142399-19-7Relevant academic research and scientific papers
Discovery and optimization of new chromium catalysts for ethylene oligomerization and polymerization aided by high-throughput screening
Jones, David J.,Gibson, Vernon C.,Green, Simon M.,Maddox, Peter J.,White, Andrew J. P.,Williams, David J.
, p. 11037 - 11046 (2007/10/03)
High throughput screening (HTS) of a 205 member Schiff base salicylaldimine ligand library derived from salicylaldehydes bearing bulky ortho-substituents, i.e., 9-anthracenyl, 1,4,5,8-tetramethylanthracenyl or triptycenyl, reacted in-situ with (p-tolyl)CrCl2(thf)3, identified two new classes of highly active chromium based systems for the Oligomerization and polymerization of ethylene, respectively. The polymerization system comprises bidentate ortho-substituted anthracenyl Schiff bases bearing small primary or secondary alkyl imine substituents. The Oligomerization catalysts are based upon tridentate orthotriptycenyl-substituted Schiff bases with pyridylmethyl or quinolyl substituents. Validation tests confirmed polymerization productivities of up to 3000 g·mmol-1h-1bar-1 for the polymerization catalyst systems while the oligomerization catalysts gave productivities up to 10 000 g·mmol-1h-1bar -1. Key catalyst precursors have been characterized by X-ray crystallography.
Novel polymerisation catalysts
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, (2008/06/13)
Novel complexes having the formula (I) are disclosed, wherein M is a Group 6 metal and T is its oxidation state; X represents an atom or group covalenty or ionically bonded to M; b is the valency of the atom or group X; L is a group datively bound to M, and n is from 0 to 4; Z is oxygen or sulphur; A1 to A3 are each independently N or P or CR, with the provisio that at least one is CR; R1 is a polycyclic hydrocarbyl group; Q is CR5, PR5R5 or N; each R and R5 to R7 are all independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or SiR′3 where each R′ is independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl, and any two or more of each R and R5 to R7 may be linked to form cyclic substituents. These complexes have utility as catalysts for the polymerisation of 1-olefins.
An Intramolecular Arene-Triflate Coupling Reaction for the Regiospecific Synthesis of Substituted Benzofluoranthenes
Rice, Joseph E.,Cai, Zhen-Wei
, p. 1415 - 1424 (2007/10/02)
An intramolecular triflate-arene coupling reaction mediated by bis(triphenylphosphine)palladium(II) chloride has been developed for the synthesis of each of the isomeric benzofluoranthenes.This reaction, which results in formation of a new five-membered ring, proceeds in highest yields when performed using 0.1 equiv of the palladium catalyst, 3 eqiv of lithium chloride, and 1.2 eqiv of 1,8-diazabicycloundec-7-ene in N,N-dimethylformamide at 140 deg C.The biaryl precursors needed for the coupling reaction can be prepared by nickel(II) chloride catalyzed coupling of an aryl bromide with an magnesium bromide (prepared by ortho-lithiation of an aryl methoxymethyl ether followed by transmetalation with magnesium bromide).Using this procedure benzofluoranthene, benzofluoranthene, benzofluoranthene, and benzofluoranthene were prepared in yields of 84percent, 85percent, 93percent and 64percent, respectively.The reaction to prepare benzofluoranthene was regiospecific and afforded none of the six-membered ring product, perylene.This method was extended to the preparation of benzofluoranthene (BbF) derivatives with fluoro or methoxy groups on the benzo ring.The cyclization of compounds posessing a methoxy group on the same ring as the triflate required the addition of 0.4 equiv of triphenylphosphine to the reaction mixture.Strategies are reported for the regiospecific preparation of 4-, 5-, 6-, and 7-substituted benzofluoranthenes.Evidence is presented wich suggests the intermediacy of radicals in the oxidative-addition of aryl triflates to the palladium catalyst.
A Palladium-Catalyzed Intramolecular Arene-Triflate Coupling for the Synthesis of Fluoranthrenes and Benzofluoranthrenes
Rice, Joseph E.,Cai, Zhen-Wei
, p. 1663 - 1678 (2007/10/02)
A method for the preparation of fluoranthrenes and benzofluoranthrenes from aryl bromides and aryl methoxymethyl ethers is described.The key step in this synthesis is an intramolecular triflate-arene coupling mediated by bis(triphenylphosphine)palladium(II)chloride.Fluoranthrene, benzofluoranthrene, benzofluoranthrene, and indenopyrene were prepared in yields of 84-91percent.The regiospecific synthesis of substituted benzofluoranthrenes was demonstrated by the preparation of 6-fluorobenzofluoranthrene (72percent yield) and 5- and 6-methoxybenzofluoranthrene in yields of 73percent and 62percent respectively when the reaction was conducted in the presence of excess triphenylphosphine.Key Words: synthesis; palladium; triflate; fluoranthrene; benzofluoranthrene
