Organic Chemistry
Mostrando 13-24 de 312 artigos, teses e dissertações.
-
13. Production of Furanic Compounds and Organic Acids from Brazilian Pequi (Caryocar brasiliensis Camb.) Residues Using Green Chemistry
In the current search for renewable energy sources, residual biomass has gained ground in the concept of biorefinery. Furanic compounds such as 5-hydroxymethylfurfural (HMF), furfural (FF) and derivatives such as levulinic acid (LA), obtained from biomass, have emerged as important industrial chemical platforms. In this sense, this work aimed to use pequi ba
J. Braz. Chem. Soc.. Publicado em: 2020-07
-
14. EVOLUÇÃO DIRIGIDA DE ENZIMAS: PEQUENAS MODIFICAÇÕES, MELHORES BIOCATALISADORES
Biocatalysis is now a mature field, both in the laboratory and industrial scale. This approach counts on enzyme high selectivity, biodegradability, elegant control over the outcome of reaction conditions and as a possible solution to address some challenges in Green Chemistry faced by synthetic organic chemists. However, many wild-type ready-to-use enzymes w
Quím. Nova. Publicado em: 2020-06
-
15. PREPARAÇÃO DE HIDRAZONA E N-ACILIDRAZONA USANDO FÁRMACOS COMERCIAIS COMO REAGENTES: AULAS PRÁTICAS DE SÍNTESE DE COMPOSTOS BIOATIVOS
Several scientific works demonstrate the chemical and medicinal importance of hydrazone compounds. In this regard, the present paper proposes some practical classes of chemoinformatics and organic chemistry, using investigative and illustrative strategies, to teach the synthesis of a hydrazone and a N-acylhydrazone with proven biological activity. The motiva
Quím. Nova. Publicado em: 2020-05
-
16. ONE-POT DIASTEREOSELECTIVE SYNTHESIS OF CHIRAL TRICYCLIC L-CYSTEINE AND D-PENICILLAMINE DERIVATIVES: A LABORATORY EXPERIMENT
A one-pot diastereoselective synthesis of thiazolidine-ring fused systems derived from enantiomerically pure amino acids, L-cysteine or D-penicillamine, and achiral succindialdehyde is described as an experiment to be carried out by upper-division undergraduate students in a laboratory classroom. Reactions were performed under mild conditions, the products w
Quím. Nova. Publicado em: 2020-01
-
17. Synthesis of Hybrid Monolithic Columns Using a Click Chemistry Reaction for Application in Capillary Liquid Chromatography
Hybrid monolithic columns present characteristics of both silica and organic monoliths, such as good mechanical properties, wide pH tolerance, high permeability and stability and little swelling or shrinkage. A common way to prepare this type of material is by using alkoxysilanes and organic monomers via the sol-gel process and click chemistry reactions. In
J. Braz. Chem. Soc.. Publicado em: 24/10/2019
-
18. REVISITING THE NUCLEOPHILICITY CONCEPT IN A COMPREHENSIVE BIOMASS VALORIZATION EXPERIMENT: FROM PAPAYA SEEDS TO THIOUREA MOTIFS
The recovery of waste materials with potential for synthetic transformations is a major field in science. However, just few experiments have been devoted to undergraduate students by exploring some consistent subjects in light of simple, natural resources. Nucleophilicity is a central subject in chemistry and there are significant synthetic models to exploit
Quím. Nova. Publicado em: 21/10/2019
-
19. Methane emission induced by short-chain organic acids in lowland soil
ABSTRACT Methane (CH4) is the second major greenhouse gas after CO2, exerting a significant influence on the climate and the chemistry of the atmosphere. In lowland soil, acetate and H2/CO2 are the most important precursors of CH4 and formed from organic matter fermentation in an anaerobic environment, giving rise to short-chain organic acids (ethanoic, prop
Rev. Bras. Ciênc. Solo. Publicado em: 14/10/2019
-
20. HYBRID ATOMIC ORBITALS IN ORGANIC CHEMISTRY. PART 2: CRITIQUE OF PRACTICAL ASPECTS
The importance of hybrid atomic orbitals, in both general and organic chemistry, is reviewed. Every contemporary textbook of organic chemistry introduces the directed-valence (e.g. sp3, sp2, sp) model, but the suitability of these hybrid orbitals for use in the teaching of molecular structure has been increasingly questioned. Based on a critical survey of th
Quím. Nova. Publicado em: 26/08/2019
-
21. HYBRID ATOMIC ORBITALS IN ORGANIC CHEMISTRY. PART 1: CRITIQUE OF FORMAL ASPECTS
The importance of hybrid atomic orbitals, both historically and mathematically, is reviewed. Our new analysis of the original derivation of the sp3, sp2, sp model reveals serious errors. Based on a critical survey of the literature, we submit six formal criteria that deprecate the use of hybrid orbitals in a pedagogical context. A sound mathematical basis of
Quím. Nova. Publicado em: 26/08/2019
-
22. 1H NMR STUDY OF THE HOST-GUEST CHEMISTRY IN A SUPRAMOLECULAR HELICATE FEII 2L3 SOLUTION
A novel [FeII2L3]4+ metallo-organic helicate results from subcomponent self-assembly of a C3-symmetric triamine (4,4',4''- (1,3,5-triazine-2,4,6-triyl) trianiline), octahedral iron(II) and 2-formyl pyridine in CH3CN solution. The constitution of this supramolecular helicate was confirmed by ESI-MS and 1H NMR spectra. Different planar aromatic guests were sel
Quím. Nova. Publicado em: 27/05/2019
-
23. Streamlined Synthesis of 6-((1H-1,2,3-Triazol-4-yl)methyl)-1H-pyrrolo [3,4-d]pyridazin-1-one System via Sequential N-Alkylation, CuAAC, and [4 + 2] Cyclization Reactions
An efficient sequential three-step reaction methodology for the synthesis of three new series-1-(prop-2-yn-1-yl)-1H-pyrroles, methyl 4-acetyl-1-((1H-1,2,3-triazol-4-yl)methyl)-1H-pyrrole-3-carboxylates and 6-((1H-1,2,3-triazol-4-yl)methyl)-2,6-dihydro-1H-pyrrolo[3,4-d]pyridazin-1-ones-is reported. The methodology comprises: (i) N-alkylation reactions of poly
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
-
24. Potential Therapeutic Targets of the Endocannabinoid System in Common Neurodegenerative Disorders and Organic Acidemias
Abstract The cannabinoid chemistry is currently being addressed in preclinical approaches as a viable therapeutic alternative for the management of a wide range of signs, symptoms, and some biochemical hallmarks of many neurological pathologies (such as neuroinflammation and neurodegeneration). This clinical orientation is grounded on the consistent promisso
J. inborn errors metab. screen.. Publicado em: 16/05/2019