As novel calixarene or macrocyclic types of extractants, 37,38,39,40,41,42-hexakis(carboxymethoxy)-5,11,17,23,29,35-hexakis(1,1,3,3-tetramethylbutyl)calix [6]arene and 25,26,27,28-tetrakis(carboxymethoxy)-5,11,17,23-tetrakis(1,1,3,3-tetramethylbutyl)calix [4]arene as well asp-(1,1,3,3-tetramethylbutyl)phenoxy acetic acid, as their monomeric analog, and 2,6-bis[2-carboxymethoxy-5-(1,1,3,3-tetramethylbutyl}benzyl]-4-(1,1,3,3-tetramethylbutyl)phenoxyacetic acid as a linear trimer analog, have been synthesized in order to investigate their extraction abilities of rare earth metal ions, RE3+ (RE=Y, La, Pr, Nd, Sm, Eu, Gd, Ho, Er), from an aqueous nitrate solution. It was found that the calixarene derivatives provide much higher extractability and greater separation efficiency than do the monomeric analog and the other acidic carboxylate extractants. The selectivity for rare earth elements in this system is not affected by the ring size. In extraction from an aqueous mixture of nitric acid-glycine, the stoichiometry of the extracted species was determined and the extraction equilibrium constants as well as the separation factors were evaluated for each extractant. A stripping test was also performed and the stripping of rare earths was found to be successfully achieved with diluted hydrochloric acid. Calixarenepolyols and their derivatives have been attracting much attention as novel types of interesting host compounds.l-3 Their recognition ability for metal ions can be one of the remarkable features as a specific receptor.They have plural phenolic hydroxyl groups which can be relatively easily chemically modified. It is expected that the introduction of ion-exchangeable functional groups into them will make them effective extractants, due to a chelating effect, and also that the cyclic structures and their rigid skeletons contribute to a high selectivity, owing to their size-discriminating ability for metal ions with different ionic radii.A number of studies have been conducted on calixarenes or their derivatives as receptors for metal ions. Izatt et al. carried out extraction of alkali metal ions with 5, 1 1 , 17,23-tetra-t-butylcalix 26,27,11,17,23,29,38,39,40,41,38, 39,40,41,11,17,23,29,38,39,40,41,11,17,23,29,arene extract uranyl ion (U022+) efficiently and selectively as a complex with a pseudo planar penta-or hexacoordinate geometry.5 Yoshida et al. reported that 5,11,17, 23,29,38,39,40,41,hexol can extract copper(II) ions from an alkaline ammoniacal solution.6 Masuda et al. reported on the extraction of silver(I), palladium(II), and nickel(II) ion with 5, 1 1 , 1 7,23,29,35-hexa-t-butylcalix[6]arene-37,38, 39,40,41,42-hexol 37,38,39,40,41,42-hexakis(carboxymethoxy)-5,11,17,23,29,35-hexa-t-butylcalix[6]arene and 25,26,27, 28-tetrakis(carboxymethoxy)-5,11,17,23-tetra-t-butylcalix[4]arene.9However, the calixarene derivatives with t-butyl groups as alkyl radicals so far investigated have poor solubility in ordinary organic diluents, such as kerosene, benzene or toluene, and, consequently, are not necessarily...

A new surfactant, dioleyl phosphoric acid (DOLPA), has been applied to the extraction of hemoglobin using reversed micelles. The reversed micelles formed by DOLPA can easily extract hemoglobin from aqueous to reversed micellar solutions. DOLPA is the first surfactant to extract hemoglobin completely without using any cosurfactants. On the basis of the difference between DOLPA and AOT reversed micelles in the forward extraction behavior of hemoglobin, the nature of the interfacial complex that would be formed between surfactants and hemoglobin at the oil--water interface was found to be the dominant factor in determining the extraction efficiency of hemoglobin be reversed micelles. In addition, back-transfer studies of hemoglobin from the DOLPA reversed micelles were also carried out by the phase transfer method. It was found that hemoglobin, once dissolved into the DOLPA reversed micelles, is not transferred to a fresh aqueous solution even when the conditions are adjusted to not allow the forward transfer of hemoglobin. However, the addition of several kinds of alcohol drastically improved the yield in the back-transfer of hemoglobin. The efficiency in the back-transfer of hemoglobin strongly depends on the aqueous conditions that are in contact with the reversed micelles, such as pH, ionic strength, and alcohol concentration. A pH higher than the pI of hemoglobin, a salt concentration lower than that of the water pool, and the proper concentration of alcohol are required for the recovery aqueous phase to ensure the back-transfer of hemoglobin from the DOLPA reversed micelles.

Enantioselective esterification of menthol with fatty acids using a surfactant‐coated lipase was carried out in organic media. The surfactant‐coated lipase originating from Candida cylindracea appeared to be highly enantioselective and good biocatalyst for the resolution of racemic menthol. The enzymatic activity of the lipase in organic media was significantly increased by a coating with a nonionic surfactant. The reaction rate of the coated lipase was more than 100 times that of the powder lipase. In order to investigate the effect of the organic solvent on enantioselectivity, 19 kinds of solvents were employed. The nature of the organic solvent strongly affected the efficiency of the biocatalyst and the enantioselectivity. Among them, isooctane was the best organic solvent from the viewpoint of reaction rate and enantioselectivity. The effect of reaction temperature on esterification was also investigated. The optimal reaction temperature was around 35 °C. The enzymatic activities using n‐saturated fatty acids with different alkyl chain lengths were compared, and long‐chain fatty acids were found to be better substrates than shorter ones. The relationship between the initial rate of the esterification and the carbon number of the fatty acid was not linear. These results suggest that there are inherent Km values for each fatty acid.

No abstract

Novel reversed micellar solutions formulated with a mixture of AOT (dioctyl sulfosuccinate) and DOLPA (dioleyl phosphoric acid) show good potential for use in reversed micellar protein extraction operations. Chymotrypsin is easily extracted from an aqueous phase into organic isooctane containing 10 mM AOT and DOLPA in a 4:1 ratio. The extraction ability of the mixed reversed micelles of 10 mM was higher than that of 200 mM AOT alone. The results of extraction indicated that the AOT-DOLPA mixed reversed micelles are very useful for separating and enriching chymotrypsin. Back-extraction of chymotrypsin from the organic phase to a fresh aqueous phase is also accomplished by adding an alcohol to the organic phase. Although the back-transfer of chymotrypsin from the reversed micelles formed by AOT alone is very slow and difficult, in the AOT-DOLPA mixed reversed micelles, the back-extraction can be achieved completely by addition of 10% (v/v) isobutyl alcohol to the reversed micellar phase. The time to attain to the equilibrium of back-extraction was reduced from more than 24 to 2 h by adding the alcohol. On the basis of the activity data, the best composition of AOT and DOLPA was a 4:1 ratio and the total surfactant concentration was 10 mM. The activity of chymotrypsin recovered from the mixed reversed micelles was higher than that of the initial protein before the forward-transfer. This result means that the novel mixed reversed micellar solutions are useful not only in separation but also in purification of proteins.