Lipophilic Alcohol Research Articles

Electrochemical Study of the Complex-Forming Properties of Phosphorylated Glucoluril

Complex-forming ability of glucolurildiphosphonic acid synthesized via the classical Arbuzov reaction has been studied using natural fatty lipophilic alcohol cholesterol. As a result of voltammetric examinations, an approach for the production of new sensitive electrochemical sensor for cholesterol detection has been proposed; this sensor exhibits much higher efficiency in comparison with other existing samples.

The effect of a solvent modifier in the cesium extraction by a calix[4]arene: a molecular dynamics study of the oil phase and the oil–water interface

We report a molecular dynamics (MD) study of the effect of a fluorinated lipophilic alcohol (referred to as "cs3" by Delmau et al, Solvent Extr. Ion Exch., 2005, 23, 23) used as a phase modifier in the solvent extraction of Cs(+) NO(3)(-) by a calix[4]arene. It is shown that adding cs3 to a chloroform phase improves the solvation of all partners of the extraction system, i.e. the free calixarene ligand L, its LCs(+) complex and its counterion. This effect is most pronounced for the NO(3)(-) anion that is H-bonded to the -OH and terminal -CF(2)H protons of cs3. On the average, the dissociated nitrate interacts with 2 to 4 cs3 molecules, whereas the associated nitrate (LCs(+)NO(3)(-) complex) interacts with one cs3 dimer. The remaining modifier molecules are mainly dissolved in the solution as dimers or trimers and, to a lesser extent, as monomers and tetramers. Insights into the question of ion pairing in the organic phase are obtained via free energy perturbation (FEP) calculations, showing that the LCs(+)NO(3)(-) paired complex is more stable than its analogue with the dissociated anion. Furthermore, the nitrate dissociation energy is ca. twice as small in the cs3-modified solution than in a pure chloroform phase. We also simulated chloroform/cs3/water ternary systems, showing that the modifiers are surface active and stabilize the formation of water nanodroplets, while other modifier molecules drag some water to the organic phase. Calixarene complexes also adsorb at the aqueous interface in the presence of modifiers, confirming the importance of interfacial phenomena in the assisted cation extraction process. The microscopic insights obtained by the simulations are consistent with experimental results and allow us to better understand why the extraction is enhanced after addition of modifiers to the organic phase.

A Kinetic Study of 2-Ethyl-1-hexanol Oxidation by Dichromate Using Clay-Supported 1-Butyl 4-aza-1-azonia Bicyclo[2.2.2]octane Chloride as the Phase-Transfer Catalyst

Selective oxidation of primary alcohols to aldehydes is a long-standing problem of organic chemistry (Bueler, C. A.; Pearson, D. E. Survey of Organic Synthesis; Wiley-Interscience: New York, 1977; Vol. 2, p 480; House, H. O. Modern Synthetic Reactions, 2nd. ed.; W. A. Benjamin: Menlo Park, California, 1972; p 257; Epstein, W. W.; Sweet, F. W. Chem. Rev. 1967, 67, 247; Landini, D.; Montanari, F.; Rolla, F. Synthesis 1979, 134). The use of potassium dichromate as a synthetically useful oxidizing agent is reported for the oxidation of an industrially important lipophilic alcohol, employing modified clay as the phase-transfer catalyst. The phase-transfer catalysis results in nearly complete oxidation of the 2-ethylhexanol in 40 min at room temperature, with high selectivity to the 2-ethylhexanal, compared to 48 h in its absence. Kinetic studies show the reaction occurs via transfer of Cr2O72- into the organic phase. The emphasis will be on simplicity of the condition as a preparative organic method, selectivity with regard to over-oxidation, efficiency, and mildness of conditions.

Microemulsions as Cutting Fluid Concentrates: Structure and Dispersion into Hard Water

Microemulsions of O/W, of bicontinuous or W/O type were formulated from a paraffinic oil, a lipophilic alcohol (n‐decyl alcohol), an aqueous phase made of MonoEthanolAmine Borate (MEAB) and hard water, and a hydrophilic mixture of cationic and nonionic surfactants. In addition to their intrinsic properties (in particular stability), these microemulsions have some of the most important properties of cutting fluid concentrates, that is to say the easiness with which the emulsion forms when they are dispersed into hard water (a synthetic water that mimics mains water) and the production of very stable emulsions. Actually, their dispersion into hard water at the volume ratios 5/95, 20/80, and 60/40 led to the formation of oil‐in‐water emulsions with an average droplet diameter of 50–150 nm. Three mechanisms of emulsion formation have been identified (i) the dispersion of droplets already present in the system for O/W microemulsion; (ii) the bursting of swollen bilayer structures for bicontinuous microemulsions and; (iii) the formation‐bursting sequence of transient swollen bilayer structures for W/O microemulsions. The shift towards highly hydrophilic conditions during the emulsification process plays a major role in achieving emulsions with these small droplet sizes. Their high stability is to a great extent the result of the small size of the droplets and also the fact that droplets are coated with a layer of charged surfactant complexes.

Analysis of polyethoxylated surfactants in microemulsion-oil–water systems

A normal-phase method for the separation of ethylene oxide number (EON) oligomers by high performance liquid chromatography (HPLC) is described. Isocratic HPLC with mixed solvent on silica column allows to separate oligomers up to EON = 18. Gradient programming moves the limit up to EON = 20. For higher EON values (up to 50) a NH 2 column has to be used, either with isocratic or gradient mode. Detection was performed using UV detector. The partition of surfactant in the oil–water system over the entire concentration range below the CMC was determined. Surfactant-oil–water systems were studied according to the unidimensional scan. The surfactant content in the oil, microemulsion and water phases was determined by HPLC. The addition of a lipophilic alcohol in a Winsor III system produced a decrease in the partition coefficient of the surfactant between the water and oil phases.

Inhibition of plasminogen activator inhibitor release in endothelial cell cultures by antisense oligodeoxyribonucleotides with a 5'-end lipophilic modification.

A series of conjugates containing residues of lipophilic alcohols covalently bound to 5' end of oligodeoxyribonucleotides targeted against human plasminogen activator inhibitor (PAI-1) mRNA was synthesized via the oxathiaphospholane approach. The highest anti-PAI-1 activity in EA.hy 926 endothelial cell cultures was found for conjugates containing menthyl or heptadecanyl groups linked with an oligonucleotide complementary to a segment of human PAI-1 mRNA. The phosphodiester antisense oligonucleotides, which otherwise exhibit only limited anti-PAI-1 activity, were found to be more active than phosphorothioate oligonucleotides when conjugated to lipophilic alcohol residues. For menthyl conjugates an evidence of antisense mechanism of inhibition was found.

Application of Oxathiaphospholane Method for the Synthesis of Oligodeoxyribonucleotide 5′-O-Conjugates

2-Thiono-1,3,2-oxathiaphospholane derivatives of lipophilic alcohols including borneol, cholesterol, menthol and heptadecanol were synthesized and reacted with support-bound oligodeoxyribonucleotides containing free 5′-hydroxyl groups. The reaction is catalyzed by DBU and leads to oligodeoxyribonucleotide conjugates possessing a lipophilic alcohol residue bound at the 5′-end via a phosphorothioate linkage.

Effects of adjuvants on the performance of a novel powdery mildew fungicide, 1-(4-chlorobenzyl)-4-phenylpiperidine

The effects of adjuvants on the performance of a dispersible concentrate formulation (DCI) of a novel powdery mildew fungicide, 1-(4-chlorobenzyl)-4-phenylpiperidine (I) were investigated. The method involved assessment, under glasshouse conditions, of the therapeutic (curative) control of infections of powdery mildew (Erysiphe graminis DC f.sp. hordei Marchal) on barley (Hordeum vulgare, L.) eight to nine days after spray application to plants that had been inoculated one day prior to spraying. The results from the first trial showed that marked improvements (∽five-fold) in the performance of DCI could be obtained by the spray tank addition of some types of surfactant adjuvants and a series of further trials investigating a wide range of adjuvants was conducted. Nonylphenol, alkylamine and alcohol ethoxylates varying in mean ethylene oxide content between 5 and 20 moles were highly effective. There were indications that optimum performance enhancements were obtained with these surfactants containing between 5 and 10 moles ethylene oxide. Lower enhancements, sometimes only marginal, were obtained from trisiloxane, phosphate ester, propylene oxide, alkylamine-propylene oxide and castor oil ethoxylates and also alkyl polyglucoside biosurfactants. Negligible adjuvant enhancements were observed with emulsifiable paraffinic/naphthenic and rape seed oils, though slightly better enhancements were seen with an emulsifiable transmethylated rape seed oil and, interestingly, larger enhancements with an emulsifiable lipophilic alcohol. A final trial identified the alcohol ethoxylate, ‘Dobanol’ 91-6, as the most effective adjuvant and that its optimum application rate under glasshouse conditions was 250 g ha-1. This information will be used to guide the design of field trials. © 1997 SCI

Close Correlation between Heat Shock Response and Cytotoxicity in Neurospora crassa Treated with Aliphatic Alcohols and Phenols

In Neurospora crassa the aliphatic alcohols methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, ethylene glycol, glycerol, and allyl alcohol and the phenolic compounds phenol, hydroquinone, resorcinol, pyrogallol, phloroglucinol, sodium salicylate, and acetylsalicylic acid were analyzed with respect to their capacities to induce heat shock proteins (HSP) and to inhibit protein synthesis. Both the alcohols and phenols showed the greatest levels of HSP induction at concentrations which inhibited the overall protein synthesis by about 50%. The abilities of the different alcohols to induce the heat shock response are proportional to their lipophilicities: the lipophilic alcohol isobutanol is maximally inductive at about 0.6 M, whereas the least lipophilic alcohol, methanol, causes maximal induction at 5.7 M. The phenols, in general, show a higher capability to induce the heat shock response. The concentrations for maximal induction range between 25 mM (sodium salicylate) and 100 mM (resorcinol). Glycerol (4.1 M) shifted the concentration necessary for maximal HSP induction by hydroquinone from 50 to 200 mM. The results reveal that the induction of HSP occurs under conditions which considerably constrain cell metabolism. The heat shock response, therefore, does not represent a sensitive marker for toxicity tests but provides a good estimate for the extent of cell damage.

Retrograde Transition in the Phase Behavior of Surfactant-Oil-Water Systems Produced by an Alcohol Scan

The phase behavior of surfactant-oil-water systems is affected by the so-called formulation variables, i.e., by the nature of the components or their physicochemical characteristics. One of the formulation variables is the alcohol effect, which accounts for the type and concentration of alcohol. In most cases the addition of a lipophilic alcohol contributes to the increase of the amphiphile mixture lipophilicity at the interface, which results in a WI→WIII→WII transition, similar to the one observed when the water salinity is increased. However, in some cases the Winsor II phase behavior is never reached with the alcohol content increase, and a WI→WIII→WI so-called retrograde transition is exhibited instead. Such an anomalous case is analyzed here for a system containing a commercial nonionic polyethoxylated surfactant,n-heptane, water, and n-pentanol, the concentration of the latter playing the role of the formulation variable. HPLC analysis of the different phases indicates that the surfactant oligomer partitioning between phases is affected by the alcohol content. The retrograde transition due to the increase in alcohol content is shown to come from the strong increase in the partitioning of lipophilic and balanced oligomers into the oil phase, with the remaining surfactant, in particular the interfacial mixture, becoming more hydrophilic

Enhancement of Propranolol Hydrochloride and Diazepam Skin Absorption In Vitro: Effect of Enhancer Lipophilicity

□ The enhancement of model hydrophilic (propranolol hydrochloride) and lipophilic (diazepam) drug penetration across rat and hairless mouse skin in vitro has been studied. Preliminary experiments established that most n-alkanes having chain lengths of between 7 and 16 promote the flux of both drugs. For propranolol, enhancement varied parabolically with carbon number; for diazepam, heptane was ineffective and all others were essentially equipotent. Enhancement by n-nonane was then compared with that by n-nonanol. Propranolol flux was increased by both enhancers, whereas diazepam penetration was not affected by the less lipophilic alcohol. The enhancement of propranolol by n-nonane and n-nonanol was examined as a function of adjuvant concentration in the applied formulation. Maximum increases in maximum penetration rates of 6.5-fold (n-nonane) and 8.2-fold (n-nonanol) were determined. As expected, the enhancement was saturable, indicative of a maximally perturbed stratum corneum. Finally, the penetration enhancing abilities of six monoterpenes were assessed. The purely hydrocarbon analogues promoted both propranolol and diazepam transport to an extent similar to that of n-nonane. The terpenes with hydrogen-bonding ability, however, only enhanced propranolol flux (at a level comparable to n-nonanol). While the data reported do not directly reveal mechanistic information on percutaneous penetration enhancement, they do provide a starting point for the rational investigation of interrelationships between drug, enhancer, and skin. Such information is clearly essential for the optimization and exploitation of transdermal drug delivery.

Lipophilic Tartaric Acid Esters as Enantioselective Ionophores

AbstractTartaric acid esters with lipophilic alcohol moieties can discriminate between enantiomeric ammonium ions such as norephedrinium ions. Quantitative results were obtained by partitioning the components between water and 1, 2‐dichloroethane. The stereoselectivity was characterized by the free energy difference of the partition process (ΔΔG). Diamond‐lattice sectors were used to construct models of the (unstable) lipophilic ester/ammonium salt complexes from X‐ray structures of the individual components (esters and ammonium salts). These models can be used to interpret the effect of structure and configuration of the alcohol moiety on the stereoselectivity and enantioselectivity towards 1‐phenyl‐2‐amino‐1‐propanol (norephedrine) salts.

An improved procedure for the synthesis of choline phospholipids via 2-bromoethyl dichlorophosphate.

Choline phospholipids can be conveniently synthesized by reaction of a lipophilic alcohol, such as diacylglycerol, with 2-bromoethyl dichlorophosphate followed by nucleophilic displacement of the bromine with trimethylamine. We found that the low yields often encountered in the initial phosphorylation step are particularly due to exchange of both chlorines for alkoxy functions (triester formation) and to chlorination of the alcohol by 2-bromoethyl dichlorophosphate. However, these drawbacks can be overcome by proper choice of the reaction medium and by optimizing other reaction conditions. The procedure described is efficient and most versatile, and it lends itself to the preparation of a wide range of choline phospholipids containing a glycerol, diol, or long-chain alkyl backbone and bearing various aliphatic functions. Proton and carbon-13 nuclear magnetic resonance spectroscopy proved useful in establishing the homogeneity and structures of the synthetic intermediates and byproducts and of the choline phospholipids synthesized.