Monoalkyl Ethers Research Articles

New focus of the cloud point/Krafft point of nonionic/cationic surfactants as thermochromic materials for smart windows.

A nonionic poly(oxyethylene) monoalkyl ether (C12(EO)6) and a cationic hexadecylpyridinium bromide (HPB) were used to achieve warm/cool transparency transition switchability, depending on the decrease in the hydration of the EO-headgroup of C12(EO)6 above the cloud point (Tc) and the crystallization of HPB below the Krafft point (Tk). The liquid state shows the advantage of being free-flowing, frost-resistance, flexible-adjustment and solar-energy-storing-capability due to the moisture-rich characteristics, while the hydrogel state exhibits free-standing properties.

Test and research on suppressing fire of lithium-ion battery with water mist containing additive

In order to improve the fire extinguishing effect on lithium-ion battery fires, the paper experimented with compound solution of sodium dodecylbenzenesulfonate-dodecanol-sodium carbonate at a ratio of 3:2:2, polyfiouroalkyll betaine-alkylglycoside-potassium carbonate at a ratio of 2: 3: 3 and monoalkyl ether phosphate potassium-fatty acid ester polyoxyethylene etherurea at a ratio of 3:2: 3. The fire of the lithium-ion battery was extinguished with water mist containing additive compound solution by building lithium-ion battery fire extinguishing experimental platform. The experiment selected four different concentrations of 0.5%, 1%, 1.5%, and 2%. The results showed that the polyfluoroalkyl betaine-alkyl glycoside-potassium carbonate compound solution had better fire extinguishing effect in the early stage of thermal runaway, and the battery did not reignite. The sodium dodecylbenzene sul-fonate-dodecanol-sodium carbonate compound solution took the least time to reduce the battery temperature to below 200 °C. In the later period, the sodium dodecylbenzenesul-fonate-dodecanol-sodium carbonate compound solution has the greatest advantage in cooling rate. In the gas absorption test, the sodium dodecylbenzenesulfonate-dodecanoll-sodium carbonate compound solution has the best absorption effect on methane, and the polyfluoroalkyl betaine-alkyl glycoside-potassium carbonate compound solution releases CO. The concentration of the compound has a more obvious drop than the other two compound solutions.

Получение олеофильного сорбента и изучение его нефтепоглотительных свойств

In recent years, in the sphere of water purification, there has been successfully developed the direction of producing effective sorbents of petroleum products associated with altering the nature of their surface with compounds of various classes. An effective method is the hydrophobization process involving a special processing of materials by immersion in solutions or melts of water repellents, spraying them on the surface, etc. As water repellents, there are used silicon organic compounds, paraffin, monoalkyl ethers of polyethylene glycol, high molecular weight compounds, etc. The hydrophobizer itself must have good adhesion to the material and, being evenly distributed during the processing, it can form bonds with the surface, which will allow it not to be washed out and not to dissolve further during operation. However, hydrophobization has some disadvantages, such as the complexity of obtaining a modified surface which would be resistant to leaching, a considerable material consumption, a high cost, etc. In this work, we have investigated the possibilities of hydrophobization of expanded perlite with quaternary ammonium salts in order to reduce its water absorption. The optimal parameters of the hydrophobization process have been established. It is shown that among the used ammonium modifiers, the greatest beneficial effect is observed for catamine AB-18: under static conditions, the sorption capacity of expanded perlite samples modified with its 1 % solution is 2-3.5 times higher than the corresponding indicator of the original.

Loss of a membrane phase under soft confinement conditions imposed by a porous silica colloids network

Poly(ethylene glycol) mono-alkyl ether (CnEm) nonionic surfactants can form various liquid crystalline phases in water that are not altered by a change of pH nor by the presence inorganic materials. Their nonionic membrane phases were thus used as model system to mimic biological cell membranes and their behavior in the presence of inorganic colloids. In this study, a membrane phase formed by the triethylene glycol monodecyl ether (C10E3) nonionic surfactant was used as a model system to study the impact of topological constraints, and other confinement effects imposed / induced by aerosil gels. Smoked silica aerosil nanoparticles formed porous gels when aerosils interacted by siloxane bonds, in which both the pore volume and surface disorder were modulated by the concentration of nanoparticles with diameters of 7, 16, 20 & 40 nm. With the use of small angle X-ray scattering (SAXS) and polarized optical microscopy (POM) techniques as probes, the nonionic membranes could be stabilized at high temperatures, up to 8 °C higher than with bulk systems. These collapsed at high aerosil concentrations where, however drastic effects of confinement (finite size, interaction to the surface) altered the rigidity of the membranes. These effects led to a slowing down of the dynamics and a change in the elastic properties of the membranes that were not able to adapt within the aerosil gels, leading to their collapse into micellar phases. Since aerosils gels can be aligned by weak stimuli, one of a research prospects may concern the understanding of the confinement of nonionic membrane phases formed by the C10E3 as well as other CnEm surfactants in these anisotropic soft confinement matrixes.

Quantitatively Assessing the Salting-Out Capacity of Inorganic Salts with Respect to Ethoxylated Surfactants

The results from assessing the salting-out capacity of inorganic salts with respect to poly(ethylene glycol) monoalkyl ethers (DS-10 and ALM-10 synthanols) are summarized. The effect the length of the aliphatic substituent in a molecule of a surfactant has on the salting-out capacity is determined. The correlation dependences between the energy of hydration of ions and their salting-out capacity are determined for poly(ethylene glycol) monoalkyl ethers and ethoxylated nonylphenols (AF 9-12 and AF 9-25 neonols).

Radical-Hydroboration-Involved One-Pot Synthesis of Boron-Handled Glycol Derivatives

A one-pot two-step protocol for the direct synthesis of boron-handled glycol derivatives is reported. The procedure starts by an NHC–boryl-radical-promoted regioselective hydroboration of glycol-protected cinnamaldehydes. After that, the reaction mixture is treated with pinacol in the presence of HCl, leading to the direct formation of pinacol boronate handled glycol monoalkyl ethers. In this acid-triggered conversion, a reductive ring-opening of glycol-derived acetal moiety takes place, during which an NHC–borane unit serves as the hydride source.

Partial Molar Volumes and Partial Molar Isentropic Compressions of Two Poly(ethylene glycol) Monoalkyl Ethers, C4E2 and C1E3, at Infinite Dilution in Water at Temperatures T = 278–343 K and Atmospheric Pressure

Density and speed of sound data for dilute aqueous solutions of two poly(ethylene glycol) monoalkyl ethers, H–(CH2)n–(O–CH2–CH2)m–OH for n = 4, m = 2 and n = 1, m = 3, were measured using the Anton...

Anchimerically Assisted Selective Cleavage of Acid-Labile Aryl Alkyl Ethers by Aluminum Triiodide and N,N-Dimethylformamide Dimethyl Acetal.

Aluminum triiodide is harnessed by N,N-dimethylformamide dimethyl acetal (DMF-DMA) for the selective cleavage of ethers via neighboring group participation. Various acid-labile functional groups, including carboxylate, allyl, tert-butyldimethylsilyl (TBS), and tert-butoxycarbonyl (Boc), suffer the conditions intact. The method offers an efficient approach to cleaving catechol monoalkyl ethers and to uncovering phenols from acetal-type protecting groups such as methoxymethyl (MOM), methoxyethoxymethyl (MEM), and tetrahydropyranyl (THP) chemoselectively.

Partial molar volumes of organic solutes in water. XXX. Two poly(ethylene glycol) monoalkyl ethers, C4E2 and C1E3, at temperatures T = 298 K to 573 K and pressures up to 30 MPa

Densities of dilute aqueous solutions of two aliphatic poly(ethylene glycol) monoalkyl ethers, H-(CH2)4-(O-CH2-CH2)2-OH (diethylene glycol monobutyl ether, C4E2) and H-CH2-(O-CH2-CH2)3-OH (triethylene glycol monomethyl ether, C1E3) measured in the temperature range from (298 to 573) K and at pressures up to 30 MPa using an automated flow vibrating-tube densimeter are reported. Standard molar volumes were evaluated from the measured data. A comparison with data previously measured for selected members of the homologous series of similar solutes (poly(ethylene glycols), glymes, 2-alkoxyethanols) is presented.

Molecular Modeling of Surfactant Micellization Using Solvent-Accessible Surface Area.

We report a new implicit solvent simulation model for studying the self-assembly of surfactants, where the hydrophobic interactions were captured by calculating the relative changes of the solvent-accessible surface area (SASA) of the hydrophobic domains. Using histogram-reweighting grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to match both the experimental critical micelle concentrations (cmc) and micellar aggregation numbers simultaneously with a single phenomenological surface tension γSASA for the poly(oxyethylene) monoalkyl ether (C mE n) surfactants in aqueous solutions. Excellent transferability is observed: the same model can accurately predict the experimental cmc and aggregation numbers for the C mE n surfactants with the alkyl lengths m between 6 and 12 and the poly(oxyethylene) lengths n between 1 and 9. The SASA-based implicit solvent model put forward in this work is general and may be applied to study more complex amphiphilic systems such as surfactants with branched alkyl chains or surfactant-hydrocarbon mixtures.

Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide–Dimethyl Sulfoxide

Using eugenol and vanillin as model substrates, a practical method is developed for the cleavage o-hydroxyphenyl alkyl ethers. Aluminum oxide iodide (O=AlI), generated in situ from aluminum triiodide and dimethyl sulfoxide, is the reactive ether cleaving species. The method is applicable to catechol monoalkyl ethers as well as normal phenyl alkyl ethers for the removal of methyl, ethyl, isopropyl, and benzyl groups. A variety of functional groups such as alkenyl, allyl, amide, cyano, formyl, keto, nitro, and halogen are well tolerated under the optimum conditions. Partial hydrodebromination was observed during the demethylation of 4-bromoguaiacol, and was resolved using excess DMSO as an acid scavenger. This convenient and efficient procedure would be a practical tool for the preparation of catechols.

Anchimerically Assisted Cleavage of Aryl Methyl Ethers by Aluminum Chloride‐Sodium Iodide in Acetonitrile

AbstractA practical method is developed for the cleavage of catechol monomethyl ethers and o‐carbonylphenyl methyl ethers using aluminum chloride and sodium iodide in acetonitrile. Acid scavengers such as 1,3‐diisopropylcarbodiimide and CaO are used to prevent acid‐labile functional groups from side‐reactions. This method is efficient for the deprotection of various o‐hydroxyphenyl methyl ethers such as acetovanillone, eugenol, guaiacol, vanillin, isovanillin and ortho‐vanillin. The AlCl3‐NaI system is less efficient than AlI3 for the cleavage of other typical aryl alkyl ethers without a neighboring hydroxyl or carbonyl group, or for the removal of bulkier alkyl groups from catechol monoalkyl ethers. This procedure represents a convenient approach for the preparation of catechols.

The role of competitive counterion adsorption on the electrolyte induced surface ordering in methyl ester sulfonate surfactants at the air-water interface

The strong binding of Al3+ trivalent counterions to the anionic surfactants sodium polyethylene glycol monoalkyl ether sulfate and α-methyl ester sulfonate results in surface multilayer formation at the air-water interface. In contrast the divalent and monovalent counterions Ca2+ and Na+ result only in monolayer adsorption. Competitive counterion adsorption has been extensively studied in the context of surfactant precipitation and re-dissolution, but remains an important feature in understanding this surface ordering and how it can be manipulated.The α-methyl ester sulfonate surfactants are a promising class of anionic surfactants which have much potential for improved performance in many applications, greater tolerance to extreme solvent conditions such as water hardness, biocompatibility and sustainable production. Hence in this study we have used neutron reflectivity to extend previous studies on the surface ordering of the α-methyl ester sulfonate surfactant, sodium tetradecanoic 2-sulfo 1-methyl ester, in the presence of electrolyte to investigate the role of binary mixtures of electrolytes, AlCl3/CaCl2, and AlCl3/MgCl2.In the mixed electrolytes the evolution of the surface structure, from monolayer to multilayer with increasing AlCl3 concentration, is observed. It is broadly similar to that reported for the addition of only AlCl3. However with increasing CaCl2 concentration the structural evolution is shifted progressively to higher AlCl3 concentrations. Similar observations occur for the AlCl3/MgCl2 mixtures. However the presence of the MgCl2 results in an additional phenomenon; the partial co-adsorption of a more compact lamellar structure which exists until the highest AlCl3 concentrations. The results demonstrate the importance of the competitive adsorption of different counterions in driving and controlling the formation of surface multilayer structures with anionic surfactants. Furthermore it offers a facile route to the manipulation of these surface structures.

Effective osmotic cohesion due to the solvent molecules in a delocalized adsorbed monolayer

A molecular thermodynamic model is derived for an uncharged delocalized surfactant monolayer adsorbed at a liquid interface, taking explicit account for the solvent molecules present in the monolayer. The model is based on the scaled particle theory of hard-disc mixtures, and is also extended to sticky discs (i.e. attraction between the adsorbed molecules). Upon compression of the adsorbed layer, the solvent is expelled from it. The respective osmotic effect on the equation of state is shown to be equivalent to an effective lateral depletion attraction between the surfactant molecules. This effective osmotic cohesion causes an increase of the value of the attraction parameter β of the monolayer. The smaller the size of the surfactant polar head group is, the larger the effective attraction the model predicts. This trend is verified with data for the adsorption at water|air surface of alcohols, undissociated acids, and hexaethylenglycol monoalkyl ethers. The proposed theory allows the amount of solvent in the monolayer to be estimated, which is shown to be important for the neutron reflectivity of the surface.

Liquid-crystalline behavior and ion transport properties of block-structured molecules containing a perfluorinated ethylene oxide moiety complexed with a lithium salt

The liquid-crystalline behavior of fluorinated block-structured molecules and the ion transport properties of their complexes with a Li salt have been examined. The block-structured molecules comprise a perfluorinated oligo (ethylene oxide) moiety containing a terminal methyl carbonate or a terminal hydroxyl group and an octadecyl moiety. These molecules exhibit highly ordered smectic phases. The fluorinated molecule with a terminal methyl carbonate possesses an isotropization temperature lower than that of the analogous non-fluorinated molecule. The fluorinated molecule complexed with a Li salt shows ionic conductivities on the order of 10−6 S cm−1 in the smectic phase formed at ambient temperature, while conductivities on the order of 10−5 S cm−1 are observed in the isotropic phase. A perfluorinated oligo (ethylene oxide) monoalkyl ether containing a terminal methyl carbonate has been developed for potential application as quasi-solid-state electrolytes for Li-ion batteries. The fluorinated block-structured molecule self-assembles to form nanosegregated bilayer structures, which can be used for anisotropic Li ion transport when complexed with a Li salt. The complex shows ionic conductivities on the order of 10−6 S cm−1 in the ordered smectic phase formed at ambient temperature.

Comparative Study on Catalytic Dehydration of Glycerol with Alcohols

A comparative study of glycerol dehydration with alcohols (methanol, ethanol, tert-butyl alcohol) over ion exchange resin Amberlyst-35 was performed. The effect of catalyst amounts (1-15 wt.% to glycerol), reaction temperature (50-100 oC), reaction time (5-10 h), and the molar ratio of alcohols to glycerol (3:1-8:1) were carried out in 50 mL stainless steel autoclave. During the process of glycerol dehydration with alcohols, when the catalyst amount (wt.% to glycerol) is over 10%, it was observed that neither glycerol conversion nor product selectivities are changed significantly. The optimum molar ratios of glycerol to methanol, ethanol and tert-butyl alcohol were 1:6, 1:4, and 1:6, respectively. The appropriate reaction temperature and reaction time were 80 oC and 8 h at which the selectivities of di-alkyl glycerol ethers and tri-alkyl glycerol ether arrive to the highest. However, the main product was mono-alkyl glycerol ether (MAGE) in glycerol dehydration with tert-butyl alcohol due to steric hindrance influence. If MAGE is considered as the target product, the glycerol dehydration with tert-butyl alcohol could be a good choice. Additionally, the glycerol dehydration with ethanol could be a better route converting biomass material into vehicle fuel in view of its desired yields of higher ethers.

Predicting Critical Micelle Concentrations with Molecular Dynamics Simulations and COSMOmic

AbstractSurfactants are amphiphilic molecules which are capable of forming micelles. Therefore, they are used in many applications. The critical micelle concentration (CMC), the surfactant concentration at which micelles start to form, is an important property of these systems. Here, the applicability of COSMOmic (an extension of COSMO‐RS) to predict CMCs is reported for the first time. Molecular dynamics simulations were used as second method to calculate transfer free energies needed for the calculation of CMCs. In particular, CMCs for poly(oxyethylene) monoalkyl ether surfactants are determined.

The effect of glycols and their ethers on micellar behavior of cetyltrimethylammonium tosylate

The effect of glycols viz., ethylene glycol (EG), diethylene glycol (DEG) propylene glycol (PG), dipropylene glycol (DPG) and their monoalkyl ethers on the morphological features of cetyltrimethylammonium tosylate (CTAT) micelle was examined from viscosity and small angle neutron scattering (SANS) measurements. EG and DEG, and their short chain ethers showed an initial increase in viscosity followed by a decrease while long chain PG, DPG and their ethers showed a monotonous decrease in viscosity. SANS results support the viscosity behavior. These trends are explained on the basis of hydrophobicity of the additives that determines its location in the micelle exerting an effect on micelle morphology. The critical micelle concentrations (CMCs) of CTAT determined tensiometrically for selected systems are also reported. This study helps in fine tuning of rheology of micellar systems in the presence of gycols and their ethers often used with surfactant systems.

Diffusion of monoalkyl ethers of poly(ethylene glycols) and octyl-β-D-glucopyranoside in micellar solutions

Diffusion coefficients of monoalkyl ethers of poly(ethylene glycols), С8Е4 and С12Е5, and octyl-β-D-glucopyranoside have been measured in aqueous micellar solutions within wide ranges of temperatures and concentrations by dynamic light scattering. The study of the С12Е5–water system containing cylindrical micelles has been supplemented with viscosity measurements, which make it possible to better monitor structural transformations and phase transformations.

Scent gland constituents of the Middle American burrowing python, Loxocemus bicolor (Serpentes: Loxocemidae).

Analysis by gas chromatography/mass spectrometry of the scent gland secretions of male and female Middle American burrowing pythons (Loxocemus bicolor) revealed the presence of over 300 components including cholesterol, fatty acids, glyceryl monoalkyl ethers, and alcohols. The fatty acids, over 100 of which were identified, constitute most of the compounds in the secretions and show the greatest structural diversity. They include saturated and unsaturated, unbranched and mono-, di-, and trimethyl-branched compounds ranging in carbon-chain length from 13 to 24. The glyceryl monoethers possess saturated or unsaturated, straight or methyl-branched alkyl chains ranging in carbon-chain length from 13 to 24. Alcohols, which have not previously been reported from the scent glands, possess straight, chiefly saturated carbon chains ranging in length from 13 to 24. Sex or individual differences in secretion composition were not observed. Compounds in the scent gland secretions of L. bicolor may deter offending arthropods, such as ants.