Showing papers on "Acetonitrile published in 1979"

The azidonitration of tri-O-acetyl-D-galactal

Abstract: Reaction of 3,4,6-tri-O-acetyl-D-galactal with excess ceric ammonium nitrate and sodium azide in acetonitrile produced 2-azido-1-nitrate addition products (53% β-galacto, 22% α-galacto, and 8% α-ta...

A coordination chemistry study of a nickel surface. The chemistry of nickel (111) with triply bonded molecules

Abstract: The chemistry of the (111) surface of nickel has been investigated for a series of molecules with unsaturated bonds: acetonitrile, methyl isocyanide, cyanogen, acetylene, 2-butyne, carbon monoxide, and ethylene. Acetonitrile, as in coordination chemistry, was weakly bound to the nickel surface and was readily and completely displaced by carbon monoxide at 300/sup 0/K. This nitrile formed a simple ordered surface structure at 300/sup 0/K; the observed (2 x 2) unit cell would accommodate acetonitrile molecules, normal to the surface, on every other nickel atom. The isomeric methyl isocyanide molecule was strongly bound to the surface, was not reversibly desorbed on temperature increase, and was not displaced by carbon monoxide. Dehydrogenation of the isocyanide occurred at approx. 380/sup 0/K and above 800/sup 0/K N/sub 2/ evolved to leave only carbon on the nickel crystal surface. Cyanogen was also strongly chemisorbed: thermal desorption gave N/sub 2/ at approx. 800/sup 0/K in contrast to platinum surfaces which reversibly desorb cyanogen. Cyanogen on the Ni(111) surface formed an extremely stable, ordered (6 x 6) structure at approx. 400/sup 0/K. Acetylene, 2-butyne, and ethylene were irreversibly chemisorbed on the nickel surface.

Thermodynamic properties for transfer of electrolytes from water to acetonitrile and to acetonitrile + water mixtures

Abstract: The free energies, enthalpies and entropies of transfer of a variety of electrolytes, including alkali metal halides, silver halides, tetraphenylarsonium and tetraphenylboride salts, from water to acetonitrile and water + acetonitrile mixtures have been measured. The enthalpies and entropies of transfer show a complex dependence upon solvent composition, which is discussed in terms of the effects of solvent sorting in the immediate neighbourhood of the ions, and of the effect of the solvated ions on the bulk solvent properties. The large structural effects occurring when ions are dissolved in water do not, however, appear to make a net significant contribution to the free energies of solution (and transfer) of electrolytes. Thus the overall free energies of transfer and their dependence upon solvent composition may be very simply interpreted in terms of the assumption that alkali metal and halide ions interact more strongly with water, and silver ions with acetonitrile, without reference to any special structural properties of water.

A Nuclear Magnetic Resonance Study of Water+-Acetonitrile Mixtures

Abstract: Water proton chemical shifts at 308 K and CN-group 13C chemical shifts at 300 K, relative to methyl protons and methyl carbon respectively, have been determined as a function of composition for the water + acetonitrile system. The composition variation of the water proton shift, particularly, suggests that in this system there may be as many as five structurally distinct composition regions, whose possible structures are discussed. This system appears to be more similar to systems like water + dioxan than to most other water + organic solvent systems, except for the complexity of the structural discontinuities in the water + acetonitrile system.

Preparation of [Fe(C5H5)(dppe)(NCCH3)]Br and Its Conversion to Several Fe(C5H5)(dppe)X Compounds

Abstract: The compound [Fe(C5H5)(dppe)(NCCH3)]Br is conveniently prepared by irradiation of Fe(C5H5)(CO)2Br and dppe (dppe = 1,2-bis(diphenyl-phosphino)ethane) in acetonitrile. The acetonitrile ligand is easily displaced by anionic ligands (X− = CN−, SCN−, SPh−, I−, Br−, CH3 − (as CH3MgI) and H− (as LiAlH4)) to give the complexes Fe(C5H5)(dppe)X.

Organic sulfonic acid stripping composition and method with nitrile and fluoride metal corrosion inhibitor system

Abstract: Improved organic stripping compositions useful in removing polymeric organic substances, such as photoresist, from metal substrates which comprise one or more organic sulfonic acids, one or more organic solvents and, optionally phenol. The inhibitors system includes 5 to 300 ppm by weight of fluoride per weight of composition and between about 0.01 and about 5 weight percent of a nitrile compound such as acetonitrile or malononitrile.

On the role of solvent in complexation equilibiria. II. The acid-base chemistry of some sulfhydryl and ammonium-containing amino acids in water—acetonitrile mixed solvents

Abstract: The macroscopic and microscopic acid-base chemistry of a series of sulfhydryl and ammonium-containing amino acids HS−R−NH3 [R=−CH2CH(COOH)−, cysteine (CYS); R=−C(CH3)2CH(COOH)−, penicillamine (PEN); R=−CH(COOH)CH2CH2CONHCH(−CH2)CONHCH2COOH, glutathione (GSH)] was characterized in water and its binary mixtures with acetonitrile (16.3, 34.2, and 53.9 mass % acetonitrile). Macroscopic acid dissociation constants were obtained by potentiometric titration using the glass-calomel electrode pair. Microscopic acid dissociation constants were calculated from ultraviolet absorption measurements at ca. 232 nm where the deprotonated sulfhydryl group absorbs. The macroscopic constants decrease uniformly as the solvent becomes enriched in acetonitrile. The microscopic constants, which characterize the relative concentrations of the two monoprotonated tautomers of the molecules (I and II)

Photo-induced cyclodimerization of electron-rich aromatic olefins in the presence of transition metal complexes

Abstract: Irradiation of an acetonitrile solution of phenyl vinyl ether in the presence of various metal complexes[Fe(III) and Mn(II) complexes] gave two cyclodimers. Similar irradiation of 1,1-dimethylindene and 1,1-diphenylethylene afforded the corresponding cyclodimers. In these photodimerization, the metal complexes with ligands such as 2,2′-bipyridine and 1,10-phenanthroline served as catalysts for electron-transfer reaction.

A quantitative study of the aluminium trichloride–acetonitrile system using X-ray crystallography, electrical conductivity, aluminium-27 and chlorine-35 nuclear magnetic resonance and Raman spectroscopy. The characterization of the pentakis(acetonitrile)chloroaluminium(III) ion in the solid state and in solution

Abstract: The compounds MCl3(M = Al, Ga, or In) yield electrically conducting solutions in acetonitrile. Boron trichloride gives non-conducting solutions and, contrary to previous work, this is interpreted as due to the presence of a molecular solute BCl3·MeCN. The electrical-conductivity data for AlCl3 in acetonitrile are discussed in detail and it is shown that from the results obtained it is not possible to differentiate between 1 : 1 and 1 : 2 electrolyte behaviour. Quantitative Raman and 27Al n.m.r. spectra demonstrate that ca. 70% of the aluminium in solutions of AlCl3 in acetonitrile is present in the form of [AlCl4]–. An X-ray single-crystal study of the solid adduct AlCl3·2MeCN crystallizing from such a solution shows that this adduct is correctly formulated as the auto-complex [AlCl(NCMe)5]2+2[AlCl4]–·MeCN. Further 27Al n.m.r. studies on solutions of Al[ClO4]3 in acetonitrile and of the solute AlCl[ClO4]2, in conjunction with the work on AlCl3 demonstrate that [AlCl(NCMe)5]2+ is the major cationic constituent of aluminium trichloride solutions in acetonitrile. The electrical-conductivity, Raman, and n.m.r. data on these solutions are all satisfactorily interpreted by the principal ionization scheme [AlCl(NCMe)5]2+2[AlCl4]– which is the formulation found for the crystal. The ionization of AlCl3, but the non-ionization of BCl3, in solution in acetonitrile is attributed principally to the ability of aluminium to adopt a co-ordination number of greater than four in ions such as [AlCl(NCMe)5]2+.

Photosensitized (electron transfer)[2e + 4e] cross-cycloaddition of alkylated olefins to phenylated olefins

Abstract: The [2e + 4e] cross-cycloaddition products are formed when an acetonitrile solution of 1,1-diphenyl-ethylene or 2-phenylnorbornene and isobutene or 2,3-dimethylbut-2-ene is irradiated in the presence of the photosensitizers (electron transfer) methyl p-cyanobenzoate or 1,4-dicyanobenzene.

A Study of the Ligand Exchange Reaction of Tetrakis(μ-trifluoroacetato)dimolybdenum(II) in Acetonitrile by 19F NMR Spectroscopy

Abstract: The dimeric molybdenum(II) complex, Mo2(CF3COO)4, forms Mo2(CF3COO)4·(CH3CN)2 in acetonitrile, where solvent molecules are attached to positions trans to the metal–metal bond (apical positions). The rate of ligand exchange between Mo2(CF3COO)4 ((1.31–8.28)×10−2 M; M=mol dm−3) and CF3COONa ((1.31–4.56)×10−1 M) was measured in acetonitrile by the use of 19F NMR spectroscopy. The rate is independent of the total concentration of CF3COONa and is linearly dependent on that of Mo2(CF3COO)4. The first-order rate constant (kex) is (1.1±0.2)×104 s−1 (25 °C), and the activation parameters are ΔH\eweq=(8.2±0.8) kcal mol−1 and ΔS\eweq=(−15±3) K−1 mol−1. Under the given conditions the complex seems to exist as Mo2(CF3COO)4·CF3COO−, where the underlined ligand occupies one of the apical positions, and the following mechanism is proposed (solvent molecules are omitted; asterisks indicate the molecule substituting for the coordinated ligand).Mo2(CF3COO)4·CF3COO−+*CF3COO−\oversetfast\ightleftarrowsMo2(CF3COO)4·*CF3COO−+CF...

The influence of intermolecular interactions on the polymerization, 3. Radical polymerization of 1-naphthyl methacrylate and 2-naphthyl methacrylate in acetone and acetonitrile†

Abstract: Polymerizations of 1-naphthyl methacrylate and 2-naphthyl methacrylate in acetone and in acetonitrile were carried out in the presence of 2,2′-azoisobutyronitrile at 55 and 60°C, respectively. The polymers precipitate during the polymerization. Poly(1-naphthyl methacrylate)s are partly soluble in common organic solvents. The polymerization medium does not influence noticeably the intrinsic viscosity of the resulting polymers. The tacticity was determined by 1H NMR analysis after conversion of the poly(naphthyl methacrylate)s into poly(methyl methacrylate)s. Poly(naphthyl methacrylate)s obtained in acetone and acetonitrile have a higher content of isotactic triads than those obtained in solvents with low dielectric constants. The observed results correlate with the changes in the 1H NMR spectra of the monomers depending on the dielectric constants of the solvents.

Phosphorylation of alcohols via anodic P-halogenation of dialkyl hydrogen phosphites.

Abstract: Trialkylphosphates, (RO)2P(O)OR', were prepared from dialkyl hydrogen phosphites, (RO)2PHO, and lithium chloride in R'OH by constant current electrolysis at a glassy carbon anode. Electrolysis at an anode having a larger area and at a lower current density gives better yields of the products. The electrolytic phosphorylation was also performed in acetone and in acetonitrile.