Procedures For Reactions Research Articles

A review of China's compensation program for adverse reactions following immunization.

Vaccination is a compelling measure to battle infectious diseases and protect public health. However, because of the constraints on human cognition, it is difficult to ensure that vaccines are safe. Adverse reactions to immunization can cause individual injury. In numerous countries, no-fault programs have been established to compensate individuals for vaccine-related injuries. China also established a vaccine injury compensation system with its own unique characteristics. The Vaccine Administration Law was promulgated in 2019 to establish a compensation system for those who experience adverse reactions following immunization; nevertheless, the compensation system is imperfect. Even when the applicable terms are applied to deal with vaccine-related injuries, some issues remain, such as unreasonable diagnosis and evaluation procedures for adverse reactions, excessively strict standards regarding proof and inconsistent compensation standards across the country. Therefore, to provide effective compensation for vaccine recipients, it is important to clarify the standards of proof and establish a sensible vaccine injury compensation system that includes Corona Virus Disease 2019 vaccine-injury compensation.

Coupling photocatalytic water oxidation with reductive transformations of organic molecules

The utilization of readily available and non-toxic water by photocatalytic water splitting is highly attractive in green chemistry. Herein we report that light-induced oxidative half-reaction of water splitting is effectively coupled with reduction of organic compounds, which provides a light-induced avenue to use water as an electron donor to enable reductive transformations of organic substances. The present strategy allows various aryl bromides to undergo smoothly the reductive coupling with Pd/g-C3N4* as the photocatalyst, giving a pollutive reductant-free method for synthesizing biaryl skeletons. Moreover, the use of green visible-light energy endows this process with more advantages including mild conditions and good functional group tolerance. Although this method has some disadvantages such as a use of environmentally unfriendly 1,2-dioxane, an addition of Na2CO3 and so on, it can guide chemists to use water as a reducing agent to develop clean procedures for various organic reactions.

Awareness, knowledge, and attitude toward adverse drug reaction (ADR) reporting among healthcare professionals in Ghana.

Background:Spontaneous reporting systems are the commonest means of reporting adverse drug reactions (ADRs) worldwide. Under-reporting remains a challenge particularly in developing countries among healthcare professionals (HCPs) who are considered the primary stakeholders in the reporting of ADRs. The challenge with studies in countries such as Ghana is that the focus has been on a single professional group or health facility. This study examines the rate of reporting as well as awareness, knowledge, and attitudes toward ADR reporting across professional groups (doctors, nurses, and pharmacist) and selected health facilities (ownership types: government, quasi-government, and private; hierarchy: district, regional, and teaching) in Ghana.Method:A cross-sectional survey was conducted to select and interview 424 healthcare professionals (HCPs) from 8 hospitals in the Greater Accra and Eastern regions of Ghana on issues of ADR reporting, awareness, knowledge, and attitudes toward ADR reporting. Valid responses from 378 HCPs were obtained and analyzed using frequencies and percentages.Findings:The results suggest that about 82.8% of the HCPs interviewed have come across an ADR incidence, but only 52.6% of them have reported such incidence, with pharmacist (66.7%) being the most likely to report. The results further suggest that about 85.8% of HCPs are aware of ADR reporting procedures and display positive attitudes toward same. In addition, the knowledge of HCPs on ADR reporting is low with training being a major area of need.Conclusion:There is the need for healthcare managers and the regulator to pay attention to existing gaps in awareness, attitudes, and most importantly knowledge of HCPs on structures and modalities for ADR reporting.Plain Language Summary Awareness, knowledge, and attitude toward adverse drug reaction (ADR) reporting among healthcare professionals in Ghana Reporting of unpleasant reactions related to the use of medicinal products has been very low in less developed countries. Studies conducted in Ghana to examine the reporting of unpleasant reactions associated with the use of medicinal products have focused mainly on one health facility or health care provider group. This article examines the level of awareness, knowledge, and attitudes toward the reporting of unpleasant reactions to the use of medicinal products.The authors used a quantitative method to examine the level of awareness, knowledge, and attitude toward reporting of unpleasant reactions to medicinal products. The study was conducted in eight hospitals in Greater Accra and Eastern regions of Ghana using a structured questionnaire. Only 378 out of 424 healthcare providers returned the completed questionnaire.The findings of the study show that 213 of the healthcare providers have encountered at least one patient with an unpleasant reaction to the use of medicinal products, although only 112 reported the unpleasant reactions. Pharmacists were found to be more likely to report unpleasant reactions as 12 out of 18 pharmacists who responded to the questionnaire indicated that they report the unpleasant reactions seen.In addition, 321 of the healthcare providers knew of the reporting procedures for unpleasant reactions to a medicinal product in Ghana. Only 219 healthcare providers knew of the reporting procedures in the facilities in which they worked, however. Furthermore, the knowledge of healthcare providers on the method of reporting is low.

The many roles of solvent in homogeneous catalysis - The reductive amination showcase

In the global effort to fight climate change, the design and development of novel procedures for complex chemical multi-step reactions is essential for the transformation of chemical industry. The transformation of chemical production processes from petrochemicals towards renewable, sustainable feedstock and the identification of green solvent candidates require a careful assessment of the effects of solvent on thermodynamics and kinetics. As a prime example for the many roles of solvent in chemical catalysis, the reaction mechanism of the homogeneous rhodium-catalyzed reductive amination of 1-undecanal from plant oils with diethylamine forming the long-chain tertiary N,N-diethylundecylamine is investigated. The many roles of solvent during the course of a chemical reactions become apparent when direct substrate-solvent and catalyst-solvent interactions are considered and their polarization effects. Hydrogen bond forming solvent molecules promote the enamine intermediate formation in terms of thermodynamics and kinetics by actively participating as proton transfer agents but a de-solvation penalty for polar groups compromises the overall pathway. The sophisticated bidentate phosphine (SulfoXantPhos)RhH reducing catalyst controls the regioselectivity of the reaction by dedicated ligand-substrate interactions. Its activity is critically dependent on the strength of solvent coordination. The effect of solvent on the reaction rate becomes apparent from a solvent screening of the transition state of the rate-determining step and give a perspective on solvent control of rate constants in this complex multi-step reaction. Only in presence of an appropriate solvent, the calculated Gibbs free potential energy surface becomes shallow and flat and delivers thermodynamic and kinetic parameters in good agreement with experiment.

Facile synthesis of per(6-O-tert-butyldimethylsilyl)-α-, β-, and γ-cyclodextrin as protected intermediates for the functionalization of the secondary face of the macrocycles.

Per(6-O-tert-butyldimethylsilyl)-α-, β- and γ-cyclodextrin derivatives are well-known as synthetic intermediates that enable the selective mono-, partial, or perfunctionalization of the secondary face of the macrocycles. Although silylation of the primary rim is readily achieved by treatment with tert-butyldimethylsilyl chloride in the presence of pyridine (either alone or mixed with a co-solvent), the reaction typically results in a mixture containing both under- and oversilylated byproducts that are difficult to remove. To address this challenge in preparing a pure product in high yield, we describe an approach that centers on the addition of a controlled excess of silylating agent to avoid the presence of undersilylated species, followed by the removal of oversilylated species by column chromatography elution with carefully designed solvent mixtures. This methodology works well for 6-, 7-, and 8-member rings (α-, β-, and γ-cyclodextrins, respectively) and has enabled us to repeatedly prepare up to ⁓35 g of ≥98% pure product (as determined by HPLC) in 3 d. We also provide procedures for lower-scale reactions, as well as an example of how the β-cyclodextrin derivative can be used for functionalization of the secondary face of the molecule.

Reliability of test procedures for postural reactions in people with acute stroke

Background/Aims:Regaining and maintaining balance requires postural reactions such as righting reactions, equilibrium reactions, and protective reactions. There is a lack of uniform, standardised, and reliable testing procedures for postural reactions. The aim of the present study was to examine the intra- and interrater reliability of a newly developed postural reactions assessment for use in people with acute stroke.Methods:The Postural Reactions Test was developed based on the literature, on previous tests, and on input from an expert panel. A total of 10 physiotherapists assessed a total of 20 video recordings of people with acute stroke performing each postural reaction. These assessments were carried out on two occasions at least 2 weeks apart. The study thus included 400 ratings.Findings:For intrarater reliability, the overall proportion of agreement was 86 − 93% for the different postural reactions. For interrater reliability, the most common score for each participant and the number of physiotherapists giving that score were noted. A median of 9–10 out of 10 physiotherapists scored the same value.Conclusions:The results indicate that the Postural Reactions Test can be used to reliably assess function in people with acute stroke and that the test can complement the existing assessments for people with affected postural control.

Practical Synthetic Procedures for the Iron-Catalyzed Intermolecular Olefin Aminohydroxylation Using Functionalized Hydroxylamines

A set of practical synthetic procedures for the iron-catalyzed intermolecular olefin aminohydroxylation reactions in gram scale is reported. In these transformations, a bench-stable functionalized hydroxylamine is applied as the amination reagent. This method is compatible with a broad range of synthetically valuable olefins including those that are incompatible with the existing aminohydroxylation methods. It also provides valuable amino alcohol building blocks with regio- and stereo-chemical arrays that are complementary to known methods.

Bringing research into a first semester organic chemistry laboratory with the multistep synthesis of carbohydrate-based HIV inhibitor mimics.

Benefits of incorporating research experiences into laboratory courses have been well documented, yet examples of research projects designed for the first semester introductory organic chemistry lab course are extremely rare. To address this deficiency, a Carbohydrate-Based human immunodeficiency virus (HIV) Inhibitor project consisting of a synthetic scheme of four reactions was developed for and implemented in the first semester organic lab. Students carried out the synthetic reactions during the last 6 of 10 total labs in the course, generating carbohydrate-based dimeric target molecules modeled after published dimers with application in HIV therapy. The project was designed to provide a research experience through use of literature procedures for reactions performed, exploration of variation in linker length in the target structure, and synthesis of compounds not previously reported in the scientific literature. Project assessment revealed strong student support, indicating enhanced engagement and interest in the course as a direct result of the use of scientific literature and the applications of the synthesized carbohydrate-based molecules. Regardless of discussed challenges in designing a research project for the first semester lab course, the finding from data analysis that a project implemented in the first semester lab had significantly greater student impact than a second semester project should provide motivation for development of additional research projects for a first semester organic course.

ChemInform Abstract: Chemoselective O‐Acylation of Hydroxyamino Acids and Amino Alcohols under Acidic Reaction Conditions: History, Scope and Applications

AbstractReview: 112 refs.

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications.

Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of catalytically active macromolecular networks in the form of soluble polymers, crosslinked polymer beads or nanoparticulate systems. The objective of the present review is to increase awareness of the existence and convenience of this methodology, assess its competitiveness compared to newer and more elaborate procedures for chemoselective O-acylation reactions, spur its further development, and finally to chronicle the informative, but poorly documented history of its development.

Open-chain remote stereocontrol using allylgermanes

Alk-2-enyl(trialkyl- and -triaryl)germanes are transmetallated by tin(IV) halides at −78 °C with 15 min being sufficient for the transmetallation to proceed effectively to completion. Alk-2-enyl(trialkyl)germanes are transmetallated by both tin(IV) chloride and tin(IV) bromide under these conditions, but the corresponding triphenylgermanes are only transmetallated using tin(IV) chloride. These observations led to procedures for reactions of 5-substituted-pent-2-enyl- and -hex-2-enyl-germanes with aldehydes that proceed with useful levels of 1,5- and 1,6-stereocontrol in favour of the (Z)-1,5-anti- and (Z)-1,6-syn-alkenols, respectively. Slightly improved stereoselectivities were obtained using (Z)-alk-2-enylgermanes. The reaction of (Z)-6-hydroxyhept-2-enyl(triethyl)germane with benzaldehyde when promoted using tin(IV) bromide gave a 3-ethenyl-6-methyl-2-phenyltetrahydropyran rather than the expected homoallylic alcohol.

Extension of the quantum-kinetic model to lunar and Mars return physics

The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high-mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. A recently introduced molecular-level chemistry model, the quantum-kinetic, or Q-K, model that predicts reaction rates for gases in thermal equilibrium and non-equilibrium using only kinetic theory and fundamental molecular properties, is extended in the current work to include electronic energy level transitions and reactions involving charged particles. Like the Q-K procedures for neutral species chemical reactions, these new models are phenomenological procedures that aim to reproduce the reaction/transition rates but do not necessarily capture the exact physics. These engineering models are necessarily efficient due to the requirement to compute billions of simulated collisions in direct simulation Monte Carlo (DSMC) simulations. The new models are shown to generally agree within the spread of reported transition and reaction rates from the literature for near equilibrium conditions.

Palladium-catalyzed C-N and C-O bond formation of N-substituted 4-bromo-7-azaindoles with amides, amines, amino acid esters and phenols.

Simple and efficient procedures for palladium-catalyzed cross-coupling reactions of N-substituted 4-bromo-7-azaindole (1H-pyrrole[2,3-b]pyridine), with amides, amines, amino acid esters and phenols through C–N and C–O bond formation have been developed. The C–N cross-coupling reaction of amides, amines and amino acid esters takes place rapidly by using the combination of Xantphos, Cs2CO3, dioxane and palladium catalyst precursors Pd(OAc)2/Pd2(dba)3. The combination of Pd(OAc)2, Xantphos, K2CO3 and dioxane was found to be crucial for the C–O cross-coupling reaction. This is the first report on coupling of amides, amino acid esters and phenols with N-protected 4-bromo-7-azaindole derivatives.

The Q-K model for gas-phase chemical reaction rates

The quantum-kinetic, or Q-K, model is based on the quantum vibration model that is employed in the computation of gas flows at the molecular level by the direct simulation Monte Carlo (DSMC) method. The Q-K procedure for dissociation is physically realistic within the context of the vibration model in that the reaction occurs upon the selection of the vibrational level that corresponds to dissociation. An analogous, but entirely phenomenological, procedure has been presented for endothermic exchange and chain reactions. These procedures for the endothermic reactions have been well validated, but the existing procedures for the corresponding exothermic reactions have proved to be problematic. This paper presents new procedures for the exothermic reactions that are computationally efficient and provide a near exact match with the equilibrium constant of statistical mechanics. The Q-K model does not depend on the availability of continuum rate coefficients. Instead, the simplicity of the new DSMC procedures allows analytical expressions to be written down for the corresponding rate coefficients in an equilibrium gas. These are used to validate the Q-K model for reactions in high temperature air and in hydrogen-oxygen combustion. The development of the Q-K model has been driven by the need for efficient reaction procedures in DSMC applications that often involve the computation of billions of simulated collisions. It is not intended to compete with the modern theories for gas-phase chemical reactions that employ more accurate physical representations of real reactions. At the same time, the degree of validation of the model is such that the analytical expressions for the rate coefficients that correspond to the model should be useful in their own right.

Efficient synthesis of racemic β-aminophosphonates via aza-Michael reaction in water

Water as a solvent significantly accelerates the addition of various amines to diethyl vinylphosphonate to yield β-aminophosphonates without any catalyst compared to known procedures for such aza-Michael reactions. The products are obtained in quantitative yields and high purity over short reaction times. Using a reactant ratio (vinylphosphonate/amine) of 2:1 resulted in double phosphorylation of primary amines.

Isolation and characterization of a novel tetrahydro‐[2,2′]bipyrrolyl dimer as an impurity from a knorr reaction

AbstractA novel dimer, tetraethyl 2,2′,3,3′‐tetramethyl‐1,1′,2,2′‐tetrahydro‐4H,4′H‐2,2′‐bipyrrolyl‐5,5,5′,5′‐tetracarboxylate, has been isolated as an impurity (0.4% yield) from a Knorr reaction for the synthesis of ethyl 3,5‐dimethylpyrrole‐2‐carboxylate from 2,4‐pentanedione and diethyl oximinomalonate in a dissolving zinc reduction. The solid‐state structure of this novel dimer was determined by X‐ray crystallography. Knorr reactions typically rely upon the requisite pyrrole being the only water‐insoluble crystalline material present in the reaction mixture, and so work‐up and purification procedures for Knorr reactions should be monitored carefully given the water‐insolubility of this dimer. Investigations regarding mechanistic implications and reductive dimerization are underway.

Testing novel short-cut methods for complex kinetic characterisation in early safety assessment of a chemical process

One of the hazards of most concern in the chemical industry is the thermal hazard, which is governed by the thermodynamics and kinetics of the usually complex chemical reactions. To develop risk analysis indices the approximate knowledge of the reaction path, kinetics and thermal effects are crucial elements. While standardised tests to experimentally determine the ‘thermal stability data’ and assessment procedures for runaway reactions are developed, their interpretation is difficult to be generalised because they have been developed in the context of a specific process, and they often contain empirical as well as rationally deduced elements and rules. This paper illustrates major advantages and result improvements in thermal risk analysis when two short-cut techniques are combined: the experimental ‘Differential Scanning Calorimetry’ ( DSC) and the numerical ‘Modified Integral Transformation Procedure’ ( MIP). The DSC is useful in investigating the n-th order kinetics and overall thermal effect of a reaction following an elaborated strategy; attempts to fit more complex kinetics fail especially in the model discrimination step. The MIP ( Maria and Rippin, 1997) performs a short-cut kinetic model identification by considering previous information stored in databanks and incomplete information about the process. By coupling the DSC and MIP techniques quick identification of a (reasonable) complex chemical kinetics becomes possible. Exemplification is made for an auto-catalytic process with incomplete data by obtaining: i) a more exact evaluation of the safety index TMR ad compared with those derived from classical DSC; ii) a more robust estimate of the kinetics by using the databank information in overcoming poor-conditioning due to incomplete data.

Stable Carbon and Oxygen Isotope Analysis of Natural Calcite and Dolomite Mixtures using Selective Acid Extraction

Abstract Accurate analysis of coexisting calcite and dolomite for d13C and d18O is generally hindered by the difficulty in the physical separation of these minerals. The difference in the reaction rates of calcite and dolomite with phosphoric acid, has been used to chemically separate these carbonates. Previously established procedures are only suitable for samples containing 1:1 calcite-dolomite pairs. However, these are sometimes tedious and time-consuming. Using mixtures of calcite and dolomite, two different selective acid extraction procedures (for reactions at 25°C), one for calcite-rich and the other for dolomite-rich carbonates, have been developed. Reduction of grain size (to 37μm - 45μm) increased the reaction rate and hence decreased the total reaction time to a reasonable interval (=72 hours for dolomite). Applying these procedures, d13C and d18O of calcite and dolomite/ankerite of carbonatites from Amba Dongar and Sung Valley carbonatite complexes of India were measured and their temperatures of crystallization determined. Accurate isotopic compositions of individual carbonates of calcite-dolomite mixtures can be determined for geological interpretations by these procedures.

NMR spectroscopic studies of I = 1/2 metal ions in biological systems

This article reviews the use of nuclear magnetic resonance methods of spin 1/2 metal nuclei to probe the metal binding site(s) in a variety of metalloproteins. The majority of the studies have involved native Zn(II) and Ca(II) metalloproteins where there has been isostructural substitution of these metal ions with the I = 1/2 111/113Cd(II) ion. Also included are recent studies that have utilized the 109Ag(I) ion to probe Cu(I) sites in yeast metallothionein and 199Hg(II) as a probe of the metal binding sites in mercury resistance proteins. Pertinent aspects for the optimal execution of these experiments along with the procedures for the metal substitution reactions are discussed together with the presentation of a 113Cd chemical shift correlation map with ligand type and coordination number. Specific examples of protein systems studied using the 111/113Cd and 109Ag nuclei include the metallothionein superfamily of Zn(II)- and Cu(I)-binding proteins from mammalian, invertebrate, and yeast systems. In addition to the structural features revealed by these metal ion nuclear magnetic resonance studies, important new information is frequently provided about the dynamics at the active-site metal ion. In an effort for completeness, other less frequently used spin 1/2 metal nuclei are mentioned.Key words: metallothionein, 111/113Cd, 199Hg, 109Ag, 57Fe, 205Tl, 195Pt, 207Pb, 119Sn, nuclear magnetic resonance.

NMR spectroscopic studies of I = 1/2 metal ions in biological systems.

This article reviews the use of nuclear magnetic resonance methods of spin 1/2 metal nuclei to probe the metal binding site(s) in a variety of metalloproteins. The majority of the studies have involved native Zn(II) and Ca(II) metalloproteins where there has been isostructural substitution of these metal ions with the I = 1/2 (111/113)Cd(II) ion. Also included are recent studies that have utilized the 109Ag(I) ion to probe Cu(I) sites in yeast metallothionein and 199Hg(II) as a probe of the metal binding sites in mercury resistance proteins. Pertinent aspects for the optimal execution of these experiments along with the procedures for the metal substitution reactions are discussed together with the presentation of a 113Cd chemical shift correlation map with ligand type and coordination number. Specific examples of protein systems studied using the (111/113)Cd and 109Ag nuclei include the metallothionein superfamily of Zn(II)- and Cu(I)-binding proteins from mammalian, invertebrate, and yeast systems. In addition to the structural features revealed by these metal ion nuclear magnetic resonance studies, important new information is frequently provided about the dynamics at the active-site metal ion. In an effort for completeness, other less frequently used spin 1/2 metal nuclei are mentioned.