RESUMO
Phenolic compounds have long been of great importance in the pharmaceutical, food, and cosmetic industries. Unfortunately, conventional extraction procedures have a high cost and are time consuming, and the solvents used can represent a safety risk for operators, consumers, and the environment. Deep eutectic solvents (DESs) are green alternatives for extraction processes, given their low or non-toxicity, biodegradability, and reusability. This review discusses the latest research (in the last two years) employing DESs for phenolic extraction, solvent components, extraction yields, extraction method characteristics, and reviewing the phenolic sources (natural products, by-products, wastes, etc.). This work also analyzes and discusses the most relevant DES-based studies for phenolic extraction from natural sources, their extraction strategies using DESs, their molecular mechanisms, and potential applications.
Assuntos
Produtos Biológicos/química , Fracionamento Químico/métodos , Fenóis/isolamento & purificação , Solventes/químicaRESUMO
This review article describes the use of some of the most popular chiral auxiliaries in the asymmetric synthesis of biologically active compounds. Chiral auxiliaries derived from naturally occurring compounds, such as amino acids, carbohydrates, and terpenes, are considered essential tools for the construction of highly complex molecules. We highlight the auxiliaries of Evans, Corey, Yamada, Enders, Oppolzer, and Kunz, which led to remarkable progress in asymmetric synthesis in the last decades and continue to bring advances until the present day.
RESUMO
In the title compound, C(15)H(12)N(4)OS(2), the bond distances in the fused heterocyclic system show evidence for aromatic-type delocalization in the pyrazole ring with some bond fixation in the triazine ring. The thiophenyl substituent is slightly disordered over two sets of atomic sites having occupancies of 0.934 (4) and 0.066 (4). The non-H atoms in the entire molecule are nearly coplanar, with the planes of the furanyl substituent and the major orientation of the thiophenyl substituent making dihedral angles of 5.72 (17) and 1.8 (3)°, respectively, with that of the fused ring system. Molecules are linked into centrosymmetric R2(2)(10) dimers by C-H...O hydrogen bonds and these dimers are further linked into chains by a single π-π stacking interaction. Comparisons are made with some related 4,7-diaryl-2-(ethylsulfanyl)pyrazolo[1,5-a][1,3,5]triazines which contain variously substituted aryl groups in place of the furanyl and thiophenyl substituents in the title compound.