Yohji Nakatsuji

Surface-active properties of novel cationic surfactants with two alkyl chains and two ammonio groups

A series ofbis-quaternary ammonium salts was easily prepared by the reaction of a long-chaintert-alkylamine with epichlorohydrin, and their surface-active properties were measured. The prepared amphipathic compounds had good water solubility and showed characteristic surface-active properties, particularly, extremely excellent foaming ability and foam stability for some specific compounds, such as the compound with a dodecyl and a tetradecyl group as the lipophilic chains. Their critical micelle concentration, which decreased with increased alkyl chainlength, is two orders of magnitude lower compared with the conventionalmono-quaternary ammonium salts. In comparison with surface-active properties ofbis-quaternary ammonium salts, prepared from various organic dichlorides, there are little differences based on the kind of connecting group in the surface-active properties except for foaming.

Synergism in binary mixtures of surfactants 12. Mixtures containing surfactants with two hydrophilic and two or three hydrophobic groups

Abstract Molecular interactions between several anionic sulfonate surfactants containing two hydrophilic groups and two or three hydrophobic groups in the molecule (gemini surfactants) and a zwitterionic surfactant (N,N-dimethyl-1-tetradecanamine oxide) or a polyoxyethylenated non-ionic surfactant (C12H25(OC2H4)7OH or C12H25(OC2H4)8OH) were measured at 25°C in aqueous 0.1 M NaCl solution. The strength of the interaction with the zwitterionic surfactant decreases with increase in the minimum area per sulfonate group of the gemini surfactant at the air/water interface. The interaction with the zwitterionic surfactant or the polyoxyethylenated non-ionic surfactant is also weakened by the presence of multiple ether linkages in the hydrophilic group of the gemini surfactant. The latter surfactants with these linkages show a smaller increase, compared with gemini surfactants without them, in their interaction with the zwitterionic surfactant upon reduction of the pH of the solution. They also show an increase with this change in their area per molecule at the air/water interface and an increase in their interaction with an alkanesulfonate surfactant (C12H25SO3Na), increases not shown when neither surfactant has multiple ether linkages in the molecule. It is suggested that the relative ease of protonation of the multiple ether oxygen atoms in the doubly charged anionic gemini molecule accounts for these observations. The interaction in mixed micelles is much weaker than in mixed monolayers at the air/water interface; this is attributed to the difficulty of incorporating a surfactant with multiple hydrophobic groups into a micelle. The compounds studied all show synergism in surface tension reduction efficiency and effectiveness when mixed with the amine oxides, consistent with the synergism parameters. They also show synergism in mixed micelle formation with the amine oxide, except for a compound with three alkyl chains and one with a trioxyethylene group in the hydrophilic part. This is attributed to steric inhibition of micelle formation. As a result of protonation, the anionic gemini surfactants with multiple ether oxygen atoms in the molecule show little or no synergism when mixed with a polyoxyethylenated non-ionic surfactant. Synergism in the surface tension reduction effectiveness for these compounds when mixed with an alkanesulfonate at a low pH, however, is indicated.

Diphenylphosphinooxazoline ligands with a chiral binaphthyl backbone for Pd-catalyzed allylic alkylation

Novel diphenylphosphinooxazoline ligands with a chiral binaphthyl backbone were prepared. It was interestingly found that the two diastereomeric ligands afforded two enantiomeric products, respectively, with excellent catalytic activities and enantioselectivities for the palladium-catalyzed allylic alkylation, regardless of the identical (S)-oxazoline ring existing in both ligands. This is the first example using an (S)-oxazoline ligand to afford an (R)-product for this reaction.

Novel chiral P,N-ferrocene ligands in palladium-catalyzed asymmetric allylic alkylations

Abstract Novel chiral P,N-ferrocene ligands, 1-diphenylphosphino-1′-oxazolinylferrocenes, were prepared from ferrocene via 1,1′-bis(tributylstannyl)ferrocene and 1-diphenylphosphino-1′-methoxycarbonylferrocene as intermediates, and with this new kind of ligand up to 91% ee with 99% chemical yield was afforded for the palladium-catalyzed allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethylmalonate anion. The complexation behavior of this kind of ligand with dichlorobis(acetonitrile)palladium and bis(μ-chloro)(1,3-diphenyl-η 3 -allyl)dipalladium was investigated.

Preparation, surface-active properties and acid decomposition profiles of a new “soap” bearing a 1,3-dioxolane ring

New soap-type surfactants bearing a 1,3-dioxolane ring were prepared in good yields by the acid-catalyzed condensation of 1-O-alkylglycerols (alkyl: decyl, dodecyl, tetradecyl, heptadecyl, octadecyl, orcis-9-octadecenyl) with oxocarboxylic acid esters, followed by alkaline hydrolysis without any expensive reagent and special equipment. These surfactants were soluble in alkaline water at room temperature. Their critical micelle concentrations were much smaller than that of sodium dodecanoate. An alkaline solution of the octadecyl homologue was nonfoaming, but the other homologues, including thecis-9-octadecenyl derivative, showed high foaming ability in alkaline solutions. The structural effect of these compounds on the area per molecule at the surface is also discussed. Because these surfactants contain a 1,3-dioxolane ring, they can be utilized as a new acid-decomposable type of cleavable surfactant. At pH 1, they decompose almost completely into nonsurface-active species after 80 min.

Novel C2-symmetric diphosphine ligand with only the planar chirality of ferrocene

Abstract The first C 2 -symmetric diphosphine ligand possessing only the planar chirality of ferrocene was prepared from 1,1′-bis(diphenylphosphino)-2,2′-bis(oxazolinyl)ferrocene by the transformation of the oxazoline moieties in the molecule and with this new chiral ferrocene diphosphine ligand, up to 92% ee was obtained for the palladium-catalyzed allylic alkylation of 1,3-diphenyl-2-propenyl acetate with 2,4-pentanedione.

NOVEL AXIAL CHIRAL CATALYST DERIVED FROM BIPHENYL LIGAND BEARING ONLY TWO ORTHO-SUBSTITUENTS

Abstract The two diastereomers of novel C 2 -symmetric bisoxazoline ligand bearing only two ortho -substituents 4 exist in equilibrium in solution. However, when the ligand was coordinated with Cu(I), only one of the two possible diastereomeric complexes, 5 -(S,S,S) , was formed. With this complex as a chiral catalyst, up to 92% ee was attained for the asymmetric cyclopropanation of styrene with diazoacetate.

Novel C2-symmetric chiral bisoxazoline ligands in rhodium(I)-catalyzed asymmetric hydrosilylation

Abstract Novel C 2 -symmetric chiral bisoxazoline ligands with four asymmetric centers were readily synthesized from the two enantiomers of tartaric acid and several aminoacids via the corresponding bis(β-hydroxylamide)s and dimesylates as successive intermediates. With these novel chiral bisoxazoline ligands, rhodium(I)-catalyzed hydrosilylation of acetophenone was carried out and the effects of the combination of the four asymmetric centers as well as the substituent on oxazoline ring of the ligands on the reaction were studied.

Complexing ability of N-oligoethylene glycol monoaza crown ethers with sodium and potassium cations

Abstract N-Oligoethylene glycol monoaza crown ethers were prepared, and the notable effect of oxyethylene oxygen atoms of the side chain on complexing ability with sodium and potassium cations was confirmed.

New cleavable surfactants derived from glucono-1,5-lactone

New amido nonionic cleavable surfactants were synthesized in good yields by the acetalization of glucono-1,5-lactone with octanal, 2-octanone or 2-undecanone, followed by amidation with monoethanolamine, diethanolamine or morpholine. These compounds possessed good water solubilities. The compounds derived from 2-octanone showed higher critical micelle concentrations than the compounds from octanal. For the same hydrophobic chain, both the micelle-forming property and the ability to lower surface tension increased with the change in the terminal amide group in the order diethanolamide<morpholide<monoethanolamide. Interestingly, in spite of their relatively short hydrophobic chains, these compounds showed greater ability to lower surface tension than conventional nonionic surfactants, such as alcohol ethoxylates. Furthermore, their acid-decomposition properties were determined. Their decomposition rates were also compared with that of the corresponding carboxylate type of compound derived from glucono-1,5-lactone.