3083-10-1Relevant academic research and scientific papers
Thermodynamics of Protonation of Tetramines with Different Degrees of N-Methylation
Barbucci, Rolando,Barone, Vincenzo,Micheloni, Mauro,Rusconi, Luisa
, p. 64 - 68 (1981)
In an attempt to give further insight into the effect of increasing methylation on the protonation of polyamines we studied the tetramines hexamethyltriethylenetetramine (trienMe6) and N,N,N"',N"'-tetramethyltriethylenetetramine (trienMe4).The results are discussed with special reference to the related compound triethylenetetramine (trien).Different methylation of both terminal and inner nitrogens apparently affects the thermodynamic functions.The ΔG0, ΔH0, and ΔS0 values suggest a unique protonation mechanism starting with the terminal nitrogen atoms.The stepwise entropy chenges are discussed on the basis of the releasing of water molecules.
Copper-(I) and -(II) complexes with tertiary linear polyamines of the type Me2NCH2(CH2NMeCH2) nCH2NMe2 (n = 1-4)
Golub, Gilad,Cohen, Haim,Paoletti, Piero,Bencin, Andrea,Meyerstein, Dan
, p. 2055 - 2060 (1996)
2,5,8,11-Tetramethyl-2,5,8,11-tetraazadodecane, 2,5,8,11,14-pentamethyl-2,5,8,11,14-pentaazapentadecane, and 2,5,8,11,14,17-hexamethyl-2,5,8,11,14,17-hexaazaoctadecane, form stable complexes with CuI in aqueous solutions. On the other hand 2,5,8-trimethyl-2,5,8-triazanonane, does not. This indicates that the stabilization of CuI by tertiary amine ligands in aqueous solutions requires at least four nitrogens. The electronic spectra and the electrochemical properties of the [CuLi]2+ complexes over a wide pH range were studied and potentiometric titrations were made of solutions containing equimolar concentrations of CuII and Li. The nature of the complexes present in these solutions is discussed.
Method for preparing alkoxyamines from nitroxides
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, (2008/06/13)
The invention relates to a process for preparing alkoxyamines. This process consists in mixing, in an organic solvent, a metal salt, a ligand for the metal, a halocarbon compound ZX and a nitroxide, in keeping the reaction medium stirring at a temperature of between 20° C. and 90° C. until the nitroxide has disappeared, in recovering the organic phase, in washing it with water and then in isolating the alkoxyamine by evaporating the organic solvent under reduced pressure.
Coordination to RMg+ and RZn+ cations
Tang, Hui
, p. 4810 - 4819 (2008/10/08)
Addition of a second coordinating agent (coord*) to a solution of RM(coord)+A- (R = ethyl or neopentyl, M = Zn or Mg, A- = 1,2,3,4-tetraphenylcyclopentadienyl) can provide equilibrium mixtures of these compounds, coord, and RM(coord*)+A-. This exchange with RMg(coord)+ requires the addition of a small amount of R2Mg, but added R2Zn is not necessary for exchanges with RZn(coord)+. The equilibrium constants provide information about the relative abilities of different coordinating agents to coordinate to RM+ and reveal significant differences between coordination to RMg+ and RZn+. Reactions of RM(coord)+ with R′2M (R = ethyl or neopentyl for RMg(coord)+ and ethyl, isopropyl, tert-butyl, neopentyl, or p-methylphenyl for RZn(coord)+) provide equilibrium mixtures of these components, R′M(coord)+, and R2M. The equilibrium constants provide information about the effect of R on stability. An X-ray structure of p-methylphenylzinc(2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane)+ shows that just three of the N atoms are coordinated to Zn. The effects of coord, R, and metal on RM(coord)+ stability are discussed, and the abilities of coordinating agents to coordinate to RM+, to slow allylic isomerization of (CH2 double bond CMeCH2)2Zn, and to convert R2Zn to RZn(coord)+ are compared.
Notes. High-valent Ruthenium Oxo Complexes of NNN'N'-Tetramethyl-3,6-dimethyl-3,6-diazaoctane-1,8-diamine (L1). X-Ray Crystal Structure Determination of cis-III(L1)Cl2>ClO4
Che, Chi-Ming,Tang, Wai-Tong,Lam, Michael Hon-Wah,Mak, Thomas C. W.
, p. 2885 - 2888 (2007/10/02)
The reaction of K2 with NNN'N'-tetramethyl-3,6-dimethyl-3,6-diazaoctane-1,8-diamine (L1) in ethanol yielded cis-III(L1)Cl2>(1+), which was isolated as the ClO4(1-) salt.The optical spectrum of cis-III(L1)Cl2>ClO4 in acetonitrile displays one intense band at 375 nm attributed to a p?(Cl) d?*(Ru) transition. cis-III(L1)Cl2>ClO4 has been characterized by X-ray crystallography: space group P21/c, a = 11.716(5), b = 13.089(4), c = 12.981(5) Angstroem, β=94.28(2) deg, Z = 4, and R = 0.076 for 1913 observed Mo-Kα data.The co-ordination geometry around the metal ion is distorted octahedral with cis arrangement of the two chloride ligands.The average Ru-N and Ru-Cl bond distances are 2.17(1) and 2.345(4) Anstroem, respectively.Treatment of cis-III(L1)Cl2>ClO4 with silver(I)p-toluenesulphonate in hot water and then H2O2 gave VI(L1)(O)2>(2+) isolated as the ClO4(1-) salt. VI(L1)(O)2>2 is diamagnetic (μeff = 0) and has an intense i.r. band at ca. 850 cm-1 attributed to νasym(Ru=O) stretching.The E1/2 value of the VI(L1)(O)2>(2+)/IV(L1)(O)(H2O)>(2+) couple in 0.1 mol dm-3 CF3CO2H is 0.79 V vs. a saturated calomel electrode.The reaction of VI(L1)(O)2>2 with styrene produced benzaldehyde.
Di-, Tri-, Tetra-, and Pentacationic Alkylammonium Salts. Ligands Designed To Prevent the Nonspecific Electrostatic Precipitation of Polyanionic, Functionalized Cyclopentadienyltitanium-Substituted Heteropolytungstate Electron Microscopy Labels with Cationic Biomolecules.
Keana, John F. W.,Wu, Yexin,Wu, Guanli
, p. 2571 - 2576 (2007/10/02)
This work relates to the use of organic functionalized heteropolytungstates (HPTs) as protein-specific electron microscopy labels.The objective is the development of a polycationic ligand that prevents the nonspecific precipitation reaction observed between certain polycationic biomolecules and polianionic heteropolytungstates.Simple tetra- and pentaammonium salts between Keggin HPT 1b or Dawson HPT 2b and amines 3-6 or quaternary ammonium compounds 8 and 9 were all of low aqueous solubility as were salts derived from the oxygenated partners 7, 11, 12, and 15-18.However, tetrakis quaternary salt 23a, which is made up of several highly oxygenated alkyl groups, effectively prevents precipitation between Dawson HPT 2b and the exemplary basic proteins lysozyme and poly-L-lysine as well as the lectin concanavalin A.
AFFINITIES OF CROWN ETHERS, GLYMES, AND POLYAMINES FOR ALKALI PICRATES IN TOLUENE. APPLICATION OF POLYMER-SUPPORTED LINEAR POLYETHERS.
Xu,Smid
, p. 3790 - 3796 (2007/10/02)
This work reports the measurements of K values for polyamines, glymes, a few glycols (including that of a long-chain polyethylene glycol, carbowax 6000), and some frequently used cation-binding ligands as complexers of lithium or sodium picrate in toluene as solvent. K values for different resins obtained with the same soluble ligand provide a comparison of the effectiveness of these resins in binding ionic solutes.
