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The Hofmeister series characterizes the ability of salt anions to precipitate polyampholytes/proteins. However, the variation of protein size in the bulk solution of acids and the effect of salts on the same have not been studied well. In this article, the four acids (CH3COOH, HNO3, H2SO4, and HCl) and their effects on the hydrodynamic radius (RH) of gelatin in the bulk solution are investigated. The effects of Na salt with the same anions are also considered to draw a comparison between the interactions of acids and salts with polyampholytes. It is suggested that the interactions of polyampholytes with acids are different from those of salts. The interaction series of polyampholytes with acids with respect to the RH of the polyampholyte is C H 3 CO O − > N O 3 − > C l − > S O 4 2 − whereas the interaction series with salts is S O 4 2 − > C H 3 CO O − > C l − > N O 3 − . These different interactions are due to equilibration between acid dissociation and protonation of polyampholytes. Another important factor contributing to the interactions in weak acids is the fact that undissociated acid hinders the movement of dissociated acid. Experiments and simulations were performed to understand these interactions, and the results were identical in terms of the trend in RH (from the experiments) and the radius of gyration (Rg) (from the simulations). It is concluded that the valence of ions and dissociation affect the interaction in the case of acids. However, the interactions are influenced by the kosmotropic and chaotropic effect, hydration, and mobility in the case of salts. [ABSTRACT FROM AUTHOR]

Designing and predicting self-organized pattern formation in out-of-equilibrium chemical and biochemical reactions holds fundamental significance. External perturbations like light and electric fields exert a crucial influence on reaction-diffusion systems involving ionic species. While the separate impacts of light and electric fields have been extensively studied, comprehending their combined effects on spatiotemporal dynamics is paramount for designing versatile spatial orders. Here, we theoretically investigate the spatiotemporal dynamics of chlorine dioxide-iodine-malonic acid reaction-diffusion system under photo-illumination and circularly polarized electric field (CPEF). By applying CPEF at varying intensities and frequencies, we observe the predominant emergence of oscillating hexagonal spot-like patterns from homogeneous stable steady states. Furthermore, our study unveils a spectrum of intriguing spatiotemporal instabilities, encompassing stripe-like patterns, oscillating dumbbell-shaped patterns, spot-like instabilities with square-based symmetry, and irregular chaotic patterns. However, when we introduce periodic photo-illumination to the hexagonal spot-like instabilities induced by CPEF in homogeneous steady states, we observe periodic size fluctuations. Additionally, the stripe-like instabilities undergo alternating transitions between hexagonal spots and stripes. Notably, within the Turing region, the interplay between these two external influences leads to the emergence of distinct superlattice patterns characterized by hexagonal-and square-based symmetry. These patterns include parallel lines of spots, target-like formations, black-eye patterns, and other captivating structures. Remarkably, the simple perturbation of the system through the application of these two external fields offers a versatile tool for generating a wide range of pattern-forming instabilities, thereby opening up exciting possibilities for future experimental validation. [ABSTRACT FROM AUTHOR]

Fragmentation methods such as MIM (Molecules-in-Molecules) provide a route to accurately model large systems and have been successful in predicting their structures, energies, and spectroscopic properties. However, their use is often limited to systems at equilibrium due to the inherent complications in the choice of fragments in systems away from equilibrium. Furthermore, the presence of charges resulting from any heterolytic bond breaking may increase the fragmentation error. We have previously suggested EE-MIM (Electrostatically Embedded Molecules-In-Molecules) as a method to mitigate the errors resulting from the missing long-range interactions in molecular clusters in equilibrium. Here, we show that the same method can be applied to improve the performance of MIM to solve the longstanding problem of dependency of the fragmentation energy error on the choice of the fragmentation scheme. We chose four widely used acid dissociation reactions (HCl, HClO4, HNO3, and H2SO4) as test cases due to their importance in chemical processes and complex reaction potential energy surfaces. Electrostatic embedding improves the performance at both one and two-layer MIM as shown by lower EE-MIM1 and EE-MIM2 errors. The EE-MIM errors are also demonstrated to be less dependent on the choice of the fragmentation scheme by analyzing the variation in fragmentation energy at the points with more than one possible fragmentation scheme (points where the fragmentation scheme changes). EE-MIM2 with M06-2X as the low-level resulted in a variation of less than 1 kcal/mol for all the cases and 1 kJ/mol for all but three cases, rendering our method fragmentation scheme-independent for acid dissociation processes. [ABSTRACT FROM AUTHOR]

The fragmentation of fulminic acid, HCNO, after excitation and ionization of core electrons was investigated using Auger-electron–photoion coincidence spectroscopy. A considerable degree of site-selectivity is observed. Ionization of the carbon and oxygen 1s electron leads to around 70% CH+ + NO+, while ionization at the central N-atom produces only 37% CH+ + NO+, but preferentially forms O+ + HCN+ and O+ + CN+. The mass-selected Auger-electron spectra show that these fragments are associated with higher binding energy final states. Furthermore, ionization of the C 1s electron leads to a higher propensity for C–H bond fission compared to O 1s ionization. Following resonant Auger–Meitner decay after 1s → 3π excitation, 12 different ionic products are formed. At the C 1s edge, the parent ion HCNO+ is significantly more stable compared to the other two edges, which we also attribute to the higher contribution of final states with low binding energies in the C 1s resonant Auger electron spectra. [ABSTRACT FROM AUTHOR]

Here we report a visible-light facilitated radical addition strategy for the preparation of various natural or unnatural α-amino acids from readily available glycine derivatives and alkenes. A key aspect in achieving this side carbon chain introduction reaction, while circumventing the well-documented cyclization pathway, was the employment of a radical-polar crossover strategy under redox neutral conditions. [ABSTRACT FROM AUTHOR]

Microfluidic mixing has significant applications in various fields, including materials synthesis and biochemical analysis. In this study, we propose a universal strategy to enhance mixing efficiency in microfluidic chips. This strategy initially divides the liquid into branches, which then converge in an interdigitated manner at the beginning of the mixing segment. This branch-convergence structure reduces the flow width of each liquid, thereby decreasing the diffusion distances required for mixing. Under the conditions of this study, the mixing efficiency could be improved by approximately 10 times. Importantly, this enhancement strategy only requires changing the structure of the liquid inflow channel without changing the structure of the mixing segment. Thus, this strategy has broad applicability, any mixing section with different principles and structures can be connected downstream of the branch-convergence structure. In addition, we applied this universal mixing enhancement strategy to the continuous synthesis of lactic-co-glycolic acid nanoparticles, resulting in a higher uniformity of synthesized nanoparticles compared to unenhanced devices. [ABSTRACT FROM AUTHOR]

We have been able to induce a series of lactonisation reactions of unsaturated acids using a carbocationic intermediate formed in situ. The transformation generates five and six membered lactone rings AND forms a new exocyclic C–C bond at the same time, thus removing the need for further derivatisation of typical lactonisation products (such as from iodo lactonisation). The reaction is operationally straightforward, does not employ any metals and utilises readily accessible alcohol and unsaturated acid substrates. [ABSTRACT FROM AUTHOR]

During the deamination and amination processes of meso -diaminopimelate dehydrogenase (meso -DAPDH) from Symbiobacterium thermophilum (StDAPDH), residue R71 was observed to display distinct functions. H154 has been proposed as a basic residue that facilitates water molecules to attack the D-chiral carbon of meso -DAP during deamination. Inspired by the phenomenon of R71, the effects of H154 during deamination and amination were investigated in this study with the goal of enhancing the amination activities of StDAPDH. Single site saturation mutagenesis indicated that almost all of the H154 mutants completely lost their deamination activity towards meso -DAP. However, some H154 variants showed enhanced k cat / K m values towards pyruvic acid and other bulky 2-keto acids, such as 2-oxovaleric acid, 4-methyl-2-oxopentanoic acid, 2-ketobutyric acid, and 3-methyl-2-oxobutanoic acid. When combined with the previously reported W121L/H227I mutant, triple mutants with significantly improved k cat / K m values (2.4-, 2.5-, 2.5-, and 4.0-fold) towards these 2-keto acids were obtained. Despite previous attempts, mutations at the H154 site did not yield the desired results. Moreover, this study not only recognizes the distinctive impact of H154 on both the deamination and amination reactions, but also provides guidance for further high-throughput screening in protein engineering and understanding the catalytic mechanism of StDAPDH. • H154 was first experimentally identified to be the fatal residue for deamination. • H154 mutation boosted the amination towards pyruvic acid and bulky 2-keto acids. • Coupling H154 variants with W121L/H227I resulted in enhanced amination activities. • The first report on the contrary effects of H154 during deamination and amination. • A reminder to update the high-throughput screening for DAPDH amination activity. [ABSTRACT FROM AUTHOR]

Pd-catalyzed regioselective amination of unactivated alkene remains a challenge and is of great interest. Herein, a palladium-catalyzed and ligand-controlled strategy for the Markovnikov selective oxidative amination of 4-pentenoic acid has been described. The protocol effectively reverses the carboxylic acid-directed anti-Markovnikov selectivity in oxidative amination of 4-pentenoic acid, successfully constructing γ-ketoamide derivatives. [ABSTRACT FROM AUTHOR]

A series of boron difluoro bis(diiminate) complexes have been prepared and used to obtain triflate substituted fluoroborane complexes. The corresponding well-defined bis(borenium) cations were subsequently synthesized and structurally authenticated. We are also presenting the first experimental and theoretical study of bis(borenium) cations that are derivative of cationic borinic acid. [ABSTRACT FROM AUTHOR]

The synthesis of bis-lactone and butenolide derivatives was described using alkylidene Meldrum's acid as nucleophiles. The process operates in a triple cascade through an auto tandem catalysis promoted by DBU. [ABSTRACT FROM AUTHOR]

An improved practical and efficient procedure for the synthesis of non-racemic unnatural α-amino acids through a stereocontrolled rearrangement is reported. Carboxylic acids are converted into azanyl esters RCO2 NHBoc followed by an iron-catalyzed 1,3-nitrogen migration to provide non-racemic α-amino acids in an asymmetric (α-monosubstituted α-amino acids) or enantioconvergent fashion (α,α-disubstituted α-amino acids). Under optimized conditions using a fluorinated chiral iron catalyst and 2,2,6,6-tetramethylpiperidine as the base in a solvent mixture of 1,2-dichlorobenzene and CHCl3 , enantioselectivities of up to 98% ee were obtained. Such high ee values are important for practical purposes, allowing the direct use of many of the obtained N-Boc-protected α-amino acids for subsequent applications. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) is one of the top bio‐based platform molecules that can be converted into many valuable chemicals. Herein, we report the sustainable synthesis of LA acid from various sugars using heteropolyacid catalysts. By using a Box–Behnken design of experiment, both LA yield (up to 69 mol%) and complete suppression of parasitic humin formation could be achieved within a 5 h reaction time at 140°C using fructose as a substrate. The effects of various reaction parameters like temperature, sugar concentration, addition of organic co‐solvent and reaction time on LA yield and humin formation were examined in a three‐dimensional space. Moreover, the results could be successfully transferred to other sugars like glucose or cellobiose, paving the way for an atom‐efficient and sustainable LA synthesis process. [ABSTRACT FROM AUTHOR]

Quasi‐tetrahedral o‐azophenylboronic acid (azoB‐ROH), which contains the protic solvent ROH, is a key species in the colorimetric sensing of saccharides by o‐azophenylboronic acid (azoB). In this study, we compared the reactivity of azoB‐ROH with that of trigonal azoB and tetrahedral o‐azophenylboronate (azoB‐OH−), and clarified the reaction mechanism of azoB‐ROH with cis‐1,2‐cyclopentanediol and D‐glucose. Analysis of the kinetics of the reactions of azoB with cis‐1,2‐cyclopentanediol and D‐glucose in DMSO:water = 1:9 and azoB with cis‐1,2‐cyclopentanediol in tetrahydrofuran containing a small amount of methanol revealed that there was not much difference in the reactivity of azoB‐H2O and azoB‐OH−, although the reactivity of azoB was higher than that of azoB‐MeOH, that is, the reaction mechanism of azoB‐H2O was essentially the same as that of azoB‐OH−. [ABSTRACT FROM AUTHOR]

Anaplerotic reactions catalyzed by pyruvate carboxylase (PC) and phosphoenolpyruvate carboxylase (PEPC) have important roles in the production of l -lysine to replenish oxaloacetic acid (OAA) in Corynebacterium glutamicum. However, the relative contributions of these enzymes to l -lysine production in C. glutamicum are not fully understood. In this study, using a parent strain (P) carrying a feedback inhibition-resistant aspartokinase with the T311I mutation, we constructed a PC gene-deleted mutant strain (PΔPC) and a PEPC gene-deleted mutant strain (PΔPEPC). Although the growth of both mutant strains was comparable to the growth of strain P, the maximum l -lysine production in strains PΔPC and PΔPEPC decreased by 14% and 49%, respectively, indicating that PEPC strongly contributed to OAA supply. l -Lysine production in strain PΔPC slightly decreased during the logarithmic phase, while production during the early stationary phase was comparable to production in strain P. By contrast, strain PΔPEPC produced l -lysine in an amount comparable to the production of strain P during the logarithmic phase; l -lysine production after the early stationary phase was completely stopped in strain PΔPEPC. These results indicate that OAA is supplied by both PC and PEPC during the logarithmic phase, while only PEPC can continuously supply OAA after the logarithmic phase. [Display omitted] [ABSTRACT FROM AUTHOR]

Two aggregation induced emission molecules (TPE‐MZ and QM‐Py‐TPE) have been synthesized and characterized. Similar to conventional AIE based molecules, both molecules displayed good sensitivity towards water fraction and viscosity of dispersing medium. The fluorescent emission intensity of TPE‐MZ gradually reduced with increasing concentration of oleic acid and elaidic acid within the range of 0.2–5 mM. The inflection points of TPE‐MZ fluorescent emission maximum for oleic acid and elaidic acid were observed at 1.40 and 0.80 mM, respectively. The corresponding inflection points of QM‐Py‐TPE were 1.80 and 2.00 mM for oleic acid and elaidic acid, respectively. Sensor combination (TPE‐MZ:QM‐Py‐TPE=2 : 1) emitted pink and yellow fluorescence in elaidic and oleic acid. Fluorescent emission ratio of I646/I508 of sensor combination displayed acceptable linear relationship (R2=0.9826) with concentration of oleic acid (within the concentration of 4 mM). Thus, the sensor combination was capable of oleic acid and elaidic acid naked‐eye discriminating and quantitively sensing. [ABSTRACT FROM AUTHOR]

Symmetrical biaryl compounds are vital chemical feedstocks in the fine chemical industry. Homocoupling, which produces aryl‐aryl reagents, remains the predominant method for their synthesis. Previously, Yaghi et al. reported a patent demonstrating the high performance of HKUST‐1 in homocoupling reactions involving arylboronic acids with electron‐withdrawing substituents. However, reactions with electron‐donating substituents yielded lower results. In this study, we introduce optimized protocols for HKUST‐1 catalyzed homocoupling of arylboronic acids with electron‐donating substituents, achieving symmetrical biaryl products with yields up to 93 %. We also observed significant hydroxylation byproducts competing with homocoupling products when the reaction was exposed to air, especially for arylboronic acids with electron‐donating substituents. This heterogeneous HKUST‐1 catalyst demonstrated recyclability for up to three cycles without a significant decline in catalytic activity. [ABSTRACT FROM AUTHOR]

Inhibitors of the interaction between Neuropilin-1 (NRP-1) and Vascular Endothelial Growth Factor-A165 (VEGF-A165) hold significant promise as therapeutic and diagnostic agents directed against cancers overexpressing NRP-1. In our efforts in this field, a few series of strong and fairly stable peptide-like inhibitors of the general formula Lys(Har)1-Xaa2-Xaa3-Arg4 have been previously discovered. In the current work, we focused on Lys(Har)-Dap/Dab-Pro-Arg sequence. The aim was to examine whether replacing C-terminal Arg with its homologs and mimetics would yield more stable yet still potent inhibitors. Upon considering the results of modelling and other factors, ten novel analogues with Xaa4 = homoarginine (Har), 2-amino-4-guanidino-butyric acid (Agb), 2-amino-3-guanidino-propionic acid (Agp), citrulline (Cit), 4-aminomethyl-phenylalanine [Phe(4-CH2-NH2)] were designed, synthesized and evaluated. Two of the proposed modifications resulted in inhibitors with activity slightly lower [e.g. IC50 = 14.3 μM for Lys(Har)-Dab-Pro-Har and IC50 = 19.8 μM for Lys(Har)-Dab-Pro-Phe(4-CH2-NH2)] than the parent compounds [e.g. IC50 = 4.7 μM for Lys(Har)-Dab-Pro-Arg]. What was a surprise to us, the proteolytic stability depended more on position two of the sequence than on position four. The Dab2-analogues exhibited half-life times beyond 60 h. Our results build up the knowledge on the structural requirements that effective VEGF-A165/NRP-1 inhibitors should fulfil. [ABSTRACT FROM AUTHOR]

The reaction between 6‐aminouracils and isatins having no substitution on nitrogen was carried out in acetic acid at 80 °C. This was followed by the oxidative decarboxylation of the resulting intermediates in the presence of Pb(OAc)4, resulting in the synthesis of the corresponding 6‐aminouracil substituted pyrimido[4,5‐b]quinolines with good to excellent yields. Additionally, the reaction of 6‐aminouracils, isatin derivatives, and 1,3‐dimethylbarbituric acid yielded similar results, and the corresponding products were efficiently obtained with symmetric and asymmetric structures. Furthermore, N‐substituted isatins were also subjected to the reaction conditions and the resulted spirooxindoles prepared, showing resistance against oxidation with (Pb(OAc)4. Notably, the condensation reaction of N‐substituted isatins with N‐arylaminouracils was also investigated, leading to spiro[indoline‐3,5′‐pyrimido[4,5‐b]quinoline] derivatives. [ABSTRACT FROM AUTHOR]

An efficient synthesis of spiro[2.3]hexane‐ and spiro[3.3]heptane‐derived α‐amino acids is reported. The used methods are divided on two different approaches. First of them involves modification of commercially available spirocyclic diesters via monohydrolysis, Curtius rearrangement and functional groups deprotection sequence. Alternative approach was based on Bucherer ‐ Bergs hydantoine synthesis with its subsequent cleavage to the target amino acid fragment. The proposed synthetic schemes offer the desired product in 31–52 % overall yield on up to 22.5 g scale. Acid‐base titration of the obtained spirocyclic amino acids revealed lowered pI values compared to the parent 1‐amino‐cyclohexane‐ and ‐cycloheptanecarboxylic acids. [ABSTRACT FROM AUTHOR]

In this work, a simple hydrothermal synthesis method is used to prepare photocatalytic NiO/WO 3 -biochar composite material, which is applied to catalyze the one-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with synergistic hydrogen production. The optoelectronic properties of NiO/WO 3 -biochar composite material are characterized. The results indicate that the p-n heterojunction-coupled biochar structure between NiO and WO 3 in the NiO/WO 3 -biochar composite is an important prerequisite for ensuring the one-step oxidation reaction of 5-hydroxymethylfurfural. The experimental results reveal the possible reaction pathways. Under the optimal ratio of NiO/WO 3 -biochar composite material, the 5-hydroxymethylfurfural conversion rate reaches 100%, the 2,5-furandicarboxylic acid yield reaches 99.6%, and the Faraday efficiency of hydrogen evolution is 98%. This study provides a new approach for the one-step photocatalytic synthesis of 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural, as well as a novel and efficient catalyst for photocatalytic oxidation technology. [Display omitted] • NiO/WO 3 -biochar composite is successfully prepared. • Mechanism of hydrogen production by photocatalytic reaction of straw is analyzed. • HMF undergoes photocatalytic one-step oxidation to FDCA with 99.6% efficiency. [ABSTRACT FROM AUTHOR]

The origin of the enantiospecific decomposition of L - and D -tartaric acid on chiral Cu surfaces is elucidated on a structure-spread domed Cu(110) crystal by spatially resolved XPS and atomic-scale STM imaging. Extensive enantiospecific surface restructuring leads to the formation of surfaces vicinal to Cu(14,17,2) which are responsible for the enantiospecificity. [ABSTRACT FROM AUTHOR]

Ketones are ubiquitous patterns found in various biological molecules and natural products. In recent years, a number of acylation methods have been developed based on the use of α-oxocarboxylic acids as acyl-transfer reagents, with particular emphasis on the photoinduced decarboxylative acylation of α-keto acids. This review focuses on the latest advancements in acylation methodologies through the decarboxylation of α-keto acids over the past several years, highlighting their product diversity, selectivity, and applicability. Where possible, the mechanistic rationale is presented, providing a positive outlook for the promising future of this field. [ABSTRACT FROM AUTHOR]

An efficient and environmental protocol for the synthesis of 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones under mild benign conditions has been developed. This facile one‐pot approach to 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones from commercially available benzoxazoles and α‐keto acids which only promoted by DIPEA. The protocol exhibits a wide range of applicability in terms of benzoxazoles and α‐keto acids. Notably, the 2‐aryl benzothiazoles can be produced under the similar reaction conditions. [ABSTRACT FROM AUTHOR]

An alternative approach to synthesize bis‐indolylmethanes (BIMs) via a unique p‐toluenesulfonic acid (PTSA) catalyzed dual Csp3−Csp2 bond‐breaking reaction has been reported here. In the reported protocol, 1,3,5‐trimethoxybenzene (TMB), an electron‐rich and sterically bulky arene, acts as a carbon‐based leaving group which can be recovered after the completion of the reaction. In this process, several BIMs of various indole derivatives can be synthesized from symmetrical triarylmethanes (TRAMs) containing bis‐TMB motifs. By modifying the reaction conditions, we could control the sequential bond cleavage of two Csp3−Csp2 bonds in starting TRAM. [ABSTRACT FROM AUTHOR]

A visible-light-induced directed decarboxylative disulfuration of α-keto acids and oxamic acids was developed. As a result, a series of versatile mono acyl disulfide derivatives was synthesized under mild and sustainable reaction conditions. This protocol has a broad substrate scope, good functional-group tolerance, and excellent synthetic applications. [ABSTRACT FROM AUTHOR]

Asymmetric decarboxylative Mannich addition of β‐keto acids or malonic acid half‐esters to β,γ‐alkynyl‐α‐ketimino esters catalyzed by cinchona alkaloid‐derived squaramide has been developed. The reaction proceeded by forming a nucleophilic enolate after decarboxylation, followed by its addition to β,γ‐alkynyl‐α‐ketimino esters facilitated by the bifunctional catalyst. A broad range of substrates with various substituents are tolerated in this reaction, yielding a series of α,α‐disubstituted amino acid derivatives bearing alkynyl functional groups in high yields with good to excellent enantioselectivities. The practicality of this method was demonstrated by a gram‐scale reaction and subsequent elaboration of the Mannich adducts. [ABSTRACT FROM AUTHOR]

A photoinduced EnT-mediated generation of sulfonamidyl radicals has been accomplished using rationally designed iminophenylacetic acid oxime ester reagents under metal-free conditions. This approach offers a mild, regio- and diastereoselective synthesis of N-sulfonyl diamines via diamination of alkenes and (hetero)arenes. [ABSTRACT FROM AUTHOR]

We describe a full account of our synthetic strategy leading to the first total synthesis of the manzamine alkaloid lissodendoric acid A. These efforts demonstrate that strained cyclic allenes are valuable synthetic building blocks and can be employed efficiently in total synthesis. [ABSTRACT FROM AUTHOR]

First case of regiospecific formation of indole fused with a triterpene scaffold is observed. Starting from 3‐oxo‐24‐nor‐allobetulin Fischer reaction with phenylhydrazine under the influence of weak acid catalyst led to 3H‐indole (indolenine) 4. This process was accompanied by a change in the configuration of the methyl group at C‐4 that was confirmed by x‐ray diffraction method. On the other hand, 3,2‐indole 5 was synthesized under the influence of strong acid catalyst (using phenylhydrazine hydrochloride in AcOH acid or phenylhydrazine in MeOH with a few drops of HCl). [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities. The main structural feature of their framework is a trans‐fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings. Herein, we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates. This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone. Finally, it facilitates the synthesis of the entire skeletal structure of the pseudolaric acid family of natural products, excluding the B‐ring functionalization. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop an effective method for obtaining perrhenic acid from available ammonia waste solutions using the solvent extraction method. An ammonia waste solution was used as the test material, with Re and NH4+ concentrations of 13.5 and 43.7 g/dm3, respectively. The scope of this study includes the following: the selection of an appropriate extractant for testing, and the examination of the impact of individual parameters on the efficiency and selectivity of extraction and stripping. The obtained results made it possible to determine the conditions for the production of perrhenic acid via the extraction method using organic solutions of trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101). The outcome of this study was the development of a method for obtaining perrhenic acid and the production of the acid sample with an efficiency of >90% and a Re concentration of >100 g/dm3. [ABSTRACT FROM AUTHOR]

For the first time, novel method for the preparation of previously undescribed substituted 2-arylfuro[3,2-b]chromen-3-ylacetic acids was developed. The considered approach includes multicomponent reaction of various arylglyoxals, 3-hydroxy-4H-chromen-4-ones, and Meldrum's acid. The studied condensation is a telescoped process consisting of primary base-catalyzed interaction of starting compounds in acetonitrile and conclusive cyclization to target furo[3,2-b]chromen-3-ylacetic acids under acidic conditions. The readily available starting materials, convenient experimental procedure and simple isolation of the final products are advantages of presented method. [ABSTRACT FROM AUTHOR]

I report a simple and efficient one-pot route for the synthesis of 1-[aryl(selenoacetamido)methyl]-2-naphthol derivatives from the condensation of 2-naphthol, an aryl aldehydes and selenoacetamide in the presence of catalytic amounts of p-toluenesulfonic acid (p-TSA) under reflux conditions. This new protocol offers advantages such as mild reaction conditions, short reaction time, easy work-up, and use of an inexpensive and nontoxic catalyst and good yields. [ABSTRACT FROM AUTHOR]

C-Glycosyl amino acids are a group of C-glycosides in which a carbohydrate molecule is attached to the side chain or backbone of the amino acid via a C–C bond. Despite the numerous methods that have been developed for their synthesis, the C-glycosyl α-amino acids and their oligomers are relatively unexplored. In this work, we presented a protocol for the synthesis of oligomers containing alternating C-glycosyl α-amino acids and proteinogenic α-amino acids. The methodology is based on the modification of α-acyloxyamides obtained from the Passerini reaction using α- D -galactopyranose- and α- L -sorbofuranose-derived aldehydes as C-glycosyl donors. The protocol enabled the synthesis of homo- and heterochiral tetramers, and homo- and heterovalent tetramers in very good yields. [ABSTRACT FROM AUTHOR]

Acid treatment can alter the functional properties of whey protein isolate (WPI), but the effect of different acids on properties of WPI‐stabilised Pickering emulsion gel (PE) is unknown. Compared with WPI‐PE, droplet size of the acid‐treated WPI‐PE decreased but its zeta potential, apparent viscosity, binding water capacity and curcumin encapsulation were enhanced. Due to the formation of the tightest gel structure of malic acid‐Pickering emulsion gel, it showed the highest viscoelastic modulus, bound water content and gel stability. This work would introduce a novel method for the development of PEs with good gelatinisation and curcumin delivery system for food processing. [ABSTRACT FROM AUTHOR]

Here we present a hybrid catalytic pathway for efficient synthesis of 5-aminomethyl-2-furancarboxylic acid (AMFC), a bio-based nylon-6 analogue monomer, from 5-hydroxymethylfurfural (HMF). This method combines homogeneous-catalyzed selective oxidation of HMF to 5-formyl-2-furancarboxylic acid (FFCA) with heterogeneous-catalyzed reductive amination using ammonia as the nitrogen source. Through this relay strategy, we achieve significant enhancements in overall efficiency, resulting in isolation yields of up to 92% for highly selective and scalable AMFC production from HMF. [ABSTRACT FROM AUTHOR]

α‐Trifluoromethyl alkenes are versatile CF3‐containing feedstocks. They have been widely used to construct gem‐difluoroalkene scaffolds through β−F elimination. The application of α−CF3 alkenes as trifluoromethylating reagents has been less explored. Herein, we report an efficient route for the synthesis of β‐trifluoromethylated ketones from readily accessed α−CF3 styrenes and aromatic carboxylic acids under photoredox catalysis. The reactions proceed by phosphoranyl radical promoted deoxygenation of aromatic acids, generating acyl radicals for subsequent hydroacylation of α−CF3 styrenes. The valuable trifluoromethyl‐containing compounds could be produced in good yields under mild conditions. [ABSTRACT FROM AUTHOR]

We report here a concise synthesis of the anti-tumor-promoting (−)-larikaempferic acid methyl ester, a novel and rearranged abietane-type diterpene natural product containing a unique tetracyclic skeleton with a trans-hydrindane, an oxabicyclo[3.2.1]octane, and six stereogenic centers. Our synthesis starts with the cheap and abundant abietic acid and features an oxidative C–C bond cleavage followed by a transannular aldol reaction to skeletally rearrange the 6–6–6 tricyclic carbon skeleton of abietic acid to the desired 6–5–7 tricyclic carbon skeleton and an intramolecular oxa-Michael addition to form the oxa bridge. This skeletal rearrangement strategy enabled us to synthesize (−)-larikaempferic acid methyl ester in 9 steps. [ABSTRACT FROM AUTHOR]

Functional materials that exhibit circularly polarized luminescence (CPL) have shown immense potential in applications such as 3D optical displays and advanced information encryption. However, facile and efficient regulation of the multiple emission properties in chiral systems has remained a challenge due to the scarcity of suitable materials and the complexity of the systems. Herein, a multiple CPL regulation platform is fabricated by the helical co‐assembly of an aldehyde‐functionalized fluorane dye (Rhodol‐CHO, 6′‐(diethylamino)‐3′‐hydroxy‐3‐oxo‐3H‐spiro[isobenzofuran‐1,9′‐xanthene]‐4′‐carbaldehyde) and chiral liquid crystals, which can efficiently combine multiple stimuli‐responsive characteristics and high optical activity. By introducing acid, base, and compounds containing primary amino (─NH2) groups, the CPL property of the system can be easily modified. The obtained CPL systems exhibit apparent asymmetry, with glum values reaching 0.54–0.75). Further, these CPL modules are successfully applied in multi‐mode information encryption, highlighting their practical utility. Therefore, this study presents a novel strategy for developing materials with diverse CPL behaviors based on a simple‐designed platform, advancing further applications of CPL materials. [ABSTRACT FROM AUTHOR]

The switchable synthesis of 3-aminoindolines and 2′-aminoaryl acetic acids from the same substrates, 3-azido-2-hydroxyindolines, was developed through denitrogenative electrophilic amination of Grignard reagents. The key to success is the serendipitous discovery that the reaction conditions, including solvents and reaction temperature, can affect the chemoselectivity. It is noteworthy that isotope-labeling experiments revealed the occurrence of the aziridine intermediate in the production of 2′-aminoaryl acetic acids. [ABSTRACT FROM AUTHOR]

β-Costic acid is a sesquiterpene phytoalexin with acaricidal activity against Varroa destructor and antitrypanosomal activity. A concise and efficient method was developed for the synthesis of β-costic acid via the allylic oxidation of β-selinene, a component of celery seed oil. [ABSTRACT FROM AUTHOR]

This study aims to prove the ability of crude cellulase enzymes from snails for protoplasting Aspergillus oryzae cells and its application for strain improvement with UV mutagenesis. Snail enzyme was obtained from Achatina fulica by dissolving its digestion track and fractionating it with ammonium sulfate. The activity of fractions was measured Spectrophotometrically and used for cell protoplasting for 2 hours, then irradiated with UV for 10, 15, and 20 minutes, respectively, with 5 cm in the distance. Screening of mutants is carried out with 1% FeCl3, and the potential mutant strain was tested for kojic acid production in an aerobic state and determined by Spectrophotometry at 268 nm. The cellulase activity in crude snail enzyme was 11.5807 U/ml and increased to 16.3984 U/ml after fractionation. The best protoplast formation was obtained with a 60% fraction, which showed transparent performance under the microscope. The UV mutagenesis of protoplasts showed that the highest number of potential mutants was obtained from UV treatment for 15 minutes (41.67%). The potential mutants look dark brown (DBC), such as strain 10H3, and produced higher kojic acid concentration than the parent strain. In conclusion, UV mutagenesis of Aspergillus oryzae through protoplasting by crude cellulase of snail enzyme was effective and improved kojic acid concentration. [ABSTRACT FROM AUTHOR]

5-Alkylated barbituric acids are an important class of compounds that constitute the basic moiety of several clinically used hypnotic drugs. Here we report a catalyst-free domino Knoevenagel-Michael addition involving barbituric acid, aldehyde, and N,N-disubstituted aniline in solvent acetonitrile to synthesize 5-alkylated barbituric acid derivatives (72–94% yield) without using any chromatographic separation techniques. The C-4 position of aniline acts as the Michael donor. All the reactions are successfully performed without catalysts, providing an environment-friendly and economical route for the synthesis. Moreover, catalyst-free reactions are less sensitive to air and moisture unlike many metal catalysts, with easy separation of products, and simple operating procedures as there is no need for catalyst weighing, recovery, and removal. A plausible mechanism is also proposed based on control experiments. [ABSTRACT FROM AUTHOR]

Acid fracturing is a technique to enhance productivity in carbonate formations. In this work, a thermal–hydraulic–mechanical–chemical (THMC) coupling model for acid fracture propagation is proposed based on a phase-field approach. The phase-field variable is utilized as an indicator function to distinguish the fracture and the reservoir, and to track the propagation of the fracture. The resulting system is a nonstationary, nonlinear, variational inequality system in which five different physical modules for the displacement, the phase-field, the pressure, the temperature, and the acid concentration are coupled. This multi-physical system includes numerical challenges in terms of nonlinearities, solution coupling algorithms, and computational cost. To this end, high fidelity physics-based discretizations, parallel solvers, and mesh adaptivity techniques are required. The model solves the phase-field and the displacement variables by a quasi-monolithic scheme and the other variables by a partitioned schemes, where the resulting overall algorithm is of iterative coupling type. In order to maintain the computational cost low, the adaptive mesh refinement technique in terms of a predictor-corrector method is employed. The error indicators are obtained from both the phase-field and concentration approximations. The proposed model and the computational robustness were investigated by studying fourteen cases as well as some mesh refinement studies. It is observed that the acid and thermal effect increase the fracture volume and fracture width. Moreover, the natural fractures and holes affect the acid fracture propagation direction. Highlights: thermal–hydraulic–mechanical–chemical coupling system was established for acid fracture propagation based on a phase-field method. The acid fluid equations including diffusion, transport and reaction were derived. The penalization method was introduced based on physical reality. Acid fracture problem is a kind of dynamic heterogeneous problem. The adaptive mesh refinement was extended to help researchers get smooth simulation results and save computation costs. [ABSTRACT FROM AUTHOR]

L-ascorbic acid represents one of the most potent antioxidant, photoprotective, anti-aging, and anti-pigmentation cosmeceutical agents, with a good safety profile. However, the main challenge is the formulation of stable topical formulation products, which would optimize the penetrability of L-ascorbic acid through the skin. The aim of our research was to evaluate the performance of ascorbyl palmitate on the skin, incorporated in creams and emulgels (2%) as carriers, as well as to determine the impact of its incorporation into liposomes on the penetration profile of this ingredient. Tape stripping was used to study the penetration of ascorbyl palmitate into the stratum corneum. In addition, the sensory and textural properties of the formulations were determined. The liposomal formulations exhibited a better penetration profile (p < 0.05) of the active substance compared to the non-liposomal counterpart, leading to a 1.3-fold and 1.2 fold-increase in the total amount of penetrated ascorbyl palmitate in the stratum corneum for the emulgel and cream, respectively. Encapsulation of ascorbyl palmitate into liposomes led to an increase in the adhesiveness and density of the prepared cream and emulgel samples. The best spreadability and absorption during application were detected in liposomal samples. The obtained results confirmed that liposomal encapsulation of ascorbyl palmitate improved dermal penetration for both the cream and emulgel formulations. [ABSTRACT FROM AUTHOR]

Soil acidity is one of the most important constraints to maize production in Angola, where both yellow and white maize is essential for food and feed requirements. In this study, four yellow acid soil tolerant donor lines from the International Maize and Wheat Improvement Centre (CIMMYT)—Colombia were crossed with ten yellow elite lines adapted to the mid-altitude climatic conditions developed by CIMMYT—Zimbabwe, in order to identify donor lines, which can be potential sources of acid tolerance genes in breeding programs in Angola and within the mid-altitude climatic zones. The two groups of parents were crossed using a line by tester mating design, yielding 36 crosses with sufficient seed, which were evaluated alongside six acid tolerant commercial hybrids, during the 2014–16 cropping seasons at nine sites, representing acid and non-acid soils in Angola and Zimbabwe. A significant (p < 0.05) line and line × tester effect for grain yield performance was observed across acid and non-acid conditions. Acid tolerance donor lines CY3 and CY1 showed the highest positive GCA effects for grain yield. In addition, crosses involving these two donor lines had the best yielding ability and stability under both acid and non-acid conditions. For instance, the crosses CH142464 (ZY2 × CY3) and, CH142447 (ZY2 × CY1) were the best combinations for grain yield performance under both acid and non-acid soil conditions, and were stable compared to the commercial check hybrids. Crosses involving the acid tolerant donor lines mostly flowered earlier than the commercial checks. Overall, the data showed the potential of tropically-adapted exotic yellow maize acid tolerance donor lines in improving productivity of sub-tropical maize under both low-pH and well-managed soil conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hot trub is a macronutrient‐ and micronutrient‐rich by‐product generated in the brewing industry, which is still underrated as a raw material for reprocessing purposes. In this context, this study aimed to investigate the extraction of bitter acids' and xanthohumol from hot trub as well as identify the significance of parameters for the process. The research assessed various extraction parameters, such as pH, ethanol concentration, temperature, and solid‐to‐liquid ratio, using a Plackett–Burman design. RESULTS: Ethanol concentration and pH were the most significant parameters affecting extraction yield. β‐acids were found to be the principal components of the bitter acids, with a maximum concentration near 16 mg g−1, followed by iso‐α‐acids and α‐acids achieving 6 and 3.6 mg g−1, respectively. The highest yields of bitter acids were observed in the highest ethanol concentration, while pH was relevant to extraction process in treatments with low ethanol ratios. Concerning the xanthohumol extraction, the approach achieved maximum concentration (239 μg g−1) in treatments with ethanol concentration above 30%. Despite their variances, the phytochemicals exhibited comparable extraction patterns, indicating similar interactions with macromolecules. Moreover, the characterization of the solid residues demonstrated that the extraction process did not bring about any alterations to the chemical and total protein profiles. CONCLUSION: Ethanol concentration was found to have the most significant impact on the extraction of bitter acids and xanthohumol, while temperature had no significant effect. The solid remains resulting from the extraction showed potential for use as a protein source. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Composition, structure, energy parameters, and existence regions of hydrate complexes formed in the HClO4–H2O system are studied by IR spectroscopy and quantum chemical methods. Three concentration-structural regions are determined. The HClO4–H2O solutions diluted to the 1:13.3 molar ratio of components contain and solvate-separated ions, each hydrated by four water molecules. More concentrated solutions (1:13.3-1:5) contain hydrated ion pairs that are contact ion pairs if the [HClO4]:[H2O] ratio falls within the region 1:9-1:5. As the acid concentration increases further up to the transition of the HClO4–H2O system into the solid phase, pair complexes are formed. The structure of the latter is formed by a cycle of two contact ion pairs connected by two H-bonds. The solid phase consists of interacting polymer chains formed by and ion pairs. [ABSTRACT FROM AUTHOR]

A novel copper(II) complex based on N-2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid is prepared, its structure is studied by XRD (CCDC No. 2215117). The crystal of the complex is formed by monomeric [CuLH2O]NO3 units. The metal centers of the units have an octahedral coordination environment formed by nitrogen atoms of pyridine and the amino group, oxygen atoms of the sulfo group, and water molecules located in the equatorial plane. On the axial axis, there are oxygen atoms of the sulfo groups of the neighboring ligands forming a 1D coordination polymer. [ABSTRACT FROM AUTHOR]