Synthesis and Properties of Complexane Type Trimeric Surfactants

Yoshimura, Tomokazu; Onitsuka, Emika; Esumi, Kunio

doi:10.4011/shikizai1937.75.75

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“…1,3 In the solubility measurement, the temperature in a thermostat was maintained within 0.05 C at the desired temperature. Commercial ethanol (reagent grade, Wako Chemical Industries Ltd.) was dried by refluxing overnight over calcium hydride, and was then distilled.…”

Section: Methodsmentioning

confidence: 99%

“…1 In practice, the hydrophobic character of mer- 3 ] are based upon the solubility differences of these isomers in ethanol. 4 Thus, the solubility determinations for the mer-isomers of various [Co(aa) 3 ] and for the fac-isomers of some [Co(aa) 3 ] in ethanol were attempted over the temperature range of 5 to 50 C. From these data, Á dis H and Á dis S of these chelates in ethanol were estimated.…”

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confidence: 99%

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Comparison of the Dissolution Behavior in Ethanol with the Dissolution Behavior in Water for Tris(amino acidato)cobalt(III)

Yoshimura

2004

Bulletin of the Chemical Society of Japan

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The free energy (Á dis G ), enthalpy (Á dis H ), and entropy of dissolution (Á dis S ) for tris(amino acidato)cobalt(III) were estimated from the temperature dependence of the solubilities in water, aqueous Bu 4 NBr solutions, and ethanol. and Á tr S of the transfer process from water to Bu 4 NBr solutions indicate that these chelates have rather a hydrophilic character. In addition to these chelates, for, and so on, the dissolution behavior in ethanol was compared with that in water by using Á dis G , Á dis H , and Á dis S in both solvents. The dissolution behavior of these chelates may be divided into two groups, that is, a group composed of hydrophilic chelates and another group composed of hydrophobic chelates. In the former, the solubilities in water are larger than those in ethanol owing to both smaller Á dis H and larger Á dis S in water. In the latter, the solubilities in ethanol are larger than those in water owing to larger Á dis S in ethanol.In a previous study, 1 differences in solubilities in water among two geometrical isomers (mer-and fac-isomers) and two optical isomers (Ã-and Á-isomers) of tris(amino acidato)-cobalt(III) ([Co(aa) 3 ]) were examined. In a series of studies on the dissolution behavior of [Co(aa) 3 ], the Ã-and Á-isomers have been expressed as the (þ)-and (À)-isomers, respectively. The symbols (þ) and (À) represent the dextrorotatory and levorotatory at 589 nm, respectively. For most [Co(aa) 3 ], the merisomers were more soluble than the fac-isomers, and for each geometrical isomer the (À)-isomer was more soluble than the (þ)-isomer. However, in the case of tris(L-threoninato)cobalt-(III) ([Co(L-thr) 3 ]), the solubility of the fac-(þ)-isomer was larger than that of the mer-(þ)-isomer. The reversed dissolution behavior, that the fac-isomer is more soluble than the mer-isomer, has also been qualitatively found for tris(-alaninato)coblt(III) ([Co(-ala) 3 ]).2 Unfortunately, the solubility of fac-(À)-[Co(L-thr) 3 ] could not be determined because of its insufficient yield. In this study, in order to confirm the abovementioned reversed dissolution behavior, the syntheses and separations of fac-(À)-[Co(L-thr) 3 ] and fac-[Co(-ala) 3 ] were repeated until sufficient yields for the solubility determinations were effected.It has been reported that the introduction of hydroxy groups into side chains of amino acids brings about an increase in the enthalpy (Á dis H ) and entropy of dissolution (Á dis S ) in water for [Co(aa) 3 ], presumably because of an inhibitory effect of the hydroxy group on the hydrophobic hydration of the parent [Co(aa) 3 ].1 In practice, the hydrophobic character of mer- An examination of the dissolution behavior in solvents other than water is effective for distinguishing an effect characteristic of water, such as hydrophobic hydration. While the solubilities of [Co(aa) 3 ] in organic solvents have been little determined because of extremely low solubility, procedures for the separation of some optical isomers of [Co(aa) 3 ] are based upon the solubility differences o...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%