1932-04-3Relevant articles and documents
Crystal structure of a butyllithium 1,2-dipiperidinoethane dimer complex
Nichols, Michael A.,Sobinsky, Rachel M.,Hunter, Allen D.,Zeller, Matthias
, p. 433 - 438 (2007)
The crystal structure of butyllithium solvated by 1,2-dipiperidinoethane, BuLi?DPE-6, which has been used as an initiator for a number of important commercial anionic polymerization reactions, is reported. The complex crystallizes from pentane as a centrosymmetric dimer in the monoclinic space group P21/n with a∈=∈9.8619(12), b∈=∈17.963(2), c∈=∈10.3655(12) A, β∈=∈114.090(2)° and Z∈=∈2. The dimer is located on a crystallographic inversion center. The crystal under investigation was found to be non-merohedrally twinned. In contrast to the two other dimeric BuLi complexes previously structurally characterized in the solid state, BuLi?DPE-6 has a planar central Li 2C2 core. Semi-empirical (PM3) calculations were used to determine the lowest energy conformations of the dimer and also identified three structural motifs that affect Li2C2 dimer ring planarity. Springer Science+Business Media, LLC 2007.
Selective synthesis of formamides, 1,2-bis(N-heterocyclic)ethanes and methylamines from cyclic amines and CO2/H2 catalyzed by an ionic liquid-Pd/C system
Li, Ruipeng,Zhao, Yanfei,Wang, Huan,Xiang, Junfeng,Wu, Yunyan,Yu, Bo,Han, Buxing,Liu, Zhimin
, p. 9822 - 9828 (2019/11/11)
The reduction of CO2 with amines and H2 generally produces N-formylated or N-methylated compounds over different catalysts. Herein, we report the selective synthesis of formamides, 1,2-bis(N-heterocyclic)ethanes, and methylamines, which is achieved over an ionic liquid (IL, e.g., 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIm][BF4])-Pd/C catalytic system. By simply varying the reaction temperature, formamides and methylamines can be selectively produced, respectively, in high yields. Interestingly, 1,2-bis(N-heterocyclic)ethanes can also be obtained via the McMurry reaction of the formed formamide coupled with subsequent hydrogenation. It was found that [BMIm][BF4] can react with formamide to form a [BMIm]+-formamide adduct; thus combined with Pd/C it can catalyze McMurry coupling of formamide in the presence of H2 to afford 1,2-bis(N-heterocyclic)ethane. Moreover, Pd/C-[BMIm][BF4] can further catalyze the hydrogenolysis of 1,2-bis(N-heterocyclic)ethane to access methylamine. [BMIm][BF4]-Pd/C was tolerant to a wide substrate scope, giving the corresponding formamides, 1,2-bis(N-heterocyclic)ethanes or methylamines in moderate to high yields. This work develops a new route to produce N-methylamine and opens the way to produce 1,2-bis(N-heterocyclic)ethane from cyclic amine as well.
Visible-light photo-catalytic C-C bond cleavages: Preparations of N,N-dialkylformamides from 1,2-vicinal diamines
Zhao, Yaohong,Cai, Shunyou,Li, Jing,Wang, David Zhigang
supporting information, p. 8129 - 8131 (2013/08/28)
A range of 1,2-vicinal diamines were smoothly converted into N,N-dialkylformamides under the synergistic actions of Ru(bpy) 3Cl2 photo-catalyst, 45 W household lighting bulb, and Cs2CO3 basic additive under very mild reaction conditions. The process involves visible light-enabled photo-catalytic cleavage of C-C bond as the strategic event.
