Solvolysis Of Trans Research Articles

Kinetic Studies of Solute-Solvent Interactions in the Solvolysis of Trans- [Co (4-Teri-Butylpyri Dine)4C12)Clo4 in Organic-Aqueous Mixtures

The kinetics of solvolysis of trans-[Co(L)4 C12] C1O4 where (L-4-tert-butylpyr-idine) were followed spectrophotometrically in water-dioxane and water-dimethylsulfoxide media (0-60% v/v) over the temperature range (40-55°C). Non-linear plots were found for the logarithm of the rate constant of the first-order reaction versus the reciprocal of the relative permittivity, 3**r, of the mixed solvent. This behaviour can be attributed to the differential solvation of the initial and transition states of the complex. The enthalpies and entropies of activation showed compensating extrema with the mole fraction of solvent, leading to a small variation in the free energy of activation. By applying a free-energy cycle, it was found that the difference between the values of the free energy of transfer of the cations in the transition and initial states were negative, indicating that the cation in the transition state is more solvated than that in the initial state.

Kinetic and Thermodynamic Studies of Uncatalysed and Hg(Ii)-Catalysed Solvolysis of a Chlorocobalt(Iii) Complex in Binary Aqueous Media

The kinetics of solvolysis of trans — [Co(py)4Cl2]ClO4 have been investigated in aquo-organic solvent media such as water + ethanol (0-60% v/v) and water -+ urea (0-40% w/w) in the temperature range 40-60°C. The first-order rate constant varies nonlinearly with the reciprocal of the relative permittivity ∊r. The solvolysis of these types of complex involves a rate-determining dissociative step corresponding closely to 100% separation of Co3+ … Cl in the transition state. The Gibbs energy cycle relating the Gibbs energy of activation in water and in the mixtures to the Gibbs energies of transfer of individual ionic species between water and the mixtures Δ G°t(Cl) can be applied. Moreover, more than one extrema in the enthalpies and entropies of activation are found with both binary aqueous solvent mixtures. The solvolysis of trans — [Co(py)4Cl2]ClO4 has also been studied in the presence of Hg(II) and the ionic strength dependence of the reaction rate has been analysed.

Kinetics and thermodynamics of solvolysis of a cationic and an anionic chlorocobalt (III) complex in water-ethanol mixtures

Rate constants and derived thermodynamic activation parameters are reported for solvolysis of trans-[Co(3Mepy)4Cl2]+ and [Co(CN)5Cl]3− ions in water-rich mixtures of water with ethanol at various temperatures and are analyzed by initial- and transition-state contributions. The variation of enthalpies and entropies of activation with solvent composition show extrema in composition ranges where the physical properties of the mixtures, influenced by changes in solvent structures, also show extrema. From the application of a free-energy cycle to the process of the initial state going to the transition state, it is concluded for the solvolysis of both complexes that the Co(III) species in the transition state is more stable in water + ethanol mixtures than in the initial state.

The influence of solvent structure on the solvolysis oftrans-dichlorotetra (4-ethylpyridine) cobalt(III) perchlorate

The solvolysis oftrans-[Co(4-Etpy)4Cl2]ClO4, was followed spectrophotometrically in water/isopropanol at different temperatures. The activation energy varied nonlinearly with the mole fraction of the co-solvent,χ2. The plot of logk versus D s −1 was also non-linear. These features were attributed to the differential solvation of the initial and transition states. On plotting ΔH† versus ΔS†, the points fall very close to straight line. The isokinetic temperature was found to be 334K, indicating that the solvolysis reaction is controlled by ΔS† and not ΔH†. The change in ΔH† and ΔS† with the mole fraction of the cosolvent shows extrema at the composition range where changes in solvent structure occur. The influence of the solvent structure on the complex ion in the transition state dominates over that in the initial state, where −ΔG t 0 [Co(4-Etpy)4Cl]2+>−ΔG t 0 [Co(4-Etpy)4Cl2]+.

ChemInform Abstract: Preparation and Solvolysis of trans,trans,trans‐Tricyclo(7.3.1.05,13)tridecan‐3‐yl Toluene‐p‐sulfonates in Acetic Acid and Aqueous Hexafluoropropan‐2‐ol. The Role of Non‐Chair Conformers and the Question of Internal Return in the Limiting SN1 Solvolytic Mechanism.

AbstractAn improved cyclization of (I) leads to the ether (II), which is reduced by a modified Birch reduction to give the two main products (III) and (IV).

Solvent effects on the initial and transition states upon solvolysis oftrans-dichlorotetra(4-ethylpyridine) cobalt(III) perchlorate in water +t-butanol mixtures

The solvolysis of trans-[Co(4-Etpy)4Cl2]+ (1) (Etpy=ethylpyridine) was investigated in water and in a wide range of water+methanol mixtures. The effect of temperature on the solvolysis was considered and the thermodynamic parameters of activation were calculated. The free energies of transfer of (1) in the initial state were calculated from the solubility of the complex [Co(4-Etpy)4Cl2]2[ReCl6]. The free energy of transfer of the cation (1) in the transition state was calculated using a free energy cycle. The effect of the solvent structure on (1) is dominant in the transition state, where −ΔGto(1) transition >−ΔGto(1) initial. Comparison of the present thermodynamic data with those obtained previously fortrans-[Co(4-Mepy)4Cl2]+, (2), andtrans-[Co(py4Cl2]+, (3) in the same solvent mixture, shows that the stability increases in the order: (1), (2)<(3) at low mole fraction of the co-solvent, contrary to expectation, while at high mole fraction the order of increasing stability is: (1)<(3)<(2). The results were interpreted on non-electrostatic grounds.

Kinetics of the solvolysis of thetrans-dichlorobis (Diaminoethane)-cobalt(III) ion in aqueous ethylene carbonate and aqueous propylene carbonate

The kinetics of the solvolysis of trans-[Coen2Cl2]+ have been followed in mixtures of water with either ethylene carbonate or propylene carbonate over a range of temperatures. Both the enthalpy and entropy of activation for the first order loss of a chloride ion to give [Coen2Cl]2+ in water + ethylene carbonate show a maximum at low mole fractions of ethylene carbonate. As similar extrema in ΔH‡ and ΔS‡ for the same process for this complex and others in water +2-propanol and in water + t-butanol correlate well with extrema in the physical properties of the mixtures which are influenced by changes in solvent structure, it is suggested that these new extrema can be attributed to solvent structure effects. The application of a free energy cycle to the loss of the chloride ion in water and in the mixtures suggests that, although changes in solvent structure influence the cation in the transition state more than the cation in the initial state in water + ethylene carbonate, in water + propylene carbonate the influence of changes in solvent structure approximately balances. This is compared with the application of the free energy cycle to the same process in mixtures of water with a range of cosolvents using kinetic data available in the literature.

ChemInform Abstract: KINETICS OF SOLVOLYSIS OF THE TRANS‐DICHLOROTETRA(4‐METHYLPYRIDINE)COBALT(III) ION IN WATER AND IN WATER‐PROPAN‐2‐OL MIXTURES

The solvolysis of trans-[Co(4-Mepy)4Cl2]+ followed spectrophotometrically in water and in water–propan-2-ol is always first order in the complex, showing no isosbestic points. The logarithm of the rate constant shows no linear correlation with the reciprocal of the dielectric constant or with the Grunwald–Winstein Y factor. However, extrema in the variation of the enthalpy and entropy of activation correlate well with the extrema in the physical properties of the mixture which are related to changes in solvent structure. Correlation of the free energies of activation in the mixture with that in water using Gibbs free energies of transfer of individual ionic species suggests that the effect of changes in solvent structure on the complex ion in the transition state dominates over that on the complex ion in the initial state. These findings are compared with similar results for the solvolysis of other CoIII complexes in water–propan-2-ol and in mixtures of water with other co-solvents.

Kinetics of solvolysis of the trans- dichlorotetra(4-methylpyridine)cobalt(III) ion in water and in water–propan-2-ol mixtures

The solvolysis of trans-[Co(4-Mepy)4Cl2]+ followed spectrophotometrically in water and in water–propan-2-ol is always first order in the complex, showing no isosbestic points. The logarithm of the rate constant shows no linear correlation with the reciprocal of the dielectric constant or with the Grunwald–Winstein Y factor. However, extrema in the variation of the enthalpy and entropy of activation correlate well with the extrema in the physical properties of the mixture which are related to changes in solvent structure. Correlation of the free energies of activation in the mixture with that in water using Gibbs free energies of transfer of individual ionic species suggests that the effect of changes in solvent structure on the complex ion in the transition state dominates over that on the complex ion in the initial state. These findings are compared with similar results for the solvolysis of other CoIII complexes in water–propan-2-ol and in mixtures of water with other co-solvents.

Kinetics of the solvolysis of trans-chloroazidobis(1,2-diaminoethane)cobalt(III) ions in water and in water + propan-2-ol mixtures

Although previous kinetic results on the solvolysis of trans-[Coen2N3Cl]+ in water + co-solvent mixtures suggest that plots of log (rate constant) against the reciprocal of the dielectric constant are linear and independent of the co-solvent used, such a plot for propan-2-ol as co-solvent shows considerable curvature. The conclusion that might be drawn from the earlier results that the influence of solvent structure on the initial and transition states is about the same does not apply here and the application of a free-energy cycle to the process initial state → transition state in water and in the mixed solvent shows that the effect of solvent structure dominates the complex in the transition state. Enthalpies and entropies of activation for the solvolysis are correlated with changes in the physical properties of the mixtures and are compared with those for the cis-complex.

Stereochemistry of allylic rearrangements. XV. Ion-pair return associated with the solvolysis of trans-.alpha.-methyl-.gamma.-phenylallyl-p-nitrobenzoate in aqueous acetone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of allylic rearrangements. XV. Ion-pair return associated with the solvolysis of trans-.alpha.-methyl-.gamma.-phenylallyl-p-nitrobenzoate in aqueous acetoneHarlan L. Goering and Ernest C. LinsayCite this: J. Am. Chem. Soc. 1969, 91, 26, 7435–7439Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https://doi.org/10.1021/ja01054a035RIGHTS & PERMISSIONSArticle Views91Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (627 KB) Get e-Alerts Get e-Alerts