18292-36-9Relevant academic research and scientific papers
The Double-Faced Nature of Hydrogen Bonding in Hydroxy-Functionalized Ionic Liquids Shown by Neutron Diffraction and Molecular Dynamics Simulations
Niemann, Thomas,Neumann, Jan,Stange, Peter,G?rtner, Sabrina,Youngs, Tristan G. A.,Paschek, Dietmar,Warr, Gregory G.,Atkin, Rob,Ludwig, Ralf
, p. 12887 - 12892 (2019)
We characterize the double-faced nature of hydrogen bonding in hydroxy-functionalized ionic liquids by means of neutron diffraction with isotopic substitution (NDIS), molecular dynamics (MD) simulations, and quantum chemical calculations. NDIS data are fit using the empirical potential structure refinement technique (EPSR) to elucidate the nearest neighbor H???O and O???O pair distribution functions for hydrogen bonds between ions of opposite charge and the same charge. Despite the presence of repulsive Coulomb forces, the cation–cation interaction is stronger than the cation–anion interaction. We compare the hydrogen-bond geometries of both “doubly charged hydrogen bonds” with those reported for molecular liquids, such as water and alcohols. In combination, the NDIS measurements and MD simulations reveal the subtle balance between the two types of hydrogen bonds: The small transition enthalpy suggests that the elusive like-charge attraction is almost competitive with conventional ion-pair formation.
Carbocyclizations employing 2-Silyl-1,3-dithians
Grotjahn, Douglas B.,Andersen, Niels H.
, p. 306 - 307 (1981)
Dithianyl anions capable of carbocyclization via either direct or Michael addition to a carbonyl unit can be generated from 2-trimethylsilyl-1,3-dithians.
Selective synthesis of halosilanes from hydrosilanes and utilization for organic synthesis
Kunai, Atsutaka,Ohshita, Joji
, p. 3 - 15 (2007/10/03)
Selective synthesis of halosilanes has been examined. Various types of halosilanes and halohydrosilanes, such as R3SiX, R2SiHX, R2SiX2, RSiH2X, RSiHX2 (X=Cl, Br, F), were obtained by the reactions of the corresponding hydrosilanes with Cu(II)-based reagents selectively in high yields. This method could be also applied to the synthesis of chlorofluorosilanes and chlorohydrogermanes. On the other hand, iodo- and bromosilanes and germanes were obtained by Pd- or Ni-catalyzed hydride-halogen exchange reactions of hydrosilanes with alkyl or allyl halides. Their synthetic applications have been demonstrated by using iodo- and bromosilanes and chlorofluorosilanes.
Carbofunctional silacyclobutanes 1. Synthesis of 1-(ω-hydroxyalkyl)silacyclobutanes
Ushakov,Fedorova
, p. 901 - 910 (2007/10/03)
A four-step synthesis of 1-(ω-hydroxyalkyl)- and 1-(4-hydroxyphenyl)silacyclobutanes was carried out. The influence of the structure of the initial compounds and the reaction conditions on the ratio of the reaction products formed was studied. The stabili
REGIOSELECTIVITY OF RADICAL CYCLIZATION OF UNSATURATED ORGANOSILICON THIOLS
Kirpichenko, Svetlana,Tolstikova, Lyudmila,Suslova, Elena,Albanov, Aleksander,Voronkov, Mikhail
, p. 47 - 54 (2007/10/03)
Regiochemistry of radical cyclizations of isomeric dimethylsila-substituted 5-hexene-1-thiols (1 and 2) and 6-heptene-1-thiols (5 and 6) has been studied.It has been found that the ring closure of alkenylthiyl radicals having a vinyl group at silicon is a
Cyclic ethers as educts for the synthesis of lepidoptra pheromones
Poleschner,Heydenreich,Martin
, p. 1231 - 1235 (2007/10/02)
ω-Iodo(trialkylsiloxy)alkanes 2 prepared by ring opening of cyclic ethers with iodotrimethylsilane, are useful starting materials for the synthesis of pheromone components. Reaction with triphenylphosphine to give the corresponding Wittig reagent and subsequent coupling with lithium (Z)-dihex-1-enylcuprate gives (Z)-alken-1-ols 5 and 7, after deprotection, in good yields. The direct coupling of 2 with alkynes failed because of competition reactions, however, the more stable ω-iodo-1-(tert-butyldimethylsiloxy)alkanes were able to undergo C,C-coupling with alkynes. The thus formed 1-(tert-butyldimethylsiloxy)-5-decyne (13c) was hydrogenated and deprotected to give (E)-5-decen-1-ol (15c).
Efficient Synthesis of Siloxy Dienes from α,β-Unsaturated Ketones
Hansson, Lars,Carlson, Rolf
, p. 188 - 192 (2007/10/02)
A novel method for the preparation of siloxy dienes has been developed.The reaction system was established by a multivariate screening experiment, where catalysts and solvents were selected according to their principal properties.The best system was lithium bromide-chlorotrimethylsilane-triethylamine in tetrahydrofuran.Optimum experimental conditions were determined by response surface methods.The following substrates were used: 2-butenone, 4-methyl-3-penten-2-one, 4-methoxy-3-buten-2-one, 1-acetylcyclohexene, 2-cyclohexenone, 2-cyclopentenone, 4-phenyl-3-buten-2-one, 4-(4-methoxyphenyl)-3-buten-2-one, and 4,4-dimethyl-2-cyclohexenone.Isolated yields were in the range of 82 - 96percent.
Interhalogen-Catalyzed Cleavages of Ethers and Esters with Trimethylsilyl Bromide or Chloride
Friedrich, Edwin C.,DeLucca, George
, p. 1678 - 1682 (2007/10/02)
The cleavages of various dialkyl ethers, trimethylsilyl alkyl ethers, and alkyl esters by trimethylsilyl bromide are strongly catalyzed by iodine monobromide.This catalyzed cleavage procedure using iodine monobromide makes possible synthetic applications for trimethylsilyl bromide which were previously ruled out by problems with its low reactivity.Cleavages of benzylic and tertiary alkyl ethers and esters by trimethylsilyl chloride are feasible when catalyzed by iodine monochloride.However, other systems are essentially unreactive toward trimethylsilyl chloride even in the presence of iodine monochloride.
