Search results for "Lithium"
showing 10 items of 680 documents
Bimolecular reduction of 9-alkyl-3-nitrocarbazoles
2007
AbstractReduction of 9-alkyl-3-nitrocarbazoles (Ia–Ie) with lithium aluminium hydride gave corresponding 9,9′-dialkyl-3,3′-azocarbazoles (IIa–IIe) in moderate yield. By the action of zinc dust in alcohol and aqueous alkali on I or II, 5,13-dialkyldiindolo[3,2-a,d]phenazines (IIIa–IIId) were obtained. Parent compounds, viz. 3,3′-azocarbazole (IIf) and diindolo[3,2-a,d]phenazine (IIIf) could not be obtained in these ways. Compound IIf was obtained in Vorländer reaction and IIIf by thermal decomposition of 3-azidocarbazole. Formation of IIIa–IIId is explained as a result of ortho-benzidine rearrangement of hypothetical 9,9′-dialkyl-3,3′-hydrazocarbazoles.
Towards the Next Generation of Lochmann-Schlosser Superbases: A Potassium Neopentyl/Alkoxy Aggregate used in the Tetra-Functionalization of Ferrocene
2018
Lochmann-Schlosser superbases are formed by mixing alkyllithium with potassium alkoxides. These reagents could prove their synthetic usefulness and reliability in many reactions over five decades. However, despite many efforts, the real source of the exceptional reactivity remained a secret. The seemingly manageable system of four components (lithium, potassium atoms, alkyl groups, and alkoxy groups) and their interaction is obscured by poor solubility and fierce reactivity. Recent progress was achieved by using neopentyllithium, leading to alkane-soluble aggregates with varying lithium/potassium content and a flexible alkyl/alkoxy ratio. Herein, we isolated two new alkane-soluble alkyl/alk…
Deprotonation of Fluoro Aromatics Using Lithium Magnesates.
2004
Abstract 3-Fluoropyridine was deprotonated on treatment with 1/3 equiv of Bu 3 MgLi in THF at −10 °C. The lithium arylmagnesate formed was either trapped with electrophiles or involved in a palladium-catalyzed cross-coupling reaction with 2-bromopyridine. The use of a less nucleophilic lithium-magnesium-dialkylamide, (TMP) 3 MgLi, allowed the reaction of 3-fluoroquinoline, giving the 2,2′-dimeric derivative. 2-Fluoropyridine and 2,6-difluoropyridine were deprotonated using 1/3 equiv of the highly coordinated magnesate Bu 4 MgLi 2 in THF at −10 °C in the presence of a substoichiometric amount of 2,2,6,6-tetramethylpiperidine. 1,3-Difluorobenzene reacted similarly when treated with Bu 3 MgLi;…
Considering lithium-ion battery 3D-printing via thermoplastic material extrusion and polymer powder bed fusion
2021
Abstract In this paper, the ability to 3D print lithium-ion batteries through Pmnbspace thermoplastic material extrusion and polymer powder bed fusion is considered. Focused on the formulation of positive electrodes composed of polypropylene, LiFePO4 as active material, and conductive additives, advantages and drawbacks of both additive manufacturing technologies, are thoroughly discussed from the electrochemical, electrical, morphological and mechanical perspectives. Based on these preliminary results, strategies to further optimize the electrochemical performances are proposed. Through a comprehensive modeling study, the enhanced electrochemical suitability at high current densities of va…
Chiral Lanthanocene Derivatives Containing Two Linked Amido−Cyclopentadienyl Ligands: Heterobimetallic Structure and Lactone Polymerization Activity
1997
Reaction of 2 equiv of dilithium amido−cyclopentadienide Li2(C5R4SiMe2NCH2CH2X) (C5R4 = C5Me4, C5H3tBu; X = OMe, NMe2) with anhydrous LnCl3 (Ln = Y, Lu) gave C2-symmetric complexes of the type Li[Ln(η5:η1-C5R4SiMe2NCH2CH2X)2] containing a heterobimetallic core. The molecular structure of Li[Y(η5:η1-C5Me4SiMe2NCH2CH2OMe)2] was determined by single-crystal X-ray structural analysis, which showed it to exhibit both a pseudotetrahedral yttrium as well as a tetrahedral lithium center. In accordance with a formal 20-electron configuration at the rare earth metal center Ln, the amido-nitrogen atoms are shown to be pyramidalized. In the case of Li[Y(η5:η1-C5H3tBuSiMe2NCH2CH2X)2], mixtures of the tw…
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.
Photoiodocarboxylation of Activated C═C Double Bonds with CO2 and Lithium Iodide
2018
The photolysis at 254 nm of lithium iodide and olefins 1 carrying an electron-withdrawing Z-substituent in CO2-saturated (1 bar) anhydrous acetonitrile at room temperature produces the atom efficient and transition metal-free photoiodocarboxylation of the C═C double bond. The reaction proceeds well for terminal olefins 1 to form the new C-I and C-C σ-bonds at the α and β-positions of the Z-substituent, respectively, and is strongly inhibited by polar protic solvents or additives. The experimental results suggest that the reaction channels through the radical anion [CO2•-] in acetonitrile, yet involves different intermediates in aqueous medium. The stabilizing ion-quadrupole and electron don…
Lithium enediolates and dienediolates of carboxylic acids in synthesis: Alkylation with secondary halides
1998
Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.
ChemInform Abstract: Lithium Enediolates and Dienediolates of Carboxylic Acids in Synthesis: Alkylation with Secondary Halides.
2010
Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.
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…