Tertiary Ones Research Articles

Catalytic Asymmetric Barbier Reaction of Ketones with Unactivated Alkyl Electrophiles.

The Barbier reaction is a reductive-type addition of an aldehyde or ketone with an organic electrophile in the presence of a terminal metal reductant, providing a straightforward and efficient method for carbon-carbon bond formation. This reaction possesses the advantage of circumventing the preparation of moisture- and air-sensitive organometallic reagents. However, the catalytic Barbier reaction of ketones to construct tetrasubstituted stereogenic centers is largely underdeveloped, despite its great potential for accessing synthetically challenging chiral tertiary alcohol. Particularly, the leveraging of unactivated alkyl electrophiles as coupling components is still rarely exploited. Herein, we disclose a photoredox-assisted cobalt-catalyzed asymmetric alkylative Barbier-type addition reaction of ketones to address the aforementioned challenges, thereby allowing for the construction of highly congested tetrasubstituted carbon centers. The alkyl addition fragments could be either readily accessible unactivated alkyl halides or redox-active esters generated through a decarboxylative pathway. Both types of alkyl electrophiles include primary, secondary, and tertiary ones, thus affording diverse enantioenriched tertiary alcohols with a broad substrate scope. This enantioselective protocol is applied for the expedient synthesis of core structure of Sofdra, a very recent FDA-approved drug in 2024. The newly developed bisoxazolinephosphine (NPN) ligand enables high enantioselectivity in this asymmetric reductive addition process.

Vinyl and Alkynyl Substituted Heterocycles as Privileged Scaffolds in Transition Metal Promoted Stereoselective Synthesis.

ConspectusBiologically active compounds and pharmaceutically relevant intermediates often feature sterically congested stereogenic centers, in particular, carbon stereocenters that are either tertiary tetrasubstituted ones or quaternary in nature. Synthons that comprise such bulky and often structurally complex core units are of high synthetic value and represent important incentives for communities connected to drug discovery and development. Streamlined approaches that give access to a diverse set of compounds incorporating acyclic bulky stereocenters are relatively limited, though vital. They enable further exploration of three-dimensional entities that can be designed and implemented in discovery programs, thereby extending the pool of molecular properties that is inaccessible for flat molecules. However, the lack of modular substrates in particular areas of chemical space inspired us to consider functionalized heterocycles known as cyclic carbonates and carbamates as a productive way to create sterically crowded alkenes and stereocenters.In this Account, we describe the major approximations we followed over the course of 8 years using transition metal (TM) catalysis as an instrument to control the stereochemical course of various allylic and propargylic substitution processes and related transformations. Allylic substitution reactions empowered by Pd-catalysis utilizing a variety of nucleophiles are discussed, with amination being the seed of all of this combined work. These procedures build on vinyl-substituted cyclic carbonates (VCCs) that are simple and easy-to-access precursors and highly modular in nature compared to synthetically limited vinyl oxiranes. Overall these decarboxylative conversions take place with either "linear" or "branched" regioselectivities that are ligand controlled and offer access to a wide scope of functional allylic scaffolds. Alternative approaches, including dual TM/photocatalyzed transformations, allowed us to expand the repertoire of challenging stereoselective conversions. This was achieved through key single-electron pathways and via formal umpolung of intermediates, resulting in new types of carbon-carbon bond formation reactions significantly expanding the scope of allylic substitution reactions.Heterocyclic substrate variants that have triple bond functional groups were also designed by us to enable difficult-to-promote stereoselective propargylic substitution reactions through TM catalysis. In these processes, inspired by the Nishibayashi laboratory and their seminal findings in the area, we discovered various new reactivity patterns. This provided access to a range of different stereodefined building blocks such as 1,2-diborylated 1,3-dienes and tetrasubstituted α-allenols under Cu- or Ni-catalysis. In this realm, the use of lactone-derived substrates gives access to elusive chiral γ-amino acids and lactams with high stereofidelity and good structural diversity.Apart from the synthetic efforts, we have elucidated some of the pertinent mechanistic manifolds operative in these transformations to better understand the limitations and opportunities with these specifically functionalized heterocycles that allowed us to create complex synthons. We combined both theoretical and experimental investigations that lead to several unexpected outcomes in terms of enantioinduction models, catalyst preactivation, and intermediates that are intimately connected to rationales for the observed selectivity profiles. The combined work we have communicated over the years offers insight into the unique reactivity of cyclic carbonates/carbamates acting as privileged precursors. It may inspire other members of the synthetic communities to widen the scope of precursors toward novel stereoselective transformations with added value in drug discovery and development in both academic and commercial settings.

Primary, Secondary, and Tertiary Interactions for Fleet HumanRobot Interaction: Insights from Field Testing

A growing number of domains for Human-Robot and Human-Machine Interactions (HRI/HMI) will involve fleets of autonomous machines. In these fleet environments, robots will encounter not just primary interactors in one-on-one encounters, but also secondary, and even tertiary ones who are bystanders to direct human-to-robot interactions. Thus, the interaction paradigms used by such robots may need to be reconsidered to meet a growing diversity of interactions as fleet HRI/HMI applications continue to grow. Relying on use cases from field testing in mock urban environments, the purpose of this paper is to discuss our lessons learned when supporting multiple “layers” of interactors and how they relate to needs that Human Factors and Ergonomic (HF/E) science can help to address.

Synthesis of 1,4‐Dicarbonyl Compounds via Visible‐Light‐Induced Decarboxylative Radical Cascade Reactions

AbstractWe herein report a method for the synthesis of 1,4‐dicarbonyl compounds using light‐activated electron donor‐acceptor (EDA) complexes. This multi‐component reaction involves the photoactivation of EDA complexes formed by carboxylic acid derivatives, triphenylphosphine, and sodium iodide, resulting in single‐electron reduction. The subsequent decarboxylation fragmentation leads to the formation of nucleophilic alkyl free radicals, which can undergo sequential radical coupling reactions with electron‐deficient and electron‐rich olefins. This method has been successfully applied to various aliphatic carboxylic acid derivatives, including tertiary, secondary, and primary ones, as well as multiple types of electron‐deficient olefins and enol silyl ethers. The entire process is conducted under mild conditions, indicating its potential for the synthesis of valuable synthetic compounds.

A fluorescent receptor for alkylammonium ions based on an anthryl-linked triazole-modified hexahomotrioxacalix[3]arene

A novel C3-symmetrical anthracene-functionalized hexahomotrioxacalix[3]arene L was synthesized via Click chemistry and its chemosensing properties with alkylammonium ions were investigated. The significant fluorescence enhancements were observed with addition of alkylammonium ions (including primary and tertiary ones), indicating a high selectivity for alkylammonium ions. Our studies demonstrated that the detection limit on fluorescence response of the sensor to is in the 10–6 M range. The mechanism of the interaction between the L and alkylammonium ions has been investigated in detail by 1H NMR spectroscopic titration experiments. Density functional theory (DFT) quantum chemical calculations were conducted to estimate the electronic interaction energies (ΔIE) between the chemosensor L and alkylammonium ions.

Carboxylic Acid Directed γ-Lactonization of Unactivated Primary C-H Bonds Catalyzed by Mn Complexes: Application to Stereoselective Natural Product Diversification.

Reactions that enable selective functionalization of strong aliphatic C-H bonds open new synthetic paths to rapidly increase molecular complexity and expand chemical space. Particularly valuable are reactions where site-selectivity can be directed toward a specific C-H bond by catalyst control. Herein we describe the catalytic site- and stereoselective γ-lactonization of unactivated primary C-H bonds in carboxylic acid substrates. The system relies on a chiral Mn catalyst that activates aqueous hydrogen peroxide to promote intramolecular lactonization under mild conditions, via carboxylate binding to the metal center. The system exhibits high site-selectivity and enables the oxidation of unactivated primary γ-C-H bonds even in the presence of intrinsically weaker and a priori more reactive secondary and tertiary ones at α- and β-carbons. With substrates bearing nonequivalent γ-C-H bonds, the factors governing site-selectivity have been uncovered. Most remarkably, by manipulating the absolute chirality of the catalyst, γ-lactonization at methyl groups in gem-dimethyl structural units of rigid cyclic and bicyclic carboxylic acids can be achieved with unprecedented levels of diastereoselectivity. Such control has been successfully exploited in the late-stage lactonization of natural products such as camphoric, camphanic, ketopinic, and isoketopinic acids. DFT analysis points toward a rebound type mechanism initiated by intramolecular 1,7-HAT from a primary γ-C-H bond of the bound substrate to a highly reactive MnIV-oxyl intermediate, to deliver a carbon radical that rapidly lactonizes through carboxylate transfer. Intramolecular kinetic deuterium isotope effect and 18O labeling experiments provide strong support to this mechanistic picture.

Specific Binding of Primary Ammoniums in Aqueous Media by Homooxacalixarenes Incorporated into Micelles.

The development of artificial receptors for efficient recognition of analytes in water is a challenging task. Homooxacalix[3]arene-based receptor 1, which is selective toward primary ammoniums in organic solvents, was transferred into water following two different strategies: direct solubilization and micellar incorporation. Extensive 1H NMR studies showed that recognition of ammoniums is only observed in the case of micellar incorporation, highlighting the beneficial effect of the microenvironment of the micellar core. The selectivity of the system for primary ammoniums over secondary and tertiary ones was also maintained. The hydrophobic effect plays an important role in the recognition properties, which are counterion-dependent due to the energy penalty for the dissociation of certain ammonium salts in the apolar micellar core. This study shows that the straightforward self-assembly process used for the encapsulation of artificial receptors in micelles is an efficient strategy for developing water-soluble nanosized supramolecular recognition systems.

Protonated amines mediated CO2 mineralization of coal fly ash and polymorph selection of CaCO3

The extensive consumption of acid and alkaline reagents is the most critical challenge hindering the development of the pH-swing process for CO2 mineralization. To deal with the problem, the present paper demonstrates the feasibility of using protonated amine as the reagent in coal fly ash (CFA) based leaching-mineralization process. The protonated amine could leach Ca2+ from CFA and be converted into free amine. The free amine was supposed to be in-situ regenerated into protonated amine by grab protons released from the CaCO3 precipitation reaction. 13 typical amines with varying amino types, pKa values, and side-chain length, were selected to systematically investigate the effects of amino groups on Ca2+ leaching performance from CFA, carbonation performance, CaCO3 nucleation, and crystal growth, as well as the process mechanism. Results indicated that effective Ca leaching, CaCO3 precipitation, and protonated amine regeneration were achieved. There was a linear relationship between the Ca utilization efficiency and pKa values of different amines. TEA obtained the highest CaCO3 yield and Ca utilization efficiency of 56.8 % and 16.8 %, respectively. In addition, amines provided excellent control of the size, polymorph, and morphology of the CaCO3 product. The primary amino group had a more pronounced effect on vaterite stabilization than secondary and tertiary ones. Introducing a side chain could promote the vaterite transforming to calcite and increasing chain length could decrease the vaterite particle size. Moreover, the maximal utilization efficiency in MEA was 15.9 % at conditions: 160 g/L solid to liquid ratio, 58 % degree of protonation, and 2.0 mol/L MEA concentration.

Canonical description of exotic general massive gravity

Exotic General Massive Gravity is the next-to-simplest gravitational theory fulfilling the so-called third-way consistency, the simplest being Minimal Massive Gravity. We investigate the canonical structure of the first-order formulation of Exotic General Massive Gravity. By using the Dirac Hamiltonian formalism, we systematically discover the complete set of physical constraints, including primary, secondary, and tertiary ones, and explicitly compute the Poisson bracket algebra between them. In particular, we demonstrate that the consistency condition for the tertiary constraints provides explicit expressions which can be solved algebraically for the auxiliary fields f and h in terms of the dreibein e. In this configuration, to confirm that the theory is ghost-free, the whole set of constraints is classified into first and second-class ones showing the existence of only two physical degrees of freedom corresponding to one massive graviton. Furthermore, we identify the transformation laws for all of the dynamical variables corresponding essentially to gauge symmetries, generated by the first-class constraints. Finally, by taking into account all the second-class constraints, we explicitly compute the Dirac matrix together with the Dirac’s brackets.

Use of Multi-Method Approach for a Gravity Irrigation Network Diagnosis: Case of Karfiguela Paddy Field in Burkina Faso

Burkina Faso is an agricultural and landlocked country whose agriculture is dependent on climatic hazards. Irrigated agriculture therefore appears as an alternative to secure, intensify and sustainably increase agricultural production. However, irrigation systems in Burkina Faso suffer from numerous technical, organizational, land and structural problems, which strongly undermine their performance. This is the case of the irrigated perimeter of Karfiguéla which since its development in 1977, has experienced insufficient water. This research has contributed to the reflection on the performance and operation of gravity irrigation networks on the irrigated perimeter in Burkina Faso and the contribution of satellite images in the mapping of irrigated perimeters. Then, an approach based on a mapping of hydraulic networks and on four main diagnostic methods were used: 1) mapping of hydraulic networks, 2) a detailed visual inspection of hydraulic infrastructure, 3) estimation of canals’ hydraulic efficiency, 4) surveys of the various actors involved in the management of the perimeter. These methods lead to the same results concerning the state of degradation and the functioning of irrigation networks in wet seasons. In terms of results, Karfiguéla perimeter has a net area of 360 ha and is supplied by a network made up of a supply canal, a primary canal, four (4) secondary canals, 37 tertiary ones, and quaternary ones for plots of water supply, all in ordinary concrete except the quaternary which are in rammed soil. The efficiency of the canals in the rainy season, greater than 100%, shows that the irrigation network during this period functions as a drainage network while the real drainage network is disorderly and non-functional. The damage to the irrigation network, siltation, grassing, erosion, overturning, large cracks and many others are all the more severe as we advance toward the Quaternary. The Strickler roughness coefficient values of the order of 68 for the feeder, 47 for the primary, between 32 and 52 for the secondaries and 31 for the tertiaries also reflect a high degradation of the channels. Upkeep and maintenance are rare and generally poorly executed. Improving the performance of irrigation on the perimeter requires a complete rehabilitation of the hydraulic network, the reinforcement of the management and maintenance capacity of the operators’ works and the search for a water resource complementary to the Comoé River to support irrigation, for example, the exploitation of the alluvial aquifer which unfolds under the perimeter and is easily accessible through rudimentary wells and sumps. All this is essential to ensure the sustainability of the rice-growing activity, which has a concentration of nearly 1200 farmers.

Modelling Economic Effects of the Media Influence as Methodological Basis for Strategizing the Media System

This research focused on the impact of media industry on other sectors of the economy. Advertising is considered as a basic implementation mechanism of media’s economic impact on the economy. The study used the original classification of the effects of economic impact on the market at all levels, developed by the author. It examined the highest level of advertising associated with the shift in market structure and economic interactions of its members and elements. The effects of this type — tertiary ones — include not only changes in the properties of equilibrium due to advertising, but also the emergence of new types of market participants whose economic activity is determined exclusively by advertising-related goals. To describe such effects, models of marketing channels are used — a special kind of production chains that connect the preceding and subsequent units with the help of contracts for advertising and promotional activities, and models of multi-sided markets, complementing the analysis with the study of the behavior of intermediary firms that place advertisements in the media. and linking producers and consumers. Classical models of two-sided markets, considering media as platforms connecting consumers with producers, do not consider the simultaneous consumption of goods and content by the audience and the nature of the producing firms’ problems. Therefore, in this paper, the focus of the study was on the models of a three-sided market, which includes three types of participants (consumers, media firms and industrial firms). It is proposed to put such models of intersectoral relations as the basis for quantitative methods of strategizing the media system, including at the national level. At the level of strategizing of individual media enterprises or holdings, the proposed model makes it possible to predict the long-term strategies of competitors. At the industrial level of strategy development, the proposed methodology makes it possible to build key indicators that determine the strategic priorities of the industry development based on the properties of the three-sided market equilibrium.

Symptom and Age Homophilies in SARS-CoV-2 Transmission Networks during the Early Phase of the Pandemic in Japan.

Simple SummaryIn the early stages of the COVID-19 pandemic, Japan conducted contact tracing extensively and published detailed records of thousands of anonymized patients. We leveraged the registry data to perform an exponential random graph model (ERGM) network analysis to examine demographic and symptomological homophilies of SARS-CoV-2 transmission networks in Hokkaido and Kanagawa. Our analysis showed: (1) Age, symptom, and asymptomatic status homophilies in both prefectures; (2) Asymptomatic infections increased as the virus was passed from primary cases to secondary and tertiary ones; (3) Transmission was mostly seen at the primary and secondary levels, with none occurring beyond quaternary; (4) Transmission occurred primarily in healthcare settings, as well as in families.Kanagawa and Hokkaido were affected by COVID-19 in the early stage of the pandemic. Japan’s initial response included contact tracing and PCR analysis on anyone who was suspected of having been exposed to SARS-CoV-2. In this retrospective study, we analyzed publicly available COVID-19 registry data from Kanagawa and Hokkaido (n = 4392). Exponential random graph model (ERGM) network analysis was performed to examine demographic and symptomological homophilies. Age, symptomatic, and asymptomatic status homophilies were seen in both prefectures. Symptom homophilies suggest that nuanced genetic differences in the virus may affect its epithelial cell type range and can result in the diversity of symptoms seen in individuals infected by SARS-CoV-2. Environmental variables such as temperature and humidity may also play a role in the overall pathogenesis of the virus. A higher level of asymptomatic transmission was observed in Kanagawa. Moreover, patients who contracted the virus through secondary or tertiary contacts were shown to be asymptomatic more frequently than those who contracted it from primary cases. Additionally, most of the transmissions stopped at the primary and secondary levels. As expected, significant viral transmission was seen in healthcare settings.

Mistreatment by Patients: An Analysis of the Patient-related Social Stressors among Slovenian Healthcare Workers.

IntroductionHealthcare workers (HCWs) are often exposed to mistreatment by patients, which has negative effects on both staff and institutions. To take appropriate action to help HCWs in this context, patient-related social stressors (PSS) should be explored. The purpose of the research was to identify the most pronounced patient behaviour contributing to the social stress (SS) of HCWs, and compare PSS between different HCWs and different types of healthcare institutions.Methods750 HCWs from Slovenian public health centres and hospitals participated in the online survey. Although the non-probability sampling was used, the sample was representative according to gender and HCW type (doctors, nurses and other HCWs).ResultsThe results show that the most pronounced patient behaviour contributing to the SS of HCWs are attitudes and behaviour of patients that are challenging in terms of what is – from the HCWs’ point of view – considered as acceptable and reasonable (disproportionate patient expectations), and unpleasant, humourless, and hostile patients. HCWs in primary institutions meet less verbally aggressive and unpleasant patients than in tertiary ones. Although among all HCWs less educated ones are more exposed to inappropriate behaviour, doctors are those HCWs who experience more inappropriate behaviour.ConclusionManagers should enable HCWs to get comprehensive patient service training, oriented towards improving relationship management and patient-HCW relationships.

Diagnosis of celiac disease in clinical practice: Present and future

IntroductionEuropean guidelines for the diagnosis of celiac disease (CD) have been updated in 2020. The primary objective was to review the compliance with the diagnostic criteria for CD, according to ESPGHAN 2012. Secondarily, to describe the clinical characteristics of the patients and to assess the changes that would be implied by the application of the new 2020 criteria. Patients and methodsRetrospective multicenter study in which 10 centers participated. Patients from 0 to 16 years old with a new diagnosis of CD in 2018–2019 were included. Clinical, serological variables and the performance of intestinal biopsy (IB) were collected. Results163 patients were included (57% female) with a median age of 7.6 years (SD 4.4). The form of presentation was: 47.8% classical, 30.7% no classical and 21.5% asymptomatic, with differences depending on age. Total IgA and anti-transglutaminase IgA antibodies were performed in all centers as the first diagnostic step. IgA anti-endomysial antibodies (EMA) were performed in 80%, and HLA haplotype in 95%. Of the total, 78 cases (47.9%) met criteria for not performing intestinal biopsy (IB). IB was indicated in the remaining 85 patients, but was not performed in 29 cases (17.8%). The performance of IB was lower in the secondary hospitals than in the tertiary ones (p < 0.05).If we applied the ESPGHAN 2020 criteria, we would disregard the HLA study, and 21 more patients would not have required IB (going from 47.9% to 60.7% of the total). ConclusionsDiscrepancies are observed in the application of the ESPGHAN 2012 diagnostic criteria due to the different accessibility to EMA and endoscopic IB in secondary centers. With the ESPGHAN-2020 criteria, around 60% of patients will be able to be diagnosed without IB, provided that the determination of EMA is ensured.

Pattern of paediatric conditions seen in the children emergency room of an urban hospital in South-Eastern Nigeria

Background: Children Emergency Room (CHER) is a vital health care services point in many hospitals and can contribute beneficially in the evaluation of many hospitals ncluding tertiary ones. It enables many paediatric cases to be managed in the hospitals without being admitted into the paediatric wards with good outcomes. Material and Methods: This was a retrospective study involving review of records of all the children seen in the CHER between January 2012 and June 2012. The objectives were to look at the pattern and outcome of paediatric conditions in CHER with the aim of providing data for further evaluation and improvement. A proforma developed by the authors was used in collecting the relevant information from the patients’ records. The data collected was simply analyzed. Results: The total of 486 paediatric patients who satisfied the inclusion and exclusion criteria were seen in the CHER. Those less then one year of age constituted 58.6% of the patients. Majority (56.8%) of the patients were males. Also 52.9% of the patients lived in the rural areas. There was preponderance (96.7%) of medical conditions. Majority of both the males (78.6%) and females (72.4%) were discharged. Only 6.17% of the patients died while 15.6% were admitted into the wards. Conclusion: There was a preponderance of varieties of medical conditions in our environment with infections constituting the majority with resultant relative high mortality. Thus improvement in the uptake of the different childhood survival strategies including immunization and breast feeding will help in minimizing these problems.

Synthesis and Physicochemical Properties of C-Borylated Esters and Amides Based on the closo-Dodecaborate Anion

The nucleophilic addition of the monocarbonyl derivative of the closo-dodecaborate anion [B12H11CO]– with N- and O-nucleophiles has been studied. This process proceeds under mild conditions in high yield. Not only primary and secondary amines but also tertiary ones can be added. The resulting borylated derivatives are thermally unstable, and the C–O and C–N bonds split upon heating forming the initial [B12H11CO]– anion. In an acidic medium in aqueous solutions, borylated derivatives hydrolize forming the carboxylate derivative of general formula [B12H11COOH]–.

Diagnosis of celiac disease in clinical practice: present and future

European guidelines for the diagnosis of celiac disease (CD) have been updated in 2020. The primary objective was to review the compliance with the diagnostic criteria for CD, according to ESPGHAN 2012. Secondarily, to describe the clinical characteristics of the patients and to assess the changes that would be implied by the application of the new 2020 criteria. Retrospective multicenter study in which 10 centers participated. Patients from 0 to 16 years old with a new diagnosis of CD in 2018-2019 were included. Clinical, serological variables and the performance of intestinal biopsy (IB) were collected. 163 patients were included (57% female) with a median age of 7.6 years (SD 4.4). The form of presentation was: 47.8% classical, 30.7% no classical and 21.5% asymptomatic, with differences depending on age. Total IgA and anti-transglutaminase IgA antibodies were performed in all centers as the first diagnostic step. IgA anti-endomysial antibodies (EMA) were performed in 80%, and HLA haplotype in 95%. Of the total, 78 cases (47.9%) met criteria for not performing intestinal biopsy (IB). IB was indicated in the remaining 85 patients, but was not performed in 29 cases (17.8%). The performance of IB was lower in the secondary hospitals than in the tertiary ones (p < 0.05). If we applied the ESPGHAN 2020 criteria, we would disregard the HLA study, and 21 more patients would not have required IB (going from 47.9% to 60.7% of the total). Discrepancies are observed in the application of the ESPGHAN 2012 diagnostic criteria due to the different accessibility to EMA and endoscopic IB in secondary centers. With the ESPGHAN-2020 criteria, around 60% of patients will be able to be diagnosed without IB, provided that the determination of EMA is ensured.

Specific Binding of Primary Ammonium Ions and Lysine-Containing Peptides in Protic Solvents by Hexahomotrioxacalix[3]arenes.

The binding of ammonium ions by two homooxacalix[3]arene-based receptors was studied using NMR spectroscopy and in silico methods. Both receptors are shown to endocomplex, even in a protic environment, a large variety of primary ammonium ions, including biomolecules. The binding mode is similar for all guests with the ammonium ion deeply inserted into the polyaromatic cavity and its NH3+ head nearly in the plane defined by the three oxygen atoms of the 18-crown-3 moiety, thus enabling it to establish three H-bonds with the ethereal macrocycle. The remarkable electronic, size, and shape complementarity between primary ammonium ions and the two cavity-based receptors leads to an unprecedented specificity for primary ammonium ions over secondary, tertiary, and quaternary ones. These binding properties were exploited for the selective liquid-liquid extraction of primary ammonium salts from water and for the selective recognition of lysine-containing peptides, opening new perspectives in the field of peptide sensing.

Alkylation of 5-Substituted Tetrazoles with Various Alcohols in 1,2-Dichloroethane in the Presence of BF3·Et2O

The alkylation of 1H-tetrazole, 5-methyl-1H-tetrazole, and 5-phenyl-1H-tetrazole with primary, secondary, and tertiary alcohols, including benzylic and allylic ones, have been studied in 1,2-dichloroethane in the presence of boron trifluoride–diethyl ether complex. Neither primary nor secondary saturated alcohols alkylated tetrazoles in the given system. Tertiary alcohols such tert-butyl alcohol and adamantan-1-ol reacted with unsubstituted and 5-substituted tetrazoles to give 70–85% of the corresponding 2-alkyl-5-R-tetrazoles with high regioselectivity. The alkylation of 1H-tetrazole with benzyl alcohol afforded 55% of 2-benzyl-2H-tetrazole as the only product. The alkylation of 1H-tetrazole with various allylic alcohols led to the formation of mixtures of 2-alkyl-2H-tetrazoles with isomeric alkyl substituents.

The relationship between the pH value of dilute effluent streams and system durability in the separate bed electrodeionization process

The successful application of electrodeionization (EDI) for the preparation of ultra-pure water has been encouraging researchers to explore its feasibility in the treatment of heavy metal electroplating wastewaters. Based on the separate bed membrane stack, the relationship between the pH of dilute effluent streams and its long-term operation stability was investigated. The pH, conductivity, electric current and voltage were recorded on-line with cupric ions contents measured off-line. The microstructure and morphology of ion exchange resins and membranes were studied with infrared spectroscopy and scanning electron microscopy. It is the adsorption saturation in the cation exchange resins-filled compartment (CR-cell) that results in the acidity of dilute effluent waters due to the consumption of hydroxide ions in the anion exchange resins-filled compartment (AR-cell). The periodic change of acidity and alkalinity of dilute effluents was caused by the alternative processes of adsorption saturation and hydrolysis regeneration in CR-cell. The conversion of quaternary amines into tertiary ones of the anion resins and membranes owing to hygro-thermal aging weakened alkaline and shortened the acid-base change period. Increasing stack voltage and intermittent leaching play an important role in prolonging the service life of EDI, and make it feasible to remove heavy metal ions from industrial wastewaters.