13179-96-9Relevant articles and documents
AN ELECTRON SPIN RESONANCE STUDY OF THE PHOTOLYSIS OF BIS(β-ALKOXYALKYL)MERCURIALS
Bloodworth, A.J.,Davies, Alvyn G.,Savva, Rolando A.,Winter, Jeremy N.
, p. 1 - 8 (1983)
Bis(β-alkoxyalkyl)mercurials are much more photosensitive than the unsubstituted dialkylmercurials, and when they are irradiated in solution with ultraviolet light, the ESR spectra of the appropriate β-alkoxyalkyl radicals are observed.Spectral data are presented for 14 such radicals and the values of a(Hβ) are discussed in terms of possible conformational preferences.
Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
, p. 1996 - 2003 (2017/02/26)
Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
Upgrading biomass-derived furans via acid-catalysis/hydrogenation: The remarkable difference between water and methanol as the solvent
Hu, Xun,Westerhof, Roel J. M.,Wu, Liping,Dong, Dehua,Li, Chun-Zhu
, p. 219 - 224 (2018/04/16)
In methanol 5-hydroxymethylfurfural (HMF) and furfuryl alcohol (FA) can be selectively converted into methyl levulinate via acidcatalysis, whereas in water polymerization dominates. The hydrogenation of HMF, furan and furfural with the exception of FA is
Thermodynamic stabilities of Cu+ and Li+ complexes of dimethoxyalkanes (MeO(CH2)nOMe, n = 2-9) in the gas phase: Conformational requirements for binding interactions between metal ions and ligands
Mishima, Masaaki,Maeda, Hideyuki,Than, Soe,Irie, Maki,Kikukawa, Kiyoshi
, p. 616 - 623 (2007/10/03)
The relative free energy changes for the reaction ML+ = M + + L (M = Cu+ and Li+) were determined in the gas phase for a series of dimethoxyalkanes (MeO(CH2)nOMe, n = 2-9) by measuring the equilibrium constants of ligand-transfer reactions using a FT-ICR mass spectrometry. Stable 1:1 Cu+-complexes (CuL +) were observed when the chain is longer than n = 4 while the 1:2 complexes (CuL2+) were formed for smaller compounds as stable ions. The dissociation free energy for CuL+ significantly increases with increasing chain length, by 10 kcal mol-1 from n = 4 to 9. This increase is attributed to the release of constrain involved in the cyclic conformation of the Cu+-complexes. This is consistent with the geometrical and energetic features of the complexes obtained by the DFT calculations at B3LYP/6-311G level of theory. On the contrary, the corresponding dissociation free energy for LiL+ increases only 3 kcal mol -1 from n = 2 to 9, although the structures of the 1:1 Li +-complexes are also considered to be cyclic. From these results it is concluded that the Cu[MeO(CH2)nOMe]+ requires linear alignment for O-Cu-O, indicating the importance of sd σ hybridization of Cu+ in the first two ligands binding energy, while the stability of the Li+ complex is less sensitive to binding geometries except for the system forming a small ring such as n = 1 and 2. Copyright
Direct methylation of primary and secondary alcohols by trimethyl phosphate to prepare pure alkyl methyl ethers
Van Dyke Tiers, George
, p. 1223 - 1233 (2007/10/03)
Primary and secondary alcohols and diols react autocatalytically with trimelhyl phosphate plus small amounts of polyphosphoric acid at 185°C to give the corresponding methyl ethers. High purity and good yields are achieved when the ether is distilled from the reaction mixture as it is formed. By controlled addition even low-boiling alcohols can be methylated successfully. The reaction mechanism is undetermined. Peroxide formation in ethers is inhibited by storage over 10 molal KOH. Pure isotropic optical crystals are used for refractometer calibration. Improved physical property and NMR data (1H and 13C) are reported for thirteen methyl ethers. Simple two-point linear extrapolation of NMR shifts (especially 13C) to infinite dilution produces highly reproducible δ°-values (to 0.01 ppm or better) which uniquely characterize a molecule even when unidentified and/or not isolated from a mixture. This capability appears not to have been recognized in the literature. Acta Chemica Scandinavica 1998.
Fingerprinting a Transition-Structure Guest by a Building-Block Approach with an Incremental Series of Catalytic Hosts. Structural Requirements for Glyme and α,ω-Dimethoxyalkane Catalyses in N-Methylbutylaminolysis and Butylaminolysis of 4-Nitrophenyl Acetate in Chlorobenzene
Hogan, John C.,Gandour, Richard D.
, p. 55 - 61 (2007/10/02)
Glymes, H-(CH2OCH2)n-H, GLM(n), catalyze butylaminolysis of 4-nitrophenyl acetate in chlorobenzene.Values of kcat/Oxy, where Oxy is the number of oxygens in the catalyst, increase with oligomer length up to triglyme, GLM(4), and then plateau.Optimal catalysis on a per oxygen basis requires a -(CH2OCH2)4-fragment, which suggests a four-point recognition of the secondary ammonium ion of the zwitterionic tetrahedral intermediate (TI) (J.Org.Chem. 1991, 56, 2821-2826).Dissection of individual structural components and reassembly to the same structure of the complexverifies this model.The following kinetic studies of 4-nitrophenyl acetate in chlorobenzene have accomplished the task: (a) methylbutylaminolysis catalyzed by GLM(n), n = 2-4; (b) methylbutylaminolysis catalyzed by α,ω-dimethoxyalkanes, CH3O-(CH2)n-OCH3, DME(n), n = 2-10 and 12; and (c) butylaminolysis catalyzed by DME(n), n = 2-10 and 12.Experiment a has revealed that kcat/Oxy is the same for GLM(2) - GLM(4).Optimal catalysis for breakdown of a zwitterionic TI with one ammonium proton only requires a -(CH2OCH2)2-fragment.Experiment b has shown that kcat/Oxy is largest for DME(2) with the values for the remaining DMEs 2 - 2.5-fold lower.A -CH2CH2- is the best spacer between the two oxygens.Thus, bifurcated hydrogen-bond formation between the two oxygens and the one ammonium proton enhances catalysis.Experiment c has revealed that kcat/Oxy for DME(2) exceeds the remaining DMEs by 3 - 3.6-fold, except for DME(8) and DME(10), which have values of kcat/Oxy only 1.7-fold slower.DME(8), the carba analogue of GLM(4), likely binds the two ammonium protons individually with the two oxygens.DME(10) behaves similarly.GLM(4) catalysis of butylaminolysis identifies -(CH2OCH2)4- as an optimal size.DME(8) catalysis confirms this size, although the two catalysts stabilize the two-proton ammonium ion differently.GLM(4) catalyzes butylaminolysis by forming two bifurcated hydrogen bonds.This suggested structure defines the size of the ammonium ion, which agrees with X-ray structural studies of polyether-ammonium complexes.Mechanistic proposals of butylaminolysis of aryl esters require such an ion.The results of this study confirm the stucture of the ion in the rate-limiting step.This building-block approach is a method for "fingerprinting" ammonium ions in transition structures of ionogenic reactions.
Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
Kirmse, Wolfgang,Jansen, Ulrich
, p. 2607 - 2625 (2007/10/02)
Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
