The production and consumption of biodiesel in Brazil and worldwide have considerably increased in the last decades. As a consequence, the waste glycerol (glycerin) as a byproduct from this synthetic process has also increased since approximately 10-30% of glycerol is generated in the biodiesel synthesis process. Therefore, the reuse of glycerol after the biodiesel synthesis is highly desired. However, waste glycerol purification is still a costly process. In this context, herein, we propose a synthetic alternative for the use of waste glycerol as a solvent and promoting medium for condensation reactions of 1,8-diaminonaphthalene and different aldehydes. The reactions were carried out using the waste glycerol without prior purification at room temperature for 30 min, affording the synthesis of a series of perimidines in excellent yields. Furthermore, a comparative study was performed between the use of commercial glycerol or waste glycerol in the reactions, and the results showed that the waste glycerol is more efficient considering the product yields. The use of waste glycerol as a green solvent and a promotion medium for organic processes is a robust, sustainable, and economically viable option for the application of this undesired byproduct of biodiesel synthesis.

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping. We present the preparation of a green-colored hydroxide by the exchange of Mg²⁺ on the crystalline lattice with Ni²⁺ in MgO, using three nickel salts. MgO_st was prepared by the colloidal starch suspension method, using cassava starch. The oxides and hydroxides, before and after, were characterized by X-ray diffraction (XRD), and show that a phase change occurs: a transition from periclase (MgO) to brucite (Mg(OH)₂) due to the incorporation of nickel ions from different salts (acetate, chloride, and nitrate), resulting in the solid solution [Ni_xMg_1−x(OH)₂]. The FTIR spectrum corroborates the crystallographic structure identified through XRD patterns, confirming the formation of a crystal structure resembling brucite. The new samples present a green color, indicative of the incorporation of the Ni²⁺ ions. The antimicrobial activity of products resulting from the doping of magnesium oxide with nickel and the precursor MgO_st was assessed through the minimum inhibitory concentration (MIC) test. The evaluation included three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Salmonella gallinarum (ATCC 9184), and a yeast strain, Candida albicans (ATCC 10231). The obtained results were promising; the tested samples exhibited antimicrobial activity, with a MIC ranging from 0.312 to 0.625 μg.μL⁻¹. The nickel compound, derived from the precursor chloride salt, demonstrated superior MIC activity. Notably, all tested samples displayed bactericidal activity against the S. aureus strain and exhibited a broad spectrum of inhibition, encompassing both Gram-positive and Gram-negative strains. Only the nickel compounds derived from precursors with acetate and nitrate anions demonstrated antimicrobial activity against C. albicans, exhibiting a fungistatic behavior. Based on the conducted studies, [Ni_xMg_1−x(OH)₂] has emerged as a promising antimicrobial agent, suitable for applications requiring the delay or inhibition of bacterial growth.

Herein, we report the synthesis, characterization, and catalytic evaluation of cobalt hydroxide chloride [Co₂(OH)₃Cl] in the solvent-free synthesis of 2-substituted 2,3-dihydroperimidines. The presented method aligns with several green chemistry principles, offering operational simplicity, purification by recrystallization, no by-product formation, high yields (64–99%), and short reaction times. A total of 16 dihydroperimidines were synthesized to demonstrate substrate scope versatility. Additionally, the catalyst was successfully recycled and reused in multiple cycles without significant loss. Its robustness was further confirmed by gram-scale synthesis, achieving an 89% yield.

Phenoselenazines are nitrogen and selenium-based heterocyclic compounds that have important biological activities. However, their preparation methods are scarce and difficult to handle. The synthesis of a phenoselenazine from a simple and robust CuO nanoparticle catalyzed methodology, using bis-aniline-diselenide and 1,2-dihalobenzenes under microwave irradiation. Also, the double-cross-coupling reaction mechanism for C-Se and C-N bond formation, including the observation of a reaction intermediate by mass spectrometry have been studied.

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping or by adsorption. We present the preparation of green colored hydroxide by the adsorption of nickel ions by porous MgO. MgO was prepared by the colloidal starch suspension method and used to remove nickel ions from the aqueous solution. The oxides and hydroxides, before and after adsorption, were characterized by X-ray diffraction technical, and show that a phase change occurs, a transition from periclase (MgO) to brucite (Mg(OH)2) due to the interaction with nickel salts (acetate, chloride, and nitrate). The FTIR spectrum corroborates with the DRX data on the formation of brucite like crystal lattices. The new samples present a green color, indicative of the incor-po-ration of the Ni2+ ions. Mixed oxides in the form of brucite were used in microbiological tests and showed action against fungi and bacteria, with bactericidal, bacteriostatic, or fungistatic function. Green brucite (NixMg1-x(OH)2) can be used as an inorganic pigment in white or colorless paints with a special biocidal property.

Practical laboratory experiments are essential to connecting theory to practical application and providing important support for academic training; however, many curricula still lack effective practical activities. This work proposes a didactic laboratory experiment highlighting the organic synthesis of a heterocyclic perimidine, providing an integrative approach to concepts such as carbonyl group addition and substitution (imine formation), thin-layer chromatography (TLC), liquid-liquid extraction, recrystallization, and yield calculations. Furthermore, a comparison was made between water and glycerol as environmentally friendly (green) solvents. Characterization techniques such as melting point, spectroscopy NMR 1H and 13C, vibrational spectroscopy (FTIR) and UV-Vis were also used for product identification and discussion. The experiment was designed for undergraduate students and offered an opportunity to explore a variety of concepts in organic chemistry while integrating sustainable practices with fundamental techniques, demonstrating its potential as an effective and engaging educational tool.