107-25-5Relevant articles and documents
Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands
Selikhov, Alexander N.,Shavyrin, Andrey S.,Cherkasov, Anton V.,Fukin, Georgy K.,Trifonov, Alexander A.
, p. 4615 - 4624 (2019)
A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an ν3 coordination mode, while in 6 it is ν1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5-7 is retained in their C6D6 solutions. Complexes 4-7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of DME led to the formation of the symmetrical bis(carbazolyl) complex products [tBu4Carb]2Ln(DME)4 (Ln = Sm (8), Yb (9)) isolated in the form of separated ion pairs.
Trends in alkyl substituent effects on nucleophilic reactions of carbonyl compounds: Gas phase reactions between ammonia and R1R2COCH3+ oxonium ions
Bache-Andreassen, Lihn,Uggerud, Einar
, p. 705 - 713 (2003)
The reactivity of carbonyl substituted methyl oxonium ions (R1R2COCH3-) towards ammonia has been investigated using an FT-ICR mass spectrometer and ab initio calculations. The monosubstituted ions (R1=H: R2 = H, CH3, C2H5 and i-C3H7) show different reaction patterns with variable degree of: (1) nucleophilic substitution, (2) addition elimination and (3) proton transfer, when reacted with ammonia. In all cases addition-elimination dominates over nucleophilic substitution, and the observed reactions are slow. The trends in reactivity are consistent with the alkyl group's electronic properties, as expressed by a single parameter linear or slightly non-linear model.
Influence of Boiling on the Radiolysis of Diglyme
Vlasov,Kholodkova,Ponomarev
, p. 312 - 318 (2018)
The radiolysis of diethylene glycol dimethyl ether (diglyme) in a boiling state has been studied for the first time. Boiling facilitates the cleavage of internal C–O bonds, weakens the cage effect and diglyme regeneration processes, and facilitates the exchange and dimerization reactions of radicals. As compared with radiolysis at room temperature, the amount of unsaturated products of diglyme fragmentation formed during irradiation in the boiling state is smaller by a factor of 4, and the disproportionation products of heavy radicals are found in negligible amounts, if any. The yield of radiolytic decomposition of diglyme under boiling conditions is ～15 molecule/100 eV, which is higher than that at room temperature by a factor of almost 1.5.
Decompositions of Ionized Isopropyl Methyl Ether: Complex-Mediated and Direct Processes in Unimolecular Dissociations
McAdoo, David J.,Traeger, John C.,Hudson, Charles E.,Griffin, Lawrence L.
, p. 1524 - 1530 (1988)
Methane and methyl losses from ionized isopropyl methyl ether (1) were characterized to improve our understanding of ion-neutral-complex-mediated dissociations in the gas phase.Photoionization appearance energies demonstrate that the onsets for the two reactions differ by only 2+/-1 kJ mol-1, consistent with the two processes being related by a common bond cleavage.Isotope effects confirm that the transition states for bond scission to form the complex and subsequent hydrogen transfer to form methane are at very similar energies.Loss of methane becomes insignificant 20-30 kJ mol-1 above its onset, whereas loss of methyl increases rapidly for at least 100 kJ mol-1 above threshold.From this it is concluded that the decompositions of 1 are complex-mediated near threshold but shift to a direct mechanism at higher energies, i. e., that decomposition is ion-neutral-complex-mediated over only a narrow range of energies just above threshold.
Gaseous 1-Methyl-1-oxoniacycloalkanes as Stable Intermediates on the C3H7O+ and C4H9O+ Potential Energy Surfaces
Angelini, Giancarlo,Speranza, Maurizio
, p. 1217 - 1219 (1983)
The nature and the isomeric distribution of the neutral products obtained from the gas-phase attack of CH5+, C2H5+, and CH3FCH3+ ions on cyclic CnH2nO (n = 2, 3, and 4) ethers provide the first experimental evidence in favour of 1-methyl-1-oxoniacyclopropane and 1-methyl-1-oxoniacyclobutane as stable intermediates on the corresponding potential energy surface.
Hochaktive Katalysatorsysteme fur die Vinylethersynthese aus Acetylen und Alkoholen-Kaliumalkoholat/Kronenether in Kohlenwasserstoffen
Steinborn, Dirk,Mosinski, Holger,Rosenstock, Thomas
, p. C45 - C50 (1991)
The activity of well-known alkaline-containing catalyst systems for the formation of vinyl ethers from alcohols and acetylenes can be remarkably increased by using a superbasic system: KOR-crown ether in an aprotic solvent (especially in hydrocarbons).To achieve a high catalytic activity a low concentration of alcohol in the hydrocarbon phase is essential.The results are discussed in terms of solvatation of alcoholate anion.
Phosphine-Catalyzed Vinylation at Low Acetylene Pressure
Bienewald, Frank,Comba, Peter,Hashmi, A. Stephen K.,Menche, Maximilian,Rominger, Frank,Schafer, Ansgar,Schaub, Thomas,Sitte, Nikolai A.,Tuzina, Pavel
, p. 13041 - 13055 (2021/09/18)
The vinylation of various nucleophiles with acetylene at a maximum pressure of 1.5 bar is achieved by organocatalysis with easily accessible phosphines like tri-n-butylphosphine. A detailed mechanistic investigation by quantum-chemical and experimental methods supports a nucleophilic activation of acetylene by the phosphine catalyst. At 140 °C and typically 5 mol % catalyst loading, cyclic amides, oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were successfully vinylated. Furthermore, the in situ generation of a vinyl phosphonium species can also be utilized in Wittig-type functionalization of aldehydes.
Method for synthesizing vinyl methyl ether by using ethylene glycol dimethyl ether
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Paragraph 0029-0043, (2020/11/01)
The invention discloses a method for synthesizing vinyl methyl ether by using ethylene glycol dimethyl ether. The synthesis method comprises the step of carrying out elimination reaction on ethylene glycol dimethyl ether under the catalytic action of solid alkali to obtain vinyl methyl ether and methanol, wherein the solid alkali is magnesium oxide, cerium dioxide, calcium oxide or calcium-magnesium mixed oxide, and in the calcium-magnesium mixed oxide, the molar ratio of calcium to magnesium is 0.1-4. According to the method for preparing the vinyl methyl ether by catalyzing the ethylene glycol dimethyl ether with the solid alkali, provided by the invention, the raw materials are wide in source and green; the catalyst is efficient, cheap and good in stability; the yield of the target product can reach 80%; the byproduct methanol can be recycled to prepare reaction raw materials; and the method is low in equipment requirement and small in investment, and has very important practical application value.
Chloro and alkyl rare-earth complexes supported by ansa-Bis(amidinate) ligands with a rigid o-phenylene linker. Ligand steric bulk: A means of stabilization or destabilization?
Tolpygin, Aleksei O.,Shavyrin, Andrei S.,Cherkasov, Anton V.,Fukin, Georgy K.,Trifonov, Alexander A.
, p. 5405 - 5413 (2012/11/13)
ansa-Bis(amidinate) ligands with a rigid o-phenylene linker, C 6H4-1,2-{NC(tBu)N(2,6-R2C6H 3)H}2 (R = Me (1), iPr (2)), were successfully employed for the synthesis of rare-earth chloro and alkyl species. The reaction of dilithium derivatives of 1 and 2 with LnCl3 (Ln = Y, Lu) afforded the monomeric bis(amidinate) chloro lanthanide complexes [C6H 4-1,2-{NC(tBu)N(2,6-R2C6H3)} 2]Y(THF)(μ-Cl)2Li(THF)2 (R = Me (3), iPr (5)) and [C6H4-1,2-{NC(tBu)N(2,6-Me2C 6H3)}2]LuCl(THF)2 (4). Bis(amidinate) ligands in complexes 3 and 4 are coordinated to the metal atoms in a tetradentate fashion, while the bulkier ligand in 5 is tridentate. The alkane elimination reactions of 1 and 2 with equimolar amounts of (Me 3SiCH2)3Ln(THF)2 (Ln = Y, Lu) allowed us to obtain the monoalkyl complexes [C6H4-1,2- {NC(tBu)N(2,6-R2C6H3)}2]Ln(CH 2SiMe3)(THF)n (Ln = Y, R = Me, n = 1 (6); Ln = Lu, R = Me, n = 1 (7); Ln = Y, R = iPr, n = 2 (8)). The kinetics of thermal decomposition of complexes 6-8 were measured, and for 6 the activation energy was obtained from the temperature dependence of the rate constants (E a = 67.0 ± 1.3 kJ/mol). Complexes 6 and 7 turned out to be inert toward H2 and PhSiH3. Surprisingly, complex 8 was inert toward H2 and PhSiH3 but rapidly cleaved C-O bonds of DME. The reaction resulted in the formation of the methoxy complex {[C 6H4-1,2-{NC(tBu)N(2,6-iPr2C6H 3)}2]Y(μ2-OMe)]}2(μ 2-DME) (9) and methyl vinyl ether.
Competition between reaction and intramolecular energy redistribution in solution: Observation and nature of nonstatistical dynamics in the ozonolysis of vinyl ethers
Quijano, Larisa Mae M.,Singleton, Daniel A.
supporting information; body text, p. 13824 - 13827 (2011/10/12)
Experimental product ratios in ozonolyses of alkyl vinyl ethers in solution do not fit with expectations based on statistical rate theories. The selectivity among cleavage pathways increases with the size of the alkyl group but to an extent that is far less than RRKM theory would predict. Trajectory studies account for the observed selectivities and support a mechanism involving a competition between cleavage of the primary ozonide and intramolecular vibrational energy redistribution. A statistical model is presented that assumes that RRKM theory holds for a molecular subset of the primary ozonides, allowing the rates of energy loss from the ozonides to be estimated from the observed product ratios.
