The Addition of Nitriles to Tetramesityldisilene: A Comparison of the Reactivity between Surface and Molecular Disilenes

The addition of acetonitrile, propionitrile, and phenylacetonitrile to tetramesityldisilene (Mes₂Si?SiMes₂) was examined. In general, 1,2,3‐azadisiletines and the tautomeric enamines were formed, although a ketenimine was formed as the major product in the addition of phenylacetonitrile to the disilene. In the presence of LiCl, the mode of addition changed for both acetonitrile and propionitrile: insertion into the α‐CH bond of acetonitrile and/or formation of the formal HCN adduct was observed. Preliminary investigations of the reactivity of the nitrile adducts are also reported. A comparison between the reactivity of nitriles with Mes₂Si?SiMes₂ and the Si(100)‐2×1 surface was made both in terms of the types of adducts formed and their reactivity. Some insights into the surface chemistry are offered.     

The formation of acrylonitrile over solid base catalysts

The reaction of methanol and acetonitrile to form acrylonitrile has been studied over solid base catalysts derived from MgO. High surface area MgO produced the best yields of acrylonitrile and propionitrile, but higher specific activity was achieved by impregnating the MgO support with chromium oxide. This revised version was published online in June 2006 with corrections to the Cover Date.     

A novel three-component reaction of N-fluoropyridinium salts: a facile approach to imidazo[1,2-a]pyridines

The reaction of N-fluoropyridinium triflate with isonitriles in acetonitrile and propionitrile in the presence of NaBH(OAc)₃ led to the formation of the corresponding imidazo[1,2-a]pyridines in 44-73% yields. The proposed reaction mechanism involves the intermediate formation of a highly reactive carbene species and apparent reduction of the pyridinium intermediate with NaBH(OAc)₃ to yield the targeted heterocycles.     

TPD study on Cr/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol

Summary The TPD technique was used to investigate the desorption behaviour of methanol and acetonitrile on the Cr/MgO catalyst prepared by an impregnation method. Catalytic properties of the Cr/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol were also studied. The catalytic activities are related to the dissociative desorption temperature of CH₃OH or CH₃CN on the catalysts.     

Soft-SAFT modeling of vapor–liquid equilibria of nitriles and their mixtures

Nitriles are strong polar compounds showing a highly non-ideal behavior, which makes them challenging systems from a modeling point of view; in spite of this, accurate predictions for the vapor–liquid equilibria of these systems are needed, as some of them, like acetonitrile (CH₃CN) and propionitrile (C₂H₅CN), play an important role as organic solvents in several industrial processes. This work deals with the calculation of the vapor–liquid equilibria (VLE) of nitriles and their mixtures by using the crossover soft-SAFT Equation of State (EoS). Both polar and associating interactions are taken into account in a single association term in the crossover soft-SAFT equation, while the crossover term allows for accurate calculations both far from and close to the critical point. Molecular parameters for acetonitrile, propionitrile and n-butyronitrile (C₃H₇CN) are regressed from experimental data. Their transferability is tested by the calculation of the VLE of heavier linear nitriles, namely, valeronitrile (C₄H₉CN) and hexanonitrile (C₅H₁₁CN), not included in the fitting procedure. Crossover soft-SAFT results are in excellent agreement with experimental data for the whole range of thermodynamic conditions investigated, proving the robustness of the approach. Parameters transferability has also been used to describe the isomers n-butyronitrile and i-butyronitrile. Finally, the nitriles soft-SAFT model is further tested in VLE calculation of mixtures with benzene, carbon tetrachloride and carbon dioxide, which proved to be satisfactory as well.     

Dielectric relaxation of acetonitrile and propionitrile in benzene and carbon tetrachloride solutions

Dielectric permittivities and losses have been measured at wavelengths of 3 × 10⁴, 10.0, 3.23, 1.95, 1.25, and 0.40 cm at three temperatures 24, 40, and 60°C for benzene and carbon tetrachloride solutions of acetonitrile and propionitrile at a fixed concentration of 25 mole per cent. The far-infrared spectra in the range 10–150 cm⁻¹ of dilute solutions of both the nitriles have been investigated. A single relaxation time has been obtained for acetonitrile at each temperature whereas the dielectric data of propionitrile indicate the presence of multiple dispersion regions at microwave frequencies.     

Study on Fe/MgO catalysts for acrylonitrile synthesis from acetonitrile and methanol

A series of Fe/MgO catalysts were prepared and used for acrylonitrile synthesis from acetonitrile and methanol. The catalysts were characterized by means of XRD, CO₂-TPD and CH₃OH-TPD. The Fe/MgO catalysts exhibit high catalytic activity and selectivity to acrylonitrile, which is due to the combined effect of Fe and MgO. This revised version was published online in August 2006 with corrections to the Cover Date.     

Viscosity of Alkali–Metal Iodides in Propionitrile and Acetonitrile Mixtures at 25°C

The relative viscosities were measured for LiI, NaI, KI, RbI, Bu₄NBPh₄, and Bu₄NI in a wide range of mixtures of propionitrile and acetonitrile at 25°C to obtain Jones–Dole Bcoefficients. The Bcoefficients of these electrolytes were large and positive. The values of ionic Bcoefficients allow us to assess the behavior of ions in the solvent mixtures.     

Synthesis of methyl acetoacetate from acetone and dimethyl carbonate with alkali-promoted MgO catalysts

The synthesis of methyl acetoacetate (MAA) by methoxycarbonylation of acetone with dimethyl carbonate (DMC) was carried out in the presence of MgO and alkali-promoted MgO catalysts. From among Li, Na, K, and Cs, potassium was found to be the most effective promoter to improve the activity of MgO. The effect of K/MgO with variable content of K was also investigated, and the individual catalysts were characterised by the XRD, BET, SEM, CO₂-TPD, and in situ CO₂ IR techniques. The results showed that the addition of a small amount of K (1.97 mass %) could promote MAA formation, but a higher K loading caused a decrease in the yield of MAA, which might result from particle agglomeration and the presence of stable potassium carbonates. In situ FTIR experiments of co-adsorbed reactants indicated that the reaction probably proceeded via abstraction of H_α from acetone by base sites.     

Mechanism of [M+H]+ formation in atmospheric pressure photoionization mass spectrometry: Identification of propionitrile in acetonitrile with high mass accuracy measurement and tandem mass spectrometry and evidence for its involvement in the protonation phenomenon

The role of propionitrile in the production of [M+H]+ under atmospheric pressure photoionization (APPI) was investigated. In dopant-assisted APPI using acetone and anisole, protonated acetone and anisole radical cations were the most prominent ions observed. In dopant-free or direct APPI in acetonitrile, however, a major ion in acetonitrile was detected and identified as propionitrile, using high accuracy mass measurement and collision induced dissociation studies. Vaporizing ca. 10(-5) M althiazide and bendroflumethazide under direct APPI in acetonitrile produced their corresponding protonated species [M+H]+. In addition to protonated acetonitrile, its dimers, and acetonitrile/water clusters, protonated propionitrile, propionitrile dimer, and propionitrile/water clusters were also observed. The role of propionitrile, an impurity in acetonitrile and/or a possible product of ion-molecule reaction, in the production of [M+H]+ of althiazide and bendroflumethazide was further investigated in the absence of dopant using propionitrile-d5. The formation of [M+D]+ species was observed, suggesting a possible role of propionitrile in the protonation process. Additionally, an increase in the [M+H]+ signal of althiazide and bendroflumethazide was observed as a function of propionitrile concentration in acetonitrile. Theoretical data from the literature supported the assumption that one possible mechanism, among others, for the formation of [M+H]+ could be attributed to photo-initiated isomerization of propionitrile. The most stable isomers of propionitrile, based on their calculated ionization energy (IE) and relative energy (DeltaE), were assumed to undergo proton transfer to the analytes, and mechanisms were proposed.     

Selective Separation of Aliphatic Nitriles by Employing a Two‐Dimensional Interdigitated Coordination Polymer

A room‐temperature slow diffusion reaction of the metal nitrates [M=Zn^II and Co^II] with 5‐azido isophthalic acid (AIPA) and 1,4‐bis(4‐pyridyl)‐2,3‐diaza‐1,3‐butadiene (BPDB) resulted in a new two‐dimensional interdigitated coordination polymer, [M(C₈H₃N₃O₄)(C₁₂H₁₀N₄)] ⋅ DMF [DMF=dimethyl formamide (C₃H₇NO)]. The non‐bonded DMF molecules were found to exchange through a single‐crystal to single‐crystal (SCSC) fashion with many aliphatic nitrile compounds. More importantly, the present compound, I⋅DMF (Zn) appears to absorb cis ‐crotononitrile selectively from the cis /trans mixture as well as a mixture containing the structural isomer (allylnitrile). It also preferentially absorbs propionitrile from an equimolar mixture of acetonitrile, propionitrile, and butyronitrile (1:2:1). The cobalt compound exhibits anti‐ferromagnetic behavior.     

Synthesis,structure, and catalase-like activity of a novel manganese(II) complex: Dichloro[1,3-bis(2′-benzimidazolylimino)isoindoline]manganese(II)

Reaction of the ligand 1,3-bis(2′-benzimidazolylimino)isoindoline with manganese(II) chloride in acetonitrile/methanol leads to the novel mononuclear manganese(II) complex 1,3-bis(2′-benzimidazolylimino)isoindolinedichloro manganese(II) [Mn(bimindH)Cl₂], which has been characterized by various techniques such as elemental analysis, IR, UV–Vis, ESR spectroscopy, and X-ray diffraction. The ligand bimindH was synthesized by fusing phthalonitrile and 2-aminobenzimidazole at high temperature until ammonia evolution ceased. The catalase-like activity of the complex was tested in propionitrile, and it proved to be active in the dihydrogen peroxide dismutation. Based on kinetic studies the reaction is first-order in relation to both the complex and hydrogen peroxide.     

Compatibility Range in Polymer Mixtures. An approach using analogue calorimetry and group contribution procedures

The mixing enthalpies of blends of polymethylmethacrylate (PMMA) with poly(styrene-co-acrylonitrile) (SAN) were investigated by analogue calorimetry through the determination of the excess enthalpies of pseudobinary model mixtures corresponding to the addition of methyl-i-butyrate to a binary mixture of acetonitrile or propionitrile plus toluene or ethylbenzene. A group contribution procedure, based on UNIQUAC equation, was also devised and the polymeric mixing enthalpies were calculated from properly defined group contributions. Enthalpies for polymeric interactions were introduced into the Flory-Huggins equation and the miscibility window of PMMA-SAN mixtures was calculated. The results show a qualitative agreement with the experimental miscibility data and indicate that both the analogue calorimetry and the group contribution procedures yield correct results when acetonitrile, and not propionitrile, is chosen as the model for the polyacrylonitrile repeat unit of the copolymer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of nitriles from acetonitrile and methanol in the presence of oxide catalysts

The promoting effect of potassium included in Cr/MgO catalysts for the synthesis of nitriles from acetonitrile and methanol was found. The 5% Cr-0.5% K/MgO catalyst exhibited the highest activity in the synthesis of nitriles. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1540–1542, August, 1997.     

共轭高分子的研究——Ⅶ.脂肪腈类的聚合

<正> 聚腈作为新的一类共轭高分子而引起注意。本文在前报的基础上进一步选择了一系列脂肪腈(乙腈、丙腈、戊腈、庚腈和苯乙腈),系统地研究它们在络合能力较强的付氏试剂(BF_3和TiCl_4等)作用下的聚合反应与机理,同时测定了各聚腈的物理性能。 1.腈的络合聚合 腈类与付氏试剂可形成定组成的络合物结晶:     

Selective mono-C-methylations of arylacetonitriles and arylacetates with dimethylcarbonate: a mechanistic investigation

The very high mono-C-methylation selectivity (>99%) of arylacetic acid derivatives (ArCH2X; X = CN, CO2Me) with dimethyl carbonate (DMC) is due to a mechanism that involves consecutive methoxycarbonylation, methylation, and demethoxycarbonylation steps. Important aspects of this mechanism are clarified herein by a kinetic investigation. In the case of arylacetonitriles, at 140 degrees C, the comparison of the rate constants of model reactions involving 2-phenyl propionitrile, phenylacetonitrile, 2-methoxycarbonylphenylacetonitrile, and 2-methyl-2-methoxy carbonylphenyl acetonitrile (compounds 1a-4a, respectively) with DMC indicates that the methylation process is the fastest and the irreversible step, which drives the overall reaction to completion. The situation is reversed for arylacetic esters, where the methylation is more difficult than the demethoxycarbonylation reaction; therefore, a higher reaction temperature is required.     

The Photochemistry of Diazomethane-Acetonitrile Mixtures. The Reaction of Methylene with Acetonitrile

The photochemistry of diazomethane-acetonitrile gaseous mixtures has been studied. Propionitrile was produced by the reaction of methylene radicals with acetonitrile. At lower pressures the product propionitrile decomposes and the measured decomposition rates are 1.14×10⁹ sec^?1 and 2.70×10⁸ sec^?1 at 3660 and 4358 Å, respectively.     

Microgram detection of nitriles using resin beads

Summary Some nitriles (benzonitrile, acetonitrile, propionitrile, butyronitrile, and cyanoacetic acid) can be detected by means of ion exchange resin beads after hydrolysis with dil. H₂SO₄ to produce ammonium ions. The ammonium ions are retained by the resin and then detected by the indophenol blue color using sodium hypochlorite and phenol. The new method is more sensitive and selective than the existing methods.

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Zusammenfassung Einige Nitrile (Benzo-, Aceto-, Propio-, Butyronitril und Cyanessig-säure) lassen sich mit Hilfe von Austauscherharz-Perlen nach Hydrolyse mit verd. Schwefelsäure zur Freisetzung von Ammoniumionen nachweisen. Diese werden an dem Harz festgehalten und dann durch Bildung von Indophenolblau mit Hilfe von Hypochlorit und Phenol nachgewiesen. Diese Methode ist empfindlicher und selektiver als bisher existierende Verfahren.

     

Adsorption of succinonitrile at the mercury-aqueous solution interface: Unusual role of a fixed dipole in the adsorbed molecule

The adsorption of succinonitrile (SN) on a polarized Hg electrode has been studied from 0.25 M NaF aqueous solutions by means of both capacity and electrocapillary curves. Adsorption isotherms have been found to be strictly congruent with respect to both charge and potential. The charge of maximum adsorption is at ?4.6 μC cm^?2 and ΔG_ads⁰, the free energy of adsorption at zero coverage, decreases more rapidly as the charge is made positive with respect to O_max^M than on the other side. The adsorption obeys a Frumkin isotherm with a=?1.87 corresponding to attraction and saturation concentration of 4.8×10^?10 mol cm^?2 corresponding to an area per molecule of about 34.5 Ų. Experimental results suggest that SN adsorbs flat on the surface but, unlike acetonitrile and propionitrile, the CN groups are slightly turned towards the solution. This is responsible for the absence of electronic interaction of the CN groups with the metal at positive charges, which is apparent with the other two nitriles. Implications of the particular structure of the adsorbed molecule on the other adsorption parameters are discussed in detail.     

The Stereospecific Substitution of the Xenon Atom in cis‐Perfluoroalk‐1‐enylxenon(II) Salts by Hydrogen,Halogens, and the Phenyl Group

The substitution of the xenon atom in reactions of [cis‐C_nF_2n+1CF=CFXe][Y] salts with benzene, iodide, and bromide anions in propionitrile solution by the phenyl group, or iodine, and bromine atoms, respectively, occurred stereospecifically. When a propionitrile solution of [cis‐C₂F₅CF=CFXe][AsF₆] was kept at —40 °C without an additional reactant, the fluoroalkene cis‐C₂F₅CF=CFH was the only isomer obtained.