Surface active substances containing an oligo(hexafluoropropene oxide) chain as a hydrophobic and oleophobic moiety

Oil soluble surface active substances,(HFPO)_n-Ar, where Ar is an aryl group and (HFPO)_n is an oligo(hexafluoropropene oxide) group, n = 2 ? 5, were prepared and tested for their surface activities in toluene or $\text{m}$-xylene. Addition of a small amount of (HFPO)_4–6-Ar (0.2–0.5 wt%) was found to decrease remarkably the surface tension of these solvents (down to 12–14 dyn·cm_?1 at 20 °C). Water soluble surfactants (HFPO)_n-Ar′SO₃Na, where Ar′ is an arylene group, were also prepared by sulfonation of (HFPO)_n-Ar. Some of these substances (n = 4 ? 6) decreased the surface tension of water down to 16 dyn·cm^?1 at 20 °C in the concentration of 1O^?4–1O^?5 mole·1^?1.     

Lyotropic liquid crystalline phase behavior of amphiphilic monomers and polymers having a rod-like hydrophobic moiety

Distinct changes in the lyotropic mesophase behaviour of nonionic polyethyleneglycol containing amphiphiles are observed, when rigid, rod-like molecular units are introduced into the hydrophobic part of these amphiphiles, or when the amphiphiles are added as side chains to poly(methylhydrogene siloxane), yielding amphiphilic side chain polymers. Low molar mass amphiphiles with a dominating rigid, rod-like hydrophobic unit form planar-like micelles which aggregate into lamellar mesophases. Compared with their corresponding low molar mass amphiphiles, amphiphilic side chain polymers show a distinct stabilization of mesophases composed of anisometric micelles, i.e. hexagonal H₁-phases (built up by rod shaped micelles), and lamellar L -phases (built up by planarshaped micelles). In addition, several of the polymeric amphiphiles exhibit the formation of a lyotropic nematic N_c-phase regime. Optically isotropic I₁-phases composed of approximately spherical-like micelles are, on the other hand, disfavoured by the polymerfixation. Investigations of monodisperse amphiphilic side chain oligomers reveal a linear relationship between the thermal stability of the individual mesophases and the logarithm of the degree of polymerization. Changes in mesophase behaviour, due to the introduction of rigid, rod-like molecular units into the hydrophobic part of the low molar mass amphiphiles, are ascribed to packing restraints of the amphiphiles in the micelles. Alterations in mesophase behaviour which occur as a consequence of polymerfixation are discussed in terms of changes in micellar kinetics, packing restraints, and changes in the interaction between adjacent hydrophobic layers of neighbouring micelles.     

Instance of direct replacement of a nitro group attached to an unsaturated center of a coumarin by a mercapto group

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1135–1136, August, 1990.     

Self-assembling structures of long-chain sugar-based amphiphiles influenced by the introduction of double bonds

Nine phenyl glucoside or galactoside amphiphiles possessing a saturated or unsaturated long alkyl-chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembly properties were investigated by using energy-filtering TEM (EF-TEM), SEM, CD, XRD, and FT-IR techniques. Compound 2, possessing one cis double bond in the lipophilic portion, exhibited twisted helical fibers, which formed a bilayered structure with a 3.59 nm period, while 3 exhibited helical ribbons and left-handed nanotubular structures with 150-200 nm inner diameters and a wall thickness of approximately 20 nm. Very interestingly, 4, possessing three cis double bonds, exhibited a nanotubular structure with an inner diameter of approximately 70 nm and a d spacing value of 4.62 nm. On the other hand, 7, possessing two trans double bonds in the lipophilic region, exhibited crystal- or plate-like structures, which formed a bilayer structure with a d spacing value of 3.93 nm. These results indicate that the self-assembly properties are strongly dependent on the type of double bond. Furthermore, 8 and 9, with the galactopyranose moiety, revealed helical ribbon and well-defined double helical fiber structures, respectively. These findings support the view that the orientation of the intermolecular hydrogen-bonding interaction between the sugar moieties plays a critical role in producing the nanotubular structures. According to CD and powder XRD experiments, the relatively strong intermolecular hydrogen-bonding interaction of the glucopyranoside moiety in 3 and 4 provided a highly ordered chiral packing structure. Even though these compounds formed a weak hydrophobic interaction between lipophilic groups, it led to the formation of the nanotubular structure.     

New type of ruthenium sensitizers with a triazole moiety as a bridging group

A new type of ruthenium sensitizers JK-91 and JK-92 with a triazole moiety as a bridging group were designed and synthesized in an attempt to increase the π-conjugated system. Two compounds work as highly efficient sensitizers for the dye-sensitized nanocrystalline TiO₂ solar cell. Under standard AM 1.5 sunlight, the sensitizer JK-91 yielded a short-circuit photocurrent density of 12.55 mA/cm², an open-circuit voltage of 0.73 V, and a fill factor of 0.73, corresponding to an overall conversion efficiency of 6.75%.     

Facile activation of dihydrogen by an unsaturated heavier main group compound

The germanium alkyne analogue Ar'GeGeAr' (1, Ar' = C6H3-2,6(C6H3-2,6-Pri2)2) reacts with 1, 2, or 3 equiv of dihydrogen at room temperature, and at 1 atm pressure, to afford a mixture of the products Ar'HGeGeHAr' (2), Ar'H2GeGeH2Ar' (3), or Ar'GeH3 (4). The relative amounts of each product are governed by the number of equivalents of hydrogen used. A mechanism for the initial step in the reaction is proposed. The appearance of 4 among the reaction products was accounted for in terms of either its dissociation to monomers or isomerization to the bridged Ar'Ge(mu-H)2GeAr'. The reactions were monitored by 1H NMR spectroscopy. The products 2, 3, and 4 were characterized by X-ray crystallography, and 4 was synthesized independently by the reduction of Ar'Ge(OMe)3. These reactions represent the first direct addition of hydrogen to a closed shell unsaturated main group compound under ambient conditions.     

A low-molecular-mass gelator with an electroactive tetrathiafulvalene group: tuning the gel formation by charge-transfer interaction and oxidation

A new low-molecular-mass gelator with one TTF and one urea group is described. It was found that the gel formation can be tuned by formation of CT complexes and oxidation.     

A novel low-molecular-mass gelator with a redox active ferrocenyl group: tuning gel formation by oxidation

A novel low-molecular-mass gelator containing a redox-active ferrocenyl group, cholesteryl glycinate ferrocenoylamide (CGF), was intentionally designed and prepared. It was demonstrated that the gelator gels 13 out of the 45 solvents tested. Scanning electron microscopy (SEM) measurements revealed that the gelator self-assembled into different supramolecular network structures in different gels. Chemical oxidation of the ferrocenyl residue resulted in phase transition of the gel from gel state to solution state. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding between the gelator molecules in the gel was one of the main driving forces for the formation of the gels.     

Oxidation with sodium peroxide Direct introduction of a γ carbonyl group into α,β unsaturated ketosteroids

Aqueous sodium peroxide oxidises the conjugated Δ⁴-3-ketosteroids $\text{1a}$-$\text{1d}$ to the corresponding Δ⁴-3-4-diones in good yield. Saturated carbonyl and alcohol groups are not affected by the reaction.     

S-benzoxazolyl as a stable protecting moiety and a potent anomeric leaving group in oligosaccharide synthesis

As a part of a program for developing new versatile building blocks for stereoselective glycosylation and convergent oligosaccharide synthesis, we demonstrated that S-benzoxazolyl (SBox) glycosides are stable toward major protecting group manipulations employed in carbohydrate chemistry. On the other hand, they can be glycosidated under relatively mild reaction conditions to afford either 1,2-trans or 1,2-cis-linked disaccharides. Selective and chemoselective activations of the SBox moiety were also proved to be feasible, which was demonstrated by synthesizing a number of oligosaccharide sequences.     

Synthesis and solution behavior of hydrophobic association water-soluble polymers containing arylalkyl group

Copolymers of acrylamide (AM) and N-arylalkylacrylamide (AAM) have been synthesized by free radical micellar copolymerization in aqueous solution utilizing sodium dodecyl sulphate (SDS) as the surfactant and ammonium persulfate/sodium bisulfite as the redox initiator. Some factors affecting synthesis, such as the amount of AAM, SDS and 2-acrylamide-2-methylpropane sulfate, are described. Solution behaviors of these polymers were studied. The results show that with the increase of AAM content, the intrinsic viscosity decreases, Huggins constant increases and the viscosification effect increase. The addition of NaCl and CaCl₂ results an increase of solution viscosity, and the addition of surfactant has a significant and complex effect to solution viscosities. The polymers exhibit good temperature tolerance property, shear-thickening and thixotropy behavior.     

Stereospecific 2-vinylcyclohexanol formation via internal attack of an allylsilane moiety on an aldehyde group

Acid catalyzed cyclization of ($\text{E}$)-HCO-(CH₂)-₄-CH=C(Me)-CH(SPh)SiMe₃ affords $\text{cis}$-2-substituted cyclohexanol, while ($\text{Z}$) compound affords the $\text{trans}$ isomer. Those cyclized products are transformed to the corresponding α-methyl γ-lactones.     

Drawing and dynamic-mechanical behavior of syndiotactic polystyrene an introduction

The drawing behavior of syndiotactic polystyrene was analyzed at different temperatures. Amorphous films were used and, depending on drawing temperature, strain-induced or thermal-induced cold crystallization was observed. This phenomenon, when present, greatly affects the drawing behavior. The dynamic-mechanical behavior of drawn samples was analyzed, and the obtained results indicate that the glass transition is affected by drawing, and that the effect depends drastically on the drawing temperature. Particularly interesting is the dynamic behavior at high temperature where the elastic modulus is weakly affected by temperature also near the melting point.     

Key side products due to reactivity of dimethylmaleoyl moiety as amine protective group

Dimethylmaleoyl (DMM) moiety has become an important amine protective group in sugar chemistry. We disclose herein that DMM-containing D-glucosamine analogues, because of their electrophilic nature, are prone to reactions with strong nucleophiles, such as hydrazine, resulting in a set of undesired side products that are difficult to detect, yet proved to be problematic for organic synthesis.     

Fluoride-induced chemiluminescent decomposition of 1,2-dioxetanes bearing a phenyl moiety substituted with a methyl having an electron-withdrawing group

A new type of dioxetane bearing a 3-(cyanomethyl)phenyl (1a), 3-(methoxycarbonylmethyl)phenyl (1b), 3-(benzoylmethyl)phenyl (1c), or 3-[cyano(methoxycarbonyl)methyl]phenyl group (1d) decomposed through an intermediary dioxetane bearing a benzylic carbanion to afford crimson to yellow light on treatment with TBAF in DMSO.     

Synthesis and characterization of liquid-crystalline side group polymers with benzylideneaniline as mesogenic moiety

Two new thermotropic liquid-crystalline side group polymers were synthesized, characterized and compared with the liquid-crystalline monomeric analogues. Some packing features of these polymeric liquid crystals are discussed.

Investigations were carried out by differential calorimetry (D.S.C.), polarization microscopic observation and X-ray diffraction on non-aligned and magnetic field-aligned samples in the wide and small angle region.

The synthesized polymers contain as mesogenic moiety a benzylideneaniline group which is attached in the 4 position via a hexamethylene spacer to a poly-methacrylate backbone. The benzylideneaniline group is substituted in 4′ position with an ethoxy or butoxy group (PEt or PBu). The monomeric analogues are denoted MEt and MBu. The two polymers show a phase sequence crystalline-smectic A-nematic-isotropic. The liquid-crystalline temperature range is observed between 90 and 150°C. The monomeric MEt exhibits only a monotropic nematic, MBu an enantiotropic nematic and a smectic A phase.     

Thermodynamics of mixtures containing unsaturated hydrocarbons by quasichemical group contributions

The quasichemical group surface interaction method was tested for its ability to correlate and predict vapor-liquid equilibrium (VLE) and molar excess enthalpy (H ^E ) in binary systems 1-octyne-1-propanol, 1-nonyne-1-propanol, 1-nonyne-1-butanol, 1-butylcyclopentene-nonane, 1-butylcyclopentene-1-butanol and 3-ethylcyclopentene-1-butanol. All computations involve using the few sets of group parameters obtained for CHC/OH by a change of the number of H ^E experimental points and the minimization function. For alkylcyclopentene systems, acyclic C=C group parameter as well as those of cyclic C=C and special cyclopentene groups have been used. The results have been compared with those obtained previously by the Wilson and UNIFAC methods.Communicated at the Festsymposium celebrating Dr. Henry V. Kehiaian's 60^th birthday, Clermont-Ferrand, France, 17–18 May 1990