Luciano Menini

Novel highly selective catalytic oxychlorination of phenols

The highly selective oxychlorination of various phenols catalyzed by CuCl2 under mild conditions, in which chloride ions are used as chlorinating agents and dioxygen as a final oxidant, has been developed.

Cobalt catalyzed autoxidation of monoterpenes in acetic acid and acetonitrile solutions

Abstract Oxidation of limonene, α-pinene and β-pinene with dioxygen in acetic acid and acetonitrile solutions containing catalytic amounts of CoCl 2 has been studied. Limonene and α-pinene give both allylic oxidation and epoxidation products in a molar ratio of near 1/1, with chemoselectivities for corresponding products being higher in acetonitrile than those in acetic acid. On the other hand, oxidation of β-pinene leads essentially to allylic products, i.e. highly valuable pinocarveol, pinocarvone, myrtenol and myrtenal. In acetic acid, a combined selectivity for these products does not exceed 40% due to the concomitant substrate isomerization and acetic acid addition, while in acetonitrile, good selectivities of up to 85% at a 40–50% substrate conversion have been achieved.

Palladium catalyzed oxidation of renewable terpenes with molecular oxygen: oxidation of α-bisabolol under chloride-free conditions

The palladium/p-benzoquinone catalyzed aerobic oxidation of α-bisabolol, a bio-renewable substrate with strong therapeutic potential available from various essential oils, has been developed. The reaction gives three main products arising from the oxidation of the sterically encumbered trisubstituted double bonds of the substrate, either endocyclic or exocyclic or both. Novel poly-functionalized sesquiterpenoids obtained with high combined selectivity from the oxidation of α-bisabolol are potentially useful as components of synthetic perfumes, cosmetics and pharmaceuticals. The system promotes an efficient dioxygen-coupled catalytic turnover in the absence of auxiliary redox-active co-catalysts under superatmospheric oxygen pressure. Alternatively, the reaction can be performed at atmospheric pressure in the presence of catalytic amounts of copper acetate as an electron transfer mediator for the regeneration of BQ during the catalytic cycle.

Palladium catalyzed oxidation of renewable terpenes with molecular oxygen: oxidation of α-bisabolol under chloride-free nonacidic conditions

A novel selective palladium catalyzed oxidation of α-bisabolol by molecular oxygen under chloride-free nonacidic conditions has been developed. α-Bisabolol is a sesquiterpenic alcohol available from essential oils of various plants. The reaction proceeds in aqueous methanol solutions over the Pd(OAc)2/Cu(OAc)2 catalytic system and gives exclusively the products resulting from the interaction of palladium with a sterically encumbered internal acyclic double bond. No concomitant oxidation of the second double bond, the endocyclic one, occurs. Novel poly-functionalized sesquiterpenoid compounds obtained at the oxidation of α-bisabolol are potentially interesting for cosmetic, fragrance and pharmaceutical applications.

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by 1H NMR, 13C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL-1. Most of the tested compounds presented MIC values ≤220 μg mL-1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

Chemotype diversity of Psidium guajava L.

The essential oil of Psidium guajava L. has been studied for pharmacological and industrial purposes, without considering the plants genotype regarding the heterogeneity of its composition. The present study aimed to characterize the chemotype diversity of the essential oil extracted from the leaves of 22 genotypes of P. guajava grown in two different environments in the state of Espírito Santo, Brazil, and to identify the different chemical markers present in these plants. Essential oil from the leaves of the P. guajava genotypes was extracted by hydrodistillation, and its chemical composition was analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Thirty-three compounds were identified, comprising 87.5-99.0% of the total composition, with a prevalence of sesquiterpenes in all samples. The major compounds identified consisted of (E)-trans-Caryophyllene, α-Humulene, trans-Nerolidol, β-Bisabolene, β-Bisabolol, and Hinesol, the first of which was identified as a possible chemical marker for the species. Multivariate factor analysis of the chemical composition of P. guajava oil identified three chemotypes: Commercial - PAL, SEC, PS, PET, C7, C11, and C17MI, characterized by high levels of β-Selinene, α-Selinene, Hinesol, and 14-hydroxy-epi-(E)-caryophyllene, with β-Selinene and α-Selinene as the chemical markers; C10 and C13, exhibiting high levels of Elemol, trans-Nerolidol, trans-β-Eudesmol, and (2Z, 6Z)-Farnesol, which were indicated as chemical markers, and Cortibel - C1, C2, C3, C4, C5, C6, C8, C9, C12, C14, C15, C16, C17LI, which retained high levels of α-Cedrene, cis-α-Bergamotene, α-Humulene, Humulene epoxide, epi-α-Cadinol, β-Bisabolol, and α-Bisabolol, with β-Bisabolol and α-Bisabolol as the chemical markers. The use of guava genotypes with different chemotypes, that are agronomically favorable to fruit production and essential oil exploitation adds value to the crop and renders it more sustainable. Given guava crops produce large amounts of leaf biomass, resulting from successive prunings, the extraction of their essential oil, which retains commercially valuable compounds, can be feasible.

Biodiesel production from cotton oil using heterogeneous CaO catalysts from eggshells prepared at different calcination temperatures

Abstract Biodiesel is a fuel from vegetable oil or animal fat, and is a promising substitute for petroleum-derived diesel. Transesterification is the most widely used method in biodiesel production. Eggshell is rich in calcium carbonate (CaCO3), and when it is subjected to heat treatment it results in calcium oxide (CaO). CaO from eggshells was prepared at different calcination temperatures, and characterized by X-ray diffraction, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The obtained CaO was used as a catalyst. All catalysts showed good stability and excellent morphology for biodiesel synthesis. Catalytic activity was evaluated by the methyl transesterification reaction of cotton oil for 3 h, 9:1 methanol:oil molar ratio, 3 wt% (catalyst/oil weight ratio) catalyst and 60°C. Biodiesels showed an ester content of 97.83%, 97.23% and 98.08%, obtained from calcined eggshell at 800°C, 900°C and 1000°C, respectively. Biodiesel quality was affected by the acidity of the cation exchange resin. The kinematic viscosity of biodiesel was in accordance with specification, except for the biodiesel obtained from the calcined catalyst at 1000°C. The CaO from eggshells obtained at different calcination temperatures is promising for biodiesel synthesis.

QUANTIFICAÇÃO DE COMPOSTOS BIOATIVOS EM DIFERENTES PARTES DO CORPO DA FALSA MURTA Murraya paniculata (L.) Jak

Uma vez que as plantas medicinais sao identificadas e utilizadas em funcao de seus constituintes quimicos, objetivou-se com este estudo, quantificar os teores de fenolicos totais, flavonois totais e antocianinas presentes na especie vegetal Murraya paniculata (L.) Jack (murta), correlacionando os teores encontrados nas partes da planta com duas diferentes estacoes do ano (verao e inverno). As folhas de murta foram coletadas no municipio de Alegre - ES, dividindo em partes (apice, mediano e basal), obedecendo as estacoes verao/inverno. No verao, observaram-se os maiores teores de metabolicos nos ramos medianos, e basal da planta, com excecao dos fenolicos totais que apresentaram os maiores teores no inverno. Com os resultados encontrados, conclui–se que existe uma diferenca significativa entre partes da planta e epoca, e tais resultados estimulam a continuacao de estudos com esta especie.