing of gold colloids in water, traditionally considered a green approach leading to ligand‐free nanoparticles without the formation of by‐products, is reported. If carbon monoxide‐rich gold nanoparticles are observable even after synthesis in deionized water, the presence of CO2 derivatives in alkaline water environment leads to C2 and C3 coupling with the production of carboxylic acids as a typical CO2RR fingerprint. While laser processing of preformed gold colloids is selective for C2 coupling, both C2 and C3 coupling to lactic acid are observed during pulsed laser ablation of a gold target. In the latter case, it is demonstrated that it is possible to synthesize photoluminescent organometallic nanocomposites in the blue spectral region with a quantum yield of about 20% under adequate experimental conditions. In this research, new pathways are offered to be explored in energetics, photonics, catalysis, and synthesis at the nanoscale.

Oxidation of organics in water by active chlorine performed in microfluidic electrochemical reactors: a new way to improve the performances of the process

Wastewater polluted by organics can be treated by using electro-generated active chlorine, even if this promising route presents some important drawbacks such as the production of chlorinated by-products. Here, for the first time, this process was studied in a microfluidic electrochemical reactor with a very small inter-electrode distance (145 μm) using a water solution of NaCl and phenol and a BDD anode. The potential production of chloroacetic acids, chlorophenols, carboxylic acids, chlorate and perchlorate was carefully evaluated. It was shown, for the first time, up to our knowledge, that the use of the microfluidic device allows to perform the treatment under a continuous mode and to achieve higher current efficiencies and a lower generation of some important by-products such as chlorate and perchlorate. As an example, the use of the microfluidic apparatus equipped with an Ag cathode allowed to achieve a high removal of total organic carbon (about 76%) coupled with a current efficiency of 17% and the production of a small amount of chlorate (about 30 ppm) and no perchlorate. The effect of many parameters (namely, flow rate, current density and nature of cathode) was also investigated.

Fast co-pyrolysis of wood and plastic: Evaluation of the primary gaseous products

Bio-oil derived from fast pyrolysis of wood contains oxygenates and has a relatively low heating value. These are challenges that need to be tackled if wood-derived bio-oil is to be used as drop-in fuels. The bio-oil can be obtained by condensation of gaseous products. Using a material with no oxygen in addition to wood during fast pyrolysis could be a technique to reduce the formation of oxygenates and promote a hydrocarbon-rich product. This work aims to evaluate the primary gaseous products formed during fast co-pyrolysis of birch wood and plastic. The pyrolysis was performed in a micropyrolyser at 600 °C with a residence time of 5 s. Birch wood and plastic were melt-mixed at different weight ratios to study possible interaction effects upon pyrolysis. The different plastics used were low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS). The total gaseous product was between 10–20 wt% from Wood-LDPE or Wood-PP, while it was in the range 15–90 wt% from Wood-PS. The analysis of gas product found that the formation of oxygenates (up to 9 wt%) was lower than expected (up to 14 wt%) for the mixtures of wood and plastic compared to the pure materials (about 18 wt%). The reduction of oxygenates (up to 90 %) was mainly due to a lower production of ketones, carboxylic acids and aldehydes. Maximum hydrocarbons in the gas phase from binary mixtures were around 8, 15 and 55 wt% from Wood-LDPE, Wood-PP and Wood-PS, respectively. The most significant difference between experimental and estimated values assuming no interaction among hydrocarbons was observed in the case of alkenes and alkanes for Wood-LDPE, as well as alkanes for Wood-PS, while the Wood and PP mixture showed almost no signs of interaction. This work is beneficial for understanding interactions between wood and plastics, and could be used to reduce the amount of oxygenates from wood pyrolysis and reduce the need for upgrading.

Influence of pH and temperature on the performance and microbial community during the production of medium-chain carboxylic acids using winery effluents as substrate.

Winery effluents containing high ethanol concentrations and diverse organic matter are ideal substrates for producing medium-chain carboxylic acids via fermentation and chain elongation. However, the process needs to be better understood. This study presents novel insights into the bioconversion mechanisms of medium-chain carboxylic acids by correlating fermentation and chain elongation kinetic profiles with the study of microbial communities at different pH (5 to 7) conditions and temperatures (30 to 40°C). It was found that high productivities of MCCA were obtained using a native culture and winery effluents as a natural substrate. Minor pH variations significantly affected the metabolic pathway of the microorganisms for MCCA production. The maximal productivities of hexanoic (715mg/L/d) and octanoic (350mg/L/d) acids were found at pH 6 and 35°C. Results evidence that the presence of Clostridium, Bacteroides, and Negativicutespromotes the high productions of MCCA. The formation of heptanoic acid was favor when Mogibacterium and Burkholderia were present.

Modelling of reaction kinetics in production of hydroxy carboxylic acids by alkaline degradation of cellulosic waste

The reaction kinetics in alkaline degradation of cellulosic materials to monomeric compounds at elevated temperatures was studied. The target compounds are hydroxy carboxylic acids, preferably glucoisosaccharinic acid (GISA), that are valuable platform chemicals. This methodology, which focuses on depolymerizing cellulosic materials and transforming them into hydroxy carboxylic acids, has not been explored in existing literature. To this end, a rigorous mathematical model was developed that considers phenomena at macroscopic level (transformation of crystalline cellulose into amorphous) and at microscopic level (cleavage of glycosidic bonds). Experimental cellulose degradation data in 10 wt-% NaOH and 20–200 °C was correlated with the model. The agreement between the model results and the experimental data confirmed that the process obeys the proposed reaction pathway. Around 80 % of degradation occurs during the reactor warming up period. Analysis of rate constants indicates that GISA is not degraded into smaller hydroxy acids (SHA) at the temperatures studied. Instead, monosaccharides are converted into SHA as soon as they are produced. Conversion of crystalline cellulose into amorphous form was identified as the rate determining step.

A long noncoding RNA functions in pumpkin fruit development through S-adenosyl-L-methionine synthetase.

Long non-coding RNAs (lncRNAs) play important roles in various biological processes. However, the regulatory roles of lncRNAs underlying fruit development have not been extensively studied. Pumpkin (Cucurbita spp.) is a preferred model for understanding the molecular mechanisms regulating fruit development because of its variable shape and size and large inferior ovary. Here, we performed strand-specific transcriptome sequencing on pumpkin (Curcurbita maxima 'Rimu') fruits at six developmental stages and identified 5425 reliably expressed lncRNAs. Among the 332 lncRNAs that were differentially expressed during fruit development, MSTRG.44863.1 was identified as a negative regulator of pumpkin fruit development. MSTRG.44863.1 showed a relatively high expression level and an obvious period-specific expression pattern. Transient overexpression and silencing of MSTRG.44863.1 significantly increased and decreased the content of 1-aminocyclopropane carboxylic acid (a precursor of ethylene) and ethylene production, respectively. RNA pull-down and microscale thermophoresis assays further revealed that MSTRG.44863.1 can interact with S-adenosyl-L-methionine synthetase (SAMS), an enzyme in the ethylene synthesis pathway. Considering that ethylene negatively regulates fruit development, these results indicate that MSTRG.44863.1 plays an important role in the regulation of pumpkin fruit development, possibly through interacting with SAMS and affecting ethylene synthesis. Overall, our findings provide a rich resource for further study of fruit-related lncRNAs while offering insight into the regulation of fruit development in plants.

Trivalent Nickel-Catalyzing Electroconversion of Alcohols to Carboxylic Acids.

The comprehension of activity and selectivity origins of the electrooxidation of organics is a crucial knot for the development of a highly efficient energy conversion system that can produce value-added chemicals on both the anode and cathode. Here, we find that the potential-retaining trivalent nickel in NiOOH (Fermi level, -7.4 eV) is capable of selectively oxidizing various primary alcohols to carboxylic acids through a nucleophilic attack and nonredox electron transfer process. This nonredox trivalent nickel is highly efficient in oxidizing primary alcohols (methanol, ethanol, propanol, butanol, and benzyl alcohol) that are equipped with the appropriate highest occupied molecular orbital (HOMO) levels (-7.1 to -6.5 eV vs vacuum level) and the negative dual local softness values (Δsk, -0.50 to -0.19) of nucleophilic atoms in nucleophilic hydroxyl functional groups. However, the carboxylic acid products exhibit a deeper HOMO level (<-7.4 eV) or a positive Δsk, suggesting that they are highly stable and weakly nucleophilic on NiOOH. The combination (HOMO, Δsk) is useful in explaining the activity and selectivity origins of electrochemically oxidizing alcohols to carboxylic acid. Our findings are valuable in creating efficient energy conversions to generate value-added chemicals on dual electrodes.

Biochar-based solid-acid catalysts for the selective oxidation of glucose to α,β-unsaturated carboxylic acids in water

H2SO4-modified biochar loaded with TiO2nanoparticles (SBC) was synthesized via anoxic pyrolysis of rice straw biomass. This SBC material was employed for the photo-Fenton-like oxidative conversion of D(+)-glucose intoα,β-unsaturated carboxylic acids (UCAs). Varying catalyst and peroxide loadings generated multiple reactive oxygen species (ROS), including •OH and •O2–, as well as photogenerated electrons and holes. Remarkably, a 90.8 % glucose conversion rate was achieved within 4 h, with an overall carboxylic acid production rate of 463.0μ mol.gcat-1.h-1 and 330.3μ mol.gcat-1.h-1 for UCAs, while maintaining a high selectivity of 71 %. This study elucidated the mechanism through UHPLC-MS/MS analysis, demonstrating the potential of SBC for sustainable glucose valorization and renewable chemicals production.

A general strategy for recycling polyester wastes into carboxylic acids and hydrocarbons

Chemical recycling of plastic wastes is of great significance for sustainable development, which also represents a largely untapped opportunity for the synthesis of value-added chemicals. Herein, we report a novel and general strategy to degrade polyesters via directly breaking the Calkoxy-O bond by nucleophilic substitution of halide anion of ionic liquids under mild conditions. Combined with hydrogenation over Pd/C, 1-butyl-2,3-dimethylimidazolium bromide can realize the deconstruction of various polyesters including aromatic and aliphatic ones, copolyesters and polyester mixtures into corresponding carboxylic acids and alkanes; meanwhile, tetrabutylphosphonium bromide can also achieve direct decomposition of the polyesters with β-H into carboxylic acids and alkenes under hydrogen- and metal-free conditions. It is found that the hydrogen-bonding interaction between ionic liquid and ester group in polyester enhances the nucleophilicity of halide anion and activates the Calkoxy-O bond. The findings demonstrate how polyester wastes can be a viable feedstock for the production of carboxylic acids and hydrocarbons.

Bio-based production of medium-chain carboxylic acids from food waste and sludge without chemical addition: The pivotal role of mix ratio and pretreatment

Medium-chain carboxylates such as caproic acid, have a plethora of applications, ranging from food additives to bioplastics, and can be produced via microbial chain elongation (CE), a process that can be more sustainable than conventional production routes. During CE short fatty acids accept electrons from donors as lactate or ethanol elongating into medium-chain carboxylates with higher economic value and easier recoverability. Nowadays, waste activated sludge (WAS) and food waste (FW) are the most abundant waste steams generated in European cities impacting dramatically on environment, society, and economic sectors. A novel sustainable biotechnology is here proposed to produce marketable caproic acid from mixed WAS and FW with in-situ self-formed lactate without buffering agents addition. Different mix ratios between WAS and FW, and thermal pretreatment strategies were compared by fermentation batch tests. The production of lactate as electron donor (ED), together with acetate and butyrate, and hydrogen assured high production of caproate only in presence of thermal pretreated WAS, able to reduce the potential risk of lactate accumulation and drop in pH. The findings of this study demonstrate that the initial soluble carboydrate/protein ratio significantly affected the pH of the fermentation broth in the first hours of fermentation, and that only using FW and pretreated WAS mixed using a ratio of 60/40 in terms of volatile solids, CE pathway and lactate utilization as ED were promoted obtaining the highest percentage of caproate (about 21% of the total produced carboxylic acids; 2 gCOD/L).

A comparative study of two aldehyde dehydrogenases from Sphingobium sp.: the substrate spectrum and catalytic mechanism.

Biocatalytic oxidation is one of the most important and indispensable organic reactions for the development of green and sustainable biomanufacturing processes. NAD(P)+-dependent aldehyde dehydrogenase (ALDH) catalyzes the oxidation of aldehydes to carboxylic acids. Here, two ALDHs, SpALDH1 and SpALDH2, were identified from Sphingobium sp. SYK-6. They belong to different ALDH families and share only 32.30% amino acid identity. Interestingly, SpALDH1 and SpALDH2 exhibit significantly different enzymatic properties and substrate profiles. SpALDH2 has better thermostability than SpALDH1. SpALDH1 is a metalloenzyme and is activated by potassium ions, while SpALDH2 is not metallic-dependent. Compared with SpALDH1, SpALDH2 has a relatively broad substrate spectrum toward aromatic aldehydes. Based on homology modeling and molecular docking analysis, mechanisms underlying the substrate specificity of ALDHs were elucidated. For both ALDHs, hydrophobicity of substrate binding pockets is important for the catalytic properties, especially substrate specificity. Notably, optimization of the flexible loop 444-457 reforms a hydrogen bond between pyridine substrates and SpALDH1, contributing to the high catalytic activity. Finally, a coupling reaction catalyzed by ALDHs and NOX was constructed for efficient production of aromatic carboxylic acids.

Supramolecularly modulated carbon-centered radicals: toward selective oxidation from benzyl alcohol to aldehyde.

The reactivity of ketyl radicals and benzoyl radicals, two key intermediates of photo-induced oxidation of benzyl alcohol, can be stabilized by the host-guest interaction of the radicals with cucurbit[7]uril. As a result, the selectivity of photo-induced oxidation from benzyl alcohol to aldehyde is significantly improved by diminishing side reactions and inhibiting the generation of carboxylic acid products. This work presents a new route to modulate the reactivity of radical intermediates, enriching the chemistry of supramolecular intermediates and the toolbox of supramolecular catalysis.