Equilibrium constants for σ-complex formation between cyanide ion and 1,3,5-trinitrobenzene in alcoholic solvents

1969 ◽  
Vol 47 (22) ◽  
pp. 4129-4133 ◽  
Author(s):  
E. Buncel ◽  
A. R. Norris ◽  
W. Proudlock ◽  
K. E. Russell
Keyword(s):  
Complex Formation ◽  
Equilibrium Constant ◽  
Equilibrium Constants ◽  
Primary Factor ◽  
Aprotic Solvents ◽  
Kcal Mole ◽  
Cyanide Ion ◽  
Direct Calorimetry ◽  
Entropy Changes ◽  
Enthalpy Changes

Equilibrium constants have been determined spectrophotometrically for the reaction of cyanide ion with 1,3,5-trinitrobenzene in methanol, ethanol, n- and iso-propanol, and n- and t-butanol. The equilibrium constants at 25 °C vary from 39 1 mole−1 for the reaction in methanol to 500 000 1 mole−1 with t-butanol as solvent. Enthalpy changes, determined from equilibrium measurements and by direct calorimetry, vary from 0 to −15.5 kcal mole−1 and the calculated entropy changes decrease from 7 to −26 cal deg−1mole−1 as the solvent is changed from methanol to t-butanol. These results are interpreted on the basis that desolvation of the small cyanide ion is the primary factor influencing enthalpies and entropies of reaction. The equilibrium constant in t-butanol is comparable to the values observed for aprotic solvents such as chloroform and acetone.

Meisenheimer Complex Formation Between 1,3,5-Trinitrobenzene and Hydroxide Ion. Equilibrium Constants for the Dimethylformamide–Water Solvent System

1972 ◽  
Vol 50 (11) ◽  
pp. 1729-1733 ◽  
Author(s):  
E. A. Symons ◽  
E. Buncel
Keyword(s):  
Complex Formation ◽  
Aqueous Medium ◽  
Equilibrium Constant ◽  
Equilibrium Constants ◽  
Solvent System ◽  
Medium Composition ◽  
Hydroxide Ion ◽  
Spectrophotometric Methods ◽  
Water Solvent ◽  
Sigma Complex

Sigma-complex formation between 1,3,5-trinitrobenzene (TNB) and hydroxide ion has been studied quantitatively as a function of medium composition for part of the dimethylformamide (DMF)–water solvent system by spectrophotometric methods. Only a 1:1 complex is detected under the conditions of measurement, with [TNB] ≥ [OH−]. The equilibrium constant (Keq) for complex formation in 22 mol % DMF has the value 3 × 10−3 l mol−1, compared with 3 l mol−1 in purely aqueous medium. Further increases in Kcq occur as the DMF content of the medium is raised; in 50 mol % DMF Keq ≈ 105, but reliable Keq values could not be obtained in this region of medium composition. The increase in Keq with increasing DMF content is interpreted largely on the basis of hydroxide ion desolvation.

Factor analysis as a complement to band resolution techniques. VI. Complex formation between pentachlorophenol-OD and acetone

1979 ◽  
Vol 57 (20) ◽  
pp. 2707-2713 ◽  
Author(s):  
J. Korppi-Tommola ◽  
H. F. Shurvell
Keyword(s):  
Principal Component Analysis ◽  
Factor Analysis ◽  
Complex Formation ◽  
Equilibrium Constant ◽  
Isotope Effect ◽  
Infrared Spectra ◽  
Equilibrium Constants ◽  
Principal Component ◽  
Proton Donor ◽  
Good Agreement

Complex formation between pentachlorophenol-OD (PCP-OD) and acetone and acetone-d6 in CCl4 solution has been studied. Digitized infrared spectra in the O—D stretching region ν(OD) of PCP-OD and the C—O stretching region ν(CO) of acetone have been recorded from solutions of various concentrations. The present results are compared with previous work on complex formation between PCP and the same acceptor molecules. In the ν(OD) region, factor analysis (principal component analysis) and a concentration study of the areas of the resolved band components suggest that two (1:1) complexes occur in solution. The equilibrium constant obtained for one of the complexes shows an isotope effect due to deuteration of the proton donor. In the ν(CO) region, only one band due to complexed species was resolved. Equilibrium constants calculated using the results from the ν(OD) and ν(CO) regions are in good agreement with each other.

Mass spectrometric study of the thermal decomposition of dimanganese decacarbonyl and dicobalt octacarbonyl

1970 ◽  
Vol 48 (4) ◽  
pp. 593-597 ◽  
Author(s):  
D. R. Bidinosti ◽  
N. S. McIntyre
Keyword(s):  
Equilibrium Constants ◽  
Mass Spectrometric Study ◽  
Molecular Beams ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Kcal Mole ◽  
Flow Reactors ◽  
Dicobalt Octacarbonyl ◽  
Enthalpy Changes ◽  
Dimanganese Decacarbonyl

The free radicals •Mn(CO)5 and •Co(CO)4 have been produced by the pyrolysis of Mn2(CO)10 and Co2(CO)8 in graphite flow reactors. The effusing molecular beams from these reactors were analyzed mass spectrometrically. Evidence is presented for the following equilibria[Formula: see text]From the temperature dependence of the equilibrium constants, enthalpy changes of 24.9 ± 2 and 14.5 ± 2 kcal/mole, respectively, have been obtained. These enthalpy changes give D(Mn—Mn) = 21 ± 3 kcal/mole and D(Co—Co) = 13 ± 3 kcal/mole, which substantiate the earlier literature values based on electron impact measurements.

Complex Formation by Inorganic Ions

1959 ◽  
Vol 12 (3) ◽  
pp. 356 ◽  
Author(s):  
JF Duncan
Keyword(s):  
Free Energy ◽  
Complex Formation ◽  
Structural Changes ◽  
Inorganic Ions ◽  
Ionic Radii ◽  
Entropy Changes ◽  
Enthalpy Changes ◽  
Free Energy Of Formation ◽  
Formation Of Complexes ◽  
Energy Of Formation

The formation of complexes MN(m-n)+ from Mm+ and Nn- in aqueous solution is discussed in terms of simple electrostatic forces. The entropy changes are shown to depend on similar factors to those which determine the enthalpy changes. In cases where the entropy changes for a series of complexes with different Mm+ and constant Nn- are either linearly related to the enthalpy changes, or can be neglected, the free energy of formation of the complex from the ions may be predicted in unknown cases. The relations commonly used for plotting the free energy of formation of the complex from the ions as functions of a number of physicochemical quantities are shown to arise fortuitously as a consequence of the restricted range of ionic radii provided by Nature. In some cases deviations from expected behaviour show the influence of structural changes on the ease of complex formation.

Kinetics and mechanisms of the reaction of 2,4,6-trinitrocumene and 2,4,6-trinitroethylbenzene with 1,1,3,3-tetramethylguanidine in N,N-dimethylformamide solvent

1987 ◽  
Vol 65 (5) ◽  
pp. 1007-1011 ◽  
Author(s):  
Mihir K. Biswas ◽  
Arnold Jarczewski ◽  
Kenneth T. Leffek
Keyword(s):  
Carbon Atom ◽  
Complex Formation ◽  
Proton Transfer ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Reaction Parameters ◽  
Deuterium Isotope Effect ◽  
Constant Rate

The reaction of tetramethylguanidine (TMG) with trinitrocumene (TNC) and trinitroethylbenzene (TNEB) in dimethylformamide solvent has been studied with respect to products and kinetics. For TNC only σ-complex formation with the benzene ring was observed, for which the equilibrium constant, rate constants, and activation parameters were measured. For TNEB, both σ-complex formation and proton transfer from the σ-carbon atom of the ethyl group were observed. The equilibrium constants, rate constants, and activation parameters were separately determined for each reaction and a primary deuterium isotope effect, kH/kD = 13.6 (at 20 °C), was found for the proton transfer. The reaction parameters are compared to those for proton transfer from TNT to tetramethylguanidine in DMF solvent.

The Strecker reaction — an examination in terms of no-barrier theory

2008 ◽  
Vol 86 (4) ◽  
pp. 285-289 ◽  
Author(s):  
J Peter Guthrie ◽  
Goonisetty Bhaskar
Keyword(s):  
Aqueous Solution ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Reaction Rate ◽  
Equilibrium Constants ◽  
Reaction Rate Constant ◽  
Cyanide Ion ◽  
Strecker Reaction ◽  
Rate Determining Step ◽  
Iminium Ion

For those examples of the Strecker reaction where information about both rate and equilibrium is available, we have been able to calculate rate constants for the addition of cyanide ion to the iminium ion by the no-barrier theory (NBT) approach. Both experimental and calculated values are for reaction in aqueous solution. Only for the reactions of benzaldehyde with benzyl or allyl amines and HCN are the equilibrium constants and rate constants for the final, rate-determining, step directly available from the literature. For the reactions of acetone with ammonia, methylamine, or dimethylamine and HCN rate constants for the retro-Strecker cleavage and the equilibrium constants for the overall Strecker reaction have been reported. These equilibrium constants, combined with equilibrium constants for iminium ion formation, which can be extracted from information in the literature, allow calculation of the equilibrium constants for the final step of these Strecker reactions. No-barrier theory has already been applied to carbonyl additions, including cyanohydrin formation; this report provides further evidence for the generality of this approach for calculating rate constants without using any kinetic information.Key words: Strecker reaction, rate constant, equilibrium constant, no-barrier theory, computation.

Oxidation of (1-hydroxybenzyl)ferrocene and its derivatives substituted in phenyl ring with bis(triphenylsilyl) chromate

1982 ◽  
Vol 47 (12) ◽  
pp. 3375-3380 ◽  
Author(s):  
Jaroslav Holeček ◽  
Karel Handlíř ◽  
Milan Nádvorník ◽  
Milan Vlček
Keyword(s):  
Linear Dependence ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Phenyl Ring ◽  
Equilibrium Constants ◽  
Aprotic Solvents ◽  
Protonation Equilibrium ◽  
Oxidation Of Alcohols ◽  
Hammett Σ Constants ◽  
Sulphuric Acid Medium

Kinetics have been studied of oxidation of (1-hydroxybenzyl)ferrocenes substituted in phenyl ring with bis(triphenylsilyl) chromate in benzene solutions as well as protonation of these alcohols in sulphuric acid medium. Logarithms of the oxidation rate constants (kobs, 20-40 °C) and those of the protonation equilibrium constants (KR+, 25 °C) show linear dependence on the Hammett σ constants, the ρ constant values being -0.86 to -0.40 and -2.50, respectively. These negative values suggest that the both processes are influenced by the same effects and confirm the mechanism proposed earlier for oxidation of alcohols with ferrocenyl substituent by action of bis(triphenylsilyl) chromate in aprotic solvents.

ChemInform Abstract: REACTION OF 4-NITROBENZIL WITH CYANIDE ION IN APROTIC SOLVENTS

1974 ◽  
Vol 5 (41) ◽  
Author(s):  
W. C. REARDON ◽  
J. E. WILSON ◽  
J. C. TRISLER
Keyword(s):  
Aprotic Solvents ◽  
Cyanide Ion

Calorimetric determination of equilibrium constants and enthalpy changes in solution

1969 ◽  
pp. 861 ◽  
Author(s):  
James J. Christensen ◽  
J. Howard Rytting ◽  
Reed M. Izatt
Keyword(s):  
Equilibrium Constants ◽  
Enthalpy Changes ◽  
Calorimetric Determination

Ionic dissociation in complexes of iodine with triphenylarsine and triphenylstibine

1991 ◽  
Vol 69 (4) ◽  
pp. 606-610 ◽  
Author(s):  
Ying Ru Zhang ◽  
Ira Solomon ◽  
Seymour Aronson
Keyword(s):  
Complex Formation ◽  
Chemical Nature ◽  
Equilibrium Constants ◽  
Electrochemical Technique ◽  
High Iodine ◽  
Ionic Complex ◽  
Ionization Mechanisms ◽  
Iodine Complex ◽  
Ionic Dissociation ◽  
Iodine Complexes

An electrochemical technique has been employed to study the ionization of the iodine complexes of (C6H5)3As, (C6H5)3Sb, and pyridine. Several different ionization mechanisms are proposed depending on the chemical nature and concentration of the reactants. A new ionic complex, (C6H5)3MI22+ is postulated for the interaction of iodine with (C6H5)3As and (C6H5)3Sb at high iodine concentrations. Equilibrium constants have been calculated from the emf data for the various ionization steps. Key words: triphenylarsine, triphenylstibine, iodine, complex formation, ionization.

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