Seiichi Inokuma

Anionic surfactants with divalent gegenions of separate electric charge: solubility and micelle formation

In order to clarify the relationships among solubility, micelle formation, and Krafft point, anionic surfactants with three types of divalent gegenions were prepared and their micelle formation and solubility examined. The first gegenion type was characterised by localized charge(divalent metal ion), the second by diffuse charged,(1,1′-dimethyl-[4,4′] bipyridinium ion or methylviologen ion), and the last by separate charged,(l,1′-alkanediyl-bis-pyridinium ion). The effects of the unlocalized gegenions were compared with those of the localized gegenions, and the following conclusions could be drawn from the experimental results: (i) the crystalline state with gegenion of diffuse or separate charge is less stable energetically and has higher solubility, and (ii) the difference in cmc value among the three types of surfactants is relatively small when the charge separation is small, but a large charge separation gives rise to marked decrease in cmc value suggesting that the alkylchain of separate gegenion folds and penetrates the inner hydrophobic part of the micelle. Also we observed that surfactants with more water of crystallization are easier to dissolve with a smaller enthalpy change of dissolution.

Efficient intramolecular [2+2] photocycloaddition of styrene derivatives toward new crown ethers

New crown ethers, exhibiting high Li+-selectivity on the solid-liquid extraction, were prepared from α,ω-bis(p-vinylphenyl)oligo(oxyethylenes) by the title reaction in excellent yields.

Regioselective synthesis and complexation behavior of novel [60]fullerene bisadducts containing dibenzo-18-crown-6 moiety

The reaction of [60]fullerene with bis-o-quinodimethane precursor 3 containing a dibenzo-18-crown-6 moiety provided preferentially trans-4 bisadduct 5a along with a small amount of cis-2 bisadduct 5b. These bisadducts showed different ionophoric properties from each other; 5a exhibited a high complexing ability toward K+ ion, while 5b hardly showed complexation with any alkali metal ions.

Heat of micelle formation: Effect of counterions with concentrated, diffused, and separated electric charges

Heats of micelle formation were estimated from calorimetric measurements of anionic surfactants to see if there is any effect of the electrical charge of the counterion on micelle formation from the viewpoint of enthalpy change. The cationic counterions used are Na+ and Cu2+ for the concentrated electric charge, MV2+ for the diffused and 1,1′-(1,ω)-alkanediyl)bispyridiniumionsn=2, 4, 6, 8, 10, 12, 14 for the separated. The heat of micelle formation was obtained by subtracting an enthalpy change of dissolution of surfactant solid precipitated below the micelle temperature range (MTR or Krafft point) from a heat of complete dissolution of the precipitated surfactant solid around the MTR. The heats thus evaluated were found to be much more temperature-dependent than counterion-dependent. They were compared with the enthalpy change calculated from the CMC change with temperature, and the big difference between them was discussed from a thermodynamic point of view.

Bromination by means of sodium monobromoisocyanurate (SMBI)

A variety of aromatic compounds with both activating and deactivating substituents were brominated with sodium monobromoisocyanurate (SMBI) 1, diethyl ether, diethyl ether-methanesulfonic acid, trifluoroacetic acid, or sulfuric acid were employed as solvents. Thus nitrobenzene was conveniently brominated in sulfuric acid, benzene was readily monobrominated in diethyl ether-methanesulfonic acid, and phenol was selectively brominated at the ortho position under mild conditions in refluxing diethyl ether. With substituents that are easily protonated, trifluoroacetic acid may be employed as solvent in the reaction with 1, in contrast NBS was ineffective in trifluoroacetic acid. This renders 1 a superior reagent relative to NBS. In addition to aromatics, alkenes, ketones and esters were also brominated with 1. Diethyl malonate was brominated with 1 and then subjected to a Bingel reaction with NaH to afford the desired methanofullerene in reasonable yield.

Synthesis of double-looped crownophanes and their ability of amino acid transport through liquid membranes

Abstract Double-looped crownophanes were conveniently synthesized by means of intramolecular [2+2] photocycloaddition. The double-looped crownophane 13 with dodecanoic acid facilitated the transport of lithium cation selectively under competitive and passive transport conditions through a chloroform liquid membrane. The crownophanes alone transported dibasic acids efficiently and selectively, accompanied by lithium cations. These results are discussed on the basis of the hydrophilic and lipophilic balance (HLB) theory and CPK space filling models.

Synthesis and Complexing Ability of Azacrownophanes: The Cyclodextrin Catalysis of the Photochemical Cyclization Reaction

Azacrownophanes were efficiently prepared by the irradiation of precursor ammonium chlorides in the presence of γ-CD (γ-cyclodextrin) in aqueous solution, by repressing the amino group-quenching effect by inclusion of the styrene moieties in γ-CD. In liquid–liquid extraction, azacrownophanes (6 and 7) showed affinity toward both Ag+ and Pb2+ cations in a series of heavy metal nitrates. Both 6 and 7 formed 1:1 complexes with the above two cations, according to 13C NMR titration and ESI-MS analysis.

Selective ion clefts based on a three-bridged [43]cyclophane

A variety of new three-bridged cyclophanes, clefts4–14, have been conveniently prepared, and their cation-binding properties have been examined. Compounds4–6 have a special affinity for alkali metal cations. Ethyl ester5 and methyl ester4 selectively formed 2:1 complexes with K+ and Na+ ions, respectively. Clefts11–13, which possess pyridyl groups, bind Ag+ cation exclusively.1H NMR titration studies confirmed that11 or12, having 2- or 3-pyridyl groups, form a 1:1 complex with Ag+ cation, while13, with 4-pyridyl ligating groups, forms a 2:1 complex. Cleft10, with aminimide groups, also shows an affinity for Ag+ cation in a 2:1 ratio in a polar solvent, while it forms a 1:1 complex in a nonpolar solvent. The same solvent effect was observed for clefts13 and15c, which is discussed qualitatively.

KINETIC STUDY ON HUISGEN REACTION CATALYZED BY COPPER(I) : TRIAZOL FORMATION FROM WATER-SOLUBLE ALKYNE AND ALKYL AZIDE

The kinetics was examined for the copper(I)-catalyzed Huisgen reaction. Despite the complex reaction pathway, it was successfully analyzed by the second-order kinetics with equal amounts of two organic substrates in the presence of 0.1 equivalent of copper catalyst, after dividing the time course into two stages, the early and late ones. Both stages gave almost the same activation parameters. The reaction of water-soluble alkyl azide (1) was 60 times as fast as that of water-soluble aromatic azide (4) at the early stage and surprisingly 822 times after 15 min reaction time at 30 °C.

Synthesis and complexing properties of crownophanes possessing carboxyl group

A new series of crown compounds bearing two carboxyl groups (2a-c; crownophanedicarboxylic acids) were prepared via intramolecular [2 + 2] photocycloaddition of bis-styrene derivatives. In the liquid-liquid extraction, crownophanedicarboxylic acids (2a-c) showed a low affinity toward alkali metal cations, though both 2b and 2c showed an extraordinary high affinity toward zinc cation among heavy metal cations examined.