Search results for "Butyllithium"
showing 10 items of 11 documents
New conditions for the generation of dianions of carboxylic acids
1998
Abstract Lithium carboxylic acid enediolates are generated efficiently using lithium amides prepared from thienyllithium or butyllithium and either diethylamine, piperazine, N,N′-dibenzylethylenediamine, N-benzylpiperazine or 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, even in catalytic amounts.
Synthesis and X-ray Crystal Structures of (C5HiPr4)Ln(BH4)2(THF)(Ln = Nd and Sm), Versatile Precursors for Polymerization Catalysts
2000
The new half metallocenes [(C5HiPr4)Ln(BH4)2(THF)] [Ln = Sm (1) and Nd (2)], and [(C5HiPr4)U(BH4)3] (3) have been synthesized. The crystal structures of 1 and 2 and of the metallocenes [(C5HiPr4)2Ln(BH4)] [Ln = Sm (4) and Nd (5)] have been determined. The substitution of the BH4 groups of 1 and 2 by a nitrogen-based ligand is possible. In the presence of butyllithium, these complexes show an activity in isoprene and styrene polymerization.
Die vielfältigen additionsprodukte von phenylen-, naphthylen-, biphenylylen- und methylendiphenylendimethacrylaten mit radikalen aus 2,2'-azoisobutyr…
1976
Die Reaktionen von Phenylen-, Naphthylen-, Biphenylylen- und Methylendiphenylendimethacrylaten (1–4) wurden teils mit 2,2'-Azoisobutyronitril (AIBN) in Substanz oder anionisch in Losung mit Butyllithium oder Natriumdihydronaphthylid (Naphthalinnatrium), teils mit grosem Uberschus an AIBN stark verdunnt in siedendem Benzol durchgefuhrt. Neben unloslichen (vernetzten) Polymeren wurden losliche erhalten, darunter Cyclopolymere vom Typ 9, wie die Ergebnisse der Hydrolyse und anschliesende Umsetzung mit Diazomethan zu Poly(methacrylsaure-methylester)n zeigten. Die Verdunnungsreaktion ergab die Produkte 5 der unterdruckten Polymerisation, der innermolekularen Addition mit Kopf/Schwanz- und Schwan…
1987
ESR spectroscopic analyses of the deep-green solutions of living poly(2-isopropenylnaphthalene) [poly(2-IPN)] in THF at −80°C provided no evidence of the presence of radical anions as long as butyllithium (BuLi) was used as initiator. In contrast to this finding, radicals could indeed be detected if the polymerization was performed with metallic potassium in THF. These radicals were found to be only stable at low temperatures. UV/VIS spectra of solutions of 2-IPN in THF or toluene and of catalytic quantities of BuLi were recorded at temperatures between −45 and +20°C. On heating to >0°C, the colour of the deep-green solution changes irreversibly to reddish-brown, and this colour change is a…
A novel synthesis of polymers with anthracene and dihydroanthracene subunits in the main chain
1993
A new polycondensation method to connect redox-active and chromophoric subunits by forming a C-C bond and leading to a polyhydrocarbon is described. 1,ω-bis(9,10-Dihydro-9-anthry)alkanes with various alkylene spacers can be deprotonated by butyllithium to afford a monoanion in each dihydroanthracene moiety. Alkylation with dielectrophiles such as dibromoalkanes yields soluble polymers with dihydroanthracene units in the main chain. The reaction proceeds regioselectively in the 9,10-position. Aromatization generates a polymer with anthracene units. The molecular weights are determined by GPC up to Mn = 10 000. To prove the structure and to calibrate the GPC, suitable model compounds were syn…
ChemInform Abstract: New Conditions for the Generation of Dianions of Carboxylic Acids.
2010
Abstract Lithium carboxylic acid enediolates are generated efficiently using lithium amides prepared from thienyllithium or butyllithium and either diethylamine, piperazine, N,N′-dibenzylethylenediamine, N-benzylpiperazine or 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, even in catalytic amounts.
Blockcopolymere aus 2-Isopropenylnaphthalin und Hexamethylcyclotrisiloxan, 7
1985
Anionic polymerization of 2-isopropenylnaphthalene (2-IPN), with butyllithium in THF at −78°C was terminated with ethylene oxide and the resulting terminal alkoxide was used to initiate the polymerization of hexamethylcyclotrisiloxane (D3) at +40°C. This led to the formation of AB-block copolymers which were coupled to ABBA-block copolymers by addition of dichlorodimethylsilane. ABBA-blockcopolymers were obtained with contents of polymethylsiloxane (poly(DMS)) between 77 and 84% of weight and block molecular weights between 1 700 and 27 000 (poly(2-IPN)) and 13 000 and 240 000 (poly(DMS)). Phase separation in polymer films casted from different solvents was studied by electron microscopy an…
Aminoendgruppenhaltige polymere durch anionische polymerisation von vinylverbindungen mit 3-Dimethylaminopropyllithium als initiator
1975
α-Methylstyrol (in THF) sowie Styrol bzw. Butadien (in Benzol) wurden mit 3-Dimethyl-aminopropyllithium (1) als Initiator homopolymerisiert; dabei wurden aufgrund des Einflusses der tertiaren Aminogruppe bei der Polymerisation in apolarem Medium, verglichen mit der Initiierung durch Butyllithium, Veranderungen der Mikrostruktur der Polymeren beodachtet. Die Molekulargewichte der Polymeren sind hoher, als sich nach dem eingesetzten Monomer/Initiator-Verhatnis berechnete. Der Aminoendgruppengehalt der Polymeren wurde elementaranalytisch sowie NMR-spektroskopisch quantitative bestimmt; die tertiaren Aminoendgruppen konnten mit Methylijodid quantitativ zum quartaren Salz umgesetz werden, mit Br…
Beiträge zur polymerisation von 2-isopropenylnaphthalin, 3. Anionische homopolymerisation von 2-isopropenylnaphthalin
1981
The anionic homopolymerization of 2-isoprenylnaphthalene with butyllithium in tetrahydrofuran at –78°C is described. The refractive index increment amounts to dn/dc = 0,2084 ml/g for these polymers in toluene at 25°C and wavelength λ = 436 nm. Determination of the molecular weights by light scattering yielded values between 13 000 and 270 000. The second virial coefficients also determined by light scattering measurements are comparable with the corresponding data of poly(α-methylstyrene). A calibration curve is given for gel permeation chromatography of the poly(2-isoprenylnaphthalene)s, whose polymolecularity indexes Mw/Mn lie between 1,06 and 1,2. Their intrinsic viscosity/molecular weig…
ChemInform Abstract: Addition of Organolithium Reagents to Cinnamic Acids.
2010
Abstract Reaction of tert -butyllithium with p - and m -substituted cinnamic acids at low temperature affords mixtures of 1,4- and 1,3-addition products, whose composition depend on the nature of the substituents. Electron-donating and electron-withdrawing groups favour 1,4- and 1,3-additions, respectively. Linear correlations are obtained with electronic effect and with radical substituent constants.