Search results for "Ethylene"

Polymerization of ethylene in the presence of organometallic complexes formed by chloroisopropoxytitanium compounds and sesquiethylchloroaluminium

1982

The catalytic activity of organometallic complexes obtained from chloroisopropoxytitanium compounds and sesquiethylchloroaluminium has been studied. The complexes are active as catalysts for polymerization of ethylene, living high molecular weight product with high output. It is found that the molar ratio of catalyst components affects the output and molecular weight of polyethylene. The optimum molar ratiofor three catalytic systems is given.

ChemInform Abstract: Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

2016

Above 31.1 °C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO2) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO2 is presented.

1,7-Octadiene-Assisted Tandem Multicomponent Cross-Enyne Metathesis (CEYM)-Diels-Alder Reactions: A Useful Alternative to Mori’s Conditions

2012

The use of 1,7-octadiene as an in situ source of ethylene led us to develop a novel multicomponent tandem cross-enyne metathesis (CEYM)-Diels-Alder reaction. The process can be considered a relay metathesis, in which the ethylene liberated in the ring-closing metathesis (RCM) of 1,7-octadiene initiates the tandem sequence. Aliphatic, aromatic, and fluorinated alkynes and several dienophiles are compatible with the process, which is particularly efficient with aromatic alkynes. This methodology constitutes a useful variant of Mori's conditions in CEYM-related reactions.

ChemInform Abstract: 1,7-Octadiene-Assisted Tandem Multicomponent Cross-Enyne Metathesis (CEYM)-Diels-Alder Reactions: A Useful Alternative to Mori′s…

2013

The protocol relies on a relay metathesis process, in which 1,7-octadiene acts as an in situ source of ethylene.

1981

New nitrogen mustard analogues in which bis(2-chloroethyl)-amino groups are separated by oxyethylene groups, 1,14-dichloro-3,12-bis(2-chloroethyl)-3,12-diaza-6,9-dioxatetradecan (3c) and 1,17-dichloro-3,15-bis(2-chloroethyl)-3,15-diaza-6,9,12-trioxaheptadecane (3d), were synthesized by reaction of bis(2-hydroxyethyl)amine (2) with bis(2-chloroethyoxy)ethylene (1a) and with 1,11-dichloro-3,6,9-trioxaundecane (1b), respectively, followed by treatment with thionyl chloride. The analogues were then complexed with heparin. The resulting heparin-complexes show inhibiting activity against transplanted Sarcoma-180 A in mice.

Components of the Sex Pheromone of Chilo Supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal

1995

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.

Understanding the reactivity of captodative ethylenes in polar cycloaddition reactions. A theoretical study

2008

The electrophilic/nucleophilic character of a series of captodative (CD) ethylenes involved in polar cycloaddition reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The transition state structures for the electrophilic/nucleophilic interactions of two CD ethylenes toward a nucleophilically activated ethylene, 2-methylene-1,3-dioxolane, and an electrophilically activated ethylene, 1,1-dicyanoethyelene, have been studied, and their electronic structures have been characterized using both NBO and ELF methods. Analysis of the reactivity indexes of the CD ethylenes explains the reactivity of these species. While the electrophilicity of the molecules accounts for…

Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 1. Polyester der terephthalsäure

1976

Die Abbaureaktionen von Poly(athylenterephthalat) (1a), Poly(tetradeuteroathylenterephthalat) (1b), Poly(trimethylenterephthalat) (1c) und Poly(tetramethylenterephthalat) (1d) im Massenspektrometer wurden untersucht. Hierzu wurden die Polymeren direkt in der Ionenquelle des Massenspektrometers pyrolysiert und die entstehenden thermischen Bruchstucke durch Elektronenstos ionisiert und fragmentiert. Die thermisch- und elektronenstosinduzierten Abbaureaktionen lassen sich nebeneinander nachweisen. Die untersuchten polymeren Terephthalate 1a–d folgen in beiden Abbauschritten den gleichen Mechanismen und konnen anhand ihrer Pyrolyse-Massenspektren unterschieden werden. The degradation reactions …

Selective oxidation of propane and ethane on diluted Mo–V–Nb–Te mixed-oxide catalysts

2007

Abstract Te-free and Te-containing Mo–V–Nb mixed oxide catalysts were diluted with several metal oxides (SiO 2 , γ -Al 2 O 3 , α -Al 2 O 3 , Nb 2 O 5 , or ZrO 2 ), characterized, and tested in the oxidation of ethane and propane. Bulk and diluted Mo–V–Nb–Te catalysts exhibited high selectivity to ethylene (up to 96%) at ethane conversions 10 % , whereas the corresponding Te-free catalysts exhibited lower selectivity to ethylene. The selectivity to ethylene decreased with the ethane conversion, with this effect depending strongly on the diluter and the catalyst composition. For propane oxidation, the presence of diluter exerted a negative effect on catalytic performance (decreasing the forma…

ChemInform Abstract: Components of the Sex Pheromone of Chilo supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal.

2010

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.