Alcohol Molecules Research Articles

Tuning the Friction of Graphene on Mica by Alcohol Intercalation.

The friction of graphene on mica was studied using lateral force microscopy. We observed that intercalation of alcohol molecules significantly increases the friction of graphene, as compared to water. An increase of 1.8, 2.4, and 5.9 times in friction between the atomic force microscopy tip and single-layer graphene was observed for methanol, ethanol, and 2-propanol, respectively. Moreover, the friction of graphene is found to be higher for single-layer graphene than for multilayer graphene. We attribute the increase in friction to the additional vibrational modes of alcohol molecules. The significant variation of the frictional characteristics of graphene at the nanoscale by altering the intercalant could open up applications for the next-generation nanolubricants and nanodevices.

COMPUTER SIMULATION OF THE POROUS STRUCTURE OF HYDROLYSIS LIGNIN AND ITS HARD COMPO-SITES WITH COMPONENTS OF OIL FUELS AND WATER

A fragment of the supramolecular structure of lignin was simulated by cross-linking the C546H600O196 structural units along the corresponding CH–bonds followed by geometric optimization by the Polac-Ribier’s conjugate gradient method in the MNDO field of the HyperChem 8.0 software and ChemBio 13.0. The pore structure of lignin was simulated as well with optimization by the molecular mechanic’s method according to the MM2 Norman-Alinger’s algorithm taking into account the dipole-dipole interaction. Сoumaric alcohol molecule was a building block. The calculation of the energy parameters of lignin’s pore structure filling by the molecules of organic substances and water were carried out. It included a search for a global minimum of the potential energy by the molecular mechanic’s method according to the MM2 program and by the molecular dynamics method. The calculation had its basis in the “closed” pores existence in lignin. The calculated values of pore volume and specific surface area correlate with the experimental data. The way of prediction of organic substances sorption activity to lignin was proposed. This is evident from their calculated hydrophobicity parameter that correlates with the interaction energy of the molecules in the lignin pore.

Derivatization of Ions under the Conditions of Surface Assisted Laser Desorption/Ionization

A method for the chemical modification (derivatization) of ions obtained by surface assisted laser desorption/ionization (SALDI) is proposed. Derivatization is based on the interaction of desorbed ions with alcohol molecules. The method is simple, does not affect the duration of analysis and ensures the improvement of the analytical characteristics of the SALDI method, when analysis is carried out under the conditions of peak interference and strong fragmentation of analyte ions. The efficiency of the method is demonstrated in the determination of caffeine, pyrrolidine, and diphenhydramine under the conditions of atmospheric pressure sample application.

Selectivity of Carbon Nanotubes under An Electric Field on Transferring Water – Alcohol Mixtures

Carbon nanotubes (CNTs) have shown a great promise for nanofluidic-based applications such as for separation membranes. Water confined in nanotubes has different properties compared with those in bulk. Therefore, to develop a membrane with CNTs, it is very important to clarify the behavior of water in CNTs. In this study, we show effects of an electric field on water in a CNT by molecular dynamics simulation. An electric field aligns the dipole moment of water molecules and induces formation of an ordered structure in a CNT. As a result, the electrostatic interaction between water molecules within the structure becomes stronger. Strengthening of the electrostatics interaction facilitates water molecules preferring to fill a CNT over alcohol molecules. This indicates a strong separation effect for water-alcohol solutions.

Low-Temperature Conversion of Alcohols into Bulky Nanoporous Graphene and Pure Hydrogen with Robust Selectivity on CaO.

The direct conversion of biorenewable alcohols into value-added graphene and pure hydrogen (H2 ) at benign conditions is an important challenge, especially, considering the open carbon-reduced cycle. In this study, it is demonstrated that inexpensive calcium oxide (CaO, from eggshells) can transform alcohols into bulky nanoporous graphene and pure hydrogen (≈99%) with robust selectivity at the temperature as low as 500 °C. Consequently, the growth of graphene can follow the direction of alcohol flow and uniformly penetrate into bulky nanoporous CaO platelets longer than 1 m without clogging. The experimental results and density functional theory calculations demonstrate that alcohol molecules can be catalytically carbonized on the surface of CaO at low temperature. The concept of the comprehensive utilization of biomass-derived alcohols offers a carbon-negative cycle for mitigating global warming and the energy demand.

Influence of Structure-modifying Agents in the Synthesis of Zr-doped SBA-15 Silica and Their Use as Catalysts in the Furfural Hydrogenation to Obtain High Value-added Products through the Meerwein-Ponndorf-Verley Reduction.

Zr-doped mesoporous silicas with different textural parameters have been synthesized in the presence of structure-modifying agents, and then characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption at −196 °C, NH3 thermoprogrammed desorption (NH3–TPD), CO2 thermoprogrammed desorption (CO2–TPD), and X-ray photoelectron spectroscopy (XPS). These porous materials were evaluated in the furfural hydrogenation through the Meerwein-Ponndorf-Verley (MPV) reaction. The catalytic results indicate that the catalyst synthesized under hydrothermal conditions and adding a pore expander agent is more active and selective to furfuryl alcohol. However, the Zr-doped porous silica catalysts that were synthesized at room temperature, which possess narrow pore sizes, tend to form i-propyl furfuryl and difurfuryl ethers, coming from etherification between furfuryl alcohol (FOL) and isopropanol molecules (used as H-donor) by a SN2 mechanism.

Direct Synthesis of Diallyl Carbonate Via Urea Transesterification with Allyl Alcohol Over Metal Chlorides

A promising technique was studied towards diallyl carbonate (DAC) manufacture via urea transesterification with allyl alcohol over several metallic chlorides. It was revealed that the intermediate allyl carbamate (AC) was first generated via urea mono-alcoholysis with high yield, and subsequently AC further reacted with another allyl alcohol molecule to produce DAC. All the metal halides were evaluated for the overall reaction and the reaction of AC and allyl alcohol, respectively. This work found that the catalytic ability of catalysts originated from metal ions. Importantly, the highest yield of DAC could be achieved using LaCl3 as catalyst. In addition, the activation patterns of reactants were investigated using in situ FT-IR measurement. Based on the characterization results of X-ray power diffraction and elemental analysis of the lanthanum species, separated from the reaction conduced over LaCl3, a possible reaction mechanism was speculated.

Expanding production regions of α-form and β-form glycine using an antisolvent crystallization method assisted by N2 fine bubbles

To develop a crystallization technique that can enhance the production of metastable α-form and unstable β-form glycine, we studied the antisolvent crystallization of glycine using the gas–liquid interfaces around N2 fine bubbles as novel crystallization fields. In the regions near the gas–liquid interfaces, local supersaturation is generated because of the accumulation of glycine and alcohol as an antisolvent as a result of the negative electric charge on the fine bubble surface. Hence, the produced glycine polymorphs change from the stable γ-form to a α-form or β-form glycine. Additionally, local supersaturation at the gas–liquid interfaces can be expected to change via modification of the accumulation of the glycine and alcohol molecules and the interaction of glycine-water-alcohol with the different alcohol additives. At a solution temperature of 303 K, methanol (MeOH), ethanol (EtOH), or isopropanol (IPA) as an antisolvent were rapidly mixed into the saturated glycine solution. While mixing MeOH, EtOH, or IPA with the saturated glycine solution, N2 fine bubbles with an average size of 10 µm were continuously supplied to the mixed solution using a self-supporting bubble generator and a glycine polymorph was crystallized within 5 min. For comparison, an antisolvent crystallization free of N2 fine bubbles was conducted using a propeller type mixer. During antisolvent crystallization with/without fine bubble injection, the additional alcohol volume was varied to control the generation rate of the supersaturation in the bulk solution (rC/CS). Consequently, the production regions of the α-form and β-form glycine were broadened to lower rC/CS via N2 fine bubble injection. The expansion behavior for α-form or β-form glycine significantly increased because of the enhancement of local supersaturation at the regions near the gas–liquid interfaces of the N2 fine bubbles owing to the decreasing carbon number in the alcohol.

Microdrop-Assisted Microdomain Hydrophilicization of Superhydrophobic Surfaces for High-Efficiency Nucleation and Self-Removal of Condensate Microdrops.

Superhydrophobic-hydrophilic hybrid surfaces have attracted intensive interest because of their significant academic and commercial values. However, almost all reported microdomain hydrophilicization methods rely on costly micropatterning techniques that need special instruments. Here, we report a microdrop-assisted method for microdomain hydrophilicization of a low-adhesive superhydrophobic surface and demonstrate its utility in high-efficiency nucleation and self-removal of condensate microdrops. Micrometer-sized fogdrops containing polyvinyl alcohol molecules can be selectively captured by breath figures of superhydrophobic surfaces with specific sizes and spatial distributions and can be converted into desired hydrophilic microdomains after thermal evaporation. After exploring the influence of hydrophilic microdomains' distributions and sizes to surface wettability, adhesion, and condensation dynamics, we achieved an optimal hybrid surface, which possesses 240% average microdrop density, 387% microdrop self-removal rate, and 75% average microdrop diameter as compared to the contrast superhydrophobic surface with uniform chemistry nature. This method is dispensed with special equipment, easy to implement, very cheap, and eco-friendly, which would help develop other superhydrophobic-hydrophilic hybrid surfaces with different functions such as water harvesting, dehumidification, and heat exchange.

Molecule Self-Assembly Synthesis of Porous Few-Layer Carbon Nitride for Highly Efficient Photoredox Catalysis.

Polymeric carbon nitride (C3N4) has emerged as the most promising candidate for metal-free photocatalysts but is plagued by low activity due to the poor quantum efficiency and low specific surface area. Exfoliation of bulk crystals into ultrathin nanosheets has proven to be an effective and widely used strategy for enabling high photocatalytic performances; however, this process is complicated, time-consuming, and costly. Here, we report a simple bottom-up method to synthesize porous few-layer C3N4, which involves molecule self-assembly into layered precursors, alcohol molecules intercalation, and subsequent thermal-induced exfoliation and polycondensation. The as-prepared few-layer C3N4 expose more active sites and greatly enhance the separation of charge carriers, thus exhibiting a 26-fold higher hydrogen evolution activity than bulk counterpart. Furthermore, we find that both the high activity and selectivity for the oxidative coupling of amines to imines can be obtained under visible light that surpass those of other metal-free photocatalysts so far.

1-Hexanol conformers in a nitrogen matrix: FTIR study and high-level ab initio calculations

FTIR spectra of 1-hexanol trapped in a nitrogen matrix were registered in the temperature range from 10 to 40 K. The experiment has shown that only non‑hydrogen-bonded alcohol molecules were present in the sample at 10 K. Conformational analysis using high-level ROCBS-QB3 ab-initio calculations has shown that only 111 of 122 1-hexanol conformers can exist. The most stable conformer was determined. Anharmonic quantum-chemistry calculations and further special scheme of principal component analysis resulted in at least 12 unneglectable conformers in the sample, 6 of which form about 85% of FTIR spectra in the region of the stretching OH vibrations. Sample heating leads to a significant redistribution between conformers. Relative weights of different conformers at all investigated temperatures did not match Boltzmann probability distribution. Moreover, 1-hexanol structure was formed not by all the most stable structures, but only by some of them.

Theoretical study of transesterification of diethyl carbonate with methanol catalyzed by base and Lewis acid

A detailed study of mechanism of the reaction transesterification of diethyl carbonate with methanol as a model reaction of chemical recycling of polycarbonate waste has been investigated theoretically. Thermodynamics parameters have been described at B3LYP/6-311++G(df,p) level. The calculations show that in the case on non-catalytic reaction the presence of hydrogen-bonded methanol cluster can noticeably reduce the energy barrier. This complex possesses higher electron–donor and acid–base properties than free alcohol molecules, thus increasing the activity of complexes in the reaction. The calculations show that the catalysis by sodium methylate is much more preferable than the catalysis with zinc acetate.

Fe2 VO4 Hierarchical Porous Microparticles Prepared via a Facile Surface Solvation Treatment for High-Performance Lithium and Sodium Storage.

Preventing the aggregation of nanosized electrode materials is a key point to fully utilize the advantage of the high capacity. In this work, a facile and low-cost surface solvation treatment is developed to synthesize Fe2 VO4 hierarchical porous microparticles, which efficiently prevents the aggregation of the Fe2 VO4 primary nanoparticles. The reaction between alcohol molecules and surface hydroxy groups is confirmed by density functional theory calculations and Fourier transform infrared spectroscopy. The electrochemical mechanism of Fe2 VO4 as lithium-ion battery anode is characterized by in situ X-ray diffraction for the first time. This electrode material is capable of delivering a high reversible discharge capacity of 799 mA h g-1 at 0.5 A g-1 with a high initial coulombic efficiency of 79%, and the capacity retention is 78% after 500 cycles. Moreover, a remarkable reversible discharge capacity of 679 mA h g-1 is achieved at 5 A g-1 . Furthermore, when tested as sodium-ion battery anode, a high reversible capacity of 382 mA h g-1 can be delivered at the current density of 1 A g-1 , which still retains at 229 mA h g-1 after 1000 cycles. The superior electrochemical performance makes it a potential anode material for high-rate and long-life lithium/sodium-ion batteries.

The unusual reaction of alkylation of dicarboxylate phosphabetaines in alcohol media

The new reaction of alkylation of dicarboxylate phosphabetaines by alkyl halides in alcohol media has been opened. In this reaction alkyl radical enters to the ester part of molecule not from alkyl halide, but from the alcohol molecule. The structure of the isolated compounds was determined by IR and NMR spectroscopy, elemental and X-ray analysis.

Kinetics of Isoprene Polymerization in the Presence of the Catalytic System NdCl3 · nCH3CH(OH)CH3-Al(i-C4H9)3-Piperylene

A kinetic model is developed for the formation of the NdCl3 · nROH complex (ROH is isopropanol and n is the number of alcohol molecules in the complex), which relates the initial diameter of NdCl3 particles with the kinetics of NdCl3 · nROH complex formation and n. A kinetic model is also developed for isoprene polymerization in the presence of the NdCl3 · nROH-Al(i-C4H9)3-piperylene catalytic system that describes the kinetics of polymerization and molecular weight characteristics of isoprene rubber. According to the simulation, it was shown that (1) the experimentally observed increase in the polymerization rate with increasing n from 0.75 to 2.43 is caused by an increase in the concentration of chain growth sites; (2) the experimentally observed dependence of the molecular weight characteristics of isoprene rubber on n is explained by the functioning of various types of chain growth sites at different values of n and the distribution of isoprene concentration over the radius of the polymer-catalyst particle (particles of the catalytic system with chains of isoprene rubber adsorbed on its surface).

Development of sugar based biodegradable nanoencapsulators: Understanding the role of the alcohol injection method on the preparation of aqueous dispersions of sorbitan ester vesicles

Global environmental concerns on the production, usage and disposal of multiple human-made products have encouraged the study and development of new more ecological materials based on or inspired by biomolecules that may ultimately replace the current existing options. These efforts include the development of sugar-based surfactants. They have been increasingly adopted in selected applications to replace conventional surfactants. Sorbitan ester is a good example of a sugar-based surfactant already in use in the food industry as an emulsifier agent. However, in aqueous solution, the use of this type of surfactants is highly limited as nanocompartments due to their low water solubility. This problem can be overcome by using the alcohol injection method (AIM), where a small amount of alcohol is mixed with the surfactant in water to produce dispersed vesicles. Since the formation of sorbitan ester vesicles are of enormous interest for the nanoencapsulation of active substances for various applications, from food to cosmetics and pharmaceuticals, it is crucial to develop efficient ways to produce these aggregates via the alcohol injection method. The present work reports a study of the role of the alcohol structure on the formation of nanostructures of sorbitan ester. Methanol, ethanol and 2-propanol were selected to evaluate the influence of the alcohol alkyl chain length on the formation and stabilization of the vesicles. Some of the alcohol solutions were evaporated in order to probe the stability of the aggregates even after alcohol removal. Analysis by dynamic light scattering (DLS) and 1H NMR have shown a direct relation between the size of the alcohol's alkyl chain and the size of the formed sugar-based vesicles. Additionally, it is clear that the alcohol molecules remain in the vesicle, even after the evaporation process.The obtained results demonstrate that it is possible to control the size of the sugar-based sorbitan ester vesicles using the alcohol injection method. Hopefully, this research will encourage and enable the use of nanocompartments in a wider range of applications.

Theoretical Description of Mixed Film Formation at the Air/Water Interface: Carboxylic Acids-Alcohols.

The thermodynamic parameters of formation and clusterization of aliphatic alcohols CnH2n+1OH and carboxylic acids CnH2n+1COOH (n = 6–16) are calculated using the quantum-chemical semiempirical PM3 method. Four types of dimers are constructed in two directions of the spread monolayer comprising the most energetically advantageous monomer structures. The hydrophobic chains of alcohol and carboxylic acid molecules in the regarded dimers are found to be tilted within 12° to the normal of the spread monolayer. The structures of the mixed and pure surfactant dimers are the basis for the mixed alcohol–carboxylic acid monolayers of the following types: two dimensional (2D) film 1 with single distribution of the individual component in the other one, when the molecules of the first component do not interact with each other but are completely surrounded by the molecules of the second component; 2D film 2 with domain structure, when the film consists of “islands” of the individual components. The dependences of the clusterization Gibbs’ energy per one monolayer molecule on the molar fraction of the components for the mixed 2D films 1 formed by surfactants with equal alkyl chain length are found to be limited from top to bottom by the corresponding dependences for pure components. This indicates the absence of synergetic interaction between the hydrophilic head groups of carboxylic acids and alcohols and conforms to the available experimental data. The formation of the described types of mixed films is competitive. The preferential formation of 2D films 1 with single distribution of the first component among the molecules of the second one is possible when the length of the carboxylic acid hydrocarbon chain is longer by Δn = 1–2 methylene units than that of the corresponding alcohol alkyl chain. According to the fractionally linear law, the highest possible content of the carboxylic acids in such 2D films 1 depends on the Δn value and does not exceed 33.3%.

Hydrogen Bond OH...ΠGTCB in Adsorption of Isobutanol, Tert-Butanol, and Tert-Amyl Alcohol on Graphitized Thermal Carbon Black

Henry constants K1 are calculated for stable conformers of isobutanol, tert-butano, and tert-amyl alcohol molecules on graphitized thermal carbon black (GTCB). Parameters of the atom-atom potential taking into account the formation of a hydrogen bond between the adsorbate OH group with GTCB π electrons with regard to the direction are found. By density functional theory (DFT) and molecular statistical theory of adsorption the ratio between conformers stable in the gas phase and the adsorbed state are determined. The experimental Henry constants are compared with the results of the molecular statistical calculation for stable conformers of alcohols forming the bond OH...πGTCB.

Soil water repellency: A molecular-level perspective of a global environmental phenomenon

Soil water repellency affects vast regions of agricultural and native land across the globe. Sandy soils are most likely to develop non-wetting characteristics with susceptibility decreasing with clay content. This study uses molecular dynamics simulations combined with laboratory scale experiments to study the interactions and assembly of saturated C16 straight chain alcohol and carboxylic acid molecules on a range of soil surfaces. The development of severe water repellency on sand at low loading levels of palmitic acid (0.75 × 10−6 mol g−1) is explained in terms of favourable H-bonding with silica surfaces and the development of 2–3 layers of lateral aligned organic molecules on the mineral surface. The efficacy of kaolinite in lowering soil water repellency is attributed to the higher surface area of this mineral and favourable surface chemistry, which hinders formation of persistent organic multilayers.

A molecular dynamics simulation of the structure of sodium lauryl ether sulfate and poly(vinyl alcohol) at the air/water interface

The influence of a poly(vinyl alcohol) (PVA) molecule on the air/water interfacial structure of adsorbed sodium lauryl ether sulfate with one polyethylene oxide group (SLE1S) was investigated using molecular dynamics simulations. Increasing SLE1S surface density increases the interface thickness and forces both SLE1S and PVA molecules to migrate towards the air (actually vacuum) to different degrees. While most surfactants, when dilute, align parallel with the interface, increasing surfactant surface density forces tail groups gradually to align more perpendicularly to the interface. The three types of oxygen atoms in the SLE1S head group, i.e. the ionic, ester and ether oxygen atoms, form three distinct hydration shells, with PVA monomers appearing both within these shells and between the second and third shell due to its own hydrogen bonding with water and excluded volume of surfactant and water. The ionic oxygen atoms form more hydrogen bonds with water molecules and PVA than do the ester and ether oxygen atoms. The addition of PVA decreases slightly the number of hydrogen bonds between the surfactant oxygen atoms and the water molecules, as PVA chains form new hydrogen bonds with both of them. With increasing surfactant concentration, the PVA is pushed away from the bulk water, decreasing the number of the hydrogen bonds between it and water. These results are relevant to the use of polymers to aid surfactant in aqueous foaming applications.