NOPR Collection:

CO hydrogenation over intermetallic compounds

Tue, 01 Jun 1993 00:00:00 GMT

Title: CO hydrogenation over intermetallic compounds Authors: Kulshreshtha, S K; Sasikala, R Page(s): 465-471

Transfer enthalpies of tert-butyl chloride in some aquo-organic solvents

Tue, 01 Jun 1993 00:00:00 GMT

Title: Transfer enthalpies of tert-butyl chloride in some aquo-organic solvents Authors: Datta, Mira (nee Sarkar); Das, Mohon L; Datta, Jayati; Kundu, Kiron K Abstract: Transfer enthalpies, H, of tert-butyl chloride (t-BuCl) from water to aqueous mixtures of various cosolvents viz., protic ethanol (EtOH), tert-butanol (t-BuOH), ethanediol (EG) and methoxyethanol (ME), aprotic 1,2-dimethoxyethane (OME) and 1,4-dioxane (D) and dipolar aprotic N,N-dimethylformamide (DME) and dimethyl sulphoxide (DMSO), have been determined at 25°C by measuring the partial molal heats of solution at infinite dilution () with a rapid response Tronac (model 458) recording titration calorimeter by avoiding the uncertainties from hydrolysis of t-BuCI in the solvents. These values on extrapolation to zero cosolvent composition in each of the aqueous cosolvent systems lead to a common value for that of water (_w), which is equal to 6.27±0.25 kJ mol^-1. H values of the initial state (IS) of t-BirCl ( = _sH^≠ - _wH) on subtraction from the corresponding transfer activation energies ∂H^≠ (=_sH^≠ - _wH) as obtained from parallel kinetic studies of the hydrolysis/solvolysis of t-BuCl in the solvents at different temperatures, and reported elsewhere, helped determine the transfer enthalpies H (TS) of the transition state (TS). A comparative view of the composition profiles of , as well as of ∂H^≠ and H (TS) in the solvent systems reflects that while the variations in values are guided by complex structural and interaction effects in the respective solvents, H (IS) values are fairly small as compared to ∂H^≠ values. Evidently, ∂H^≠ values are guided by the contributions of H of TS rather than that of IS, contrary to what has been concluded by Arnett et al. from the corresponding studies only in aqueous ethanol system. Page(s): 472-477

Transfer free energies of trimethylammonium hydrochloride-a precursor to a potential model transition state for S_Nl-type hydrolysis of tert-butyl chloride in some aquo-organic solvents

Tue, 01 Jun 1993 00:00:00 GMT

Title: Transfer free energies of trimethylammonium hydrochloride-a precursor to a potential model transition state for S_Nl-type hydrolysis of tert-butyl chloride in some aquo-organic solvents Authors: Datta, Mira (nee Sarkar); Kundu, Kiron K Abstract: Transfer free energies, G, of trimethylammonium hydrochloride (Me₃NHCl)-a precursor to a potential model for the transition state (TS) for S_Nl-type hydrolysis of tert-butylchloride (t-BuCI), have been determined in aqueous mixtures of various organic co solvents viz protic ten-butanol (t-BuOH), ethylene glycol (EG), glycerol (GL) and methoxyethanol (ME), aprotic dimethoxyethane (DME) and dioxane (D) and dipolar aprotic 1,2-dimethylformamide (DMF) and dimethyl sulphoxide (DMSO). These have been determined by measuring the solubilities of sparingly soluble salt Me₃NHBPh₄ (Ph = phenyl) at 25ᵒC in the solvents and by using the relation:
G (Me₃NHCl) = G ( Me₃NHBPh)₄ - G (Ph₄B^-) + G (Cl^-). Page(s): 478-484

Effect of butanol and cholesterol on the conductance of AOT-aided water/xylene microemulsion

Tue, 01 Jun 1993 00:00:00 GMT

Title: Effect of butanol and cholesterol on the conductance of AOT-aided water/xylene microemulsion Authors: Mukhopadhyay, L; Bhattacharya, P K; Moulik, S P Abstract: The conductance behaviour of water- in-oil (W/O) microemulsions formed by xylene and AOT has been studied at different temperatures in the presence of cholesterol, butanol, benzyl alcohol and crown ether. The dependence of conductance on the degree of rigidity of the interface between water and oil in the microemulsion as affected by the additives has been analysed. The increased conductance at higher temperatures is explained in terms of the coalescence of dispersed water particles of microdimensions, followed by exchange of Na+ ions. Two distinct values of energy of activation for conductance have been obtained in the temperature range below and above 35°C. The temperature-dependent viscosity behavior of the microemulsion has been also studied. Page(s): 485-490

NOPR Collection:

CO hydrogenation over intermetallic compounds

Transfer enthalpies of tert-butyl chloride in some aquo-organic solvents

Transfer free energies of trimethylammonium hydrochloride-a precursor to a potential model transition state for SNl-type hydrolysis of tert-butyl chloride in some aquo-organic solvents

Effect of butanol and cholesterol on the conductance of AOT-aided water/xylene microemulsion

Transfer free energies of trimethylammonium hydrochloride-a precursor to a potential model transition state for S_Nl-type hydrolysis of tert-butyl chloride in some aquo-organic solvents