Synthesis and Monolayer Behaviors of Novel Hybrid Corynomycolic Acids Containing Semifluoroalkyl Groups.

In this work, novel hybrid-type corynomycolic acids [hybrid-OH and hybrid-COOH, with semifluoroalkyl groups (Rf-(CH2)n-: Rf = C4F9, n = 6 and Rf = C6F13, n = 3) located on the carbon atoms attached to the hydroxyl and carboxylic acid groups (C-OH and C-COOH), respectively] were successfully synthesized. The behaviors and formation of hybrid corynomycolic acid monolayers at the air-water interface were investigated by surface tension and surface pressure-area (π-A) measurements to clarify the effects of the Rf chain length, position of the semifluoroalkyl group, and surfactant molecule stereochemistry. Compared to dialkyl corynomycolic acid, both the critical micelle concentration (CMC) and the surface tension at the CMC (γCMC) of hybrid corynomycolic acids were reduced by the presence of the Rf group. With respect to the surface tension versus log concentration (γ vs. log C) isotherms, all syn-isomers of the hybrid-OH and hybrid-COOH acids showed two break points, while the anti-isomers showed only one break point. These different isotherms can be explained in terms of the steric repulsion between the two hydrophilic groups (OH and COO(-)), which depend on the stereochemistry of the surfactant. No effect of the location of the semifluoroalkyl group was observed. With respect to the formation of a monolayer film, four parameters-the lift-off area (AL), zero-pressure molecular area (A0), maximum of the Gibbs elastic modulus [EG (max)], and monolayer collapse pressure (πc)-were measured. Both AL and A0 of all hybrid corynomycolic acids were larger than the corresponding dialkyl acids due to the bulky and rigid Rf groups. Interestingly, syn- and anti-hybrids had almost identical isotherms on compression, although the values of πc of anti-hybrids were higher than those of syn-isomers. In addition, the values of EG (max) of hybrid-COOHs were slightly larger than those of the corresponding hybrid-OHs. Using the nascent soap method (agent-in-oil method), we found that anti-F4C6-OH (a hybrid corynomycolic acid) is a promising emulsifier for a ternary system comprising octane, water, and perfluoropolyether oil.

Synthesis and Monolayer Behaviors of Succinic Acid-Type Gemini Surfactants Containing Semifluoroalkyl Groups.

In this work, novel succinic acid-type gemini surfactants containing semifluoroalkyl groups, dl- and meso-2,3-bis[Rf-(CH2)n]-succinic acids (Rf = C4F9, C6F13, C8F17; n = 2, 9), were successfully synthesized, and the effects of Rf, methylene chain length (n), and stereochemistry on their monolayer behaviors were studied. Critical micelle concentrations (CMC) of dl- and meso-2,3-bis[C4F9(CH2)9]-succinic acids were one order of magnitude smaller than that of the corresponding 1+1 type surfactant, C4F9(CH2)9COOH. From surface pressure-area (π-A) measurements, the lift-off areas of the geminis were found to decrease in the order C4F9 ≥ C6F13 > C8F17, regardless of methylene chain length and stereochemistry. The zero-pressure molecular areas of the geminis were twice those of the corresponding 1+1 type surfactants. Based on Gibbs compression modulus analysis, it was clarified that 2,3-bis[C8F17(CH2)n]-succinic gemini with short methylene chains (n = 2) would form more rigid monolayers than those having long methylene chains (n = 9). Unlike for 2,3-bis(alkyl)-succinic acids, the effects of stereochemistry on the monolayer behavior of semifluoroalkylated geminis were small.

Novel fluorinated gemini surfactants with γ-butyrolactone segments.

In this work, novel γ-butyrolactone-type monomeric and dimeric (gemini) surfactants with a semifluoroalkyl group [Rf- (CH2)3-; Rf = C4F9, C6F13, C8F17] as the hydrophobic group were successfully synthesized. Dimethyl malonate was dimerized or connected using Br(CH2)sBr (s = 0, 1, 2, 3) to give tetraesters, and they were bis-allylated. Radical addition of fluoroalkyl using Rf-I and an initiator, i.e., 2,2'-azobisisobutyronitrile for C4F9 or di-t-butyl peroxide for C6F13 and C8F17, was perform at high temperature, with prolonged heating, to obtain bis(semifluoroalkyl)-dilactone diesters. These dilactone diesters were hydrolyzed using KOH/EtOH followed by decarboxylation in AcOH to afford γ-butyrolactonetype gemini surfactants. Common 1 + 1 semifluoroalkyl lactone surfactants were synthesized using the same method. Their surfactant properties [critical micelle concentration (CMC), γCMC, pC20, ΓCMC, and AG] were investigated by measuring the surface tension of the γ-hydroxybutyrate form prepared in aqueous tetrabutylammonium hydroxide solution. As expected, the CMC values of the gemini surfactants were more than one order of magnitude smaller than those of the corresponding 1 + 1 surfactants. Other properties also showed the excellent ability of the gemini structure to reduce the surface tension. These surfactants were easily and quantitatively recovered by acidification. The monomeric surfactant was recovered in the γ-hydroxybutyric acid form, and the gemini surfactant as a mixture of γ-butyrolactone and γ-hydroxybutyric acid forms.

Novel Synthesis of Anionic Gemini Surfactants from 1, 4-Diol as a Key Block Material.

In this study, a series of all-hydrocarbon anionic gemini surfactants containing COOH (adipic acid-type and suberic acid-type), SO3Na, OSO3Na, and OP=O(OH)2 functional groups was developed from 1,4-diol and 1,4-diketone as a key block material. The effect of the surfactant head groups on the surface properties was investigated by surface tension and surface pressure-area (π-A) measurements. We found that the critical micelle concentrations (CMC) of the studied geminis were smaller by one order of magnitude than those of the corresponding 1+l-type surfactants. From π-A measurements, the limiting areas of COOH-type geminis were less than twofold of the area of the corresponding 1+1-type, which indicates that the gemini structure enabled tighter packing than is possible in surfactants of the 1+l-type. In contrast, the limiting area of the OP=O(OH)2-type gemini was larger than those of the COOH-type geminis. Furthermore, the suberic acid-type gemini showed a smaller limiting area than that of adipic acid-type gemini. Therefore, we can conclude that the flexibility of the gemini at the connecting position has a significant effect on formation of the monolayer at the air/water interface.

Solubilization of fullerene into water with fluoroalkyl end-capped amphiphilic oligomers-novel fluorescence properties.

Solubilization of fullerene into water was studied by the use of fluoroalkyl end-capped acryloylmorpholine oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers. In these fluorinated oligomers, fluoroalkyl end-capped acryloylmorpholine oligomers were more effective in solubilizing fullerene into water. Interestingly, the aqueous solutions of fullerene were applicable to fluorescence analyses.

Monolayer behavior of asymmetrical ester-type tartaric gemini amphiphiles.

The ester-type asymmetrical tartaric gemini amphiphiles (C(m)-C(n), where m and n are the number of carbon atoms of hydrophobic alkanoyl group, m+n=28) bearing two carboxyl groups and two different alkanoyl groups were prepared from L-tartaric acid, and the pressure-area (π-A) isotherms for a series of asymmetrical tartaric gemini amphiphiles were studied.The π-A isotherms of asymmetrical C(m)-C(n) monolayers were classified into two groups. Group 1: The asymmetry was small (n/m <1.55), and a phase transition of the monolayer from the liquid-expanded to the liquid condensed state, and a subsequent transition to solid phases were observed. Group 2: The asymmetry was large (n/m >1.8), and only liquid-expanded state of the monolayer film was observed. Based on the subphase temperature (T(sub)) dependence of monolayer static elasticity, es, the melting temperature (T(L)) of asymmetrical C(m)-C(n) monolayer was estimated to be T(L) = 31.7°C and 50.6°C for C13-C15 and C12-C16, respectively. Furthermore, assuming that asymmetrical C13-C15 can be viewed as an equimolar mixture of symmetrical 2C13 and 2C15, the temperature dependence of monolayers of 2C13 and 2C15 mixture at various ratios were also studied. As a result, all TL values of 2C14, C13-C15 and an equimolar mixture of 2C13 and 2C15 were almost the same. However, the variation of T(L) with the molar fraction of 2C15 (X(2C15)) was remarkably different from that of solid melting point T(m) with X(2C15).

Preparation of dicarboxylic acid-type gemini surfactant via Diels-Alder reaction & ozone oxidation.

We wish to report a novel preparation method for Gemsurf analogs as well as dicarboxylic acid-type Gemini surfactant from Diels-Alder adducts of 2-trimethylsilyloxy-1,3-butadiene, in which ozone oxidation is adopted to convert C=C double bond to dicarboxylic acid without any additional oxidant.

Effects of hydrophobic chain length on temperature dependence of monolayer behavior of ester-type tartaric geminis.

Ester-type tartaric gemini amphiphiles bearing two carboxyl groups and two hydrophobic alkanoyl groups were prepared from L-tartaric acid, and the pressure-area (π-A) isotherms for a series of symmetric tartaric gemini amphiphiles were measured by the conventional film-balance technique. The effects of the length of the hydrophobic alkanoyl chains and of the subphase temperature (T(sub)) on the π-A isotherms for these compounds were examined. As the length of the hydrophobic alkyl chain increased, a more tightly packed monolayer was formed at the air-water interface. The melting temperature (T(m)) of the monolayer on the water surface was evaluated from the subphase temperature (T(sub)) dependence of the monolayer static elasticity ε(s), based on a π-A isotherm. A clear relationship between T(m) and hydrophobic carbon number (n) was observed for 2D monolayers of tartaric geminis on water surfaces, as well as for fatty acids and/or 3D solids.

Novel synthesis of N-alkoxycarbonyl amino acids and surfactant properties of their sodium salts.

N-Acyl amino acids have been prepared from fatty acid chlorides and amino acids, but it may not be easy to vary the hydrophobic groups on the view point of availability. In this work, instead of acid halides, long alkyl chloroformates were prepared by the facile reaction of alcohols and triphosgene as an induction agent of hydrophobic group on amino acids. N-Alkoxycarbonyl amino acids were synthesized from alkyl chloroformate and amino acids under Schötten-Baumann reaction condition with some modification. Surfactant properties of their sodium salts were studied by surface tension measurements, dynamic light scattering and foaming test, and compared with those of N-acyl amino acids. Sodium salts of N-alkoxycarbonyl amino acids showed an excellent surface tension lowering ability comparable to N-acyl amino acids, and they also exhibited good foaming ability and stability.

A novel synthesis of SO(3)H type gemini surfactant having semifluoroalkyl group as hydrophobic group.

In this work, novel SO(3)H type Gemini surfactants having semifluoroalkyl group (RfCH(2)CH-: Rf = C(4)F(9), C(6)F(13), C(8)F(17)) as hydrophobic group were successively synthesized by the radical addition of fluoroalkyl to 1,4-pentadiene using fluoroalkyl iodide and AIBN as initiator, and the following thiocyanization (-SCN), conversion to -SH, and oxidation to SO(3)H as hydrophilic group. Similarly, the common 1+1 type semifluoroalkyl surfactants having SO(3)H were synthesized. Surfactant properties of their sodium salts (cmc, gamma(cmc), pC(20), Gamma(cmc), and A) were investigated by measuring surface tension. As expected, the cmc value of Gemini surfactant whose fluoroalkyl is C(4)F(9) was more than one order of magnitude smaller than that of the corresponding 1+1 type. Other properties also showed the excellent efficiency of Gemini structure to reduce the surface tension.

Oxidative cleavage with hydrogen peroxide: preparation of polycarboxylic acids from cyclic olefins.

Oxidative cleavage of carbon-carbon double bonds of cyclic olefins with hydrogen peroxide in the presence of heteropolyacids has been investigated as a clean and environmentally friendly preparation of polycarboxylic acids. In the presence of 12-tungstophospholic acid (H(3)PW(12)O(40)), adipic acid was obtained in 95% yield from cyclohexene in lipophilic phase and hydrogen peroxide in aqueous phase. In addition, 1,2,3,4-butanetetracarboxylic acid was also obtained in 87% yield from 1,2,3,6-tetrahydrophtharic acid anhydride, while endic acid anhydride did not afford corresponding 2,3,6-cyclopentanetetracarboxylic acid but only lactone compound was obtained. In this oxidation process, oxidative cleavage of carbon-carbon double bonds would proceed as the sequential reactions in which the rate determining step is oxidative cleavage of vicinal-diol compounds.

Oxidation of cyclohexanediol derivatives with 12-tungstophosphoric acid-hydrogen peroxide system.

Oxidation of cyclohexanediol derivatives with 12-tungstophospholic acid-hydrogen peroxide system was investigated focusing on a reaction mechanism in the preparation of dicarboxylic acids from olefin because oxidative cleavage of vicinal diols would be a rate-determining step in oxidative cleavage of carbon-carbon double bonds. trans-1,2-Cyclohexanediol (DHC) was converted to adipic acid almost quantatively, while 1-hydroxy-2-methoxycyclohexane (HMC) gave a mixture of adipic acid, glutaric acid and monomethyl adipate. In the case of 1,4-cyclohexanediol, 4-hydroxy-cyclohexanone and many hyperoxidated products were obtained. Based on results for HMC, it is concluded that following route would be also reasonable in oxidative cleavage of vicinal diol with 12-tungstophospholic acid-hydrogen peroxide system: (1) first oxidation of vicinal diol to alpha-hydroxyketone, (2) nucleophilic attack of hydrogen peroxide attacks to carbonyl carbon, (3) Baiyer-Villiger rearrangement of dihydroxy-hydroperoxide to a cyclic ester, (4) hydrolysis and final oxidation to dicarboxylic acid.

Preparation of polycarboxylic acids by oxidative cleavage with oxygen / Co-Mn-Br system.

Adipic acid and glutaric acid were obtained from 1-hydroxy-2- acetoxycyclohexane by oxidation cleavage using molecular oxygen in the presence of cobalt acetate, manganese acetate and hydrobromic acid in acetic acid solution. Applying this method to prepare dicarboxylic acids from unsaturated fatty acids, we proposed an efficient method where reaction mixture of unsaturated fatty acids and hydrogen peroxide - formic acid can be oxidative cleaved to produce dicarboxylic acids and monocarboxylic acids in acetic acid solution with molecular oxygen / Co-Mn-Br system. For example, azelaic acid, suberic acid and other dicarboxylic acid as dicarboxylic acids were obtained from industrial oleic acid, which contained oleic acid, palmitoleic acid, linoleic acid, and linolenic acid. As a result of investigation for reaction condition, increase of partial pressure of molecular oxygen or elevation of temperature accelerated oxidative cleavage, but total yields of azelaic acid and suberic acid were slightly decreased. Besides, effect of hydrohalic acids in liquid phase air oxidation in the presence of cobalt and manganese acetates was investigated to show that HBr was the most effective. Soybean acid and tall acid containing higher amounts of linoleic acid and linolenic acid than industrial oleic acid were also oxidatively cleaved to dicarboxylic acids.

A novel synthesis of succinic acid type Gemini surfactant by the functional group interconversion of Corynomicolic acid.

2,3-Bis(undecyl)succinic acid, succinic acid type Gemini surfactant, was successfully synthesized from Corynomicolic acid by the functional interconversion of OH of Corynomicolic acid to COOH via (1) mesylation of OH of syn-isomer, (2) elimination of methanesulfonate group using base to E-alpha,beta-unsaturated ester, (3) Michael addition of CN(-) with 18-crown-6 and (4) hydrolysis. In most hydrolysis conditions, a mixture of syn- and anti-2,3-bis(undecyl)succinic acid was obtained, but hydrolysis in 75% H(2)SO(4) gave only anti-2,3-bis(undecyl)succinic anhydride. After converting a mixture of syn- and anti-2,3-bis(undecyl)succinic acids to corresponding acid anhydrides, syn- and anti-anhydride isomers were separated by column chromatography, and by following hydrolysis syn- and anti-2,3-bis(undecyl)succinic acid was selectively prepared. Based on the surface tension measurement, the effect of stereochemistry on surface tension isotherms was discussed in terms of the hydrophobic interaction between two alkyl groups and the electrostatic repulsion between two hydrophilic COO(-) groups.

Solution properties of gellan gum: change in chain stiffness between single- and double-stranded chains.

Nine samples of gellan gum in the sodium form, ranging in weight-average molar mass from 3.47 x 10(4) to 1.15 x 10(5) at 40 degrees C, were investigated by static and dynamic light scattering and viscometry in 25 mM aqueous NaCl both at 40 and at 25 degrees C. The ratios of the molar mass at 25 degrees C (in the ordered state) to that at 40 degrees C (in the disordered state) were in the range of 1.99 to 2.07, supporting the scheme of the conformational transition of gellan gum between a disassociated single chain and an associated chain composed of two molecules. Focusing on the effects of polydispersity, the intrinsic viscosities, radii of gyration, and hydrodynamic radii were analyzed on the basis of unperturbed wormlike chain models. The persistence lengths were evaluated as 9.4 nm at 40 degrees C and 98 nm at 25 degrees C.

Gelation behavior of native and acetylated konjac glucomannan.

Gelation kinetics of native and acetylated konjac glucomannan (KGM) samples in the presence of alkali (sodium carbonate) was studied by dynamic viscoelastic measurements. Molecular weight and other molecular parameters of KGM were determined by static light scattering and viscosity measurements. It was found that KGM molecules were degraded during acetylation treatment, but the molecular weights of acetylated samples were almost independent of the degree of acetylation (DA) and were about a half of that of a native sample. At a fixed alkaline concentration, increasing concentration of KGM or temperature shortened the gelation time, but increasing DA delayed it. The deacetylation reaction and subsequent aggregation process of acetylated samples needed longer time than that of native sample, and acetylated samples formed finally more elastic gels. It implied that the presence of acetyl groups exerts a strong influence on gelation behavior of KGM. It was suggested that the gelation rate of acetylated KGM and native KGM, which depends on the alkaline concentration and temperature, is an important factor that determines the elastic modulus of gels. This was supported by the experimental finding that the saturated elastic modulus tends to the same value when the ratio of alkali concentration to acetylated groups was kept constant. In slower gelation processes, junction zones are more homogeneously distributed and more numerous, leading to the more elastic gels.