Rapid Approaches for Assignment of the Relative Configuration in 1-Oxygenated 1,2-Diarylpropan-3-ols by 1H NMR Spectroscopy.

The structural elucidation of chiral molecules with more than one stereocenter is usually a tricky problem. In this paper, efficient 1H NMR spectroscopic approaches for assigning the erythro and threo configurations of 1-oxygenated 1,2-diarylpropan-3-ols were developed. By analysis of the chemical shift differences of diastereotopic methylene H2-3 (Δδ3) in CDCl3 or the chemical shift differences of H-1 and H-2 (Δδ1,2) in methanol-d4, deuterated dimethyl sulfoxide, and acetone-d6, the configurations of 1-oxygenated 1,2-diarylpropan-3-ols can be rapidly and conveniently determined.

How Alcoholic Disinfectants Affect Coronavirus Model Membranes: Membrane Fluidity, Permeability, and Disintegration.

Atomistic molecular dynamics simulations have been carried out with a view to investigating the stability of the SARS-CoV-2 exterior membrane with respect to two common disinfectants, namely, aqueous solutions of ethanol and n-propanol. We used dipalmitoylphosphatidylcholine (DPPC) as a model membrane material and did simulations on both gel and liquid crystalline phases of membrane surrounded by aqueous solutions of varying alcohol concentrations (up to 17.5 mol %). While a moderate effect of alcohol on the gel phase of membrane is observed, its liquid crystalline phase is shown to be influenced dramatically by either alcohol. Our results show that aqueous solutions of only 5 and 10 mol % alcohol already have significant weakening effects on the membrane. The effects of n-propanol are always stronger than those of ethanol. The membrane changes its structure, when exposed to disinfectant solutions; uptake of alcohol causes it to swell laterally but to shrink vertically. At the same time, the orientational order of lipid tails decreases significantly. Metadynamics and grand-canonical ensemble simulations were done to calculate the free-energy profiles for permeation of alcohol and alcohol/water solubility in the DPPC. We found that the free-energy barrier to permeation of the DPPC liquid crystalline phase by all permeants is significantly lowered by alcohol uptake. At a disinfectant concentration of 10 mol %, it becomes insignificant enough to allow almost free passage of the disinfectant to the inside of the virus to cause damage there. It should be noted that the disinfectant also causes the barrier for water permeation to drop. Furthermore, the shrinking of the membrane thickness shortens the gap needed to be crossed by penetrants from outside the virus into its core. The lateral swelling also increases the average distance between head groups, which is a secondary barrier to membrane penetration, and hence further increases the penetration by disinfectants. At alcohol concentrations in the disinfectant solution above 15 mol %, we reliably observe disintegration of the DPPC membrane in its liquid crystalline phase.

Olfactory Detection Thresholds for Primary Aliphatic Alcohols in Mice.

Probing the neural mechanisms that underlie each sensory system requires the presentation of perceptually appropriate stimulus concentrations. This is particularly relevant in the olfactory system as additional odorant receptors typically respond with increasing stimulus concentrations. Thus, perceptual measures of olfactory sensitivity provide an important guide for functional experiments. This study focuses on aliphatic alcohols because they are commonly used to survey neural activity in a variety of olfactory regions, probe the behavioral limits of odor discrimination, and assess odor-structure activity relationships in mice. However, despite their frequent use, a systematic study of the relative sensitivity of these odorants in mice is not available. Thus, we assayed the ability of C57BL/6J mice to detect a homologous series of primary aliphatic alcohols (1-propanol to 1-heptanol) using a head-fixed Go/No-Go operant conditioning assay combined with highly reproducible stimulus delivery. To aid in the accessibility of our data, we report the animal's threshold to each odorant according to the 1) ideal gas condition, 2) nonideal gas condition (factoring in the activity of the odorant in the solvent), and 3) the liquid dilution of the odorant in the olfactometer. Of the odorants tested, mice were most sensitive to 1-hexanol and least sensitive to 1-butanol. These updated measures of murine sensitivity will hopefully guide experimenters in choosing appropriate stimulus concentrations for experiments using these odorants.

Acoustic levitation and infrared thermography: a sound approach to studying droplet evaporation.

Herein we report a new technique combining acoustic levitation and infrared thermography to directly monitor droplet surface temperatures. Using it, temperature profiles were recorded during the evaporation of deionized water, methanol, n-propanol, and isopropanol. Results support the viability of this inexpensive and easily-accessed technique for studying chemical and physical changes in droplets.

2,3-Diaminopropanols Obtained from d-Serine as Intermediates in the Synthesis of Protected 2,3-l-Diaminopropanoic Acid (l-Dap) Methyl Esters.

A synthetic strategy for the preparation of two orthogonally protected methyl esters of the non-proteinogenic amino acid 2,3-l-diaminopropanoic acid (l-Dap) was developed. In these structures, the base-labile protecting group 9-fluorenylmethyloxycarbonyl (Fmoc) was paired to the p-toluensulfonyl (tosyl, Ts) or acid-labile tert-butyloxycarbonyl (Boc) moieties. The synthetic approach to protected l-Dap methyl esters uses appropriately masked 2,3-diaminopropanols, which are obtained via reductive amination of an aldehyde prepared from the commercial amino acid Nα-Fmoc-O-tert-butyl-d-serine, used as the starting material. Reductive amination is carried out with primary amines and sulfonamides, and the process is assisted by the Lewis acid Ti(OiPr)4. The required carboxyl group is installed by oxidizing the alcoholic function of 2,3-diaminopropanols bearing the tosyl or benzyl protecting group on the 3-NH2 site. The procedure can easily be applied using the crude product obtained after each step, minimizing the need for chromatographic purifications. Chirality of the carbon atom of the starting d-serine template is preserved throughout all synthetic steps.

Investigating the interaction of porcine pancreatic elastase and propanol: A spectroscopy and molecular simulation study.

The response of porcine pancreatic elastase (PPE) to propanol was examined by various techniques including UV-vis spectrophotometry, spectrofluorometry and circular dichroism, as well as molecular docking and molecular simulation. These techniques were used to investigate the structural changes and elastase activity in the presence of propanol. This work was performed at three temperatures of 303, 313 and 323 K, with the pH value of 8.5 (Tris buffer). The results of the UV-vis spectrophotometry indicated the transfer of tryptophan to an environment with low hydrophobicity. Fluorescence measurements also revealed the quenching of fluorescence intensity was induced by propanol, and dynamic quenching was the proposed quenching mechanism. Kinetic studies also suggested the inhibitory effect (noncompetitive) of propanol on elastase. Further, Circular Dichroism (CD) spectra showed that propanol caused slight alterations in the secondary structures of PPE (0.3% increase for the α-helix and 0.5% decrease for the ß-sheet). Addition of propanol decreased the Tm (Melting Temperature) parameter from 332.8 K to 330.1 K.

Interpretive search of optimal isocratic and gradient separations in micellar liquid chromatography in extended organic solvent domains.

Micellar liquid chromatography (MLC) is a reversed-phase mode with mobile phases containing an organic solvent and a micellised surfactant. Most procedures developed in MLC are implemented in the isocratic mode, since the general elution problem in chromatography is less troublesome. However, gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities, in shorter times. MLC using gradients is attractive to determine by direct injection moderate to low polar compounds in physiological samples. In these analyses, the use of initial micellar conditions (isocratic or gradient) with a fixed amount of surfactant above the critical micellar concentration, keeping the organic solvent content low, will provide better protection of the column against the precipitation of the proteins in the physiological fluid. Once the proteins are swept away, the elution strength can be increased using a positive gradient of organic solvent to reduce the analysis time. This may give rise to the transition from the micellar to the submicellar mode, since micelles are destroyed at sufficiently high concentration of organic solvent. In this work, several retention models covering extended solvent domains in MLC are developed and tested, and applied to investigate the performance in isocratic, linear and multi-linear gradient separations. The study was applied to the screening of ß-adrenoceptor antagonists in urine samples, using mobile phases prepared with sodium dodecyl sulphate and 1-propanol. Predicted chromatograms were highly accurate in all situations, although suffered of baseline problems and minor shifts for peaks eluting close to a steep gradient segment. Two columns (C18 and C8) were investigated, with the C8 column being preferable owing to the smaller amount of adsorbed surfactant.

Partition efficiency of cytochrome c with alcohol/salt aqueous biphasic flotation system.

Aqueous biphasic flotation (ABF) integrates aqueous biphasic system (ABS) and solvent sublation for recovery of target biomolecules. The feasibility of the alcohol/salt ABF for exclusive partition of cytochrome c to one specific phase of the system was investigated. Aliphatic alcohols of different carbon chain length (ethanol, 1-propanol and 2-propanol) and salts (sulfate, phosphate and citrate) were used for the phase formation. The effects of phase composition, concentration of sample loading, pH, flotation time and flow rate of the system on the partition efficiency of cytochrome c were determined. Cytochrome c was exclusively partitioned to the alcohol-rich top phase of the ABF of 18% (w/w) ethanol and 26% (w/w) ammonium sulfate with pH 6 and 20% (w/w) of sample loading. Highest partition coefficient (K) of 6.85 ± 0.21 and yield (YT) of 99.40% ± 0.02 were obtained with optimum flotation rate of 10 mL/min and flow rate of 10 min.

Reaction of 1-propanol with Ozone in Aqueous Media.

The main aim of this work is to substantiate the mechanism of 1-propanol oxidation by ozone in aqueous solution when the substrate is present in large excess. Further goals are assessment of the products, their formation yields as well as the kinetic parameters of the considered reaction. The reaction of ozone with 1-propanol in aqueous solution occurs via hydride transfer, H-abstraction and insertion. Of these three mechanisms, the largest share is for hydride transfer. This implies the extraction of an hydride ion from the activated C-H group by O3 according to reaction: (C2H5)(H)(HO)C-H + O3 → [(C2H5)(H)(HO)C+ + HO3-]cage → (C2H5)(H)(HO)C+ + HO3-. The experimentally determined products and their overall formation yields with respect to ozone are: propionaldehyde-(60 ± 3)%, propionic acid-(27.4 ± 1.0)%, acetaldehyde-(4.9 ± 0.3)%, acetic acid-(0.3 ± 0.1)%, formaldehyde-(1.0 ± 0.1)%, formic acid-(4.6 ± 0.3)%, hydrogen peroxide-(11.1 ± 0.3)% and hydroxyl radical-(9.8 ± 0.3)%. The reaction of ozone with 1-propanol in aqueous media follows a second order kinetics with a reaction rate constant of (0.64 ± 0.02) M-1·s-1 at pH = 7 and 23 °C. The dependence of the second order rate constant on temperature is described by the equation: l n   k I I = ( 27.17 ± 0.38 ) - ( 8180 ± 120 ) × T - 1 , which gives the activation energy, Ea = (68 ± 1) kJ mol-1 and pre-exponential factor, A = (6.3 ± 2.4) × 1011 M-1 s-1. The nature of products, their yields and the kinetic data can be used in water treatment. The fact that the hydride transfer is the main pathway in the 1-propanol/ozone system can probably be transferred on other systems in which the substrate is characterized by C-H active sites only.

Cononsolvency of Elastin-like Polypeptides in Water/Alcohol Solutions.

Elastin-like polypeptides (ELPs) are one of the most widely-studied classes of protein material because of their lower critical solution temperature (LCST)-like thermoresponsive behavior in aqueous solutions. Here, it is shown that ELPs also exhibit cononsolvency effects, similar to many other water-soluble polymers. The effect of solvent composition on the dilute solution phase behavior of an elastin-like polypeptide is studied here in water/alcohol blends that contain 0-40 vol % methanol, ethanol, isopropanol, or 1-propanol. In all systems studied, the ELP exhibits cononsolvency behavior at low alcohol content, as indicated by a decrease in the transition temperature of the ELP. When the alcohol added is ethanol, isopropanol, or 1-propanol, the decrease in transition temperature is followed by a region of complete ELP insolubility, and, finally, the emergence of upper-critical solution transition (UCST)-like behavior. The ELP is completely soluble at all temperatures measured at alcohol contents above 40 vol %. The effect of sodium chloride on this ELP cononsolvency in water/ethanol blends was also studied. Unlike the previously studied polymer poly( N-isoropylacrylamide) (PNIPAM), ELP exhibits nonmonotonic changes in transition temperature with the addition of sodium chloride at ethanol contents that produce UCST-like transitions of the ELP. This discovery of ELP cononsolvency in water/alcohol systems introduces a new handle with which the solubility of ELPs can be tuned.

Photochemical and photocatalytic degradation of 1-propanol using UV/H2 O2 : Identification of malonate as byproduct.

1-propanol is a primary alcohol extensively used in the pharmaceutical, chemical, and food industries. It has been also found as a contaminant in the atmosphere and is considered a model compound to mimic the behavior and fate of aliphatic alcohols exposed to environmental conditions. In order to understand that role of relevant variables, this paper presents results obtained with a simple experimental set-up to investigate the reactivity of 1-propanol under mild oxidizing conditions. Coupling this system with CE-C4 D allowed the quantification of the carboxylic acids formed. For the described experiments, aqueous solutions of 1-propanol were placed inside a photoreactor and oxidized upon the addition of TiO2 and/or H2 O2 . According to the described results, the addition of H2 O2 (0.1% w/w) was the most significant variable, roughly tripled the amount of carboxylic acids generated and led to the conversion of up to 70% of the initially available 1-propanol (1 mmol/L). More importantly, the reaction yielded the formation (within 10 min) of propionate (50 µmol/L), acetate (400 µmol/L), formate (50 µmol/L), and malonate (200 µmol/L). The latter is critically important because it represents the first example of the photochemical oxidation of both terminal carbons of the C3 -chain of 1-propanol under mild conditions, and opens new avenues for the production of this important chemical building block.

Solvent Mediation of Peptide Conformations: Polyproline Structures in Water, Methanol, Ethanol, and 1-Propanol as Determined by Ion Mobility Spectrometry-Mass Spectrometry.

Ion mobility spectrometry and circular dichroism spectroscopy are used to examine the populations of the small model peptide, polyproline-13 in water, methanol, ethanol, and 1-propanol over a range of solution temperatures (from 288 to 318 K). At low temperatures, the less-polar solvents (1-propanol and ethanol) favor the all-cis polyproline I helix (PPI); as the temperature is increased, the trans-configured polyproline II helix (PPII) is formed. In polar solvents (methanol and water), PPII is favored at all temperatures. From the experimental data, we determine the relative stabilities of the eight structures in methanol, ethanol, and 1-propanol, as well as four in water, all with respect to PPII. Although these conformers show relatively small differences in free energies, substantial variability is observed in the enthalpies and entropies across the structures and solvents. This requires that enthalpies and entropies be highly correlated: in 1-propanol, cis-configured PPI conformations are energetically favorable but entropically disfavored. In more polar solvents, PPI is enthalpically less favorable and entropy favors trans-configured forms. While either ΔH0 or ΔS0 can favor different structures, no conformation in any solvent is simultaneously energetically and entropically stabilized. These data present a rare opportunity to examine the origin of conformational stability. Graphical Abstract ᅟ.

Extraction of lycopene using a lecithin-based olive oil microemulsion.

Incorporation of many water-insoluble nutraceuticals into aqueous formulations can present a real challenge for food industry. Hence, establishment of novel technologies for concurrent extraction and solubilisation of lipophilic compounds might be of a great interest. The main objective of the present study was to prepare olive oil microemulsions using different proportions of lecithin, 1-propanol, olive oil and water to examine their abilities to form microemulsion as well as extraction of lycopene from industrial tomato pomace. Lycopene extraction using 1 g tomato pomace and 4 extraction cycles applying 5 g microemulsion composed of lecithin: 1-propanol: olive oil: water (53.33:26.67:10:10 wt%) resulted in the highest extraction efficiency (88%). Such biocompatible and food-grade microemulsion containing lycopene can be applied in many food formulations where it can present a good solubility in aqueous and non-polar media and can improve the health-promoting properties of both lycopene and olive oil.

3-NOP: Mutagenicity and genotoxicity assessment.

3-NOP (3-nitroxy-propanol) is a new development compound which reduces methane emission from ruminating animals. For registration purposes with emphasis on EU and North America data requirements, mutagenic and genotoxic potential was assessed following OECD protocols and respective guidance documents. 3-NOP mutagenicity and genotoxicity testing raised no flags with regard to these endpoints. In silico assessment of 3-NOP and its major plasma metabolite NOPA (3-nitroxy-propionic acid) were predicted negative with regard to the bacterial reverse mutation (Ames) test. Ames test, mouse lymphoma assay, in vitro micronucleus test, and the oral in vivo micronucleus test using rat bone marrow were all negative. Exposure of the rat bone marrow was verified by the presence of 3-NOP and its metabolites NOPA and HPA (3-hydroxy-propionic acid) a naturally occurring substance in mammals) in plasma following oral dosing. It is therefore concluded that 3-NOP and its metabolites pose no mutagenic and genotoxic potential.

Propanol - Sugar aqueous biphasic systems as a suitable platform for biomolecules extraction.

Aiming at designing efficient extraction processes, this work proposes the novel aqueous biphasic systems (ABS) composed of sugars and alcohols. The complete liquid-liquid phase diagrams (binodal curves and tie-lines) for several ternary systems of {water + 1-propanol / 2-propanol + sugar (mono- and di-saccharides, and their polyols)} were determined, for the first time. The main factors which affect the phase separation ability of these systems, such as temperature, structure and stereochemistry of sugars, and the alcohol type were discussed. In all the studied ABS, the top phase is alcohol-rich with lower water content, while the bottom phase is sugar-rich with higher water content. The partitioning behavior of two alkaloids (caffeine and codeine) and a flavoring antioxidant (vanillin) in the produced ABS was evaluated. In all the partitioning experiments, caffeine and vanillin have a preferable tendency to concentrate in the more hydrophobic alcohol-rich phase, however, codeine preferentially migrate to the more hydrophilic sugar-rich phase. The selectivity index of the alcohol-sugar ABS to separate compounds of the same family (caffeine and codeine) was calculated and found to be higher than 25 at optimum conditions. In general, the more soluting-out ability of sugars, the more difference in the water content of the coexisting phases, and the longer tie-line length lead to the better extraction performance of the propanol-sugar ABS. Heating has a favorable effect on the preferential partitioning of caffeine and codeine, but it is unfavorable for extraction of vanillin. From the results gathered, the novel ABS produced in this work provide efficient and money-saving extraction platforms, and can selectively separate similar biomolecules.

Performance and methane fermentation characteristics of a pilot scale anaerobic membrane bioreactor (AnMBR) for treating pharmaceutical wastewater containing m-cresol (MC) and iso-propyl alcohol (IPA).

In this study, a pilot scale anaerobic membrane bioreactor (AnMBR) was operated for 80 days to treat pharmaceutical wastewater containing m-cresol (MC) and iso-propyl alcohol (IPA). The aim of the study is to investigate the performance and methane fermentation characteristics of AnMBR at different hydraulic retention time (HRT) (48, 36, 24, 18 and 12 h). The average total removal efficiencies of MC and IPA were 95%, 96% during the 80 days, which demonstrated that the AnMBR system performed well in the MC and IPA removal. The major volatile fatty acid (VFA) was found to be acetic acid, propionic acid, butyric acid, besides, the VFA accumulated apparently when HRT decreased to 12 h. The decrease of HRT led to an increase of relative abundance of methanosarcina from 13 to 33% and a decrease in biogas yield from 0.19 to 0.05 L/gCODremoval. The biogas production was found to increase dramatically at HRT of 36 h. The trend of methane content kept stable at this stage with the average value of 78.5% which higher than other HRTs. The investigation of methanogen community showed that methanosarcinaceae was always dominant acetoclastic methanogens and methanomicrobiales was the dominant hydrogen utilizers throughout the operational period. When the HRT dropped to 12 h, the growth of the methanosarcinaceae and methanomicrobiales was observed, the amount of the methanosarcinaceae and methanomicrobiales sharply increased. After the overall research, HRT of 36 h was chosen as the most suitable operating condition due to the comprehensively preferable performance and more economical.

Enzyme activity of horseradish peroxidase in surfactant-free microemulsions.

In the present contribution, we investigated the influence of the structuring of surfactant-free microemulsions (SFME) (water/1-propanol/limonene and water/tert-butanol/limonene) on the enzyme activity of horseradish peroxidase (HRP). To this purpose, the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) with hydrogen peroxide was chosen as a model reaction. Enzymatic activities in SFMEs of varying compositions were investigated by UV-Vis spectroscopy and compared to the enzyme activity in pure buffer solution. Dynamic light, small-angle-X-ray scattering and conductivity measurements were performed in order to obtain structural information on the used SFMEs. Findings presented in this study revealed that the ability of short-chain alcohols to form mesostructures (aqueous aggregates in oil) has a crucial effect on the enzyme activity in SFMEs. Mesoscale structuring with 1-propanol (NPA) was found to be more pronounced than for the more hydrophobic tert-butanol (TBA). It was concluded that the most pronounced mesoscale-structured SFMEs lead to the highest enzymatic activities.

Efficient potential of mean force calculation from multiscale simulations: Solute insertion in a lipid membrane.

The determination of potentials of mean force for solute insertion in a lipid membrane by means of all-atom molecular dynamics simulations is often hampered by sampling issues. Recently, a multiscale method has been proposed to leverage the conformational ensemble of a lower-resolution model as starting point for higher resolution simulations. In this work, we analyze the efficiency of this method by comparing its predictions for propanol insertion into a lipid membrane against conventional atomistic umbrella sampling simulation results. The multiscale approach is confirmed to provide accurate results with a gain of one order of magnitude in computational time. We then investigate the role of the coarse-grained representation. We find that the accuracy of the results is tightly connected to the presence of a good configurational overlap between the coarse-grained and atomistic models-a general requirement when developing multiscale simulation methods.