The pKa values of water and the hydrogen ion (proton) in water are 14 and 0, respectively. Yet, many textbooks of general, organic, and, to a lesser extent, inorganic chemistry provide the incorrect ...values 15.74 and -1.74, respectively. This column briefly introduces the long-standing issue of these two different pairs of values, the consequences it bears when teaching general chemistry, and expresses the hope that it may be solved soon.
Do You Speak Chemistry? Togni, Antonio
Chimia,
10/2023, Letnik:
77, Številka:
10
Journal Article
Recenzirano
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This article is a broad personal reflection about the language of chemistry, deriving from decades of experience in both research and teaching. The three levels of thought as represented by the ...Johnstone triangle, a critical attitude towards systematic nomenclature, the concept of pure substance, and the central significance of structural formulas as the most prominent form of representation in chemistry, are the main topics discussed. The chemical transliteration of the Platonic solids is presented as a mean of expression unique to chemistry.
The aim of this article, while reviewing part of my research activities, is to illustrate the somewhat chaotic way leading from one specific topic to another - from e.g. ferrocenyl ligands for ...asymmetric catalysis, to asymmetric fluorination, to reagents for perfluoroalkylation, just to mention some of the most fruitful ones. That the way meandering through several areas of research in chemical synthesis can be described as chaotic is not primarily due to my inability to plan the work of my research group. In the contrary, it is argued that academic research, viewed as mean to educating and forming young researchers, should resist the temptation towards an increasing projectification, milestone mentality, the myth of societal relevance, and consciously aim for a more anarchical trait, much in the sense of Feyerabend's "anything goes".
Chemistry is a science fundamentally characterized by the ability of making its own study objects. Chemistry's unique sign language and representations of structural formulas are highly predictive ...tools. These aspects, together with the richness of qualitative models, make chemistry highly attractive for philosophical studies. However, philosophy of chemistry is, within the philosophy of science, a still relatively young discipline.
The purpose of this column consists in illustrating the utility of log-log diagrams for the graphical determination of the pH value of acid-base systems in dilute aqueous solution. This methodology ...allows to tackle systems going well beyond the case of mono- or diprotic acids, providing fast and accurate estimations of the pH. It is also argued that the use of so-called Sillén diagrams affords a better understanding of complex acid-base systems.
70 Years Ferrocene Togni, Antonio
Chimia,
09/2021, Letnik:
75, Številka:
9
Journal Article
Recenzirano
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Some of the most important features of ferrocene chemistry - structure, reactivity, redox properties, and applications - are presented. Their value in the context of conveying many fundamental ...aspects of molecular chemistry is considered.
The authors study the use of hypervalent iodine reagents in electrophilic trifluoromethylation reactions. Activation of the reagents by Lewis acids and. Bronsted acids are among the topics discussed.
What is the strongest Brønsted acid, the strongest base, the strongest oxidizing agent? If not understood in an absolute, once-and-forever sense, the answers to such questions may help at extending ...and reinforcing the meaning of simple concepts in first-year chemistry courses. Moreover, they serve the purpose of introducing research aspects and linking them to general chemistry.
The molecule of the week is regularly used by the author in his first-semester course General Chemistry I (Inorganic Chemistry) to illustrate, exemplify, and deepen fundamental aspects and concepts ...treated in the course. Pure sulfuric acid and its autoprotolysis is used to introduce the concepts of protochemical window and superacidity. The drug Auranofin serves at showing fundamental aspects of gold redox and coordination chemistry and the widely used disinfectant trichlo- roisocyanuric acid (TCICA) exemplifies redox processes with organic compounds.
Methyltrioxorhenium acts as a catalyst (5–10 mol %) for the direct electrophilic trifluoromethylation of various aromatic and heteroaromatic compounds using the hypervalent iodine reagent ...1-(trifluoromethyl)-1,2-benziodoxol-3(1H)-one (1). The products are formed in up to 77% yield. Mixtures of regioisomers are obtained in the case of substituted and heteroaromatic substrates. The reaction, typically carried out in chloroform solvent at 70 °C, shows a significant induction period. Monitoring by EPR shows the involvement of radical species. A small kinetic deuterium isotope effect of 1.3 is observed for benzene.
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