Thermochemical study of the solvation of alkanes in mixtures of methanol with butyl alcohol isomers

A calorimetric method was applied at 25 °C to measure the enthalpies of dissolution of cyclohexane, heptane, and decane in the methanol-n-butanol mixed solvent and hexadecane in mixtures of methanol withn-, iso-, andtert-butyl alcohols. The standard enthalpies of dissolution of alkanes were determined. It was shown that the equation proposed in the literature for calculation of the enthalpies of dissolution of alkanes in mixtures with nonspecific intermolecular solvent-solvent interactions describes satisfactorily the enthalpies of dissolution of alkanes in mixtures of methanol withn- andiso-butyl alcohols. It was suggested that there is no preferential solvation of alkanes by one of the mixed solvent components in the MeOH−BuⁿOH and MeOH−BuⁱOH mixtures; in the MeOH−Bu^tOH system, the composition of alkane solvation shell differs slightly from the solvent composition in the bulk. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 271–274, February, 1999.     

Contributions of hydrocarbon radicals and functional groups of organic molecules to enthalpies of their solvation in mixed water—tert-butyl alcohol solvents

The contributions of hydrocarbon radicals (−CH₃, >CH₂, >CH−, >C<) and functional groups (−OH, −OCOO−, −NO₂, −CN, >SO) to the enthalpies of solvation of organic molecules in mixed water—tert-butyl alcohol solvents were calculated in the whole range of compositions at 298.15 K. The influence of the composition and properties of the mixture on the solvation of different functional groups is discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1811–1814, October, 1997.     

Kamlet-Taft solvatochromic parameters of aqueous binary mixtures oftert-butyl alcohol and ethyleneglycol

The , , and * Kamlet-Taft solvatochromic parameters have been determined for aqueous mixtures of tert-butanol and ethyleneglycol from spectroscopic data.     

Solute-solvent interactions in water-tert-butyl alcohol mixtures. VI. Enthalpies of solution for halo-para-substituted benzoates

Enthalpies of solution of sodium benzoate, potassium benzoate, and potassium halo-substituted benzoates are reported at 298.15°K in water and in nine water-tert-butyl alchol mixtures. Transfer enthalpies from water to the mixed solvent go through a maximum for about 0.055 mole fraction of alcohol. Additivity of ionic contributions in the enthalpies of transfer is verified. Substituent effects on the transfer enthalpies of benzoates are discussed in terms of size of the solutes and cohesion of the solvent mixtures. For Part V, see ref. 1.     

Enthalpies of dissolution of propylene carbonate,acetonitrile, and 1,4-dioxane in mixtures of water with acetone or dimethyl sulfoxide

Enthalpies of dissolution of acetonitrile, propylene carbonate, and 1,4-dioxane in mixtures of water with acetone or DMSO were measured in the whole concentration range of the mixed solvents. Standard enthalpies of dissolution and enthalpies of transfer of solutes from water to its mixtures with acetone or DMSO were determined. In the region of small proportions of the nonaqueous component, the enthalpy of cavity formation in the mixed solvent makes the main contribution to the variation of the enthalpy of dissolution. An increase in the proportion of the nonaqueous component leads to competition between the contributions of cavity formation and specific interaction between the solute and the solvent during solvation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1747–1752, September, 1995.     

Enthalpies and heat capacities of transfer of sodium carboxylates and sodium dodecylsulfate from water to aqueoustert-butyl alcohol solutions

Integral enthalpies of solution at very low concentrations of sodium carboxylates and sodium dodecylsulfate in aqueous tert-butyl alcohol solutions at 25°C and 35°C were measured with an isoperibol submarine calorimeter. The enthalpies and heat capacities of transfer of these surfactants from water to aqueous tertbutyl alcohol solutions were derived from integral enthalpies of solution. The results are explained in terms of the structural alteration effect of the constituent hydrophobic and hydrophilic groups of the solute.     

Alkylation of acetylene by tert-butyl alcohol

A reaction of acetylene with tert-butyl alcohol in the presence of sulfuric acid leads to tert-butylacetylene.     

Solubility of dichlorotetraalkylpyridinecobalt III hexachlororhenate(IV) in water + methanol mixtures: Free energies of transfer of the complex cation from water into the mixtures

The solubility of salts [Co(3Rpy)₄Cl₂]₂]ReCl₆] has been determined in water + methanol mixtures. By comparing these with the solubilities of the salt Cs₂ReCl₆ and using calculated activity coefficients for the ions in the water+methanol mixtures, values for {G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ )–G _t ^o (Cs⁺)} can be determined where G _t ^o is the standard Gibbs free energy of transfer from water to an aqueous mixture. G _t ^o (Cs⁺) from the solvent sorting scale and from the TPTB scale are then used to calculate G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ ). These two sets of values for G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ ) on the differing scales are then inserted into a free energy cycle applied to the bond extension Co(3Rpy)₄Cl ₂ ⁺ (initial state)Co(3Rpy)₄Cl²⁺+Cl^– (transition state) for the solvolysis in water and in water + methanol mixtures to produce values for G _t ^o (Co(3Rpy)₄Cl²⁺) using both scales. Data for the solubilites of [Copy₄Cl₂]₂[ReCl₆] and [Co(4Rpy)₄Cl₂]₂[ReCl₆] have been re-calculated to compare free energies of transfer for these complex cations with those specified above.     

Electron-excited dioxygen generated by the tri-tert-butoxyaluminum—tert-butyl hydroperoxide system as an efficient oxidant of aniline and some N-substituted anilines

The tri-tert-butoxyaluminum—tert-butyl hydroperoxide system generates molecular oxygen in the electron-excited singlet state (¹O₂), which oxidizes diphenylamine, N-ethylaniline, aniline, and 2,6-diisopropylaniline to form nitroxyl radicals. The latters were identified by ESR at 240—293 K. Oxidation proceeds via the intermediate formation of nitrogen-containing N-peroxide compounds.     

Synthesis of Methyl tert-Butyl Ether from tert-Butyl Alcohol and Methanol Using Beta Zeolite Catalysts

MTBE synthesis from tert-butyl alcohol (t-BA) and methanol has been studied using beta zeolites. Increasing the reaction temperature results in an increase of t-BA conversion with concomittant decrease of MTBE selectivity. The t-BA conversion decreases with increasing calcination temperature and alkali metal ion exchange of H zeolite. The catalytic results are correlated with the surface area and the acidity of catalysts.     

Free energy of transfer of cobalt(III) complexes from water into water—t-butyl alcohol mixtures

The solubility of trans-(Coen₂Cl₂)₂ReCl₆ has been determined in water and in water +t-butyl alcohol mixtures. By comparzng these values with the solubility of Cs₂ReCl₆ in similar mixtures, values for the difference in free energy of transfer, G _t ^o (i) between water and water + t-butyl alcohol can be calculated for i =[Coen₂Cl₂]⁺ and Cs⁺. The introduction of G _t ^o (Cs⁺) then produces values for G _t ^o (Coen₂Cl₂ ⁺). The difference in G _t ^o (i) for i=[Coon₂Cl]²⁺ in the transition state and i=[Coen₂Cl₂]⁺ in the initiad' tate for the solvolysis of the trans-[Coen₂Cl₂]⁺ ion in water + t-butyl alcohol can be derived from the application of a free energy cycle: using G _t ^o (Coen₂Cl₂ ⁺) determined from the solubility measurements allows the calculation of values for G _t ^o (Coen₂Cl²⁺). G _t ^o (i) in water + t-butyl alcohol for bis (1,2-diamino) cobalt (III) ions are compared with G _t ^o (i) for tetrapyridinecobalt (III) ions.     

Thermochemistry of interactions of Na+ with benzo-15-crown-5 ether in acetonitrile-water mixtures at 298.15 K

Enthalpies of dissolution of benzo-15-crown-5 ether (B15C5) in mixtures of acetonitrile with water and in solutions of NaI and NaBPh₄ (I=0.05 mol dm^–3) in these mixtures were measured at 298.15 K. From the obtained results and appropriate literature data, the thermodynamic functions of B15C5/Na⁺ complex formation in acetonitrile-water mixtures were determined. The enthalpies of transfer of the complex B15C5/Na⁺ from pure acetonitrile to the examined mixtures were calculated and are discussed.     

Influence oftert-butyl alcohol on cyclodextrin inclusion complexes of pyrene

The effect oftert-butyl alcohol on complexes of pyrene and various cyclodextrins is investigated. The equilibrium constant for the complexation is derived from the fluorescence decay parameters. A greater than twofold enhancement of pyrene lifetime is observed in the presence oftert-butyl alcohol and -cyclodextrin or -cyclodextrin. As the number of hydroxyl groups decreases, substituted -cyclodextrins show smaller enhancements to both the fluorescence lifetime and the formation constant. These observations are explained by proposing that alcohol molecules are associated with the inclusion complex. This association increases the apparent hydrophobicity of the cyclodextrin cavity, protects the molecule from collisional quenching and deactivation, and provides additional rigidity to the system.     

Enthalpies of transfer of 2-methyl-2-propanol from water to mixtures of water with methanol,ethanol and 1,4-dioxane

The enthalpies of transfer of 2-methyl-2-propanol (TBA) from water to mixtures of water with methanol, ethanol and 1,4-dioxane have been measured. The data are considered in terms of recently developed theory, and it is found that the enthalpies of transfer can be reproduced quantitatively over most of the composition range in each solvent system. The parameters recovered from the analyses indicate that the net effect of TBA on the solvent structure is a breaking of solvent-solvent bonds and that TBA is preferentially hydrated in the aqueous alcohol systems, but randomly solvated in the water+1,4-dioxane system. It is also found that the model parameters for TBA solvation in the alcohol systems are independent of the alcohol.     

Effect of minor additives of arenes on chain termination in low-temperature cationic polymerization of isobutylene in aliphatic solvents

The influence of small concentrations (1—8 mmol L^–1) of arenes (viz., hexafluorobenzene, chlorobenzene, benzene, toluene, and mesitylene) on the molecular weight, molecular weight distribution, and degree of functionalization by terminal olefin groups was studied for polymers prepared by low-temperature (–78 °C) isobutylene polymerization in n-hexane initiated by the MeOH—AlBr₃ and Bu^tCl—AlBr₃ systems. The criteria extent of livingness k _el/k _p were calculated, where k _el and k _p are the rate constants of proton elimination and chain propagation, respectively. It was established that arenes can be involved in proton elimination from the growing carbocation, and their activity in this process increases with an increase in the basicity. Arenonium ions formed by the interaction of arenes with the components of the initiating system or with the growing ionic active centers can form complexes with counteranions, thus retarding proton elimination with the transfer to the counterion.     

ESR study of the thermal decomposition of di-tert-butoxy-tert-butyl alumotrioxide formed in the reaction of tri-tert-butoxyaluminum with tert-butyl hydroperoxide

Tri-tert-butoxyaluminum reacts with tert-butyl hydroperoxide to produce di-tert-butoxy-tert-butyl alumotrioxide, which decomposes heterolytically to form singlet dioxygen and homolytically with the O—O bond cleavage. The Bu^tOO^·, (Bu^tO)₂AlOO^·, Bu^tO^·, and (Bu^tO)₂AlO^· radicals were identified by ESR using spin traps. These findings confirm the formation of aluminum-containing trioxide. The above radicals initiate alkylarene oxidation by the tri-tert-butoxyaluminum—tert-butyl hydroperoxide system. The carbon-centered and alkylperoxy radicals originated from the oxidized substrates were identified.     

Non-catalytic condensation of aromatic aldehydes with aniline in high temperature water

Abstract

The synthesis of diamino triphenyl methanes from aniline and aromatic aldehydes was conducted in near critical water and supercritical water. The reaction parameters, such as temperature, density, and reaction time, have been studied. Significant acceleration of the condensation reaction of aniline and aromatic aldehydes can be achieved by using high temperature water, especially near the critical point, in the absence of any acid catalysts. It has been demonstrated that high temperature water act effectively in the place of conventional acid catalysts.     

Change in the reactivity of di-tert-butyl peroxide during homolysis with an increase in the degree of conversion and pressure

It was found that the differential reactivity (k _d ) of di-tert-butyl peroxide (DTBP) in a solution of 2-methoxy-(1) and 2-ethoxytetrahydropyran (2) at 130°C and pressuresp=20 and 1000 MPa is a periodic function of the degree of conversion, arbitrarily measured by the concentration oftert-butyl alcohol (TBA) formed. The functionk _d =F([TBA]) was calculated with the spline approximation (SA) of the experimental [TBA] as a function of the reaction time , giving a continuous curve of d[TBA]/d as a function of . The integral reactivityk _d =G([TBA]) calculated with the kinetic equation for a first-order reaction for decomposition of DTBP in1, 2, 1 + C ₆ H ₆ and2 + C ₆ H ₆ in three segments of in the range ofp=20–1000 MPa changes differently with an increase in the degree of conversion for differentp. The volume activation effects ( ) determined by SA of the experimental lnk _d as a function ofp were calculated for close degrees of conversion, [TBA]=0.1–0.14M. The as a function ofp obtained were compared with the similarly processed published data on decomposition of DTBP inn-heptane and dicumyl peroxide (DCP) in different aromatic solvents. The results were attributed to the effect of the type of packing of the solvent molecules surrounding the reacting molecule on the reactivity of the peroxide and not to the effect of radical recombination in the primary cage.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 829–837, April, 1992.     

HY Zeolite Modified by Liquid Silane Deposition and Its Catalytic Activity in Selective tert-Butylation of Naphthalene

HY zeolites were modified by chemical liquid deposition with i-C₄H₉Si(OC₂H₅)₃, followed by hydrothermal treatment. The samples were characterized by X-ray diffraction, N₂ adsorption and pulse mass analysis to investigate the influence on framework structure, specific surface area, pore diameter and adsorption behaviors. The catalytic performances of HY zeolite and the modified samples in the alkylation of naphthalene with tert-butyl alcohol were also evaluated. The results showed the modification of HY zeolite did not change framework structure but increased specific surface area, decreased average pore diameter, and reduced the size of pore opening. Catalytic activity of the modified HY zeolite catalyst for tert-butylation of naphthalene was decreased compared with that of HY zeolite catalyst while shape-selectivity of 2,6-di-tert-butylnaphthalene (2,6-DTBN) was increased obviously, the highest 2,6-DTBN/2,7-DTBN ratio of 6.62 obtained.     

Variation ofE T(30) polarity and the Kamlet-Taft solvatochromic parameters with composition in alcohol-alcohol mixtures

Solvatochromic parameter values, namely E_T(30) polarity, and Kamlet-Taft *, and , in alcoholic binary mixtures have been determined and correlated with solvent composition. The studied mixtures involve ethanol, methanol, 2-methoxyethanol and 1,2-ethandiol. Theoretical and semiempirical equations which embody preferential solvation of solvatochromic probes and allow the accurate interpolation of solvatochromic parameters are proposed.