Eiichi Sekido

Liquid—liquid extraction of metal ions by the thiacrown compound 1,4,8,11-tetrathiacyclotetradecane

The possibilities of thiacrown compounds in liquid—liquid extraction were tested by using 1,4,8,11-tetrathiacyclotetradecane (TTCT). Class a metals were not extracted at all; of the class ab metals, only copper(II) was extracted. Class b metals were extracted but their extractabilities varied considerably. The relationship between the distribution ratio of the b metal and its softness is discussed. The extraction behavior of copper(I) with TTCT was studied in detail. The copper(I)—TTCT cation was completely extracted at pH > 4.0 as an ion-pair with perchlorate, picrate or tetraphenylborate. The extraction of copper(I) with TTCT and picrate into different solvents decreased in the order nitrobenzene >1,2-dichloroethane > chloroform > carbon tetrachloride. A study of the extraction equilibria for copper(I) with TTCT in the presence of the picrate (Pic−) showed that copper(I) and TTCT form a 1:1 cation complex [Cu(TTCT)]+, which reacts with picrate to form the 1:1 ion-pair [Cu(TTCT)] +Pic−. The extraction constants are log Kex = 7.3 ± 0.3 and 9.0 ± 0.2 for chloroform and 1,2-dichloroethane, respectively, as the organic solvent.

Phosphate ion-sensitive coated-wire/field-effect transistor electrode based on cobalt phthalocyanine with poly(vinyl chloride) as the membrane matrix

Abstract An ion-selective coated-wire/field-effect transistor electrode responding to dihydrogenphosphate is described. The device consists of a coated-platinum wire electrode connected to the gate of a conventional field-effect transistor. Cobalt phthalocyanine is used as ion-exchange electroactive substance and poly(vinyl chloride) as the membrane matrix. The characteristics of the device are investigated and its response is studied by two methods, the linear dependence of the square root of the drain current in the saturated region on the logarithm of ion activity for sodium dihydrogenphosphate, and the dependence of the gate-source potential on the logarithm of ion activity of the same ion. A linear response is obtained in the range of ion activity 10−5-10−1 mol dm−3 and the response slope is 45 mV per decade change of H2PO4− ion activity; the selectivity coefficients are discussed.

Extraction behaviour of silver(I) with some cyclic tetrathioethers

Abstract The extraction behaviour of silver(I) with 12-, 13-, 15- and 16-membered cyclic tetrathioethers (n-ane-S4, where n represents the total number of carbon and sulphur atoms in the cyclic ligand ring) was examined stoichiometrically using the picrate ion (Pic−) for the formation of the ion pair and chloroform and 1,2-dichloroethane as solvents. The composition of the extracted species and the extraction constant were determined. Silver(I) was extracted with these four ligands (L) into chloroform and 1,2-dichloroethane as the ion-pair compound [AgL]+Pic−. The extracted species with these four ligands is different from that previously reported for 14-ane-S4, [AgL2]+Pic−.

Liquid-liquid extraction of copper(II) with cyclic tetrathioethers

Abstract Liquid-liquid extraction of the divalent metal ions manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) with 1,4,8,11-tetrathiacyclotetradecane was examined using the tetraphenylborate ion (TPB − ) for the formation of the ion pairs. Copper(II) was quantitatively extracted into 1,2-dichloroethane, whereas the other metals were hardly extracted. The extraction behaviour of copper(II) with 12–16-membered cyclic tetrathioethers ([ n ]aneS 4 , where n represents the total number of carbon and sulphur atoms int he cyclic ligand ring) was examined. Chloroform and 1,2-dichloroethane were used as extraction solvents. The order of the extractability of copper(II) was as follows: [15]aneS 4 > [16]aneS 4 > [14]aneS 4 > [13]aneS 4 > [12]aneS 4 > at 2.5 × 10 −4 M of ligands, [16] aneS 4 > [15]aneS 4 > [14]aneS 4 > [13]aneS 4 > [12]aneS 4 at 2.5 × 10 −5 M of ligands. The extracted species were examined at ligand concentrations higher than 2.5 × 10 −4 M. Copper(II) was extracted with [13]aneS 4 and [16]aneS 4 as [CuL 2 ] 2+ (TPB − ) 2 and [CuL 4 ] 2+ (TPB − ) 2 depending upon the relative concentration of the ligand to copper(II). Where L represents cyclic tetrathioethers. The extracted species with [14]aneS 4 and [15]aneS 4 were [CuL 2 ] 2+ (TPB − ) 2 and [CuL 4 ] 2+ (TPB − ) 2 , respectively. In case of [12]aneS 4 , the following three species were observed depending upon concentrations of the ligand and TPB − : [CuL 2 (OH)] + TPB − , [CuL 2 ] 2+ (TPB − ) 2 and [CuL 4 ] 2+ (TPB − ) 2 .

Acid dissociation and spectrophotometric behaviour of 8-quinolineselenol in water-dioxan mixtures

The arid dissociation constants of 8-quinolineselenol, 8-quinolinol and 8-quinolinethiol in water-dioxan mixtures of varying solvent composition were determined potentiometrically or spectro-photometrically. The absorption spectra of 8-quinolineselenol in the same solvents were also obtained. The acid dissociation phenomena, stability towards oxidation and the absorption spectra of the reagents are discussed in connection with the existing forms. It is verified that 8-quinolineselenol exists as a zwitterion in water-dioxan mixtures of low or high dioxan content.

Liquid-liquid extraction of copper(II) with cyclic and acyclic tetrathioethers

Abstract The liquid-liquid extraction of copper(II) with cyclic and acyclic tetrathioethers (L) into 1,2-dichloroethane was examined. When hexanitrodiphenylamine ion (A − ) was used as the counter anion, the extracted species [Cu(II)L(OH)] + A − was predominant at pH > 6.0. The logarithmic extraction constants log k ex were 14.65 and 14.88 for the cyclic tetrathiatetradecane and the corresponding acyclic tetrathiapentadecane, respectively.

Liquid-liquid extraction of copper(I) by cyclic tetrathio ethers

Abstract The liquid-liquid extraction of copper(I) with 12-, 13-, 15- and 16-membered cyclic tetrathio ethers ([ n ]aneS 4 , where n represents the total number of carbon and sulphur atoms in the cyclic ligand ring) was examined stoichiometrically using picrate ion (Pic − ) for the formation of the ion pair. Copper(I) was extracted with four ligands (L) into 1,2-dichloroethane as the ion-pair compound, [Cu(I)L] + Pic − . The extraction constant, K ex , with each ligand was determined. As the ring size of cyclic tetrathio ethers increases, the log K ex values, including that previously reported for [14]aneS 4 , increase from 7.7 to 9.4. The value of Δ log K ex , which represents the increase in log K ex due to the addition of one carbon atom to the macrocyclic ring, was large between [13]aneS 4 and [14]aneS 4 (Δ log K ex =1.0) and small between [14]aneS 4 and [15]aneS 4 (Δ log K ex =0.1).

The structure of the nickel—8-quinolinol complex in some organic solvents

Abstract The ultraviolet and visible absorption spectra of the nickel—8-quinolinol complex in chloroform are significantly affected by traces of water. Absorption spectra of the complex in mixed solvents, e.g. dioxane—water, dioxane—methanol and chloroform-methanol, and in chloroform solution containing water, pyridine, or 8-quinolinol are compared. An addition compound is formed in which the mole ratio of the nickel-8-quinolinol complex to the solvent or the base is 1:1 or 1:2. Polymerization occurs by mutual interaction between the nickel-8-quinolinol complexes. A degree of polymerization of 2.2 was obtained; this indicates that the binuclear compound predominates. The structure of the nickel—8-quinolinol complex in organic solvents is discussed.

Effects of the anion on the extraction of zinc with 8-hydroxyquinoline into chloroform

Abstract Zinc 8-hydroxyquinoline complexes are extracted into a chloroform phase as a mixture of two species. Which of the two is extracted predominantly into the chloroform phase depends primarily on the kind of anion in the aqueous phase. The species extracted from an aqueous phase containing nitrate, sulfate or chloride ion is predominantly the anhydride of the 1:2 zinc 8-hydroxyquinoline complex, ZnOx2 which is so readily hydrated on the contact with water and precipitates as ZnOx2·2H2O. On the other hand, in the case of perchlorate, thiocyanate or iodide ion the extracted species is predominantly the ion-pair complex containing the respective anion. The extractability of these ion-pair complexes into a chloroform phase increases on the following order: ClO4− > I− > SCN− > Br− > Cl− ⪢ SO42−.

Composition and structure of zinc 8-hydroxyquinoline complexes extracted into chloroform

Abstract The zinc 8-hydroxyquinoline complexes extracted into chloroform from an aqueous solution containing an anion, X−, such as perchlorate, thiocyanate, iodide, bromide, nitrate or sulfate ion were isolated and their compositions determined. When X− is perchlorate, thiocyanate, iodide or bromide ion, the ion-pair compound, Zn 2 Ox + X − , is predominantly extracted into the chloroform phase and two or three molecules of 8-hydroxyquinoline are attached. Thiocyanate, iodide or bromide ion coordinates to the zinc atom of Zn 2 Ox + to form Zn2Ox3X(HOx)3 with iodide or bromide ion and to form the polymer, [Zn2Ox3X(HOx)2]n with thiocyanate, which perchlorate ion remains as a counter ion in the chloroform phase. In the case of nitrate or sulfate ion, ZnOx2 is extracted and precipitates as ZnOx2·2H2O. The structures of the extracted complexes are considered.