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.

Medicines are employed in undergraduate courses as motivational strategy. The experiment herein developed compares the extraction of paracetamol from generic and brand name drugs. Tablets were used from two commercial sources purchased from local drugstores. Twenty tablets of each drug type were individually weighed to average weight analysis and mass dispersion was statistically analyzed in simulating of quality control. Average weight had variation in accordance with the limit of ±5% specified by Brazilian Pharmacopeia. Tablets of each drug were pulverized and extracted in triplicate with ethyl acetate, and the active ingredient was obtained and identified by melting point and FTIR analyzes. Comparing different student groups at different times, there was change in the mass of paracetamol extracted by a simple extraction, affording mass recovery in the range of 59±17% to 28±1%. However, mass recovery of paracetamol extraction of generic and brand name drugs was similar in each student group. Under Soxhlet extraction condition mass recovery was 80-85%. The procedure developed was adequate to undergraduate laboratory, involves simple infrastructure and execution, tablets are easily obtained, and allows discussion on pharmaceutical equivalence and interchangeability.

The synthesis of 3-coumarin-carboxylic acids and their application to the total synthesis of the natural products ayapin, coumarin, and umbeliferone in undergraduate organic chemistry experiments is described herein. The synthetic approach consists of a one-pot cyclization between salyciladehydes and Meldrum's acid in water to produce the above mentioned acids, followed by decarboxylation under basic or radical conditions.

<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>

This work describes an undergraduate experiment for the synthesis of Knoevenagel adduct of Meldrum's acid with nine aromatic aldehydes, using water as the solvent, in an adaptation of a previously reported synthetic protocol. The synthesis was straightforward, requiring a period of two hours, and is suitable for undergraduate experimental courses on green chemistry. In addition, quantitative analyses of the relative reactivity of p-nitro-benzaldehyde and p-metoxi-benzaldehyde was evaluated through the competitive reaction of equimolar amounts of these aldehydes with one equivalent of Meldrum's acid, using gas chromatography to quantify the composition of the reaction mixture.