OXYGEN IN THE COVID-19 CONTEXT: WHAT WE KNOW ABOUT THE MOLECULE WE BREATHE AND THE CENTRAL ROLE OF CHEMISTRY. In this work, the role of chemistry in the coronavirus disease 2019 (COVID-19) pandemic is highlighted through the medical oxygen supply crises in Brazil, as an example of oxygen utility in health. Starting from oxygen chemical characterization, the oxygen cycle in nature is discussed to show how oxygen is formed through photosynthesis, followed by the description of the industrial oxygen production from atmospheric air, including physical-chemical aspects. The use of medical oxygen concentrator is presented and how this device works from the chemical point of view. Besides, the noninvasive and painless oximetry is described in terms of how oxygen saturation level in blood is measured using LED - light emitting diode.

This paper deals with the solubility and reactivity of gases, especially in water, covering the main aspects that influence the dissolution process, namely polarizability of atoms or molecules in gas phase and their ability to react with the solvent. The discussion highlights the importance of solubility of gases in several biological processes, such as respiration and photosynthesis, hydrogen storage and industrial processes, as the production of carbonated beverages. The discussion also addresses the importance of gas solubility in atmospheric chemistry and aquatic environments.

<p>We described herein a solvent-free synthesis of acetanilide developed in the context of green chemistry. The synthetic approach consisted of the reaction of aniline with acetic anhydride without additives, while using smaller amounts of reagents and water than previously described for this undergraduate experiment. The E Factor was 0.6 by experienced chemists and 0.9 by students.</p>

The solubility of organic compounds is a topic of great importance in chemistry and of interest in several areas, such as materials, drugs and the environment. In this paper, the solubility of these species is discussed in terms of their properties, such as the predominant type of chemical bond, molecular structure, polarity and types of intermolecular interactions. Examples of biological processes fundamental for sustainability of life and related with the solubility of chemical species are presented and discussed.

The perception of the flavor is an important attribute of quality in marine fish and other seafoods, being the first and main factor of discrimination for the evaluation, later acceptance and preference of the product by the consumer. Recently, the simple bromophenols have been considered an important group of key flavor compounds occurring in a wide variety of seafood species like fishes, mollusks, crustaceans and algae. When present in high concentration, in seafood, the bromophenols produce an undesirable flavor and are associated with inferior quality. Meanwhile, when present in low concentration levels (for example ng g-1) these compounds produce a desirable marine - or ocean-like - flavor and enhance the existing flavor in seafood. Indeed, simple bromophenols are widespread in seafood but virtually absent in freshwater fish. Herein we present a review on these flavor components found in the marine environment.

Neste trabalho, são apresentados os potenciais de meia-onda de redução, determinados para 3-nitrofluoranteno (3-NF) = -0,51V, 1-nitropireno (1-NP) = -0,61V, 6-nitrocriseno (6-NC) = -0,64V, e 9-nitroantraceno (9-NA) = -0,84V. Os experimentos de voltametria cíclica com os nitro-PAH foram conduzidos em N,N-dimetilformamida anidra (DMF) contendo perclorato de tetraetilamônio 0,1 mol L-1 (TEAP), usando-se uma célula de três compartimentos, equipada com eletrodos de trabalho e auxiliar de platina e eletrodo de referência de Ag/AgI (fio de prata imerso em DMF / TEAP 0,1 mol L-1, contendo iodeto de tetrabutilamônio 0,05 mol L-1). Esses potenciais podem ser ordenados do menos negativo para o mais negativo, o que corresponde à mesma ordem com que decresce a ação mutagênica direta (3-NF >> 1-NP > 6-NC >> 9-NA). Assim, o 3-NF, que apresentou o potencial de meia-onda menos negativo é, entre os nitro-PAH estudados, o de maior atividade mutagênica. Deste modo, estas propriedades podem ser utilizadas como indicativas do risco à saúde humana da exposição a nitro-PAH, sendo, portanto, de grande importância em estudos toxicológicos.

In this work, we report measured electrochemical half-wave reduction potentials of 3-nitrofluoranthene (3-NF), 1-nitropyrene (1-NP), 6-nitrochrysene (6-NC) and 9-nitroanthracene (9-NA): = -0.51V; -0.61V; -0.64V; and -0.84V respectively. The cyclic voltammetry experiments with the nitro-PAH were carried out in anhydrous N,N-dimethylformamide (DMF), containing 0.1 mol L-1 tetraethylammonium perchlorate (TEAP) using a three-compartment cell fitted with Pt working and auxiliary electrodes, and a Ag/AgI reference electrode (a silver wire in 0.1 mol L-1 DMF/TEAP containing 0.05 mol L-1 tetrabutylammonium iodide). These potentials can be ordered from the less to the more negative value, which corresponds to the same order by which the direct-acting mutagenicity decreases (3-NF >> 1-NP > 6-NC >> 9-NA). Thus, 3-NF, which shows the less negative first half-wave potential value is the more active mutagenic amongst the nitro-PAH studied. In this way, these properties may be used as an indicative of the health risks, asociated to nitro-PAH exposure, and thus being of great importance in toxicological studies.

This article decribes a simple and systematic method to interpret an infrared spectrum using a flow chart to elucidate the structure of a simple organic compound. It is aimed at undergraduate courses of organic chemistry to make beginners proficient. The proposed flow chart for infrared spectrum interpretation and characterization of organic compounds is suitable for theoretical and experimental courses.