Effect of urea on the solubility of benzene and toluene in water

Ueda, Mitsuo; Katayama, Akira; Kuroki, Nobuhiko; Urahata, Toshihiro

doi:10.1007/bfb0117165

Cited by 13 publications

(13 citation statements)

References 6 publications

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“…The solubility of benzene in aqueous urea solutions has been determined by measurement of the benzene vapor pressure (27) and by freezing point depression (26). The two studies give similar values of μ 23 at 25 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The solubility of benzene in urea solutions was analyzed in a similar way, starting from quadratic equations expressing the mole fraction solubility of benzene as a function of temperature in 0, 1, 2, 4, and 8 molar urea solutions provided by (26). Hovorka et al (27) have measured infinite dilution activity coefficients (γ 2 ) of benzene in urea solutions at 10, 20, 30, and 40 °C, from which we interpolated μ 23 = (∂lnγ 2 /∂ m 3 ) m2 at 25 °C.…”

Section: Methodsmentioning

confidence: 99%

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Denaturation of RNA Secondary and Tertiary Structure by Urea: Simple Unfolded State Models and Free Energy Parameters Account for Measured m-Values

Lambert

Draper

2012

Biochemistry

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To investigate the mechanism by which urea destabilizes RNA structure, urea-induced unfolding of four different RNA secondary and tertiary structures was quantified in terms of an m-value, the rate at which the free energy of unfolding changes with urea molality. From literature data and our osmometric study of a backbone analog, we derived average interaction potentials (per Å2 of solvent accessible surface) between urea and three kinds of RNA surfaces: phosphate, ribose, and base. Estimates of the increases in solvent accessible surface areas upon RNA denaturation were based on a simple model of unfolded RNA as a combination of helical and single strand segments. These estimates, combined with the three interaction potentials and a term to account for urea interactions with released ions, yield calculated m-values in good agreement with experimental values (200 mm monovalent salt). Agreement was obtained only if single-stranded RNAs were modeled in a highly stacked, A form conformation. The primary driving force for urea induced denaturation is the strong interaction of urea with the large surface areas of bases that become exposed upon denaturation of either RNA secondary or tertiary structure, though urea interactions with backbone and released ions may account for up to a third of the m-value. Urea m-values for all four RNA are salt-dependent, which we attribute to an increased extension (or decreased charge density) of unfolded RNAs with increased urea concentration. The sensitivity of the urea m-value to base surface exposure makes it a potentially useful probe of the conformations of RNA unfolded states.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Denaturation of RNA Secondary and Tertiary Structure by Urea: Simple Unfolded State Models and Free Energy Parameters Account for Measured m-Values

Lambert

Draper

2012

Biochemistry

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“…This may explain why ethylene glycol, with a readily accessible nonpolar surface, lowers the denaturation temperature of proteins while higher polyols, which cannot easily provide a nonpolar surface, raise the denaturation temperature (47,144,293,295). Urea also increases the solubility of toluene over the whole temperature range (857)(858), presumably through direct interactions; these putative urea-aromatic ring interactions are very unlikely to be hydrogen bonds. The aqueous solubility of other sparingly soluble compounds is also known to be decreased by higher polyols (' sugaring out') and increased by protein denaturants (52,328,(508)(509).…”

Section: T H E Influence Of Temperature On Hofmeister Effectsmentioning

confidence: 99%

The Hofmeister effect and the behaviour of water at interfaces

Collins

Washabaugh

1985

Quart. Rev. Biophys.

1,534

1,455

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Starting from known properties of non-specific salt effects on the surface tension at an air-water interface, we propose the first general, detailed qualitative molecular mechanism for the origins of ion-specific (Hofmeister) effects on the surface potential difference at an air-water interface; this mechanism suggests a simple model for the behaviour of water at all interfaces (including water-solute interfaces), regardless of whether the non-aqueous component is neutral or charged, polar or non-polar. Specifically, water near an isolated interface is conceptually divided into three layers, each layer being I water-molecule thick. We propose that the solute determines the behaviour of the adjacent first interfacial water layer (I1); that the bulk solution determines the behaviour of the third interfacial water layer (I3), and that both I1 and I3 compete for hydrogen-bonding interactions with the intervening water layer (I2), which can be thought of as a transition layer. The model requires that a polar kosmotrope (polar water-structure maker) interact with I1 more strongly than would bulk water in its place; that a chaotrope (water-structure breaker) interact with I1 somewhat less strongly than would bulk water in its place; and that a non-polar kosmotrope (non-polar water-structure maker) interact with I1 much less strongly than would bulk water in its place. We introduce two simple new postulates to describe the behaviour of I1 water molecules in aqueous solution. The first, the 'relative competition' postulate, states that an I1 water molecule, in maximizing its free energy (--delta G), will favour those of its highly directional polar (hydrogen-bonding) interactions with its immediate neighbours for which the maximum pairwise enthalpy of interaction (--delta H) is greatest; that is, it will favour the strongest interactions. We describe such behaviour as 'compliant', since an I1 water molecule will continually adjust its position to maximize these strong interactions. Its behaviour towards its remaining immediate neighbours, with whom it interacts relatively weakly (but still favourably), we describe as 'recalcitrant', since it will be unable to adjust its position to maximize simultaneously these interactions.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…Many investigators have reported that lower hydric alcohols increase the solubility of nonpolar substances in water (2)(3)(4)(5)(6)(7). The enhancement in the solubility of nonpotar solutes in water by the addition of these lower hydric alcohols have been interpreted by their actions to disrupt the o water structure (6,7) or to solvate the solute molecules preferentially (5)(6)(7)(8).…”

mentioning

confidence: 97%

“…The enhancement in the solubility of nonpotar solutes in water by the addition of these lower hydric alcohols have been interpreted by their actions to disrupt the o water structure (6,7) or to solvate the solute molecules preferentially (5)(6)(7)(8). The results obtained in this study that the lower hydric alcohols increase the stability of the hydrophobic parts of the monomeric surfactant molecule in water would be explained in a same waY.…”

mentioning

confidence: 99%

Effect of alcohols on the critical micelle concentration of nonionic surfactants in water

Ueda

Urahata

Katayama

et al. 1980

Colloid Polymer Sci

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We here report the effect of alcohols on the critical micelle concentration (cmc) of nonionic surfactants in water for the study of the alcohols on the stabilities of the monomeric surfactant molecules in water.Alcohols studied here are methanol, ethylene glycol, glycerol and sorbitol. They are mono-, di-, tri-and hexahydric, respectively. And every carbon atom in the molecule of these alcohols has a hydroxyl group.The cmc of nonionic surfactants was determined using a fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate potassium salts (TNS), as an indicator. The method of the

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Effect of urea on the solubility of benzene and toluene in water

Cited by 13 publications

References 6 publications

Denaturation of RNA Secondary and Tertiary Structure by Urea: Simple Unfolded State Models and Free Energy Parameters Account for Measured m-Values

Denaturation of RNA Secondary and Tertiary Structure by Urea: Simple Unfolded State Models and Free Energy Parameters Account for Measured m-Values

The Hofmeister effect and the behaviour of water at interfaces

Effect of alcohols on the critical micelle concentration of nonionic surfactants in water

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