Condensation Products Research Articles

Accessing a Carboxyl-Anhydride Molecular Switch-Mediated Recyclable PECT Through Upcycling End-of-Use PET.

Poly(ethylene terephthalate)(PET), with an annual production of exceeding 70 million tons, is mainly utilized in disposable fields and subsequently contribute to severe environmental pollution. Conventional chemical recycling, which typically involves depolymerizing polymer into monomers, is limited due to the intricate recycling process, excess using unrecyclable solvents and low polymer conversion. Inspired by protein's molecular switches, we propose a novel polymer-to-polymer recycling strategy based on polycondensation principles upcycling waste PET to high-value recyclable poly(ethylene-co-1,4-cyclohexanedimethanol terephthalate) derivatives containing molecular switches. Upon deactivating the molecular switch, an acidification reaction occurs within the system, leading to a rapid and controllable reduction in molecular weight due to the imbalance of reactive group. Conversely, activating the molecular switch triggers a ring-closing reaction that detaches acid anhydrides, bringing about equal molar ratio of groups and thereby facilitating an increase in molecular weight. By simply incorporating a molecular switch into condensation products based on melt polycondensation, closed-loop recycling capability is achieved without necessitating excessive organic solvents or complex depolymerization processes. The present study not only presents a novel pathway for end-of-use PET upcycling but also introduces an innovative concept of molecular switching for the closed-loop recyclability of condensation polymers, thereby demonstrating significant potential for large-scale implementation.

Synthesis of a Conjugate of Gossypol with Doxorubicin

Gossypol has been shown to be a promising natural product for the anticancer drug development for treating leukemia, lymphoma, colon carcinoma, breast cancer, and other malignant disease. It is known that the conversion of aldehyde groups of gossypol into iminofragments by the treatment of various amines can reduce the toxicity of the derivative and simultaneously increase their pharmacological efficacy. This article describes the preparation and screening of antiproliferative properties of a conjugate of gossypol with antitumor antibiotic doxorubicin. It has been shown that the reaction of the amino group of doxorubicin with the aldehyde groups of gossypol gives the condensation product in which two pharmacophores are linked via enamine– enamine moieties. However, this conjugation decreased the antiproliferative activity of paternal doxorubicin and gossypol against chronic myeloid leukemia cells K562 and led to dramatic loss of potency against MDRsubline K-562/4 with expression of Р-glycoprotein (Р-gp).

Synthesis, structure, and spectral and electrochemical properties of new visible to NIR absorbing 3-pyrrolyl BODIPY derivatives.

We report the synthesis, characterization, and studies of novel 3-pyrrolyl BODIPY-based Schiff base products 3-6 and 3-pyrrolyl BODIPY-based benzo[d]thiazol-2-yl derivatives 7-8. The Schiff base compounds 3-6 were synthesized via condensation of α-formyl 3-pyrrolyl BODIPY with various amine derivatives, while the Knoevenagel condensation products 7-8 were obtained by reacting α-formyl 3-pyrrolyl BODIPY with 2-(benzo[d]thiazol-2-yl) acetonitrile and bis(benzo[d]thiazol-2-yl) methane, respectively. The compounds were thoroughly characterized by using HR-MS, 1D and 2D NMR spectroscopy, and X-ray crystallography for two compounds. The crystal structures revealed distinct conformational differences between the Schiff base product 3 and the Knoevenagel condensation product 8. In compound 3, the appended pyrrole was oriented towards the BF2-dipyrrin core and placed almost in the same plane, while in 8, the pyrrole was inverted, deviated from the BF2-dipyrrin plane, and aligned with the bis(benzothiazolyl) moiety, which adopted a transoid configuration. The Schiff base compounds 3-6 exhibited absorption bands in the region of 610-665 nm, whereas the benzo[d]thiazol-2-yl derivatives (7 and 8) showed enhanced optical properties with a red shifted absorption band that extended into the NIR region. These structural modifications of the 3-pyrrolyl BODIPY chromophore enable precise tuning of their electronic, absorption, and emission properties from the red to the NIR region. Furthermore, we also synthesized a 3-pyrrolyl BODIPY-Re(I) complex 8-Re(I) using bis(benzo[d]thiazol-2-yl)-3-pyrrolyl BODIPY 8. In the 8-Re(I) complex, the bis(benzothiazolyl) moiety adopted a cisoid configuration with a bite angle of 41.60°, and the Re(I) center exhibited a distorted octahedral geometry with a boat-like conformation. In the 8-Re(I) complex, the Re(I) was coordinated to three axial CO ligands, two nitrogen atoms from the bis(benzothiazolyl) units, and one chloride atom. DFT and TD-DFT studies corroborated our experimental findings, providing deeper insights into these compounds' structural, photophysical, and electronic properties. Overall, this study demonstrates the versatility of 3-pyrrolyl BODIPY derivatives in tuning absorption properties from the visible to the NIR region and their potential in forming stable Re(I) chelates, highlighting their potential in the development of NIR fluorophores and coordination chemistry.

From Hydrocarbons to Highly Functionalized Molecules in a Single Measurement: Comprehensive Analysis of Complex Gas Mixtures by Multi-Pressure Chemical Ionization Mass Spectrometry.

Chemical Ionization Mass Spectrometry (CIMS) is a well-established analytical method in atmospheric research, process monitoring, forensics, breathomics, and food science. Despite significant advancements in procedural techniques, several instrument configurations, especially operating at different ionization pressures, are typically needed to analyze the full range of compounds from nonfunctionalized parent compounds to their functionalized reaction products. For polar, functionalized compounds, very sensitive detection schemes are provided by high-pressure adduct-forming chemical ionization techniques, whereas for nonfunctionalized, nonpolar compounds, low-pressure chemical ionization techniques have consistently demonstrated superior performance. Here, using a MION2 chemical ionization inlet and an Orbitrap Exploris 120 mass spectrometer, we present multi-pressure chemical ionization mass spectrometry (MPCIMS), the combination of high- and low-pressure ionization schemes in a single instrument enabling quantification of the full distribution of precursor molecules and their oxidation reaction products from the same stream of gas without alterations. We demonstrate the performance of the new methodology in a laboratory experiment employing a-pinene, a monoterpene relevant to atmospheric particle formation, where MPCIMS allows us to measure the spectrum of compounds ranging from the volatile precursor hydrocarbon to highly functionalized condensable reaction products. MPCIMS carries the potential as an all-in-one method for the analysis of complex gas mixtures, reducing technical complexities and the need for multiple instruments without compromise of sensitivity.

Modeling of the processes of development of gas condensate fields in the depletion mode

Based on mathematical modeling under the influence of capillary and gravitational forces of condensate operating in depletion mode, settling in the gas-condensate layer, as a result of redistribution in height, the formation of a technogenic-condensate flow at the gas-water boundary and the production of condensate by a horizontal well drilled into it were studied. Initially, when exploiting a gas condensate formation with a five-point production well, the nature of the distribution of reservoir pressure and phases along the height, the time of formation of technogenic condensate and the interval of its location along the height of the gas field were determined. In the second case, the process of water exposure was realized by exploiting the formation with production wells to remove condensate with a horizontal well drilled into a technogenic condensate deposit. Mining wells reveal the productive height of the formation in two ways: in the first case from the upper part, in the second case from the lower part, and after entering the condensate flow, the horizontal well is introduced into operation. Exposure to water ends at 98% dilution of the horizontal well product. The results of calcuıations show that the formation of technogenic condensate at the water-gas interface in the reservoir depletion mode is the result of the segregation process. The greatest effect in increasing the condensate yield of a horizontal well drilled into a technogenic condensate field is achieved by pumping water from the upper part of the formation. Keywords: gas-condensate reservoir; segregation process; technogenic condensate fringe; horizontal well; condensate recovery coefficient.

Synthesis of cyclohexanone condensation products with high yield via ball mill process and the kinetic study of this process using “mean temperature method (MTM)”

Cyclohexanone is a significant organic compound. The cyclohexanone dimer is obtained from the condensation of cyclohexanone and can be used as a precursor for high-density jet fuel. This paper compares the ball mill process and oil bath magnetic stirring process for achieving the cyclohexanone self-condensation reaction using CaO as a catalyst. The conversion of cyclohexanone was 95.4 %, and the yield of the dimer was 93.5 % under ball mill process. The yield was significantly higher compared to the oil bath magnetic stirring process. To investigate the reason for the activity difference, the kinetic study of ball mill process and oil bath magnetic stirring process were carried out respectively. A new method, “mean temperature method (MTM)” was proposed to solve the problem of the temperature fluctuation during the ball mill process. The activation energy Ea by ball mill process was found to be 94.35 kJ/mol. The catalyst particle size was smaller, and the reaction was more adequate under the ball mill process. This paper introduces a novel approach for the kinetics study of catalytic reactions during ball mill process, that has not been previously explored in the literature.

Syntheses and evaluation of novel 3-hydroxy-1,3-diaryl-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromides as potential anticancer agents

New 3-hydroxy-1,3-diaryl-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromides have been designed, synthesized, and characterized by 1Н NMR, 13C NMR, and LCMS. The cyclic structure of the condensation products of aryl-(3,4,5,6-tetahydropyridin-2-yl)amines with α-bromoketones has been proven. It has been shown that heating 3-hydroxy-1,3-bis-(41-methoxyphenyl)-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromide in acetic anhydride accompanied by elimination of water to form 1,3-bis-(41-methoxyphenyl)-5,6,7,8-tetrahydro-imidazo[1,2-a]pyridine-1-ium bromide. Antitumor activity of 1,3-bis-(41-ethoxyphenyl)-3-hydroxy-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromide and 1,3-bis-(41-methoxyphenyl)-5,6,7,8-tetrahydro-imidazo[1,2-a]pyridine-1-ium bromide have been studied. The fully aromatic imidazo[1,2-a]pyridine-1-ium bromide system was shown to have a higher antitumor effect. According to the screening results, the tested compound showed a significant level of anticancer effect on cancer cells of colon COLO 205 (lgGI50 = -5.35, lgTGI = –4.70 and lgLC50 = –4.19) and melanoma SK-MEL-5 (lgGI50 = –5.57, lgTGI = –4.81 and lgLC50 = –4.17).

CO2 Hydrogenation through Electrochemical Hydrogen Activation in a Gas-Vapor Fed Reactor

An attractive concept in the chemical manufacturing industry is the adoption of a circular carbon economy, which can include continuous capture and conversion of CO2 into industrially relevant chemical feedstocks. This has driven considerable research interest in electrochemical CO2 reduction.1 Despite this popularity, major challenges remain even for the most advanced CO2 reduction reactors, including low conversion rates and energy efficiencies; moreover, in many cases, multiple carbon-containing products are generated, which add to costs for downstream separation.2 By contrast, thermochemical CO2 hydrogenation is well established and typically demonstrates higher energy efficiency and selectivity compared to electrochemical CO2 reduction.3,4 This notable contrast drives our interest in better understanding the physics that governs differences in reactivity between thermocatalytic and electrocatalytic CO2 reduction reactors. To address these questions, we are pursuing a unique approach that involves feeding humidified CO2 and H2, respectively, to the cathode and anode of an electrochemical membrane-electrode assembly (MEA). This presentation will cover initial work we have undertaken to design and validate this reactor for the study CO2 electro-reduction.The overall design of our reactor resembles a hydrogen fuel cell fed with humidified H2 and CO2. Thus, it was initially benchmarked through operation as an electrochemical hydrogen pump, wherein humidified Ar was fed to the cathode and humidified H2 was fed to the anode with Pt/C as the catalyst on each side of the membrane. Under these conditions, a cation exchange membrane (CEM) readily generated current densities in excess of 1 A/cm2 with monotonic decreases in polarization with increased temperature at fixed current. We then undertook analogous hydrogen pumping experiments using anion exchange membranes (AEM) that had been ion-exchanged with hydroxide, carbonate, and bicarbonate anions. We observed net proton transport between the anode and cathode chambers in each case, albeit with higher ionic resistance for AEMs in the bicarbonate form.We then undertook further studies to demonstrate the ability to reduce CO2 using H2 fed to the anode. This operating mode eliminates the need for a liquid anode feed, which dramatically reduces the driving force for CO2 crossover via bicarbonate formation. Moreover, the Pt/C anode catalyst is expected to oxidize hydrogen with minimal polarization, allowing the total cell polarization to be interpreted simply as the cathode potential on the RHE scale. CO2 reduction experiments were carried out using commercial Cu/C catalyst with online gas chromatography and NMR for product analysis of volatile and condensable products, respectively. Operation with a CEM yielded only H2(g) at the cathode, but initial experiments with an AEM in the carbonate/bicarbonate form gave high selectivity to ethanol at 70 oC.

Expanding the Substrate Selectivity of the Fimsbactin Biosynthetic Adenylation Domain, FbsH.

Nonribosomal peptide synthetases (NRPSs) produce diverse natural products including siderophores, chelating agents that many pathogenic bacteria produce to survive in low iron conditions. Engineering NRPSs to produce diverse siderophore analogs could lead to the generation of novel antibiotics and imaging agents that take advantage of this unique iron uptake system in bacteria. The highly pathogenic and antibiotic-resistant bacteria Acinetobacter baumannii produces fimsbactin, an unusual branched siderophore with iron-binding catechol groups bound to a serine or threonine side chain. To explore the substrate promiscuity of the assembly line enzymes, we report a structure-guided investigation of the stand-alone aryl adenylation enzyme FbsH. We report structures bound to its native substrate 2,3-dihydroxybenzoic acid (DHB) as well as an inhibitor that mimics the adenylate intermediate. We produced enzyme variants with an expanded binding pocket that are more tolerant for analogs containing a DHB C4 modification. Wild-type and mutant enzymes were then used in an in vitro reconstitution analysis to assess the production of analogs of the final product as well as several early stage intermediates. This analysis shows that some altered substrates progress down the fimsbactin assembly line to the downstream domains. However, analogs from alternate building blocks are produced at lower levels, indicating that selectivity exists in the downstream catalytic domains. These findings expand the substrate scope of producing condensation products between serine and aryl acids and identify the bottlenecks for chemoenzymatic production of fimsbactin analogs.

Experimental investigation on thermodynamic and environmental performance of a novel ocean thermal energy conversion (OTEC)-Air conditioning (AC) system

In the field of isolated island energy supply, the OTEC system is considered promising due to its large storage capacity, and pollution-free characteristics. To improve energy efficiency, polygeneration systems have gradually become a research hotspot for their low cost and high return features. In this context, a novel Ocean Thermal Energy Conversion system integrated with an air conditioning unit (OTEC-AC) is introduced, demonstrating capabilities in electricity, cooling capacity, and fresh water production by experiments. The effects of various flow rates and temperatures of the heat and cold sources, along with the air-conditioning system water flow rate on the system performance is explored. Besides, the overall performance of the OTEC-AC is compared with four representative OTEC models. The results indicate that there is a threshold for the influence of cold and heat source flow rate on the performance of power generation system. The OTEC-AC system shows a highest net power of 132.6 W, cooling capacity of 2.14 kW, condensate production of 3.24 kg/h, and achieves a system exergy efficiency and CO2 reduction of 34.7 % and 5801 kg/year, respectively. The annual CO2 reduction per kilowatt of installed capacity of the system is increased by 135.6 %, compared with the conventional OTEC system.

NEW UV ABSORBERS BASED ON N-(2-AMINOARYL)BENZOTRIAZOLES

A joint method for the synthesis of 1-(2-aminoaryl)-1H- and 2-(2-aminoaryl)-2H-benzotriazoles including the SNAr reaction of 1H-benzotriazole with ortho-nitrogalogenarenes and the reduction of the resulting mixture of isomeric nitro derivatives of benzotriazole, was developed. The influence of the temperature and structure of the electrophile on the selectivity of the SNAr reaction was studied. 1-(2-Nitroaryl)-1H-benzotriazole was mainly formed at high temperature. The amount of 2-(2-nitroaryl)-2H-benzotriazole increased with a decrease in the reaction temperature. The highest selectivity for 2-substituted 2H-benzotriazole was observed at 40 ºC. The electron deficiency character of the electrophile had a significant effect on the ratio of isomers formed in the substitution reaction. The amount of 2-substituted isomer in the reaction mixture became smaller with its increase. The effect of hydrochloric acid concentration on the course of the main and side processes during the reduction of N-nitroaryl derivatives of benzotriazole with tin (II) chloride in an acidic aqueous alcohol medium was studied. The use of 9% HCl led to the formation of azoxy compounds – condensation products intermediately formed during the reduction of nitroso- and hydroxylamine derivatives. Alkylation of 1-(2-aminoaryl)-1H-benzotriazole occurred in 36% HCl with alcohol used as a solvent. There were no by-products during the reduction in the i-PrOH/18% HCl system. The total yield of isomeric amino derivatives of benzotriazole was 96-99%. Separation of 1-(2-aminoaryl)-1H- and 2-(2-aminoaryl)-2H-benzotriazoles was based on the different polarity of the isomers and, accordingly, solubility in a nonpolar solvent – petroleum ether. The resulting N-(2-aminoaryl)benzotriazoles absorbed UV radiation in both the short-wave, medium- and near-wave ultraviolet ranges of the electromagnetic spectrum. 1-Substituted benzotriazoles were more effective UV absorbers in the UVC region than 2-aryl derivatives and Tinuvin P. By the ability to absorb medium-wave UV radiation 1-(2-aminoaryl)-1H-benzotriazoles were significantly inferior to the corresponding isomeric 2-(2-aminoaryl)derivative. The presence of 2-(2-aminoaryl)-2H-benzotriazole acceptor substituents enhanced the ability of the substance to absorb UV radiation compared with 2-(2-aminophenyl)-2H-benzotriazole. 2-Substituted benzotriazoles were more effective ultraviolet adsorbers in the UVB region than Tinuvin P. 2-(2-Aminophenyl)-2H-benzotriazoles also absorbed ultraviolet radiation in the range of 315-400 nm more actively than 1-substituted analogues, but were partly inferior to a commercial photostabilizer. For citation: Begunov R.S., Khlopotinin A.I., Lobanova L.V., Vorontsov S.M., Savina L.I., Danilova A.S. New UV absorbers based on N-(2-aminoaryl)benzotriazoles. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 86-94. DOI: 10.6060/ivkkt.20246711.7070.

Platinum(II) Acetimino Cyclometalated Complexes Derived from Room Temperature Ammonia Activation

AbstractTwo Pt(II) rollover cyclometalated complexes, [Pt(bpyPh−H)(DMSO)Me] (1) and [Pt(bpyPh−H)(DMSO)Cl] (2), where bpyPh−H is the C3‐deprotonated 6‐phenyl‐2,2’‐bipyridine, were reacted with aqueous ammonia in acetone at room temperature. In the case of the electron‐poor complex 2 simple substitution of DMSO by NH3 gave the amino complex [Pt(bpyPh−H)(NH3)Cl] (4), whereas the electron‐rich complex 1 produced the rare acetimine complex [Pt(bpyPh−H)(HN=CMe2)Me] (3), which was isolated and characterized. Complex 3 is stable both in solution and in the solid state, in the presence of air and water. The result is noteworthy, as the condensation product of acetone and ammonia, acetimine, is not stable under mild conditions. The reaction likely requires a Pt(II) electron‐rich complex and the presence of a carbon donor in trans position. An analogous reaction occurs with methylamine, allowing the synthesis of the secondary imine complex [Pt(bpyPh−H)(MeN=CMe2)Me], 5. Starting from this finding a series of cyclometalated acetimine complexes [Pt(N C)(HN=CMe2)Me] were isolated and characterized with other classical and rollover cyclometalated ligands with an array of different electronic and steric properties, indicating a possible extension of the reaction to various cyclometalated ligands. A preliminary study on the antimicrobial and antitumor properties of complex 3, taken as a model for this class, showed no significant effects against Gram‐positive, Gram‐negative bacteria, or yeasts, but found activity in vitro against HT29 colon cancer cell line.

Synthesis of potential anticonvulsants based on chloral hydrate and carbamazepine: their spectral characteristics and in silico ADME profiling

This paper reports the synthesis of a new potential anticonvulsant, N-(2,2,2-trichloro-1-hydroxyethyl)-5H-dibenzo[b,f]azepine-5-carboxamide. Its synthesis is based on condensing the anticonvulsant drug carbamazepine with chloral hydrate used in medical practice. The reaction was carried out in a melt or by boiling in dry benzene with the removal of the resulting water from the reaction medium. The product was obtained with yields of 88 and 79%, respectively. Replacing the hydroxyl group in the resulting condensation product with an amino group led to the formation of N-(1-amino-2,2,2-trichloroethyl)-5H-dibenzo[b,f]azepine-5-carboxamide. This synthesis was carried out in two stages. Initially, the hydroxy derivative was chlorinated with thionyl chloride. Then, by treating the resulting chlorine derivative with an aqueous solution of ammonia (25%) in MTBE medium, the target product was obtained. The structure of the obtained compounds was proven by 1H NMR and IR spectroscopy data. The SwissADME online platform showed that the synthesized compounds should have high bioavailability as well as moderate solubility in water and be able to penetrate the blood-brain barrier.

Bidirectional solar water production enabled by a breathable Janus photothermal material

Solar-driven interfacial water evaporation offers a promising solution to the global scarcity of freshwater. Despite advances in increasing evaporation rates, current condensate productivity is limited to 0.3 − 0.5 kg m−2 h−1 due to unidirectional vapor diffusion, which is insufficient to satisfy water demands. This paper introduces a bidirectional solar water production (BSWP) device that utilizes a breathable Janus photothermal material made from recycled cotton fabric. The BSWP device allows vapor to diffuse in both upward and downward directions of the evaporation interface. This design features dual condensers, addressing the limitations of traditional solar stills by reducing vapor concentration and minimizing light loss due to condensation on the top cover receiving light. Under 1 sun illumination, the BSWP device achieves a water yield of 1.06 kg m−2 h−1 with a solar-to-water efficiency of 71%. An 10-hour outdoor experiment demonstrates that the BSWP device can yield a water flux of 9.65 kg m−2, showcasing its potential for efficient water generation in practical environmental conditions. The present work provides a new perspective on the structural design of direct solar desalination configurations, potentially offering a more effective solution to cope with global water scarcity.

Assessing the impact of oil and gas activities on ambient hydrocarbon concentrations in North Texas: A retrospective analysis from 2000 to 2022

Over the past two decades, significant advancements in shale gas extraction technologies have led to a vast increase in oil and gas production in the Barnett Shale region of North Texas. This study provides a detailed analysis of the trends in air pollutants, such as total nonmethane hydrocarbons (NMHC), linked to oil and gas production changes in the Barnett shale region from 2000 to 2022. The analysis spans urban (Dallas - DAL), semi-urban (Fort Worth - FWNW), and non-urban (Denton - DEN) ambient air quality monitoring sites operated by the Texas Commission on Environmental Quality (TCEQ), highlighting how varying levels of urbanization and industrial activities influence air quality. DEN recorded the highest NMHC concentrations at an average of 210.27 ppb-C, significantly exceeding those at FWNW (83.14 ppb-C) and DAL (62.50 ppb-C). Alkanes were the predominant NMHCs across all sites, forming 96% at DEN, 89% at FWNW, and 67% at DAL. The i/n-pentane ratio at DEN suggests oil and gas activities as the main NMHC source, whereas DAL, and FWNW indicate substantial influences from urban traffic alongside industrial emissions. NMHC concentrations at DEN and FWNW correlated strongly with gas and condensate production, demonstrating a shift from condensate to gas over the study period.

Repurposing a Fully Reducing Polyketide Synthase toward 2-Methyl Guerbet-like Lipids.

In nature, thousands of diverse and bioactive polyketides are assembled by a family of multifunctional, "assembly line" enzyme complexes called polyketide synthases (PKS). Since the late 20th century, there have been several attempts to decode, rearrange, and "reprogram" the PKS assembly line to generate valuable materials such as biofuels and platform chemicals. Here, the first module from Mycobacterium tuberculosis (Mt) PKS12, an unorthodox, "modularly iterative" PKS, was modified and repurposed toward the formation of 2-methyl Guerbet lipids, which have wide applications in industry. We established a robust method for the recombinant expression and purification of this modified module (named [M1*]), and we demonstrated its ability to catalyze the formation of several 2-methyl Guerbet-like lipids (C13-C21). Furthermore, we studied and applied the promiscuous thioesterase activity of a neighboring β-ketoacyl synthase (KS) to release [M1*]-bound condensation products in a one-pot biosynthetic cascade. Finally, starting from lauric acid, we could generate our primary target compound (2-methyltetradecanoic acid) by coupling the Escherichia coli fatty acyl-CoA synthetase FadD to [M1*]. This work supports the biosynthetic utility of engineered PKS modules such as [M1*] and their ability to derive valuable Guerbet-like lipids from inexpensive fatty acids.

MANNICH REACTION’S MESMERIZING MANIFESTATIONS

After introduction of a new natural or synthetic chemical entity as a drug, the focus of research has always shifted to the modification of this chemical entity with the objective of improving ADMET properties, formulations for its efficient delivery, solubility, stability, organoleptic properties, reduction of toxicity, expansion of pharmacological range, formation of precursors, condensation products, complexation, prevention of formation of trace impurities and more. For example, the analgesic and antipyretic drug antipyrine, one of the earliest synthetic drugs, forms an intermolecular hydrogen bond with salicylic acid to give the stable compound antipyrine salicylate, also known as salipyrin. During the development of an aqueous drug formulation containing salipyrin and hexamine, 112 years ago, the unusual formation of a precipitate after some time did not go unnoticed by the young pharmacist and chemist Carl Mannich at Berlin University. Mannich then went on to explain the possible mechanism of formation of the condensation product, later to be known as the first Mannich compound or Mannich base, in a seminal, 21-page publication along with his student Krösche. The explanation was as much brilliant as it was accurate. He recognised that it was a generally applicable reaction, which would open the doors to the then difficult-to- synthesize 1,3-ketamines and which would allow the formation of open and cyclic compounds containing nitrogen – and to the world of natural product chemistry. An artistic view of the first Mannich base, which also happened to be tris-symmetrical, is reproduced below.

Phase Behavior and Rational Development Mode of a Fractured Gas Condensate Reservoir with High Pressure and Temperature: A Case Study of the Bozi 3 Block

The Bozi 3 reservoir is an ultra-deep condensate reservoir (−7800 m) with a high temperature (138.24 °C) and high pressure (104.78 MPa), leading to complex phase behaviors. Few PVT studies could be referred in the literature to meet such high temperature and pressure conditions. Furthermore, it is questionable regarding the applicability of existing condensate production techniques to such a high temperature and pressure reservoir. This study first characterized the phase behavior via PVT experiments and EOS tuning. The operating conditions were then optimized through reservoir numerical simulation. Results showed that: (1) the critical condensate temperature and pressure of Bozi 3 condensate gas were 326.24 °C and 43.83 MPa, respectively; (2) four gases (methane, recycled dry gas, carbon dioxide, and nitrogen) were analyzed, and methane was identified as the optimal injection gas; (3) gas injection started when the production began to fall and achieved higher recovery than gas injection started when the pressure fell below the dew-point pressure; (4) simultaneous injection of methane at both the upper and lower parts of the reservoir can effectively produce condensate oil over the entire block. This scheme achieved 8690.43 m3 more oil production and 2.75% higher recovery factor in comparison with depletion production.

From cassava peel (Manihot esculenta) to hydrocarbon-rich bio-oil: Catalytic flash pyrolysis as a new valorization route

The valorization of agroindustrial residues for second-generation biofuels has garnered attention due to the increasing demand for low-carbon fuels aligned with transportation sector decarbonization efforts. In this context, cassava processing residues, particularly cassava peel, remain largely unexplored but offer a cheap, abundant, and renewable feedstock that can be converted into hydrocarbon-rich biofuel. Thus, the originality of this study lies in investigating the selective conversion of cassava peel into renewable aromatic hydrocarbons through flash pyrolysis catalyzed by an environmentally friendly MFI-type zeolite synthesized from rice husk ash and diatomite residue. A micro-pyrolyzer interfaced with chromatographic separation and mass spectrometry detection was used to compare the composition of condensable volatile products from catalytic pyrolysis over HZSM-5 with those from catalyst-free pyrolysis. Cassava peel, characterized by high volatile matter content (84.3 %), low ash content (3.19 %), and reasonable energy content (15 MJ kg −1), yielded a high content of valuable platform chemicals, such as carboxylic acids and furans, when subjected to catalyst-free pyrolysis. The catalytic upgrading pyrolysis vapors over the environmentally friendly HZSM-5 catalyst yielded approximately 56.0 % industrially relevant aromatic hydrocarbons and 39.9 % light organic acids. Other strengths of using HZSM-5 in upgrading pyrolysis vapors were its low selectivity for naphthalenes, precursors for coke formation, and the production of hydrocarbons in the gasoline range. Thus, HZSM-5 was an efficient catalyst for promoting deoxygenation and improving hydrocarbon content, with high selectivity for valuable aromatic hydrocarbons. In conclusion, cassava peel showed favorable prospects for conversion into hydrocarbon-rich bio-oil, serving as a valuable precursor for low-carbon biofuels.

Mesoporous, high surface area and microrod-shaped cobalt (II) coordination polymer for assessment of molecular structure, thermolysis and non-isothermal kinetics parameters

This study is significant as it presents the assessment of molecular identification, thermal degradation, and non-isothermal kinetics of a cobalt (II) coordination polymer [Co (II) CPs] synthesized from suberoyl bis (2-ethoxybenzamide) (sbebz) and cobalt acetate through the condensation process. The condensation product sbebz was obtained from suberoyl chloride and 2-ethoxybenzamide. The XRD, FT-IR, Raman, and XPS investigated as aspects to identify its structure, purity, and chemical state. The morphological facet was confirmed by SEM and TEM. The morphology data revealed a microrod-shaped morphology of Co (II) CPs with an average particle size 0.7 µm to 1 µm. The pore size, and surface properties were examined by Brunauer-Emmett-Teller (BET) and atomic force microscopy (AFM), revealing a highly large surface area (1076 m2/g), mesoporous and monodisperse nature. The molecular interaction of ligand was estimated using protein molecule. The thermal-decomposition behavior and non-isothermal kinetics of Co (II) CPs were estimated at different heating rates (5 °C/min, 10 °C/min, 15 °C/min, and 20 °C/min) under nitrogen atmosphere by thermogravimetry/Derivative thermogravimetry (TG/DTG). As-synthesized Co (II) CPs show enhanced thermal stability compared to the ligand (sbebz). The multiple heating TG/DTG curve exhibits a more or less identical degradation profile/pattern. The kinetic parameters like order of reaction (n), pre-exponential Arrhenius factor (A), activation entropy (∆s), activation energy (Ea), activation free-energy (∆G), and activation enthalpy (∆H) were calculated using Coats-Redfern (CR) method.