Long-chain Alkanols Research Articles

Fast co-pyrolysis characteristics of high-alkali coal and polyethylene using infrared rapid heating

Optimizing secondary reactions using infrared-fast pyrolysis has proved beneficial for investigating the co-pyrolysis behavior. In this study, co-pyrolysis of high-alkali coal (PC) and polyethylene at different temperatures, co-pyrolysis of polyethylene with demineralized coal (DP), and pyrolysis of raw high-alkali coal (RC) and demineralized coal (DC) were conducted in an infrared heating reactor. The results show that the co-pyrolysis promoted the formation of tar and the highest tar yield was 16.16% at 700 °C, and the PC tar yield was higher than that of RC, DC at 500 °C with 7.51% and 5.99% respectively. The tar yields of DP and PC were 7.49% and 11.80%, respectively, and the later had a slightly higher tar yield due to the interaction with AAEM. The addition of PE coupled infrared rapid heating can efficiently reduce the nitrogen and chlorine-containing fractions while increasing the content of long-chain alkanols and linear hydrocarbons. The content of organochlorines decreased from 2.95% at 500 °C to 1.00% at 800 °C. Alkanol and linear hydrocarbons have the highest content in the co-pyrolysis tar, with the total highest content of 61.56% at 600 °C.

Long-chain alkanol–alkyl carboxylic acid-based low-viscosity hydrophobic deep eutectic solvents for one-pot extraction of anthraquinones from Rhei Radix et Rhizoma

Natural long-chain alkanol and alkyl carboxylic acid were used to prepare novel hydrophobic deep eutectic solvents (HDESs). These HDESs are liquid at room temperature and have low viscosity (<12.26 mPa‧s), low polarity (lower than that of methanol, ChCl-based deep eutectic solvents and other reported HDESs), and low density (<0.928 g/mL). A simple one-pot method based on a novel HDES–water two-phase extraction system was constructed for the extraction of weak-polarity bioactive components, anthraquinones, from Rhei Radix et Rhizoma. This HDES-based new extraction method does not consume hazardous organic solvents and can obtain a total anthraquinone yield of 21.52 mg/g, which is close to that obtained by the Chinese pharmacopoeia method (21.22 mg/g) and considerably higher than those by other reported HDESs-based extraction methods (14.20–20.09 mg/g, p < 0.01). The high extraction yield can be mainly attributed to the severe destruction of the RRR cell walls by the extraction system and the excellent dissolving ability of novel HDESs for anthraquinones.

Research on long-chain alkanol etherified melamine-formaldehyde resin MicroPCMs for energy storage

Aiming at the characteristics of melamine-formadehyde resin with poor toughness and high brittleness owing to its unique structure of trizine ring, long-chain alkanol etherified melamine-formaldehyde prepolymer was selected as shell material to synthesize MicroPCMs. The study mainly explored the effect of etherification and relevant influencing factors in the etherification process on performance of microcapsules. Through a series of characterization, the alkyl chain of dodecanol can be grafted into the methylolated melamine-formaldehyde prepolymer via etherification, contributing to enhancing the adsorption of core material and encapsulation effect of microcapsules. The optimal molar ratio of melamine, formaldehyde and n-dodecanol was 1:7:2 in etherification process. N-dodecanol-etherified melamine-formaldehyde prepolymer was synthesized via one-step method as shell material for encapsulation n-dodecanol to obtain MicroPCMs4-2. The MicroPCMs4-2 finally obtained presented complete microstructure, uniform particle size distribution, well dispersibility and satisfactory thermal energy storage performance with high enthalpy value (△Hm = 166.1 J/g, △Hc = 160.2 J/g) and effective loading (72.2%) for potential applications to thermal-regulating textiles and energy storage fibers.

Plant versus microbial signature in densimetric fractions of Mediterranean forest soils: a study by thermochemolysis gas chromatography mass spectrometry

Soil organic matter (SOM) ageing may be measured by means of molecular signatures, ratios between organic compounds which inform us about the origin and/or the degree of biochemical evolution of (or microbial contribution to) specific groups of compounds: lipids, proteins, carbohydrates, etc. Owing to the biochemical heterogeneity of decomposing substrates, it is unlikely that the degree of biochemical evolution can be approached with a single ratio. Nevertheless, obtaining a wide collection of molecular signatures can be costly. Instead of applying specific methods to obtain a collection of ratios, we apply thermally assisted hydrolysis and methylation (THM), followed by GC-MS, to obtain a panoramic view of SOM composition. From the compounds identified after THM, several ratios were obtained. Three ratios are based on aliphatic compounds: (1) ratio between short-chain (≤ 20 C) and long-chain (> 20 C) alkanoic acids, (2) ratio between branched and long-chain alkanoic acids, (3) ratio between short-chain (C18) and long-chain (C22–C24) alkanols. Four ratios are based on lignin-derived monomers: (4) vanillic acid to vanillin, (5) syringic acid to syringaldehyde, (6) a combination of the two previous, and (7) the syringyl- to total lignin monomers. Finally, three ratios are based on sugar composition: (8) fucose to glucose, (9) xylose to glucose, and (10) fucose to xylose. These ratios were applied to the study of several densimetric fractions from three organic OH horizons from Mediterranean forest soils. The fractionation gave a free-light fraction (LF), of density 2.0. The three lightest fractions (LF, OC1, and OC2) seem the least microbially reworked, whereas the denser fractions, OC3 and DF, seem the most evolved ones. Nevertheless, this is valid only as an average result, for no single fraction is made of fresh compounds only, or of highly evolved compounds only, either. The behaviour of the several ratios was inconsistent because some behave in ways opposite to the expected ones. All fractions show signs of both advanced biochemical evolution and preservation of fresh, plant-derived labile compounds. This, added to the inconsistent behaviour of many signatures, suggests that our views about the biochemical evolution of plant debris during their decomposition and humification are probably too simple.

Insights into the structure and dynamics at the hexadecane droplet–water interface in the presence of 1-alkanols as emulsifiers: Molecular dynamics studies

The structure and dynamics at the surface of nanoscopic hexadecane droplets immersed in aqueous phase with and without emulsifiers (1-alkanols of varying chain length; pentanol, heptanol, decanol and dodecanol) have been studied using atomistic molecular dynamics simulations. The nature of layering of alcohol molecules on the oil droplet is governed by the hydrophobicity of alkanols. Longer chain alkanols are more likely to penetrate into the oil droplet. The probability of tangential orientation of hexadecane molecules at the interface decreases with decreasing hydrophobic environment around the droplet. The interfacial hexadecane molecules show greater probability to obtain a puckered conformation in binary oil–water system than in ternary oil–water–alkanol systems. Decrease in hydrophobic interaction between hexadecane and water molecules due to the efficient screening of oil surface by longer chain alkanols in ternary oil–water–alkanol systems leads to greater survival probability of water molecules in the oil–water interfacial layer and enhancement in life time of H-bonds formed between alcohol and water molecules.

Preparation of Associative Polyurethane Thickener and Its Thickening Mechanism Research

Associative polyurethane (PU) thickener has been synthesized by preparing the prepolymer with the reaction of polyethylene glycol (PEG) and isophorone diisocyanate (IPDI), which then end‐capping with long‐chain alkanol. The synthesis process, as well as hydrophilic chain length, theoretical molecular weight, solvent ratio, and thickener percentages, has been researched. The results shows that it reaches the upmost thickening effect when the theoretical molecular weight is under 20000, soft‐segment length is under 4000, solvent ratio is 1 : 1, and thickener percentages are controlled at 10%. Furthermore, thickening mechanism of PU thickener has been analyzed detailedly through the measurement of the critical micelle concentration (CMC) of PU thickener and analysis of the influence of PU thickener on the particle size and morphology of PU dispersions. It has been observed from the scanning electron microscopy (SEM) that the PU aqueous dispersions produce a certain degree of flocculation when the PU thickener was added, and this flocculation structure has been proved to be a thixotropic structure through the characterization of the change of particle size before and after the thickener is introduced into the PU aqueous dispersions. The CMC measurement results present that the thickening effect will be apparent when the concentration is controlled in a low range.

Heterogeneous selective oxidation of fatty alcohols: Oxidation of 1-tetradecanol as a model substrate

Abstracts Selective oxidation of fatty alcohols, i.e., linear long-chain alkanols, has been scarcely investigated to date, despite its potential application in high value chemical's production. We report for the first time the liquid phase heterogeneous oxidation of 1-tetradecanol, used as a model molecule for fatty alcohols, according to green chemistry principles by using a Au/CeO2–Al2O3 catalyst and O2 as oxidant at normal pressure. High selectivity to tetradecanal (ca. 80%) or to tetradecanoic acid (60–70%) are reached at medium conversion (up to 38%), depending on the reaction conditions used. Comparison with similar tests of 1-octanol oxidation shows that the increase of the carbon chain length decreases the alcohol conversion and the formation of ester, probably due to a greater steric effect.

The Influence of 1-Alkanols and External Pressure on the Lateral Pressure Profiles of Lipid Bilayers

The suggestion by Robert Cantor, that drug-induced pressure changes in lipid bilayers can change the conformational equilibrium between open and closed states of membrane proteins and thereby cause anesthesia, attracted much attention lately. Here, we studied the effect of both large external pressure and of 1-alkanols of different chain lengths—some of them anesthetics, others not—on the lateral pressure profiles across dimyristoylphosphatidylcholine (DMPC) bilayers by molecular dynamics simulations. For a pure DMPC bilayer, high pressure both reduced and broadened the tension at the interface hydrophobic/hydrophilic and diminished the repulsion between the phospholipid headgroups. Whereas the effect of ethanol on the lateral pressure profile was similar to the effect of a large external pressure on a DMPC bilayer, long-chain 1-alkanols significantly amplified local maxima and minima in the lateral pressure profile. For most 1-alkanols, external pressure had moderate effects and did not reverse the changes 1-alkanols exerted on the pressure profile. Nevertheless, assuming the bent helix model as a simple geometric model for the transmembrane region of a membrane protein, protein conformational equilibria were shifted in opposite directions by addition of 1-alkanols and additional application of external pressure.

Molecular Ordering and Phase Behavior of Surfactants at Water-Oil Interfaces as Probed by X-Ray Surface Scattering

Surfactants have their primary utility, both scientific and industrial, at the liquid-liquid interface. We review recent X-ray surface scattering experiments that probe the molecular ordering and phase behavior of surfactants at the water-oil interface. The presence of the oil modifies the interfacial ordering in a manner that cannot be understood simply from analogies with studies of Langmuir monolayers of surfactants at the water-vapor interface or from the traditional view that the solvent is fully mixed with the interfacial surfactants. These studies explored the role of chain flexibility and head group interactions on the ordering of long-chain alkanols and alkanoic acids. Small changes in the surfactant may produce large changes in the interfacial ordering. The interfacial monolayer can be spatially homogeneous or inhomogeneous. Investigators have observed interfacial phase transitions as a function of temperature between homogenous phases, as well as between homogeneous and inhomogeneous phases. Finally, varying the solvent chain length can alter the fundamental character of the phase transitions and lead to the formation of multilayer interfacial structures.

Adsorption Characteristics of Self-assembled 1-Octadecanol Layer on HOPG

Long-chain alkanol, 1-C18H37OH, adsorbed from solution onto highly oriented pyrolytic graphite (HOPG) and formed ordered, oriented monolayer films at room temperature in air. The formation and structure of 1-octadecanol self-assembled monolayers (SAMs) on HOPG were examined using scanning tunneling microscopy (STM), contact angle measurement, and X-ray photoelectron spectroscopy (XPS). Our experimental results indicated that 1-octadecanol SAMs grew in domains, with molecules arranged either horizontally or vertically on the substrate. Moreover, the permutation means of the molecule showed relevance to the surface coverage of 1-octadecanol SAMs on the HOPG.

1-Alkanols and membranes: A story of attraction

Although 1-alkanols have long been known to act as penetration enhancers and anesthetics, the mode of operation is not yet understood. In this study, long-time molecular dynamics simulations have been performed to investigate the effect of 1-alkanols of various carbon chain lengths onto the structure and dynamics of dimyristoylphosphatidylcholine bilayers. The simulations were complemented by microcalorimetry, continuous bleaching and film balance experiments. In the simulations, all investigated 1-alkanols assembled inside the lipid bilayer within tens of nanoseconds. Their hydroxyl groups bound preferentially to the lipid carbonyl group and the hydrocarbon chains stretched into the hydrophobic core of the bilayer. Both molecular dynamics simulations and experiments showed that all 1-alkanols drastically affected the bilayer properties. Insertion of long-chain 1-alkanols decreased the area per lipid while increasing the thickness of the bilayer and the order of the lipids. The bilayer elasticity was reduced and the diffusive motion of the lipids within the bilayer plane was suppressed. On the other hand, integration of ethanol into the bilayer enlarged the area per lipid. The bilayer became softer and lipid diffusion was enhanced.

Vaporization and layering of alkanols at the oil/water interface

This study of adsorption of normal alkanols at the oil/water interface with x-ray reflectivityand tensiometry demonstrates that the liquid to gas monolayer phase transition at thehexane/water interface is thermodynamically favourable only for long-chain alkanols. Asthe alkanol chain length is decreased, the change in excess interfacial entropy per areaΔSaσ decreases to zero. Systems with small values ofΔSaσ formmulti-molecular layers at the interface instead of the monolayer formed by systems with much largerΔSaσ. Substitution of n-hexane by n-hexadecane significantly alters the interfacial structure for agiven alkanol surfactant, but this substitution does not fundamentally change the phasetransition behaviour of the monolayers. These data show that the critical alkanol carbonnumber, at which the change in excess interfacial entropy per area decreases to zero, isapproximately six carbons larger than the number of carbons in the alkane solventmolecules.

Assessment of bioavailability and risk of iron in phytomedicines Aconitum carmichaeli and Paeonia lactiflora

Since n-octanol, a long-chain alkanol, presents a configuration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefficients between octanol and water. n-octanol is used as a model of biomembrane. This strategy has been used in order to define the species of iron in two phytomedicines and to study the distribution of iron in decoctions of phytomedicines in the stomach and the intestine. The concentrations of iron in the original herbal materials and in n-octanol- and water-soluble species were determined by flame atomic spectrometry following mixed acid digestion. The acidities of digestive and absorptive juices (saliva, gastric juice, bile and intestine), the phytomedical composition and the compatibility of phytomedicines, i.e., the combination ratio of single phytomedicines, greatly affected the iron complexing ligands and determined the species and bioavailability of iron. The concentration of octanol-soluble iron could be used for the bioavailability assessment of iron in phytomedicines. The dosage of iron in phytomedicines could be designed according to the level of the octanol-soluble iron and the reference daily intakes for iron (18 mg/d). Risk assessment could be examined through the comparison between the level of the octanol-soluble iron and the tolerable upper intake level for iron (45 mg iron/d).

Self‐Assembly of Alkanols on Au(111) Surfaces

Self-assembled monolayers (SAMs) of alkanols (1-C(N)H(2N+1)OH) with varying carbon-chain lengths (N = 10-30) have been systematically studied by means of scanning tunneling microscopy (STM) at the interfaces between alkanol solutions (or liquids) and Au(111) surfaces. The carbon skeletons were found to lie flat on the surfaces. This orientation is consistent with SAMs of alkanols on highly oriented pyrolytic graphite (HOPG) and MoS2 surfaces, and also with alkanes on reconstructed Au(111) surfaces. This result differs from a prior report, which claimed that 1-decanol molecules (N = 10) stood on their ends with the OH polar groups facing the gold substrate. Compared to alkanes, the replacement of one terminal CH3 group with an OH group introduces new bonding features for alkanols owing to the feasibility of forming hydrogen bonds. While SAMs of long-chain alkanols (N > 18) resemble those of alkanes, in which the aliphatic chains make a greater contribution, hydrogen bonding plays a more important role in the formation of SAMs of short-chain alkanols. Thus, in addition to the titled lamellar structure, a herringbone-like structure, seldom seen in SAMs of alkanes, is dominant in alkanol SAMs for values of N < 18. The odd-even effect present in alkane SAMs is also present in alkanol SAMs. Thus, the odd N alkanols (alkanols with an odd number of carbon atoms) adopt perpendicular lamellar structures owing to the favorable interactions of the CH3 terminal groups, similar to the result observed for odd alkanes. In contrast to alkanes on Au(111) surfaces, for which no SAMs on an unreconstructed gold substrate were observed, alkanols are capable of forming SAMs on either the reconstructed or the unreconstructed gold surfaces. Structural models for the packing of alkanol molecules on Au(111) surfaces have been proposed, which successfully explain these experimental observations.

Dialkyl 3,3‘-Thiodipropionate and Dialkyl 2,2‘-Thiodiacetate Antioxidants by Lipase-Catalyzed Esterification and Transesterification

Medium- and long-chain dialkyl 3,3'-thiodipropionate antioxidants such as dioctyl 3,3'-thiodipropionate, didodecyl 3,3'-thiodipropionate, dihexadecyl 3,3'-thiodipropionate, and di-(cis-9-octadecenyl) 3,3'-thiodipropionate were prepared in high yield by lipase-catalyzed esterification and transesterification of 3,3'-thiodipropionic acid and its dimethyl ester, respectively, with the corresponding medium- or long-chain 1-alkanols, i.e., 1-octanol, 1-dodecanol, 1-hexadecanol, and cis-9-octadecen-1-ol, in vacuo (80 kPa) at moderate temperatures (60-80 degrees C) without solvents. Immobilized lipase B from Candida antarctica (Novozym 435) was the most active biocatalyst for the preparation of medium- and long-chain dialkyl 3,3'-thiodipropionates showing enzyme activities up to 1489 units/g, whereas the immobilized lipases from Rhizomucor miehei (Lipozyme RM IM) and Thermomyces lanuginosus (Lipozyme TL IM) were by far less active ( approximately 10 enzyme units/g). Maximum conversions to dialkyl 3,3'-thiodipropionates were as high as 92-98% after 4 h of reaction time. Similarly, dihexadecyl 2,2'-thiodiacetate was prepared in high yield using 2,2'-thiodiacetic acid or diethyl 2,2'-thiodiacetate and 1-hexadecanol as the starting materials and Novozym 435 as the biocatalyst.

Properties of human connexin 31, which is implicated in hereditary dermatological disease and deafness

The connexins are a family of at least 20 homologous proteins in humans that form aqueous channels connecting the interiors of coupled cells and mediating electrical and chemical communication. Mutations in the gene for human connexin 31 (hCx31) are associated with disorders of the skin and auditory system. Alterations in functional properties of Cx31 junctions are likely to play a role in these diseases; nonetheless, little is known about the properties of the wild-type channels. Here we show that hCx31 channels, like other connexin channels, are gated by voltage and close at low pH and when exposed to long-chain alkanols. Single-channel conductance of the fully open channel is approximately 85 pS, and it is permeable to Lucifer yellow, Alexa Fluor(350), ethidium bromide, and DAPI, which have valences of -2, -1, +1, and +2, respectively. In contrast to what has been reported for mouse Cx31, hCx31 appears to form functional heterotypic channels with all four connexins tested, Cx26, Cx30, Cx32, and Cx45. These findings provide an important first step in evaluating the pathogenesis of inherited human diseases associated with mutations in the gene for Cx31.

Evaluation of Three Prediction Methods for Partitioning Coefficients of Organic Solutes between a Long-Chain Aliphatic Alcohol and the Gas Phase as a Function of Temperature

Temperature-dependent experimental hexadecan-1-ol/air partition coefficients of numerous organic solutes are regressed against molecular interaction parameters to derive a linear solvation energy relationship (LSER) for each experimental temperature. The system constants derived by these regressions are linearly related to reciprocal absolute temperature, allowing their extrapolation to 298.15 K and the establishment of a LSER equation for the hexadecan-1-ol/air partition coefficients at 298.15 K. This equation yields predictions comparable to those of another LSER equation for that parameter that is independently derived by extrapolating the system constants of smaller aliphatic alcohols to the chain length of hexadecan-1-ol. This confirms that the solvation properties of the long-chain alkanols can be extrapolated from those of smaller normal alcohols. Hexadecan-1-ol/air partition coefficients for the same solutes are also predicted using SPARC and calculated from vapor pressure data from the literature...

Speciation analysis and the assessment of bioavailability of manganese in phytomedicines by extraction with octanol and determination by flame atomic absorption spectrometry

Trace elements in phytomedicines are present in the form of metallic complexes. Since n-octanol, a long-chain alkanol, presents a configuration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefficients between octanol and water. This strategy has been used in order to define the species of manganese in a number of phytomedicines and to study the distribution of manganese in decoctions of phytomedicines in the stomach and the intestine. The concentrations of manganese in the original herbal materials and in octanol- and water-soluble fractions were determined by flame atomic absorption spectrometry following mixed acid digestion. The acidities of gastric and intestinal juices, the phytomedical composition and the compatibility of phytomedicines, i.e. the combination of single phytomedicines, greatly affected the manganese complexing ligands and determined the species and bioavailability of manganese. It is concluded that a knowledge of the level of octanol-soluble manganese in a phytomedicine could form the basis of dosage design in order to avoid manganese overload.

Effect of digestive site acidity and compatibility on the species, lipopily and bioavailability of iron, manganese and zinc in Prunus persica Batsch and Carthamus tinctorus

The effects of compatibility, that is combination of Prunus persica Batsch (L.) and Carthamus tinctorus (L.), and different acidity of digestive site on the species, lipopily and bioavailability of coordinated complex of iron, manganese, and zinc in medical decoction were studied. In view of octanol, a long-chain alkanol, resembled as the configuration of carbohydrate and adipose in human body, the octanol- and water-solubility were used to define the species of trace element in phytomedicine, to identify the lipopily and bioavailability of trace element, and octanol–water system was adopted to study the distribution of trace element in decoction of P. persica Batsch (L.) (A), C. tinctorus (L.) (B), and combination of medicine A and B (C) in stomach and intestine. The total concentration, water- and octanol-solubility concentration of iron, manganese, and zinc in medicinal material A, B and C or its decoction under gastric and intestinal acidity, were determined respectively by flame atomic absorption spectrometry, analyzed and compared. The compatibility of medicine A and B enhances the extract percent, octanol-solubility concentration, and stability of coordinated complex of iron, manganese, and zinc. Different acidity of digestive site and compatibility of medicines impact on the ligands of iron, manganese, and zinc, then greatly affect the species and its quantification, the lipopily and bioavailability of trace element. Such influence is quite different for different trace element. Such factors, especially the concentration of octanol-solubility trace element, could be the basis of the dosage to avoid trace element overload.

Surfactant and Water Ordering in Triacontanol Monolayers at the Water−Hexane Interface

Our view of molecular ordering in Langmuir monolayers at the water−vapor interface influences our understanding of molecular ordering at other interfaces, including liquid−liquid interfaces for which structural information is scarce. We present a comparative study of a monolayer of a long-chain alkanol at the water−vapor and water−hexane interfaces using X-ray reflectivity to highlight significant differences between these two interfaces. The molecules in the Langmuir monolayer form an ordered phase of nearly rigid rods. In contrast, at the water−hexane interface, the triacontanol molecules form a condensed phase with progressive disordering of the chain from the −CH2OH to the −CH3 group. Surprisingly, at the water−hexane interface, the density in the headgroup region is 10−15% greater than either bulk water or the ordered headgroup region found at the water−vapor interface. It is conjectured that this higher density is a result of water penetration into the headgroup region of the disordered monolayer.