Vol. 118 No. 3 (2022)

The amino acids are of crucial importance in many research areas. This article describes a variety of C–H functionalization reactions of amino acids catalyzed by Pd in diverse positions of the carbon chain. In particular, we have developed robust and selective procedures for the γ- and δ-arylation, as well as γ- and ε-carbonylation with formation of γ-lactames and benzazepinones, respectively. These methodologies have been also extended to small peptides. In all these C–H functionalization reactions the coordinating group SO2Py plays a crucial role and can be eliminated in the final products under mild reductive conditions.

Keywords: C–H Functionalization, palladium, amino acids, sulfones, pyridine

The Pair Distribution Function (PDF) is a characterization technique that allows studying the atomic structure of chemical compounds even if they are not crystalline. In this article, we discuss the application of PDF analyses in the field of nanoporous materials. Specifically, the use of this characterization technique will be described for metal-organic frameworks, where it does not stop gaining importance due to its versatility and potential to elucidate complex structures, both at local and intermediate scales.

Keywords: Pair Distribution Function (PDF), Metal Organic Frameworks (MOFs), Local structure, Defects

History of chemistry is a powerful didactic tool for promoting a significative, contextualized, crytical and experimental learning of chemistry. This paper presents a wide framework on the educational use of history of chemistry based on research studies and a collection of several teaching experiences for secondary education in order to point out the potentialities of history of chemistry for Physics and Chemistry high school teachers.

Keywords: history of chemistry, STEM Education, Teaching, Secondary Education, Physics and Chemistry

Science dissemination is an instrument of personal and professional training through which students acquire a set of skills that enable their full development in society. This task must be implemented from the very youngest and that is why teachers must train these students to get a critical spirit and meaningful learning. From the research group of Separation Techniques and Applied Analysis (TESEA) of the University of Valladolid, an outreach proposal has been made within the framework of the Science Week of Castilla y León 2021 to tackle this situation.

Keywords: chemistry, dissemination, curiosity, education, students

The study of complex chemical concepts is often limited to the use of simple and specialised instrumentation, that is commonly found in all laboratories, although at a relatively high price. However, in recent years, technological advances and globalisation have made possible the emergence of low-cost instruments (balances, thermometers, manometers, pH meters, etc.) that, despite their low accuracy, can be very useful for detecting significant changes in a magnitude and, therefore, they can be used for didactic experiences outside traditional laboratories. This work focuses on the validation of a low-cost non-professional pH meter, used in swimming pools and fish tanks, for use them as potentiometric detector in acid-base titrations. Their use has been validated in strong acid/strong base and weak acid/strong base titrations, obtaining only a 1% error respecting to the theoretical curve in both cases. Thus, these pH-meters have been used to determine the ammonia content of a household cleaner after titration with hydrochloric acid, obtaining excellent results.

Keywords: Low cost pH-meters, potentiometric titration, acid/base titration curve, equivalence point

A historical study is carried out on Le Châtelier’s principle. After its first acceptance, the principle was widely questioned because of both its limitations and the vague and ambiguous character of the different attempts performed to qualitatively enunciate it. New criticisms emerged to the various rules that have been formulated for educational purposes. Apart from this, it is usually presented as a universal rule, easy to remember and apply, which may explain why it has been consolidated as a didactic tool within the topic of chemical equilibrium, which has led to be one of the essential elements for its assessment.

Keywords: Le Châtelier’s principle limitations, language problems, the rule as a didactic instrument, learning dificulties

The thermographic camera provides an interesting and visually appealing view of processes invisible to the human eye, related to matter and the transfer of thermal energy. At a didactic level, this new technology constitutes an effective tool for improving comprehension of chemical phenomena.

Keywords: Thermographic camera, infrared camera, thermography and chemistry

A brief introduction to the origins of the STEM movement is given. Subsequently, the problems arising from both the lack of its precise conceptualisation and the attempts to its implementation in educational settings are analysed, pointing out the criticisms its integrated approach has received from three related fields: specific didactics, cognitive psychology and curriculum theory.

Keywords: STEM, integration, inquiry, competences, knowledge