Michele Oberson de Souza

Substitution of lead catalysts by zirconium in the oxidative polymerization of linseed oil

In this study, the oxidation of linseed oil was used as a model for oxidative alkyd paint system. A comparative study between cobalt, lead and zirconium octoates as catalysts for oxidative polymerization of linseed oil has been performed. The cobalt salt catalyzes the oxidation step, and the lead and zirconium catalyze the polymerization step. Under the same reaction conditions, the zirconium catalyst is more efficient than lead. As the use of lead compounds is associated with toxicological problems, our results suggest use of the zirconium salt as a substitute for lead compounds in industrial applications.

Catalytic properties of Fe(acac)3 and Cu(acac)2 in the formation of urethane from a diisocyanate derivative and EtOH

Abstract The catalytic performance of metal– β -diketone complexes Fe(acac) 3 and Cu(acac) 2 is described for urethane formation reactions from hexamethylene diisocyanate (HDI) and ethanol. This is a model reaction for the synthesis of polyurethane resin that takes place during the application of reactive paint. The best results are obtained for the reaction between HDI and EtOH catalysed by the Fe(acac) 3 complex. The diurethane adduct selectivity is 90% with a turnover rate of 74 h −1 . Similar experiments conducted with a commercial catalyst, dibutyltin dilaurate (DBTDL), show that for the same reaction conditions no diurethane adduct is formed and that the turnover rate is lower (29 h −1 ).

Synthesis of 5-Hydroxymethylfurfural from Dehydration of Fructose And Glucose Using Ionic Liquids

A producao do 5-hidroximetilfurfural (HMF) a partir da desidratacao de acucares e uma alternativa para a obtencao de materiais de partida na producao de poliesteres, poliamidas e poliuretano a partir de fontes renovaveis. Alem disso, a oxidacao do HMF leva ao acido 2,5-furanodicarboxilico (FDCA) potencial substituto para o acido tereftalico (TA), proveniente do petroleo, intensamente utilizado na producao de polimeros, tais como, o poli(tereftalato de etileno) (PET). A substituicao do TA por materiais obtidos a partir de fontes renovaveis e de grande interesse do ponto de vista de obtencao de produtos com elevado grau de sustentabilidade.

Influence of the alcohol nature on the catalytic properties of Fe(acac)3 and Cu(acac)2 in the formation of urethane from a diisocyanate

Abstract The effect of the nature of alcohol, namely ethanol (EtOH), hydroxyethyl propionate (EPOH) and 2-hydroxypropyl propionate (PPOH), on the catalytic properties of Fe(acac) 3 and Cu(acac) 2 is evaluated in the formation of mono- and diurethanes from hexamethylenediisocyanate (HDI). The highest turnover rate,77 h −1 , was observed with the reaction between HDI and PPOH catalysed by Fe(acac) 3 , which also afforded a diurethane selectivity of 100%. Similar experiments conducted with a commercial catalyst, dibutyltin dilaurate (DBTDL), show that for the same reaction conditions, no diurethane adduct is formed and that the turnover rate is lower (19 h −1 ). A discussion concerning the probable active species is made in order to explain the activity, kinetic and selectivity results.

Low pressure ethylene oligomerization with a nickel-PÔ complex

SummaryThe oligomerization of ethylene catalyzed by nickel-PÔ complexes at room temperature and low pressure (5 to 30 bar) yields butenes, hexenes and octenes. The molecular weight distribution can be manipulated by variation of ethylene pressure and by addition of triphenylphosphine. An unexpected linear dependence between the growing factor β of the Schulz-Flory type distribution and the pressure has been observed. The equation: β=6.2 (PPh3/Ni)1.2-[0,17 P(PPh3/Ni)1.2] allows to predict the composition of the α-olefins formed under different reaction conditions.

Ordered Mesoporous ZSM-5 Employing an Imidazolium-Based Ionic Liquid

Hierarchically porous ZSM-5 was achieved by using a simple bottom-up strategy combining zeolite seeds with imidazolium-based ionic liquids. The bimodal ZSM-5 with hexagonal arranged mesopores (3 nm) shows important activity in the acid catalysis of bulky compounds relative to conventional ZSM-5.

Metallocene Supported on Inorganic Solid Supports: an Unfinished History

The production of polyolefin nanocomposites has been the field of many studies for improving polymer properties for many applications. The most important challenge on the area is the preparation of the fillers randomly dispersed on polymer matrix. It is general agreement, however, that the dispersion obtained through in situ polymerization is the most efficient and, additionally, confers to the system the advantages of heterogeneous catalysis. This contribution offer a review of characteristics of the most employed fillers, their use as metallocene catalysts supports and the application on in situ production of nanocomposites.

Assessment of Sodium Salt Anions (\(\text{SO}_{4}^{2-}\) and \(\text{NO}_{3}^{-}\)) Influence on Caffeine Partitioning in Polyethylene Glycol and 1-Butyl-3-Methylimidazolium Tetrafluoroborate Based ATPS

Liquid–liquid equilibrium (LLE) data of aqueous polyethylene glycol (PEG) + sodium salt and ionic liquid (IL) + sodium salt two-phase systems (ATPSs) were determined experimentally at 298.15 K and atmospheric pressure (91 kPa), applying PEG 1500, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]), sodium sulfate (Na2SO4) and sodium nitrate (NaNO3) as phase-forming components. PEG and IL based ATPSs were applied for caffeine partitioning study and the influence of sodium salt anions (SO42-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

Electrochemical behavior of nickel in electrolytes based on 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid for capacitor applications

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