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Alves, Oswaldo Luiz

doi:10.1590/s0100-40421999000400001

Cited by 3 publications

(7 citation statements)

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“…Recent work suggests that oligomers formed from aqueous phase photochemistry of small organic molecules may contribute significantly to the formation and development of secondary organic aerosol (SOA). 17–25 The surface-active molecules found in the SML are often biological in origin, 14,26,27 but abiotic photochemical sources may be additional, important contributors. 11,12,23,28–30 Such sunlight-driven reactions are critical in the understanding of the formation of marine-derived primary organic aerosol and SOA, 31–37 influencing visibility, human health, cloud formation, and radiative forcing.…”

Section: Introductionmentioning

confidence: 99%

“…Sunlight can drive photoinitiated chemistry of organic species at air–water interfaces, such as the sea-surface microlayer (SML). − The SML contains high concentrations of amphiphilic organic molecules and, as the boundary layer between the ocean and atmosphere, connects processes at the sea surface with the atmosphere, including the generation of sea spray aerosol. Recent work suggests that oligomers formed from aqueous phase photochemistry of small organic molecules may contribute significantly to the formation and development of secondary organic aerosol (SOA). − The surface-active molecules found in the SML are often biological in origin, ,, but abiotic photochemical sources may be additional, important contributors. ,,,− Such sunlight-driven reactions are critical in the understanding of the formation of marine-derived primary organic aerosol and SOA, − influencing visibility, human health, cloud formation, and radiative forcing. ,,− …”

Section: Introductionmentioning

confidence: 99%

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Photochemical Synthesis of Oligomeric Amphiphiles from Alkyl Oxoacids in Aqueous Environments

Rapf¹,

Perkins²,

Yang³

et al. 2017

J. Am. Chem. Soc.

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The aqueous phase photochemistry of a series of amphiphilic α-keto acids with differing linear alkyl chain lengths was investigated, demonstrating the ability of sunlight-initiated reactions to build molecular complexity under environmentally relevant conditions. We show that the photochemical reaction mechanisms for α-keto acids in aqueous solution are robust and generalizable across alkyl chain lengths. The organic radicals generated during photolysis are indiscriminate, leading to a large mixture of photoproducts that are observed using high-resolution electrospray ionization mass spectrometry, but these products are identifiable following literature photochemical mechanisms. The alkyl oxoacids under study here can undergo a Norrish Type II reaction to generate pyruvic acid, increasing the diversity of observed photoproducts. The major products of this photochemistry are covalently bonded dimers and trimers of the starting oxoacids, many of which are multitailed lipids. The properties of these oligomers are discussed, including their spontaneous self-assembly into aggregates.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photochemical Synthesis of Oligomeric Amphiphiles from Alkyl Oxoacids in Aqueous Environments

Rapf¹,

Perkins²,

Yang³

et al. 2017

J. Am. Chem. Soc.

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“…Based on these results, entry 15 was established as the best reaction conditions applied for the other performed reactions. We hy- pothesize that the low solubility of some aldehydes and reactive intermediates may explain the differences in product yields when the solvent mixtures were varied (entries [13][14][15][16][17][18][19][20]. We investigated the profile of this reaction by using other aldehydes 11b-m containing electron-donating and electron-withdrawing groups obtaining the phloroglucinol derivatives in analogous yields.…”

Section: Scheme 2 Synthesis Of Methoxylated Phloroglucinol Derivativementioning

confidence: 99%

“…The NbCl 5 used was supplied by Companhia Brasileira de Metalurgia e Mineração (CBMM) and recrystallized by sublimation following the procedure detailed in the supplementary data described in the literature. 17 TLC was performed on 0.2 mm Merck 60F 254 silica gel aluminum sheets, which were visualized with a vanillin/MeOH/H 2 O/H 2 SO 4 mixture. IR spectra were recorded on a Bruker Vertex 70 Fourier transform spectrometer using a Bruker Platinum ATR unit.…”

Section: Paper Syn Thesismentioning

confidence: 99%

One-Step Synthesis of Methoxylated Phloroglucinol Derivatives Promoted by Niobium Pentachloride: An Experimental and Theoretical Approach

et al. 2017

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S3COMPUTATIONAL DETAILS: All DFT calculations were performed with Gaussian 09 suit of programs using a ultrafine grid [2].Full optimization were conducted in vacuum employing the B3LYP functional with 6-31G(d) basis set. Frequency calculations at 295.15 K (1 atm) ensured that the stationary points represent either minima (no imaginary frequency) or transition states (single imaginary frequency) on the potential-energy surface. The pre-activated complexes were obtained from the first point of the IRC curves. To refine the electronic energy, single-point calculations were performed at the B3LYP/6-311+G(d,p) level of theory with IEF-PCM (in acetonitrile or dichloromethane) and Grimme's D3 dispersion model [3], employing the B3LYP/6-31G(d) geometries. The IRC calculations were done at B3LYP/6-31G(d) ensuring that each transition state connects reagents and products.

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“…O NbCl 5 utilizado foi recristalizado por sublimação conforme procedimento descrito na literatura. 13 As análises por cromatografia em camada delgada (CCD) foram feitas com placas de sílica gel 60 da Aldrich ® e foram visualizadas com uma solução de vanilina / metanol / água / ácido sulfúrico. Os espectros de absorção no IV foram registrados em um espectrômetro Perkin-Elmer Sistema RX-FTIR e as análises de massas de alta resolução foram realizadas em um espectrômetro de massas micrOTOF (Bruker).…”

Section: Parte Experimentalunclassified

Síntese de derivados 4-aril-3,4-di-hidrocumarínicos catalisada por NbCl5

Santos¹,

Siqueira²,

Silva‐Filho³

2013

Quím. Nova

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Recebido em 29/1/13; aceito em 17/6/13; publicado na web em 2/8/13 SYNTHESIS OF 4-ARYL-3,4-DIHYDROCOUMARIN DERIVATIVES CATALYZED BY NbCl 5 . Multicomponent reactions between phenols, b-diesters and benzaldehydes for the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives were carried out under mild conditions (room temperature) and presented moderate yields (38-88%) and reasonable reaction times (2-4 days), using niobium pentachloride as a catalyst.Keywords: niobium pentachloride; multicomponent reaction; coumarin derivatives. INTRODUÇÃOAs cumarinas foram isoladas pela primeira vez por Vogel, em 1820, de flores de trevo (Melilotus Officinalis) e de sementes de Cumaru. Atualmente, mais de 1400 tipos de cumarinas já foram descobertas e caracterizadas. São encontradas em diversas famílias do reino vegetal, como na Papilonaceae (Fabaceae), Lamiaceae, Asteraceae, Solanaceae, Poaceae, Umbelliferae e principalmente na Apiaceae e Rutaceae, nas quais são mais abundantes.1,2 Sua concentração é maior em frutos, sementes e raízes. 1 A cumarina é um princípio ativo natural que pode ser encontrado em diversas plantas e frutas, como no agrião, guaco, canela, chicória, cumaru, emburana, sucupira, chambá, carapiá, ipeca, cereja, morango, framboesa e damasco. Seu aroma é semelhante ao da baunilha.1 As cumarinas possuem propriedades anti-inflamatórias, antioxidantes, anticoagulantes, antibióticas, imunomodulatórias, antimicrobianas, antiviral e broncodilatadoras, sendo assim amplamente aplicadas na medicina no tratamento de linfoedemas, câncer, queimaduras, varizes e doenças reumáticas.3 Na indústria alimentícia, as cumarinas são utilizadas como corantes e essências, e em bebidas alcoólicas. Na indústria de cosméticos, como fixador de perfumes e em pasta de dentes. As cumarinas também apresentam diversas aplicações em diferentes áreas, sendo encontradas em borrachas sintéticas, materiais plásticos, inseticidas, detergentes, cigarros, tintas e sprays. 4 Mais recentemente os compostos cumarínicos e seus derivados têm despertado o interesse de um grande número de grupos de pesquisa, na área de novos materiais, pela possibilidade de seu uso como corantes sensibilizadores em células solares (DSSC) e lasers. As cumarinas absorvem fortemente na região do visível, por isso elas têm grande possibilidade de serem bons sensibilizadores para semicondutores com grande band gap, outro fator que favorece a utilização dos derivados cumarínicos é devido a estes compostos apresentarem um elevado rendimento quântico de fluorescência.

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Cited by 3 publications

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Photochemical Synthesis of Oligomeric Amphiphiles from Alkyl Oxoacids in Aqueous Environments

Photochemical Synthesis of Oligomeric Amphiphiles from Alkyl Oxoacids in Aqueous Environments

One-Step Synthesis of Methoxylated Phloroglucinol Derivatives Promoted by Niobium Pentachloride: An Experimental and Theoretical Approach

Síntese de derivados 4-aril-3,4-di-hidrocumarínicos catalisada por NbCl5

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