Showing papers on "Acetonitrile published in 1971"
TL;DR: In this paper, the importance of aprotic solvents in studies of the electrochemistry of organic compounds is discussed and a general mechanism for the oxidation and reduction of aromatic hydrocarbons and related substances is presented.
Abstract: The importance of aprotic solvents in studies of the electrochemistry of organic compounds is discussed and a general mechanism for the oxidation and reduction of aromatic hydrocarbons and related substances is presented. The effect of molecular structure on the electrochemical behaviour of organic compounds is illustrated by discussing the relationship between conformations of aryl-substituted anthracenes and dimethylaminophenyl-substituted ethylenes and their electrochemical properties. Techniques and methodology for electrochemical studies in nonaqueous solvents, including solution preparation and cell and electrode design, are briefly reviewed. INTRODUCTION The use of anhydrous aprotic solvents, such as N,N-dimethylformamide (DMF), acetonitrile (MeCN), and dichloromethane (CH2C12) as solvents for electrochemical studies started about fifteen years ago. Although many studies of the electrochemistry of organic compounds had been reported up to that time, most were carried out in partially or totally aqueous media. Indeed the second edition of Koithoff and Lingane's Polarography has a chapter of only six pages on nonaqueous solvents and in a discussion of the polarography of organic compounds characterizes most reductions of these as irreversible. Although the earliest applications of aprotic solvents were aimed at increasing the solubility of the organic compounds, pioneering studies by Wawzonek, Hoytink, Peover, and their co-workers2 demonstrated that the use of these solvents simplified the electrochemical behaviour of organic substances by removing or decreasing the extent of chemical reactions coupled to the electron transfer step. Under these conditions many organic electrode reactions are electrochemically reversible so that correlations of electrode potentials with spectroscopic and molecular orbital (MO) data became possible and a molecular basis of electrochemical reactions of aromatic hydrocarbons was established. Moreover, aprotic solvents provided reduction and oxidation limits beyond those obtainable in aqueous solutions, so that a wider range of potentials became available for electrochemical studies. 379
56 citations
TL;DR: In this paper, a remarkable solvent shift of the fluorescence has been found and explained in terms of the large solvation energy for the Rydberg state, which is attributed to the hydrogen-bond complex between the amines and water formed in the former's excited state.
52 citations
TL;DR: In this paper, small polar organic molecules are separated from one another on Sephadex LH-20 Modified Dextran either by sieving or by adsorption through π or hydrogen bonds.
47 citations
42 citations
Patent•
26 Apr 1971
TL;DR: In this article, a mixture containing malonic acid dinitrile is prepared by reacting acetonitrile and cyanogen chloride in the gaseous phase at temperatures from 740° to 780° C. This mixture can be purified by conversion of the principal impurities to easily separable compounds by Diels-Alder or selective hydrogenation reaction.
Abstract: Malonic acid dinitrile is prepared by reacting acetonitrile and cyanogen chloride in the gaseous phase at temperatures from 740° to 780° C. Temperatures from 750° to 760° C. with molar ratios of 1:1 to 1:5 of cyanogen chloride to acetonitrile are preferred. The crude mixture containing malonic acid dinitrile may be purified by conversion of the principal impurities to easily separable compounds by a Diels-Alder or selective hydrogenation reaction.
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TL;DR: In this paper, the temperature dependences of the EPR linewidths for vanadyl acetylacetonate, VO(acac)2, have been measured in ethanol, n−propanol, isopropanol, n‐butanol, t− butanol, trifluoroethanol, and trichloroethanol.
Abstract: The temperature dependences of the EPR linewidths for vanadyl acetylacetonate, VO(acac)2, have been measured in ethanol, n‐propanol, isopropanol, n‐butanol, t‐butanol, trifluoroethanol, and trichloroethanol. A similar study has been carried out on vandayl trifluoroacetylacetonate, VO(tfac)2, in methanol and the solvated vanadyl ion, VO2+, in water. The EPR linewidths have been measured at 25°C for VO2+ in dimethyl sulfoxide, trimethyl phosphate, acetonitrile, N ,N‐dimethylformamide, and methanol. The results are interpreted in terms of the theory proposed by Kivelson et al. to obtain rotational correlation times (τR) for the various systems. The results generally conform to the predictions of the modified Debye theory, in that τR and solvent visocity show the expected temperature dependence. Only VO(tfac)2 in methanol appears to be anomalous in this respect. A detailed analysis has shown that one of the parameters (γ) in Kivelson's expression for the linewidths is less sensitive to experimental error and ...
21 citations
TL;DR: In this paper, the thermal degradation of polyacrylonitrile (thickness ∼ 750 A ) has been studied in the temperature range 200-850°C by the micropyrolysis technique.
TL;DR: In this article, the SH stretching absorption spectra of some mercapto compounds in dilute carbon tetrachloride solutions and also in acetonitrile solutions have been measured at 20°C.
Abstract: The SH stretching absorption spectra of some mercapto compounds in dilute carbon tetrachloride solutions and also in acetonitrile solutions have been measured at 20°C. Alkyl mercaptans show absorption bands which are suggestive of the rotational isomerism around the C–S bond. The spectral data indicate that benzyl mercaptan, ω-ethoxyalkyl mercaptans, and ethyl α- and β-mercaptoalkanoates form practically no intramolecular hydrogen bond between the SH group and the hydrogen-acceptor group. In thiosalicylic acid and its ethyl ester, the hydrogen-bonding to the carbonyl group is partially possible even in acetonitrile. On the other hand, the corresponding free carboxylic acids are not hydrogen-bonded between the S atom and the carboxyl group.
TL;DR: In this paper, it was shown that In2(CO)8Br2 and acetonitrile give binuclear derivatives of the type [M(CO),3X(MeCN)]2, (X = Cl, Br, I).
TL;DR: In this paper, the infrared spectra of monoacetonitrile complexes of the formula CH3CNPtCl2Un have been shown to have the cis-configuration with the nitrile bonded through the lone pair electrons on nitrogen.
Abstract: Monoacetonitrile complexes of the formula CH3CNPtCl2Un have been prepared where Un is ethylene or carbon monoxide. The infrared spectra of these complexes showed them to have the cis-configuration with the nitrile bonded through the lone pair electrons on nitrogen. The coordinated nitrile fails to exchange with solvent nitrile even on long standing but the ethylene can be readily exchanged.
Patent•
18 May 1971
TL;DR: In this article, a radiation-sensitive catalyst precursor, a gelation inhibitor in the form of an nitrile compound such as acetonitrile present in small amounts up to several percent by weight, is presented.
Abstract: Polymerization of epoxide monomers and prepolymers, and of other materials polymerizable through the action of cationic catalysts, is controlled in compositions essentially free of volatile solvents by providing in such compositions, in association with a radiation-sensitive catalyst precursor, a gelation inhibitor in the form of an nitrile compound such as acetonitrile present in small amounts up to several percent by weight.
TL;DR: In this article, the dimer radical anion of acetonitrile has been identified in the upper crystalline phase after γ irradiation at 77°K, whereas the monomer radical anions is produced in the lower crystalline phases under the same irradiation conditions ESR studies on these species in aligned and polycrystalline samples are summarized.
TL;DR: In this article, a good Hammett correlation was found for the chlorine isotopic exchange reactions in acetonitrile between tetraethylammonium chloride and three types of substituted methyl chlorides.
Abstract: The SN2 reactions having a symmetrical transition state were studied in a dipolar aprotic solvent. A good Hammett correlation was found for the chlorine isotopic exchange reactions in acetonitrile between tetraethylammonium chloride and three types of substituted methyl chlorides, 2-arylethyl chlorides, chloromethyl aryl ethers, and chloromethyl aryl sulfides. The reaction constant was positive for 2-arylethyl chlorides and negative for the methyl chlorides possessing an α-heteroatom. The presence of oxygen and sulfur atom on the α-position to the reaction center resulted in a rate enhancement of about 105 times and 103 times, respectively. Features of the transition states of these SN2 reactions are discussed.
TL;DR: In this article, the diazo coupling reaction of 4-toluenediazonium salts with N, N-dimethylaniline in tetramethylene sulfone, acetonitrile, water, and nitromethane at 30°C was found.
Abstract: The rates of the diazo coupling reaction of 4-toluenediazonium salts with N, N-dimethylaniline in tetramethylene sulfone, acetonitrile, water, and nitromethane at 30°C are the same within a factor of 5. No significant influence of ‘gegenions’ (HSO or BF) was found. The results are explained by postulating little solvent reorganisation in the transition state. They are discussed comparatively with solvent effects in other electrophilic aromatic substitutions, particularly with regard to the reactions of nitronium salts.
TL;DR: In this article, the effect of the solvent and catalysts on the reaction of chlorosulphonyl azide with several arylamines has been studied, and the synthetic utility of the procedure as a source of arylsulphamoyl azides evaluated.
Abstract: Chlorosulphonyl azide can be made safely and efficiently by the reaction of sodium azide with sulphuryl chloride in acetonitrile. The effect of the solvent and catalysts on the reaction is discussed. The reaction of solutions of chlorosulphonyl azide with several arylamines has been studied, and the synthetic utility of the procedure as a source of arylsulphamoyl azides evaluated.
TL;DR: In this article, the exchange reaction Fe(CH3CN)62+ ╲ CH3CN in CH 3CN solvent is reported, and the value for k 1 (25°C) from the rate law R = 6k1[Fe(CH 3CN) 62+] is (5.5 ± 0.8) × 105 s-1, ΔH 1, ΔH 2, ΔS 1, ΔS 0.7, ΔA/h = 5.0 × 106 Hz.
Abstract: A 14N n.m.r. study of the exchange reaction Fe(CH3CN)62+ ╲ CH3CN in CH3CN solvent is reported. The value for k 1 (25°C) from the rate law R = 6k1[Fe(CH3CN)62+] is (5.5 ± 0.8) × 105 s-1, ΔH‡ = 9.7 ± 0.7 kcal mol-1, ΔS‡ = 0.3 ± 2.2 cal mol-1 K-1, and A/h = 5.0 × 106 Hz. These data are compared with those of related systems.
TL;DR: In this paper, the authors have shown that halogenocyclopentadienyldiquinolin-8-olatometal(IV), C5H5MXox2(M = Ti, Zr; X = Cl, Br and M = Hf, X= Cl.
Abstract: The complexes halogenocyclopentadienyldiquinolin-8-olatometal(IV), C5H5MXox2(M = Ti, Zr; X = Cl, Br and M = Hf, X = Cl), have been prepared by the direct interaction of quinolin-8-ol (oxH) and dihalogenobis(cyclopentadienyl)metal(IV)[(C5H5)2MX2] in acetonitrile solution at room temperature. Reactions of these complexes with ethanol, with ethoxide, and with hydrogen halides have been studied. I.r. (4000–80 cm.–1), n.m.r., and mass spectra are reported.
TL;DR: In this paper, the equilibrium constants for the coordination of iodide ions by the square planar cobalt(III) dimethyloxime were determined in the following solvents: dimethyl sulphoxide, dimethylformamide, methanol, ethanol, water, acetonitrile, ethyl acetate and acetone.
TL;DR: The relative stability constants of the adducts of MCl5 (M Nb, Ta) with acetonitrile, halogenoacetonitriles, pivalonitrile and acrylonitrile were determined in dilute solutions by NMR methods as mentioned in this paper.
Abstract: The relative stability constants of the adducts of MCl5 (M Nb, Ta) with acetonitrile, halogenoacetonitriles, pivalonitrile, acrylonitrile and benzonitriles are determined in dilute solutions by NMR. methods. The stability of the adducts is controlled by inductive factors. Chemical shifts and analysis of the new compounds are reported.