J.-J. Delpuech

Reduction d'azides en amines par le formiate d'ammonium par “Transfert d'Hydrogene Catalyse” (CTH)

Resume The azides are reduced to amines in very good yiels by “Catlytic Transfer Hydrogenation” (CTH) using ammonium formate.

Monodisperse perfluoro-polyethoxylated amphiphilic compounds with two-chain polar head - preparation and properties

Abstract Monodisperse new surfactant molecules -with a two-chain polyoxyethylene (EO) hydrophilic head and a perfluoroalkyl hydrophobic moiety linked together through an amide bond are synthesized by methods allowing large-scale production. Surface tension measurements (γ ~ 20 mN.m−1) show slow organization of the surfactant film at the water/air interface for longer fluorocarbon tail. Values of critical micellar concentrations and comparisons with monosubstituted amide surfactants are consistent with a high hydrophilicity of the amide function, a small influence of branching over hydrophilicity, and a hydrophobicity of each CF2 unit equivalent to 1.7 methylenes (in the analogous hydrogenated surfactants).

Synthese, proprietes complexantes et pouvoir extractant de β -diphosphoramides hydrophobes

Abstract New hydrophobic β-diphosphoramides of the type [( Me 2 N) 2 P(0)] 2 NR where R = hexyl(OHIPA), dodecyl(ODIPA) or benzyl (OBIPA) have been synthesized ; their hydrophobic character and their complexing and extracting abilities have been measured and compared to those of NIPA (R = methyl). It is shown that, among the four ligands, the compound ODIPA presents the best extracting properties because of its insolubility in water and its important complexing ability.

La mutarotation du β-D-fructose en milieu acide dans le dimethylsulfoxyde

Abstract The proton and solvent catalyzed rate constants of furanose formation are 2 to 3-fold greater than those of pyranose formation. The activation and thermodynamic parameters are calculated.

An NMR study of the complexes of Zn(II) and Cd(II) ions with tris(dimethylamino)phosphine sulphide: Ligand exchange kinetics

Abstract The preparation of the complex species [Cd(TDPS)4](ClO4)2 and [Zn(TDPS)4](ClO4)2 (TDPS = tris(dimethylamino)phosphine sulphide)

Hindered rotation around the aryl-to-nitrogen bond of n-acetyl, n-ethoxycarbonylmethyl-2-amino, 5-nitrothiophen

Abstract Two stereoisomers of the title compound are observed by H NMR at 10°. Their spectra coalesce at higher temperature (10°-90°). The equilibrium and rate constants K and k, strongly dependent on the solvent used (1,4-dioxane, tetrahydrofuran, acetone, chloroform); typical values for these parameters and the related thermodynamic functions are: K(25°)= 0.170; k(25°)=23.2s −1 ; ΔH R and ΔH ≠ =4.94 and 17.9 kcal.mol. −1 ; ΔS R and ΔS ≠ =13.1 and 7.7 e.u, in a 0.2 molar solution in 1,4-dioxane. The two isomers are shown to result from a hindered rotation around the aryl-to-nitrogen bond, presumably due to a direct resonance effect between the amide and nitro groups. The more abundant isomer was assigned a planar molecular structure in which the O atom of the amide group is close to the S atom of the thiophen ring, presumably on account of an electrostatic interaction between these two atoms which bear partial electrical charges of opposite sign.

Mixed ligand complexes containing β-diphosphoramides. I. Substitution of DMSO by NIPA in solvates of Cd(II). A cadmium-113 NMR study

Abstract The stepwise substitution of DMSO in the complex [Cd(DMSO) 6 ] 2+ , 2ClO 4 − on addition of nonamethylimidodiphosphoramide (NIPA) has been monitored by 113 Cd NMR at −22 °C in nitromethane solution. All the species [Cd(DMSO) 6−2 i (NIPA) i ] 2+ ( i = 0–3) can be observed as separate signals under these conditions and identified on the basis of signal multiplicity, due to 31 P 113 Cd coupling. The integration of the signals yields the relative concentrations of the different complexes and allows the determination of the stability constant β i corresponding to the equilibria [Cd(DMSO) 6 - 2 i (NIPA) i ] 2+ + 2 i DMSO for the different ratios of R = [NIPA]o/[Cd 2+ ] o . The values obtained are log β 1 = 3.58, log β 2 = 6.58, and log β 3 = 8.13. The distribution of the complex species has been calculated for a range of 0 R The 113Cd shielding found for the compound Cd(NIPA) 3 2+ is one of the strongest reported to date for an ionic cadmium complex containing small neutral ligands.

Synthese de composes biphosphoryles utilises comme agents complexants

Resume N-alkylated derivatives of nonamethylimidodiphosphoramide (NIPA) (Me 2 N) 2 P(O)N(R)P(O) (NMe 2 ) 2 with R = n-C 6 H 13 and n-C 12 H 25 have been synthesized to obtain powerful neutral chelating reagents much more hydrophobic than NIPA itself.

Amide hydrogen exchange rates of model peptides in dimethyl sulphoxide solutions

Abstract Proton Transfers from and to the nitrogen atom (s) α (or α and β) of a doubly protected dipeptide. Gly-Gly or PG 2 . (or tripeptide : Gly-Gly-Gly or PG 3 ) in anhydrous DMSO was followed by DMNR under conditions of both acid (sulphuric) and base (tetramethylguanidine) catalyzed exchange. Two kinetic processes are observed, one catalyzed by the hydrogen ion and the other by the conjugate base (P-) of the peptide (P). The results at 25°C are summarized by the equation. rate of peptide proton exchange = k H [H + ] + k B [P]/[H + ], with k H = 6.3 : 17.1 : 8.85 M-ls -1 and k B = 1.45 ; 5.62 ; 9.55 × 10 -13 s -1 for PG 2 (α) and PG 3 (α and β), respectively. This allows us to predict maximum half-reaction times for NH-NH (or NH-ND) exchanges of ca. 10 4 mn at pH 7 to 8 in DMSO. pK values of N-protonation (pK NH 2 +) are estimated from log k H and pK values of N-deprotonation (pK NH ) are measured by three independent methods. pK NH = 19.4 : 19.7 : 19.1 (± 0.2) for PG 2 and PG 3 (α and β). Compared to N-methylacetamide. pKNH 2 + and log k H of peptides are decreased by ca. two units, while pK NH and log k B are decreased and increased by ca. four and two units. respectively.

A comparative study of the structures, NMR properties and magnetic behaviour of complexes of cobalt(II) with octamethylpyrophosphoramide and nonamethylimidodiphosphoramide

Abstract The structure of the complex Co(NIPA)3(ClO4)2 has been determined by X-ray diffraction analysis and found to be very close to that of the corresponding OMPA complex. The magnetic susceptibilities of the OMPA and NIPA complexes have been measured by a thermomagnetic method and have allowed the calculation of χ| and χ⊥, the susceptibilities along the principal axes of the complex. The magnetic properties of the isomorphous nickel compounds have been studied for comparison. Results give evidence for the greater magnetic anisotropy of the NIPA complexes.