Diazotization Reaction Research Articles

A Hydrazone Derivative: Synthesis, Crystal Structure, Supramolecular Assembly Exploration by Hirshfeld Surface Analysis and Computational Study

The diazotization reaction of o-trifluoromethyl aniline from aromatic amines with 5,5-dimethylcyclohexane-1,3-dione was studied, as a result, 2-(2-(o-trifluoromethylphenyl)hydrazono)-5,5-dimethylcyclohexane-1 ,3-dione (THDCD) was synthesized and its structure was confirmed by X-ray diffraction analysis. The solid state assembly is stabilized by numerous intermolecular interactions which are deeply probed by Hirshfeld surface analysis. The enrichment ratio was computed for getting the contact with the highest propensity to form crystal packing interaction. The mechanical response of the crystal is predicted by voids analysis. Moreover, interaction energy calculations were performed at HF/3-21G electron density model to further inspect the supramolecular assembly of the crystal. DFT calculation was conducted using B3LYP level with 6–311++G(d, p) basic set with the help of Gaussian 09W and GaussView 6.0 packages. MEP surface, HOMO-LUMO orbitals, and NBO theory were analyzed via DFT approach. Theoretical method confirms the proposed geometry of THDCD by X-ray analysis.

Nonmetal catalyst boosting amplification of both colorimetric and electrochemical signal for multi-mode nitrite sensing

Recently, nanozymes as an outstanding alternative to natural enzymes has attracted wide attention because of its high stability performance. In this study, PNC nonmetal nanozymes with high oxidase-like activity was synthesized can specifically catalyze colorless 3,3,5,5-tetramethyl-benzidine(TMB) to form blue oxidized TMB (TMBox). In the presence of nitrite, it further oxidizes TMBox to obtain yellow derivative products attributed to nitrite inducing diazotization reaction in TMBox. Based on this principle, a colorimetric and electrochemical sensing system was developed, and the ultra-sensitive multi-mode detection of nitrite was realized by combining RGB mode of smart phone, UV–Vis spectrum and electrochemical method. Compared with single signal detection, the multi-mode sensing system can realize self-validation to achieve more reliable detection results. What's more, the developed multi-mode sensing could quickly and sensitively detect nitrite in real sample, especially RGB mode of smart phone meeting the equipment limited areas, suggesting a broad application prospects in food safety.

Accurate determination of Biotinidase activity in serum by HPLC and its utilization as second tier test for the confirmation of initial positive newborn screening results

Diagnosis of Biotinidase deficiency (BTD) is extremely important to avoid several neurodevelopmental problems in early childhood. Colorimetric and fluorometric methods lack specificity and selectivity due to several interferences resulting in a high number of false positive results. We developed an HPLC method for BTD activity in serum with fluorescent detection. In colorimetric assays, biotinidase attacks the amide linkage of the artificial substrate biotinidyl-4-aminobenzoic acid (B-PABA) and releases p-aminobenzoic acid (PABA), which is converted to a purple dye by diazotization reaction. The newly developed method injects the reaction mixture directly into the HPLC column and quantifies using a six-point calibration curve without coupling and diazotization reaction. The method is linear over the 5–1000 μmol/L range. The detection and quantitation limits were 2.5 μmol/L and 5.0 μmol/L, respectively. When compared with colorimetric assay, the correlation coefficient (R2) was 0.9963. The within-assay and between-assay precision was <10.0% for four levels of quality control samples. No significant variation in BTD activity was detected due to hemolysis, icteric, and lipemic samples. The newly developed method eliminates the potential interference due to the presence of aromatic amines and significantly reduces the false positive results observed with the colorimetric method. It is simple, specific, sensitive, faster in sample preparation, and requires a small sample volume. The newly developed HPLC method was used in our laboratory as a secondary tier test for initial positive BTD samples from newborn screening programs. To our knowledge, no similar HPLC method has been reported to date.

Fabrication of a porous Urea@MIL-100(Fe)/CI-MCC/SA hydrogel for All-In-One adsorption, removal and fluorescence monitoring of nitrite

In this paper, a novel All-In-One Urea@MIL-100(Fe)/CI-MCC/SA hydrogel platform was generated by microcrystalline cellulose (MCC) functionalized with pH-response probe (CI), MIL-100 (Fe) and sodium alginate (SA), which was as a carrier of urea to adsorb, remove and monitor NO2-. Under acidic condition, the fluorescent hydrogel platform could produce N2, CO2 and H2O through the diazotization and redox reaction between urea and NO2- with a removal efficiency up to 99.8%, and could also character a good adsorption property for NO2- due to the positive charges of protonation (the maximum adsorption capacity was 21.67 mg g−1), and the adsorption kinetics conformed to pseudo-second-order model. By carried out the NO2- removal step in fluorescent hydrogel platform, NO2- could also be detected indirectly by sensing the changes of pH within 15 min. The linear response range was 0–0.005 M, and the detection limit (LOD) was 74 μM. These results demonstrated that this All-In-One Urea@MIL-100(Fe)/CI-MCC/SA hydrogel platform had great potential in environment. This strategy for the removal and monitoring of NO2- could be employed to related applications in water purification and environmental protection. Environmental implicationNitrite is one of the important indicators of water monitoring, which is harmful to human and environment. The removal and monitoring of nitrite in industrial wastewater and surface water is very important, but there are no studies about it at present. Based on the fact that urea can react with nitrite to produce green products, we synthesized a novel functional hydrogel to achieve adsorption, removal and fluorescence monitoring of nitrite for the first time. Besides, the practicability of the material in environmental water samples was verified through the detection of nitrite in simulated wastewater.

Synthesis, antibacterial and antimonooxidase activity of 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide

A new method for obtaining 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide an antiglaucomatous drug candidate oxazopt was developed using a diazotization reaction. A combined potentiated effect of the antimicrobial action of carbapenems (meropenem) and aminoglycosides (gentamicin) against antibiotic-resistant gram-positive bacteria Enterococcus faecium, Enterococcus faecalis and gram-negative bacteria Escherichia coli and antimonooxidase effect in vitro was revealed for this compound.

Synthesis, characterization, and application of novel aryldiazenyl disperse dyes on polyester fabrics

Azo dyes are widely used for dyeing polyester fabrics but require optimization of properties like color strength and fastness. Fourteen novel disperse azo dyes were synthesized from 2,3-naphthalenediol and aniline derivatives to examine their potential for polyester dyeing. The dyes were prepared via diazotization and coupling reactions and characterized using FT-IR, UV–Vis, 1H NMR, 13C NMR, and elemental analysis. Furthermore, several techniques were employed to study the azo-hydrazone tautomerism, including UV–Vis spectroscopy, NMR spectroscopy, and computational methods. DFT computations revealed hydrazone tautomers were more stable than azo tautomers. The prepared azo dyes were applied on polyester fabrics at 2% depth using a high temperature pressure technique in water utilizing DYEWELL-002 as a dispersing agent. The color shading of dyed polyester samples ranged from peach amber to apple of my eye, depending on the coupler moieties. The fastness properties, assessed using a grey scale of dyed polyester fabrics, indicated very good to excellent grades for most dyes. Additionally, measurements of color strength (K/S), dye exhaustion (%E), as well as colorimetric colors CILAB of dyed polyester fabrics values, were measured and discussed in terms of the effect of substituents. The findings provide new insights into structure-performance relationships to design optimized disperse dyes for polyester coloration. Overall, the synthesized aryldiazenyl dyes are promising candidates for dyeing polyester fabrics across a spectrum of shades with good fastness properties.

Synthesis and Characterization of a Novel Azo-Dye Schiff Base and Its Metal Ion Complexes Based on 1,2,4-Triazole Derivatives

The study focused on producing and examining the properties of the 2-(((3-mercapto-5-(4-nitrophenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)-4-(((4-mercaptophenyl) diazenyl)phenol) ligand (L) and its complexes with three transition metal ions, namely Ni(II), Co(II), and Cu(II). The ligand was formed through diazotization and coupling reactions between 4-aminobenzenethiol and a coupling Schiff base derived from 1,2,4-triazole. The characterization of the ligand and its metal ion complexes was carried out using analytical techniques such as FTIR, 1H- and 13C-NMR, UV-visible spectroscopy, and thermal analysis (TGA and DTG). Various physical methods were employed to synthesize and analyze the properties of the three mononuclear Co(II), Ni(II), and Cu(II) complexes with the azo-dye Schiff's base ligand. Based on the microanalysis and spectroscopic results, it was determined that the coordination between the azo Schiff base ligand and the central metal ion occurred through the NOS-donating atoms of the ligand. The analysis of the electronic spectra revealed that the synthesized Co(II) and Ni(II) complexes exhibited an octahedral geometry, while the Cu(II) complex had a distorted octahedral geometry. The implications of the finding regarding the octahedral and distorted-octahedral geometries include expanding the structural diversity in coordination chemistry, providing insights into ligand-metal interactions, and understanding the influence of geometry on properties.

Capturing Acidic CO2 Using Surface-Active Difunctional Core-Shell Composite Polymer Particles via an Aqueous Medium.

Multifunctional surface-active polymeric composites are attractive materials for the adsorption of various small molecules. Herein, dual-functionalized micron-sized surface-active composite polymer particles were prepared by a three-step process for CO2 adsorption. First, polystyrene (PS) seed particles were prepared via the dispersion polymerization of styrene. PS/P(MMA-AAm-EGDMA) composite polymer particles were then synthesized by aqueous seeded copolymerization of methyl methacrylate (MMA) and acrylamide (AAm) in the presence of an ethylene glycol dimethacrylate (EGDMA) cross-linker. Finally, the amide moieties of PS/P(MMA-AAm-EGDMA) composite particles were converted into an amine-functionalized composite by using the Hofmann degradation reaction. The presence of primary amine groups on the surface of aminated composite particles was confirmed by some conventional chemical routes, such as diazotization and Schiff's base formation reactions. The formation and functionality of the PS seed, PS/P(MMA-AAm-EGDMA), and aminated PS/P(MMA-AAm-EGDMA) composite polymer particles were confirmed by Fourier transform infrared (FTIR) spectra analyses. Scanning electron microscopy (SEM) analysis revealed spherical shape, size, and surface morphologies of the PS seed, reference composite, and aminated composites. The elemental surface compositions, surface porosity, pore volume, pore diameter, and surface area of both composite particles were evaluated by energy-dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. Dynamic light scattering (DLS) and ζ-potential measurements confirmed the pH-dependent surface properties of the functionalized particles. The amount of the adsorbed anionic emulsifier, sodium dodecyl sulfate (SDS), on the surface of aminated PS/P(MMA-AAm-EGDMA) is higher at pH 4 than that at pH 10. A vice versa result was found in the case of cationic surfactant, hexadecyltrimethylammonium bromide (HTABr), adsorption. Synthesized aminated composite particles were used as an adsorbent for CO2 adsorption via bubbling CO2 in an aqueous medium. The changes in dispersion pH were monitored continuously during the adsorption of CO2 under various conditions. The amount of CO2 adsorption by aminated composite particles was found to be 209 mg/g, which is almost double that of reference composite particles.

A facile tert-butyl nitrite-assisted preparation of deamino graphitic carbon nitride (DA-gCN) as a photocatalyst for the C-H arylation of heteroarenes using anilines as radical source.

In pristine graphitic carbon nitride (g-CN), amino groups often function as structural defects that trap photogenerated charges, resulting in low photocatalytic activity as well as reaction with nitrite, aldehyde, etc., ensuing in poor product yield. Without significantly altering the optical characteristics, the removal of amino groups is necessary to increase the photocatalytic activity and structural stability of pristine g-CN. The deamino graphitic carbon nitride (DA-gCN-5) was prepared by tert-butyl nitrite (TBN)-treatment, characterized and used as a photocatalyst for the radical C-H arylation of heteroarenes using anilines as radical source. Indeed, the photophysical characteristics of DA-gCN-5 and those of pristine g-CN are very comparable, except that DA-gCN-5 has a fewer residual amino groups, higher crystallinity, and compressed structure with a different morphology. Moreover, DA-gCN-5-catalyzed C-H arylation reaction offers greater product yield in a shorter reaction time compared to that of pristine g-CN in the coupling between heteroarenes and the in situ generated aryl diazonium salts from anilines under visible light irradiation. The amino groups in pristine g-CN absorbed the TBN that was added to convert aniline into the appropriate diazonium ions during the reaction. As a result, deamino graphitic carbon nitride produced by chemical treatment has better photophysical properties and catalytic activity than pristine g-CN. Additionally, this is the first method that uses diazotization reaction for the preparation of deamino graphitic carbon nitride, as far as we are aware.

Process of Preparing 3-methyl-6-nitro-1H-indazole by Scale of 180 g/batch as an Important Intermediate for the Preparation of Pazopanib

Pazopanib hydrochloride, marketed worldwide under the brand name Votrient, is an anti-cancer medication manufactured by Novartis. It is the first and only tyrosine kinase inhibitor currently approved for the treatment of multiple histological subtypes of soft tissue sarcoma (STS). In previous studies, we presented initial results regarding the synthesis of 3-methyl-5-nitro-2H-indazole (3) as an important indazole component on a laboratory scale (approximately 10 g/batch). In this study, we have successfully synthesized this compound (3) at a scale of 200 g/batch, achieving an overall process yield of 79.6 % from the starting material ethylaniline. This yield is higher than that reported in previous publications. Some of the technical conditions that have been improved include optimizing the amount of sulfuric acid in the nitration reaction, the amount of acetic acid, sodium hydroxide in the diazotization reaction for ring closure, reaction temperature, and the feed method to control the reaction safely and achieve high efficiency at a scale of 200 g/batch.

The Mn/Yb/Er triple-doped CeO2 nanozyme with enhanced oxidase-like activity for highly sensitive ratiometric detection of nitrite

Long-term excessive intake of nitrite (NO2−) poses a great threat to human health, needing a simple and fast method to detect NO2− in food. Herein, via a simple and feasible strategy, Mn/Yb/Er triple-doped CeO2 nanozyme (Mn/Yb/Er/CeO2) was synthesized for highly sensitive ratiometric detection of nitrite. By doping Mn, Yb, Er into CeO2 lattice structure, Mn/Yb/Er/CeO2 nanozyme showed enhanced oxidase-like activity, obtaining a higher density of oxygen vacancy and a higher ratio of Ce3+ to Ce4+ than that of CeO2. The 3,3′,5,5′-tetramethylbenzidine (TMB) can be effectively oxidized by Mn/Yb/Er/CeO2 to produce the oxidized TMB (oxTMB), showing a significant absorption signal at 652 nm. Additionally, nitrite can react with oxTMB to produce yellow diazotized oxTMB, which is accompanied by an elevated absorption signal at 445 nm and a decreased absorption signal at 652 nm. Thus, based on the oxidase-mimetic activity of Mn/Yb/Er/CeO2 and the diazotization reaction between NO2− and oxTMB, a ratiometric colorimetric assay was established for NO2− detection in food. Furthermore, by integrating Mn/Yb/Er/CeO2 with a smartphone, a colorimetric smartphone-sensing platform was successfully fabricated for visualization and quantitative detection of NO2−. Notably, this two-detection mode showed excellent sensitivity, selectivity, reliability and practicability in monitoring the NO2− in real samples, impling its great potential for food safety.

Cobalt-Nitrogen Co-Doped Carbon as Highly Efficient Oxidase Mimics for Colorimetric Assay of Nitrite.

Transition metal-N-doped carbon has been demonstrated to mimic natural enzyme activity; in this study, cobalt-nitrogen co-doped carbon (Co-N-C) nanomaterial was developed, and it could be an oxidase mimic. Firstly, Co-N-C with oxidase-like activity boosts the chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to produce the oxidized TMB (oxTMB). And the aromatic primary amino group of oxTMB reacts with nitrite (NO2-) to form diazo groups. Based on this background, we developed a cascade system of a Co-N-C-catalyzed oxidation reaction and a diazotization reaction for nitrite determination. The low detection limit (0.039 μM) indicates that Co-N-C is superior compared with the vast majority of previously reported nitrite assays. This study not only provides a novel nanozyme with sufficiently dispersed active sites, but it also further applies it to the determination of nitrite, which is expected to expand the application of nanozymes in colorimetric analysis.

Surface room-temperature treatment of polyamide-based reverse osmosis membrane by diazotization reagent: Perm-selectivity regulation and mechanism

The use of acidic nitrite as diazotization reagent has been adopted previously for performance improvement of finished polyamide-based reverse osmosis membrane through post-treatment under a low temperature. However, the mechanism of diazotization reagent treatment on the membrane intrinsic permeability coefficients for both solvent and solute is still not clear and low-temperature treatment is energy intensive. This work focused on the mechanism and the efficient regulation of perm-selectivity by surface treatment of polyamide-based reverse osmosis membrane with diazotization reagent under room temperature. Polyamide based membranes were treated with diazotization reagent under temperatures between 5.0 and 25.0 °C. Membrane physico-chemical property was characterized via instrumental analysis and membrane intrinsic permeation coefficient was evaluated via cross-flow permeation test. It was found that the diazotization reagent treatments under 5.0, 15.0 and 25.0 °C could effectively enhance membrane intrinsic permeability coefficient for water (A) by 14.1, 17.7 and 21.7%, lower membrane intrinsic permeability coefficient for NaCl (B) by 60.1, 50.0 and 40.3%, and improve membrane perm-selectivity (A/B) from 5.55 bar-1 to 15.76, 13.00 and 11.31 bar-1, respectively. Mechanism exploration revealed that both the diazotization reaction occurred with end amino groups and the N-nitrosylation reaction occurred with amide bonds had a great influence on the membrane performance. Diazotization reagent treatment under different pH demonstrated that the perm-selectivity of polyamide-based membrane could be finely regulated by controlling an optimized pH of diazotization reagent at 1.5. The performance regulation efficiency of diazotization reagent treatment was also found to be related with the initial performance of the treated membrane. Under the same condition, salt rejections of 96.5% and 98.0% could be improved up to 98.3% and 98.8%, respectively. This work not only explains the mechanism of diazotization reagent treatment on regulation of membrane perm-selectivity, but also provides a room-temperature modification method suitable for performance enhancement of newly produced membrane and performance restoration of used membrane.

Locking nitrogen dopants in porous carbons through in situ grafting strategy for enhanced oxygen reduction reactions

We report here the synthesis of N-doped porous carbon (PC) through a convenient melamine pre-grafting strategy. The melamine derivative with a monolayer structure was first grafted on the surface of the micropores of PC using a suitable diazotization reaction of melamine in an aqueous solution. After pyrolysis, PC grafting with melamine derivative was converted to the obtained N-doped PC. Meanwhile, more nitrogen dopants were grafted, and nitrogen functionalities were reconstructed to generate more graphitic N and pyridinic N atoms, in which the mesopores volume was consequently enlarged. Because of the unique structures mentioned above, the as-obtained N-doped PC exhibited enhanced oxygen reduction activity under alkaline compared with the N-doped PC from the standard physical mixture of PC and melamine. Besides, the obtained N-doped PC showed a comparable half-wave potential, remarkable durability, and good methanol tolerance compared with the commercial 20% Pt/C electrocatalyst. The results presented here could guide the development of new and improving metal-free nitrogen-doped porous carbon catalysts toward oxygen reduction reaction.

Readily Accessible M-Ferrocenyl-Phenyl Sulfonate as Novel Cathodic Electrolyte for Aqueous Organic Redox Flow Batteries

Ferrocene derivatives are amongst the most promising electroactive organic electrolytes. The bottleneck problems of their application in aqueous redox flow batteries are their poor solubility and lower potential as well as the complexity of the modification methods to solve these problems. In this study, a benzenesulfonic acid group is easily introduced into the ferrocene structure by a mature diazotization reaction, and the synthesized sodium m-phenylferrocene sulfonate BASFc is used as the novel cathodic electroactive electrolyte for AORFB. The hydrophilicity and the electron-absorbing effect of the introduced benzenesulfonic group can effectively improve the water solubility and redox potential of ferrocene. Moreover, the introduction of phenyl extends the conjugated structure of ferrocene and increases its structural dimension, which may be conducive to reducing its membrane permeability and improving the structural stability to some extent. The physical structure and the electrochemical properties of BASFc are studied systematically; the feasibility of its application as a cathodic electrolyte in AORFBs is verified by assembling the half-cell and full-cell. The results verify the good electrochemical reaction kinetics of BASFc in acid electrolyte and the corresponding AORFB shows satisfactory efficiency and stability.

Synthesis, characterization, antimicrobial studies, and molecular docking studies of transition metal complexes formed from a benzothiazole-based azo ligand

ABSTRACT. The azo ligand obtained from the diazotization reaction of 2-aminobenzothiazole and 4-nitroaniline yielded a novel series of complexes with Co(II), Ni(II), Cu(II), and Zn(II) ions. The complexes were investigated using spectral techniques such as UV-Vis, FT-IR, 1H and 13C NMR spectroscopic analyses, LC-MS and atomic absorption spectrometry, electrical conductivity, and magnetic susceptibility. The molar ratio of the synthesized compounds was determined using the ligand exchange ratio, which revealed the metal-ligand ratios in the isolated complexes were 1:2. The synthesized complexes were tested for antimicrobial activity against S. aureus, E. coli, C. albicans, and C. tropicalis bacterial species. Additionally, their binding affinities were predicted using molecular docking analysis, and their pharmacokinetic and drug-likeness properties were evaluated.&#x0D; &#x0D; KEY WORDS: Azo ligand, Metal complexes, Antimicrobial studies, Molecular docking study&#x0D; &#x0D; Bull. Chem. Soc. Ethiop. 2023, 37(4), 931-944.&#x0D; DOI: https://dx.doi.org/10.4314/bcse.v37i4.10

Two Spectrophotometric Methods Based on Diazotization Coupling Reaction for Determination of Genistein in Pure and Supplement

Genistein (GEN) is one of the predominant dietary isoflavones found in legumes such as soybeans. Genistein has been recommended as an osteoporosis treatment for postmenopausal women and elderly men, with the intention of reducing cardiovascular disease and hormone-dependent malignancies. Therefore, two sensitive and simple methods for quantifying it in the supplements preparation were developed.The first method (A) comprised employing the surfactant Triton X-114 to extract the result of the diazotization reaction with 4-Aminoacetophenone(4AMA) utilizing a cloud point extraction technique. The product was extracted using micelles of a non-ionic surfactant (TritonX-114) and then spectrophotometrically detected at a specified wavelength of 437nm. The linearity of the calibration curve was in the range of 0.25 -2.75 µg/mL of GEN(r = 0.9978) under optimal conditions. The average sample recovery was determined to be between 96 and 101 %. For 2 µg/mL of GEN, the relative standard deviation (RSD) was (0.27%). The second method (B) involved using the spectrophotometric-flow injection methodology for the same diazotization coupling reaction described above, and the orange colored dyewas measured at a wave length of 437 nm.Calibration curve were linear at different concentration range of GEN 10 to 100 µg/mL , relative standard deviation RSD% were 0.23 to 1.21. The proposed methods were applied to determine the presence of GEN in Supplements.

Ni2+, Pt4+, Pd2+, and Mn2+ Metal ions Complexes with Azo Derived from Quinolin-2-ol and 3-amino-N-(5-methylisoxazol-3-yl) Benzenesulfonamide: Synthesis, Characterization, Thermal Study ,and Antioxidant Activity

Diazotization reaction between quinolin-2-ol and (2-chloro-1-(4-(N-(5-methylisoxazol-3-yl)sulfamoyl)phenyl)-2l4-diazyn-1-ium was carried out resulting in ligand-HL, this in turn reacted with the next metal ions (Ni2+, Pt4+, Pd2+, and Mn2+) forming stable complexes with unique geometries such as (tetrahedral for both Ni2+ and Mn2+, octahedral for Pt4+ and square planer for Pd2+ ). The creation of such complexes was detected by employing spectroscopic means involving ultraviolet-visible which proved the obtained geometries, fourier transfer proved the formation of azo group and the coordination with metal ion through it. Pyrolysis (TGA &amp; DSC) studies proved the coordination of water residues with metal ions inside the coordination sphere as well as chlorine atoms. Moreover, element micro-analysis and AAS that gave corresponding outcome with theoretically counting outcome. (1H &amp;13C-NMR) and magnetic quantifications can also indicate the formation of ligand-HL and occurrence of coordination. Antioxidant activities of these compounds were evaluated against (DPPH) radical and were compared to the standard natural antioxidant, ascorbic acid. The findings showed that these compounds exhibit excellent radical scavenging activities

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.

Response of axial nitrogen coordination engineering to cobalt based molecular environmental catalysts for selective reduction of CO2

It is of practical significance to use appropriate catalysts to reduce CO2 into useful products by reasonably consuming a certain amount of electrical energy. Heterogeneous cobalt phthalocyanine/carbon nanotube (CoPc/CNT) catalyst can achieve efficient catalytic reduction performance. It has been proved that the introduction of axial coordination N atoms can effectively adjust the electronic structure of CoPc, thus regulating its activity. However, there is still a lack of systematic research on the axial coordination bond modulation CO2RR process provided by N sources on the surface of carbon materials. In this work, pydridine with C=N-C (Py), cyanobenzene with C≡N (Cy), and aminobenzene with C-N-H (Am) were grafted onto CNT through diazotization reaction, and CoPc was loaded to form axially coordinated Co-N5 configuration catalysts (i.e., CoPc-Py-CNT, CoPc-Cm-CNT, and CoPc-Am-CNT), and their catalytic activities were compared. CoPc-Am-CNT with Am ligand had the strongest coordination bond energy and achieved outstanding CO2RR activity (the turnover frequency (TOF) value was 5.3 s−1), which was attributed to its impaired CO2RR energy barrier, excellent CO2 affinity, and low mass transfer resistance. While the CO Faraday efficiency of CoPc-Am-CNT at the potential below −0.75 V vs RHE was lower than those of CoPc-Cy-CNT and CoPc-Py-CNT. This was due to the fact that the electron-donating group property of Am moved the CoPc/[CoPc].- couple potential of CoPc-Am-CNT more negative, so the maximum CO Faraday efficiency of CoPc-Am-CNT could only be achieved at higher potentials (＞ −0.75 V vs RHE). This work provides new insights for the design of axial ligand catalysts and their application in eleccatalytic reduction of CO2.