摘要:

The hydrolysis ofp-nitrophenyldiphenyl phosphate (PNPDPP,7) catalyzed byN-dodecylaminoethanol (6a),N-tetradecylaminoethanol (6b),N-methyl-N-tetradecylaminoethanol (6c), andN-hexadecylaminoethanol (6d) was investigated at 25°C at various pH values in aqueous media containing additives. Added ethanol or dimethoxyethane produces very little activity of6a,b,ctoward7. The highest activities of6a,bwere found at pH 8.0 and 8.5 in solvents containing 20% glycerol or ethylene glycol. Under no conditions wasN-hexadecylaminoethanol (6d) found to be active. The kinetics of the reaction of6bwith7were also investigated in a medium containing various amounts of glycerol, polyethylene glycol 400 (PEG 400), and water at pH 7.6-8.5. The best catalytic system comprised 3 mM6bin 20% aqueous ethylene glycol, pH 8.5, which accelerated the hydrolysis of7by 1700-fold over the blank rate. Kinetic experiments conducted using [7]/[6b] = 1 and 2 demonstrate that6bexhibits true turnover catalysis. A mechanism for the catalyzed reaction is proposed.Key words: ß-aminoethanols, hydrolysis,p-nitrophenyldiphenyl phosphate, micelles, polyhydroxy alcohol

ISSN:0008-4042    

DOI:10.1139/v99-161

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Experimental solubilities are reported at 25.0°C for biphenyl dissolved in 26 different alkane, dialkyl ether, and alcohol solvents. Results of these measurements, combined with previously published biphenyl solubility data, are used to test the applications and limitations of expressions derived from Mobile Order theory. For the 40 solvents for which predictions could be made computations show that Mobile Order theory does provide fairly reasonable estimates of the saturation mole fraction solubilities. Average absolute deviation between predicted and observed values is 13.0%.Key words: biphenyl solubilities, organic nonelectrolyte solvents, solubility predictions

ISSN:0008-4042    

DOI:10.1139/v99-177

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

A study by high performance liquid chromatography of adsorption isotherm of HAP in toluene on Al(OH)3heated between 25 and 700°C shows that the rate of adsorption is maximal on the Al(OH)3heated at 300°C. The measurement of electrokinetic potential and the surface area of adsorbants approve this result. The determination of adsorption enthalpies of different HAP on the aluminium hydroxide has shown the existence of physical adsorption. The adsorbing power of Al(OH)3heated at 300°C is compared with that of other materials known or suspected very carcinogens.Key words: adsorption isotherm of HAP, aluminium hydroxi

ISSN:0008-4042    

DOI:10.1139/v99-180

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Ab initio MP2/6-311++G(d,p) structure optimizations and frequency calculations have been carried out on 10 polymers, (HX)n; on eight polyhalohydrogenate(1-) anions, HnXn+1-, and on four polyhalohydrogen(I) cations, Hn+1Xn+, (X = F and Cl) at a number of temperatures from 188 to 673 K, and at various total pressures. From the results, &Dgr;G° andKvalues have been calculated for some reactions involving these species, and the relative amounts determined under a variety of conditions:nHX –> (HX)n(n= 2-6)HX + HnXn+1-àHn+1Xn+2-(n= 0-3)HX + Hn+1Xn+àHn+2Xn+1+(n= 0, 1)There are some marked differences between the fluorine and chlorine series, but generally, the relative amounts of the large molecules and ions decrease as the temperature increases. For all reactions, lnKcan be expressed as function to the fourth power in 1/Tindicating that &Dgr;H° is more or less temperature dependent over a range of 400-500°.Key words: ab initio, thermodynamics, HCl

ISSN:0008-4042    

DOI:10.1139/v99-186

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Excess molar volumes VmEat 298.15 K and atmospheric pressure for methanol and ethanol + 2,5-dioxahexane, + 3,6-dioxaoctane, + 2,5,8-trioxanonane, + 3,6,9-trioxaundecane, + 5,8,11-trioxapentadecane, + 2,5,8,11-tetraoxadodecane, and + 2,5,8,11,14-pentaoxapentadecane have been obtained from densities measured with an Anton-Paar DMA 602 vibrating-tube densimeter. All the excess volumes are negative over the whole mole fraction range.The VmEcurves are shifted to the region rich in the alkanol, increasing their asymmetry with the number of oxygen groups in the polyethers. Results seem to remark the predominant contribution of free volume effects on interactional effects, particularly when the ethers are of the type CH3-(O-CH2CH2)m-CH3. In the case of polyethers with longern-alkyl chain ends, self-association of methanol and ethanol is more relevant. A short comparative study with results for mixtures with higher 1-alkanols and polyethers is also presented.Key words: experimental, excess volumes, 1-alkanols, polyethers, self-association, free volume effects.

ISSN:0008-4042    

DOI:10.1139/v99-189

出版商:NRC Research Press    

年代:1999

数据来源: NRC