Sandra Einloft

The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes

Abstract The reaction of 1-n-butyl-3-methylimidazolium chloride (BMIC) with sodium tetrafluoroborate or sodium hexafluorophosphate produced the room temperature-, air- and water-stable molten salts (BMI+)(BF4−) (1) and (BMI+)(PF6−) (2), respectively, in almost quantitative yield. The rhodium complexes RhCl(PPh3)3 and [Rh(cod)2][BF4] are completely soluble in these ionic liquids and they are able to catalyse the hydrogenation of cyclohexene at 10 atm and 25°C in a typical two-phase catalysis with turnovers up to 6000.

Selective two-phase catalytic ethylene dimerization by NiII complexes/AlEtCl2 dissolved in organoaluminate ionic liquids

Abstract Nickel(II) complexes dissolved in methyl-1-butyl-3-imidazolium chloride/AlCl 3 molten salt in the presence of AlEtCl 2 and aromatic solvents catalyse the dimerization of ethylene into butenes in a typical two-phase catalytic reaction. The nature of the nickel catalyst precursor has a strong influence on the reactions activity and selectivity. Thus, ethylene dimers and trimers were obtained in the presence of NiF 2 and NiCl 2 (PCy 3 ) 2 , whereas only butenes were formed using the complex [Ni(MeCN) 6 ] [BF 4 ] 2 as a catalyst precursor. In this latter case but-1-ene was formed with a selectivity of 83% and turnover frequencies of up to 1731 h -1 . Moreover, the conversion and selectivity to but-1-ene increase with increasing ethylene pressure. The use of aromatic co-solvents is also essential for the ethylene dimerization, since other hydrocarbons induce the formation of higher ethylene oligomers. Copyright

Two-phase catalytic hydrogenation of olefins by Ru(II) and Co(II) complexes dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

Abstract The interaction of RuCl 2 (PPh 3 ) 3 and 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt yields an air and water stable solution that is able to hydrogenate olefins with turnover frequencies up to 537 h −1 in a typical two-phase catalytic reaction. The complex K 3 Co(CN) 5 also affords a catalytic system with the ionic liquid that catalyzes the reduction of butadiene into but-1-ene with 100% conversion and selectivity.

Zirconium alkoxide complexes as catalysts for ethylene polymerization

The complexation of 2-hydroxy-1,4-naphtho-quinone and 3-hydroxy-2-methyl-4-pyrone with zirconium tetrachloride yielded complexes containing bidentate alkoxide ligands. In the presence of MAO or TIBA these complexes were found to be active for ethylene polymerization, producing polymers with high molecular weight. Both catalytic systems were also shown to be active when supported on silica or on MAO-modified silica.

TEREPHTHALIC ACID, NEOPENTYL GLYCOL AND TRIMETHYLOLPROPANE POLYESTERIFICATION USING VERSATILE AND HIGHLY EFFICIENT TIN COMPLEXES AS CATALYSTS PRECURSORS

The catalytic performance of the tin complexes bis(acetylacetonato)tin(II) (1), dibutyltin oxide (2), bis(chloroacetato)tin(II) (3), bis(3-hydroxy-2-methyl-4-pyrona)tin(II) (4), dibenzoatotin(II) (5) and dihydroxybutyltin chloride (6) are described for terephthalic acid, neopentyl glycol and trimethylolpropane polyesterification. The synthesized complexes, which are easy to prepare from inexpensive commercial chemicals, showed catalytic behavior comparable to the industrially used (2) and (6). The productivity values varied from 72.2 when (2) was used as a catalyst to 192.0 with (1). The best values for reaction time was obtained for the commercial catalyst (6) (6 h 26 min) and for (1) (7 h 36 min). The infrared analyses allowed us to observe bands relative to ester formation and to confirm the hydroxylation for all polymers samples. 1. INTRODUTION Polyesters have been widely used as polymeric materials. Indeed, terephthalic acid based polyesters have received special attention due to several interesting properties of Polyethylene terephthalate) or PET. This polyester is the most widely used synthetic fiber which is sold under many different trade names. PET is also commonly encountered in plastic bottles for soft drinks and in films which are used for food or liquid packaging, magnetic tapes and novelty balloons, among others applications [1], Polyesters based on isophthalic acid and terephthalic acid have been developed for use in polyester powder coatings [2]. Terephthalic acid has historically been the primary monomer providing polymers with the required glass transition temperature for coating storage stability, while contributing flexibility, weathering and chemical resistance [2]. Different metallic ions have been described that catalyse efficiently esterification and polyesterification reactions. Nondek and Mälek [3] ordered the activities of catalysts for reaction of ethylene glycol with isophthalic acid as Sn> T i 4 + »Zn >Pb,Co,Cd. The development of simple and cheaper catalytic systems for polyesterification reaction as well as new polymer materials using different monomers is important for technological and academic purposes. We have recently shown that the tin complex, bis(3hydroxy-2-methyl-4-pyrona)tin(II) (4), is highly active as polyesterification catalyst [4], In this paper we wish to report highly efficient catalysts systems based upon tin complexes, using differents ligands, for terephthalic acid (TFA), neopentyl glycol (NPG) and trimethylolpropane (TMP) polyesterification. 2. MATERIALS AND METHODS 2.1. General Procedures Routine infrared spectra were recorded on a Bomenn MB-Series Hartmann & Braun spectrophotometer. Molecular weights of the polymers were determined by gel permeation chromatography with a GPC Data Station 4.0. The acid number, i.e, the total concentration of the carboxylic groups in the reaction medium, are measured by diluting about 1.0 g of the sample in 50cm DMF. The sample is heated until fusion without boiling. Then the sample is cooled at room temperature and titrated with 0.1 Ν KOH in methanol with Phenolphthalein as indicator. The acid number [5] is calculated by (AN=V(mL) χ 56.1 χ N)/P[mgKOH/g] were V= volume of titrate liquid; N= Normality of titrate liquid and P= sample mass viscosity. 2.2. Preparation of the catalysts The complexes, (1), (3) , (4) and (5) were prepared according the procedures described in the literature [6,7,4,8], The catalysts (2) and (6) were obtained from commercial sources and used as received without further purification. 2.3. Polymerization Reactions Polymerization was carried out in a 2L reactor system consisting of a four necked round-bottom flask. The flask was equipped with an air-driven stirrer, a thermocouple, nitrogen inlet tube and two adjacent partial reflux condensers one of them charged with a packing, and the other a steam-jacketed partial reflux condenser. A tube test receiver is installed in one of the four necks. The flask is heated by means of an electrical heating mantle. The temperature is monitored via an Pt 100 thermocouple with a temperature

Não tecido de poliéster plissado para filtração de particulados

Lead is recognized by the World Health Organization as one of the most hazardous chemicals to human health, the most used non-ferrous metals. The largest use of lead and lead oxides industries, battery manufacturing and recycling of industrial lead. This paper presents an alternative cleaner production technology and economically viable, integrated industrial filtration processes to lead, applying sleeves pleated polyester with teflon company in this sector, replacing the sleeves conventional nonwoven polyester. The results show the decrease of emission to the atmosphere, due to a higher floor area of the pleated sleeves and consequent higher collection efficiency of particulate lead.

The use of crude tall oil as feed-stock for alkyd resins

Abstract The synthesis of modified alkyd resins using a crude tall oil with a content of rosin acids of 39.8 % is described. This material has the composition of fatty acids close to soybean oil, has low cost and is widely available being a forest product industrial residue. The synthetic route includes the reaction of tall oil and maleic anhydride, in the presence of the catalyst (LiOH), followed by polyesterification reaction steps, resulting in an alkyd resin with interesting properties. The acid value (AN) and viscosity were used to follow the reaction, and it appears to be dependent upon the polyalcohol used in the polyesterification step. A period of 15 hours was needed to yield a tack-free coating.