Methyl Isopropyl Research Articles

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers

How the external solvent in biocompatible reverse micelles can improve the alkaline phosphatase behavior.

In the last decade, the nature of the nonpolar solvents that can be part of reverse micelles (RMs) has been the topic of several investigations to improve their applications. In this sense, the hydrolysis of 1-naphthyl phosphate catalyzed by the enzyme alkaline phosphatase (AP) was used as a probe to investigate the effect of the change of the external solvent on RMs formulated with the anionic surfactant sodium diethylhexyl sulfosuccinate (AOT). As external nonpolar solvents, two biocompatible lipophilic esters, isopropyl myristate and methyl laurate, and the traditional nonpolar solvents, n-heptane and benzene, were used. The results were compared among the RMs investigated and with the reaction in homogeneous media. Thus, the effect of the nanoconfinement as well as the impact of the replacement of a conventional external nonpolar solvent by biocompatible solvents were analyzed. The results indicate that the catalytic efficiency in the AOT RMs is larger than that in homogeneous media, denoting a different hydration level over the AP enzyme, which is directly related to the different degrees of nonpolar solvent penetration to the RM interface. Our findings demonstrated that toxic solvents such as n-heptane and benzene can be replaced by nontoxic ones (isopropyl myristate or methyl laurate) in AOT RMs without affecting the performance of micellar systems as nanoreactors, making them a green and promising alternative toward efficient and sustainable chemistry.

Determination of two acrylates in environmental water by high performance liquid chromatography

A high performance liquid chromatography (HPLC) method was established for the determination of two acrylate substances in environmental water. The optimal chromatographic conditions were determined via exploring the effects of chromatographic column, mobile phase, column temperature, flow rate, detection wavelength and other factors on the separation effect of acrylate substances. Finally, the effective separation of methyl methacrylate and isopropyl methacrylate was realized within 6 min. The retention time of the target compound was used for qualitative analysis and the external standard method was used for quantitative analysis in the experiment. The linear relationship between the two acrylates was good in the range of 0.2-50.0 mg/L, and the correlation coefficient of standard curve was higher than 0.999. The recovery rate was 88.6%-105.3%, the relative standard deviation was 1.7%-4.1%, and the detection limit (LODs) was 0.03-0.05 mg/L. The method was simple, efficient and accurate, and suitable for the determination of acrylates in environmental water samples.

Experimental determination and modeling of liquid-liquid equilibrium for ternary mixtures composed of water, epichlorohydrin and different solvents

Liquid-liquid equilibrium (LLE) data for water + epichlorohydrin + {chloroform or isopropyl ether or methyl tert-butyl ether or isopropyl acetate or ethylacetate or 2-ethyl-1-hexanol} systems at 308.2 K under 101.3 kPa were determined. The distribution coefficient and the separation factor were used to judge the extraction efficiency of different solvents on epichlorohydrin removal from water. The Othmer-Tobias, Hand, and Bachman equations were applied to check the reliability of the experimental LLE data. Furthermore, the experimental LLE data were successfully correlated with the NRTL and UNIQUAC models with all the RMSD values were less than 0.57%.

Synthesis of dihydrocapsaicin and dihydrocapsiate exclusively from lignocellulosic platform chemicals

Biorefinery is pivotal to the sustainability of modern chemical industry. However, since biomass is oxygen-enriched, new and green chemical strategies are required for expanding the biomass derived chemical space. In this work, synthesis of natural products dihydrocapsaicin and dihydrocapsiate was achieved exclusively from lignocellulosic platform chemicals. Natural products dihydrocapsaicin and dihydrocapsiate were synthesized exclusively from lignocellulosic platform chemicals, using furfural (from hemicellulose) and methyl isopropyl ketone (from cellulose) through aldol condensation-hydrolysis-hydrodeoxygenation to synthesize 8-methylnonanoic acid and then combined with vanillin derivates (from lignin). This synthesis demonstrates the feasibility of constructing natural products entirely from renewable biomass platform through green processes. The utilization of inherent functional groups of biomass demonstrates their potential to open up chemical space.

Fabric phase sorptive extraction combined with high-performance-liquid chromatography-photodiode array analysis for the determination of seven parabens in human breast tissues: Application to cancerous and non-cancerous samples

An improved pretreatment approach of human breast tissue is demonstrated for subsequent analysis of seven parabens including methyl paraben (MPB), ethyl paraben (EPB), propyl paraben (PPB), butyl paraben (BPB), isopropyl paraben (iPPB), isobutyl paraben (iBPB), and benzyl paraben (BzPB). Specifically, a well-designed homogenization procedure, conjugated with an optimized fabric phase sorptive extraction (FPSE) protocol, resulted in a carefully outlined sample preparation process as part of a green, simple, sensitive, economical and fast HPLC-PDA analytical method in agreement with Green Analytical Chemistry (GAC) demands. Among all tested FPSE membranes, the highest extraction efficiency was achieved by employing sol-gel poly(tetrahydrofuran) (sol-gel PTHF) coating on 100% cotton cellulose fabric that represents a medium polarity microextraction device, which combined the advanced material characteristics of sol-gel sorbent and the rich surface chemistry of an inherent porous cellulose fabric substrate. The chromatographic separation was accomplished with a Spherisorb C18 column and an isocratic mobile phase consisted of ammonium acetate and acetonitrile at a flow rate of 1.4 mL/min. The total analysis time was 13.6 min. The analytical adequacy of the composite sample preparation and chromatographic separation method was strongly evidenced by its successful application in the bioanalysis of real cancerous and non-cancerous tissue samples originated from different sub regions of human breast including axila, the upper left and the right quadrant. In all samples, at least one paraben was detected, while 35% of the samples were tested positive for all seven target parabens. Moreover, concentration levels of parabens in cancerous tissues were unambiguously higher than in healthy tissues. The obtained results underlined bioaccumulation potential of parabens in human breast tissue as a consequence of constant low-dose exposure of humans, despite the statutory concentration limits. The developed methodology has demonstrated to be suitable and efficient for future epidemiological and toxicological studies.

Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid

AbstractAlkyl methanesulfonates are genotoxic impurities that should be limited to an intake of not more than 1.5 µg/day, as regulated by the International Council for Harmonization guideline M7. We herein report a trace analysis of methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), and isopropyl methanesulfonate (IPMS) in the delgocitinib drug substance using liquid–liquid extraction, with an ionic liquid as the sample-solving medium, and direct injection gas chromatography detected with a flame-ionization detector. The proposed method takes advantage of the fine solubility of ionic liquids toward the drug substance, the good extraction efficiency of alkyl methanesulfonates in liquid–liquid extraction using the Chem Elut cartridge with low-polar organic solvents, and the ability of alkyl methanesulfonates to concentrate in minimum amounts of organic solvent, resulting in excellent sensitivity and selectivity. Specifically, for the preparation of the sample solution, a mixture of 1-butyl-3-methylimidazolium chloride, water, and acetonitrile was used as the sample-solving media, extracted with diethyl ether, and the eluent was concentrated to 1 mL. The method showed good linearity, accuracy, and precision from 1 to 5 ppm, and the limits of detection of MMS, EMS, and IPMS were 0.1, 0.05, and 0.05 ppm, respectively.

無限用量にて適用した種々剤形からのイソプロピルメチルフェノールの皮膚透過性と皮膚内濃度の関係について—ヒト長期投与（安全性）試験の用量設定法ガイドライン策定のための検証結果 その1—

無限用量にて適用した種々剤形からのイソプロピルメチルフェノールの皮膚透過性と皮膚内濃度の関係について—ヒト長期投与（安全性）試験の用量設定法ガイドライン策定のための検証結果 その1—

Structural Characterization of a Cyclodextrin/l-menthol Inclusion Complex in the Solid-state by Solid-state NMR and Vibrational Circular Dichroism.

Hydrophobic and volatile flavor molecules can be encapsulated inside cyclodextrins (CyDs). Inclusion complexes are frequently used in solid or dispersed states in preserved food and cosmetics. In this study, the solid-state structures of spray-dried inclusion complexes of l-menthol in α-CyD and β-CyD were analyzed using 13C solid-state NMR and vibrational circular dichroism (VCD). The NMR signals of l-menthol and CyDs were identified in the physical mixture and the l-menthol inclusion complex of α- and β-CyD. The NMR signal of the isopropyl-methyl group of menthol in the α-CyD inclusion complex exhibited a large low-field shift, which suggested a steric hindrance between menthol and α-CyD. VCD exhibited specific changes in the intensity of bands corresponding to C-C vibrations in α-CyD and O-C stretching vibrations in l-menthol. Our results indicated that l-menthol specifically fitted the narrow space within α-CyD. The combined solid-state NMR and VCD analysis provided structural insights into the flavor inclusion complex in the solid-state.

Imim-DEHP reverse micelles investigated with two molecular probes reveals how are the interfacial properties and the coordination behavior of the surfactant

Aqueous reverse micelles (RMs) generated with the ionic liquid (IL)-surfactant 1-methylimidazolium bis-(2-ethylhexyl)phosphate (imim-DEHP) and the biocompatible solvents methyl laurate (ML) and isopropyl myristate (IPM) were studied through the use of two molecular probes: the IL 3,6-bis(dimethylamino) acridinium bis-(2-ethylhexyl) phosphate (AOBH-DEHP) and the complex N,N,N′,N′-tetramethylethylenediamine copper(II)acetylacetonate tetraphenylborate ([Cu(acac)(tmen)][B(C6H5)4]). The techniques used were absorption and emission spectroscopy. Specifically, we explore how the chemical nature of the surfactant alters RMs properties such as micropolarity, specific interactions, and restricted motion environment. Furthermore, we analyzed how the imim-DEHP assembly affects the coordination behavior of the surfactant. The results show that the interfacial properties of the imim-DEHP RMs are dominated by the chemical nature of the surfactant as a consequence of a strong interaction of the imim+ cation with water molecules. Because of this strong interaction imim+-water, the anion DEHP− has an enhanced capacity to coordinate ion Cu+2 in comparison when the surfactant is in a homogeneous medium. Also, our results demonstrate that the strength of the anion DEHP− as a ligand in imim-DEHP RMs can be modulated both through the choice of the external solvent and the water content. In summary, the obtained results are very interesting for the potential use of the imim-DEHP RMs as nanoreactors and in metals extraction.

Experimental analysis of vapour-liquid phase equilibria for binary systems of diethyl carbonate with methyl, ethyl, isopropyl, n-butyl and isoamyl acetates at 95 kPa

Experimental analysis of vapour-liquid phase equilibrium (VLE) for five binary pairs of diethyl carbonate (DEC) with methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate and isoamyl acetate was carried out in this study. VLE data were generated experimentally at local atmospheric pressure of 95 kPa in a glass dynamic recirculation still. Reliability of data was checked with the thermodynamic consistency tests by Van Ness, infinite dilution, pure component and mean absolute deviation test. Experimental data was found to be thermodynamically consistent with all tests and data was regressed with Wilson, NRTL and UNIQUAC activity coefficient models to determine binary interaction parameters. Binary pair of DEC with n-butyl acetate has shown azeotropic behaviour with minimum boiling azeotrope and a close-boiling behaviour through-out the composition range. No azeotropic behaviour was observed for the rest of the binary pairs.

Improvement of stability due to a cyclamen aldehyde/β-cyclodextrin inclusion complex

Cyclamen aldehyde (Cya) is an essential oil component with an aldehyde group. The current study examined an inclusion complex of Cya and β-cyclodextrin (βCD) and assessed its physicochemical properties, volatility, and stability. Phase solubility diagrams and 1H NMR spectroscopy indicated that Cya and βCD in a co-precipitate (CP) form a complex at a molar ratio of 1/1. Powder X-ray diffraction (PXRD) patterns revealed crystal diffraction peaks due to βCD (2θ = 8.8°, 12.5°, and 20.8°) for the PM and new diffraction peaks (2θ = 11.7° and 17.5°) for the CP. Thermogravimetry (TG) measurements indicated that Cya decreased about 18.2% in a physical mixture (PM) and about 4.4% in the CP. FT-IR and NIR spectroscopies indicated that the spectra produced by the methyl groups and isopropyl group (5908 cm−1) of Cya and by the hydroxyl groups (4756 cm−1) in the cavity of βCD shifted. {1H–1H} NOESY NMR spectra revealed couplings for the protons of the isopropyl group (1.05 ppm) and the protons of the βCD cavity (H-3: 3.66 ppm). These findings indicated that the isopropyl group of Cya is included in the wider opening of the βCD torus. Diffusion-ordered two-dimensional NMR spectroscopy (DOSY) indicated that the CP (Cya/βCD) had a diffusion coefficient of 3.21 × 10−5 cm2/s and that βCD had a diffusion coefficient of 3.25 × 10−5 cm2/s, so the CP (Cya/βCD) had colligate properties like those of βCD. A stability test at a temperature of 40 °C and RH of 82% revealed that Cya decreased about 7.4% in 7 d, but at least 29% of the CP (Cya/βCD) was retained. At a temperature of 25 °C and RH of 84%, Cya decreased about 9.7% in 7 d, but at least 76.5% of the CP (Cya/βCD) was retained. These findings indicated that formation of a complex by the CP (Cya/βCD) should reduce the volatility of Cya and improve its stability.

Solubility modeling, solvent effect and mixing properties of 5-chloro-8-hydroxyquinoline (Form I) in twelve pure solvents at various temperatures

Abstract Mole-fraction solubility of 5-chloro-8-hydroxyquinoline (cloxiquine) Form I in twelve neat solvents namely “methyl acetate (MtAC), ethyl acetate (EtAC), n-propyl acetate (n-PrAC), isopropyl acetate (IPrAC), methanol (MtOH), ethanol (EtOH), n-propyl alcohol (n-PrOH), isopropyl alcohol (IPrOH), 2-methoxyethanol, 2-ethoxyethanol, 1,4-dioxane and acetone (DMK)” was determined under 0.1 MPa in this research work. The results show that cloxiquine solubility is directly proportional to temperature in selected solvents. The general solubility order at 298.15 K is: 1,4-dioxane (0.0751) > 2-ethoxyethanol (0.0333) > n-PrAC (0.0297) > 2-methoxyethanol (0.0291) > EtAC (0.0269) > MtAC (0.0245) > IPrAC (0.0232) > DMK (0.0200) > n-PrOH (0.0076) > EtOH (0.0058) > IPrOH (0.0045) > MtOH (0.0042). Solvent effects on cloxiquine solubility were studied by Kamlet, Abboud and Taft linear solvation energy relationships (KAT-LSER) model, and the results showed that the sensitivity of solvent-solvent interaction (52.16%) was much higher than that of solute-solvent interaction (26.22%). Moreover, five activity coefficient functions (Margules, NRTL, Wilson, NRTL-SAC and UNIQUAC model) were applied for the correlation with solubility data. The average ARD (average relative deviation) is lower than 2.01% and average RMSD (root mean square deviation) lower than 5.87E−4. Five selected models provide good consistencies with experimental solubility values. Furthermore, mixing thermodynamic properties were calculated by Wilson model, the results of which suggested that the mixing of cloxiquine with selected solvents was spontaneous and entropy-driven process.

The ionic liquid-surfactant bmim-AOT and nontoxic lipophilic solvents as components of reverse micelles alternative to the traditional systems. A study by 1H NMR spectroscopy

Abstract Aqueous reverse micelles (RMs) of the ionic liquid-surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT) in the biocompatible nonpolar solvents isopropyl myristate (IPM) and methyl laurate (ML) were formulated and characterized by DLS and 1H NMR techniques; the goal is to develop less toxic and more environmentally friendly reverse micellar systems than traditional RMs formed by organic solvents such as n-heptane (n-Hp). The interfacial composition of these new micellar systems was compared with water/bmim-AOT/n-Hp RMs, analyzing the effect of changing the conventional external nonpolar solvent n-Hp for the biocompatible solvents IPM and ML. Also, they were compared with the RMs of the traditional surfactant sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) in IPM and ML to analyze the role of the bmim+ counterion compared to Na+ in the interfacial properties of the generated RMs. The results indicate that both ML and IPM can be used as nonpolar solvents to prepare RMs using bmim-AOT as surfactant. In comparison to n-Hp, IPM and ML penetrate more to the micellar interface, therefore, the ester group of the biocompatible solvent located at the micellar interface interacts with the bmim+ cation. As a consequence of this fact, the bmim+-AOT− interaction decreases when IPM or ML are used as the external solvent instead of n-Hp. In the Na-AOT/IPM and Na-AOT/ML systems, the dissimilar penetration of the external solvent makes the interfacial properties of both RMs clearly different. Interestingly, in the bmim-AOT/biocompatible solvent systems, the micellar interface properties are strongly governed by the bmim+ counterion, finding similar behavior if the external biocompatible solvent is IPM or ML.

Simultaneous Determination Of Six Parabens In Cosmetics By A New High Performance Liquid Chromatography Method With Fluorescence Detection

In this study, a new high performance liquid chromatography method with fluorescence detection was developed and validated for the simultaneous determination of methyl paraben, ethyl paraben, propyl paraben, isopropyl paraben, butyl paraben and benzyl paraben in cosmetics. Separations were achieved using a C18 guard column (2.1 Ч 10 mm, 3 µm) and a C18 analytical column (2.1 Ч 150 mm, 3 µm). Isocratic elution was applied with a mobile phase consisting of 45 % aqueous o-phosphoric acid solution (0.08 %) and 55 % methanol/water mixture (90 : 10 v/v). The excitation and the emission wavelengths were 254 and 310 nm, respectively. Column temperature was fixed at 40 єC. The linear range was 0.50-10.00 μg/mL for all of the parabens. Limits of detection and quantification were in the range of 0.29-0.32 μg/mL and 0.88-0.97 μg/ mL, respectively. Precision and accuracy values were calculated by analysis results of standard solutions at 0.50, 2.50 and 10.00 μg/mL. The developed and validated method was applied for simultaneous quantitative determination of six paraben species in cosmetic tonic and micellar water samples successfully.

Measurement and Correlation of the Solubility, Dissolution Enthalpy, and Entropy of R-2[4-(6-Chloro-2-benzoxazolyloxy)phenoxy]propanoic Acid in Different Pure Solvents

The solubility of R-2[4-(6-chloro-2-benzoxazolyloxy)phenoxy]propanoic acid (abbreviated as Fenoxaprop-P) in acetone, methyl ethyl ketone (MEK), 1,4-butyrolactone, acetonitrile, DMF, isopropyl alcohol (IPA), n-butyl alcohol and THF were measured at temperatures ranging from 273.15 to 323.15 K at atmospheric pressure using a laser detecting system. First, the solubility data were correlated by the Buchowski–Ksiazczak λh equation and modified Apelblat equation. Compared with the Apelblat equation, the Buchowski–Ksiazczak λh equation can fit the solubility data well. Then, the dissolution enthalpy, entropy and Gibbs free energy of Fenoxaprop-P were predicted by the van’t Hoff and Gibbs equation.

Nano-finishing of MEMS-based platforms for optimum optical sensing

The surface finish of the microelectromechanical systems substrate, particularly the ones that are deployed in chip-based optofluidic systems, is of utmost importance, and the overall surface finish helps in preventing light scattering and associated losses. The proposed system is made up of a microchannel with a coating on its interior which acts as a cladding layer and possesses an air-like refractive index. The water-based solutions with refractive indices higher than the coating, when confined within such channels, act as waveguides with a refractive index difference which would allow grazing incidence at the solution film interface. The microchannel is fabricated over a piece of Si along <100> direction with the help of lithography and wet etching technique. After wet chemical etching of silicon, multiple pyramidal hillocks with overall large surface roughness is observed which are not appropriate for loss-free light transmission and cause various optical losses. So the overall optimization of surface roughness created by the etching processes is critical from an optical standpoint. Roughness in the microchannel surface mainly arises due to wet etching through tetra methyl alcohol, potassium hydroxide, potassium ferricyanide and isopropyl alcohol. In this work, we have obtained surface finish upto ~1.33 nm at an etch rate of 141 nm/min which is obtained by tweaking the composition of the participating reagents in the etchants and also the etching temperature. The surface roughness obtained is quite small in comparison to the wavelength range of the visible spectrum and thus losses were greatly avoided. The low refractive index films over silicon substrate were characterized by field emission scanning electron microscopy, energy dispersive analysis of X-ray, atomic force microscopy, 3D optical profilometry and ellipsometry. The transmission results show that transmission loss was reduced by 27.42% for the coated samples with 33 nm surface roughness as compared to surface with 250 nm roughness.

Solution thermodynamic properties of flurbiprofen in twelve solvents from 283.15 to 323.15 K

In this work, solution thermodynamic properties including solubility, mixing thermodynamic properties and dissolution thermodynamic properties are investigated in detail. Gravimetric method was utilized for measuring the solubility data of flurbiprofen in twelve pure solvents including n-propanol, isopropanol, n-butanol, isobutanol, isopentanol, isopropyl acetate, methyl tert-butyl ether, isopropyl ether, acetonitrile, n-octane, n-heptane and n-hexane over the temperatures range from 283.15 to 323.15 K under atmospheric pressure. The results indicated that the solubility of flurbiprofen increased with the increasing temperature. Furthermore, the experimental solubility data were correlated by the modified Apelblat equation, λh equation, Wilson model and NRTL model. And the modified Apelblat equation can give better correlation results with lower values of ARD%. Moreover, mixing and dissolution thermodynamic properties of flurbiprofen in different solvents were calculated according to the experimental data and the NRTL model.

Synthesis of the Tripeptides Tyr-Thr-Lys Phosphorylated with Isopropyl Methyl- and (Deuteromethyl)phosphonochloridates as Reference Standards for the Analysis of Biomedical Samples

A procedure for the phosphorylation of the tripeptide Tyr-Thr-Lys with isopropyl methyl- or (deuteromethyl)phosphonochloridate is developed. The phosphorylated tripeptides are intended for use as reference standards in the analysis of blood samples of people suspected to have been exposed to acetylcholinesterase inhibitors. Conditions of hromatographic separation and purification of the synthesized compounds are determined and optimized, which ensures the preparation of high-purity phosphorylated tripeptides.

Thermodynamics and kinetics of 1-fluoro-2-methoxypropane vs Bromine monoxide radical (BrO): A computational view

CFCs containing volatile compounds are detrimental to atmospheric environment and to all living organisms. These compounds are frequently reported to be chemically stable/inert. Also their photodissociation reaction results to reasonable amount of Chlorine atoms formation in the stratospheric part of atmosphere. This eventually bring out depletion of Ozone (lives and properties protecting compound) in the stratosphere. In order to cope this environmental havoc, there is need to find substitutable compounds for CFCs and possibly predict their atmospheric effects. Ethers when fluorinated can serve as CFCs substitute. Therefore, in this work, an Insilco investigation was conducted on the thermochemistry, mechanism and kinetics of the Hydrogen abstraction reactions of partially fluorinated isopropyl methyl ether (1-fluoro-2-methoxypropane i.e. (CH2FCH(OCH3)CH3)) with Bromine monoxide radical (BrO.) using the Density Functional Theory (DFT) based M06-2X/6-311++G** strategy. To computationally refine/improve the energy data, the single-point calculations (DFT/M06-2X/6-311++G(2df,2p) were immediately executed on the reacting species involved. The Monte Carlo search on the investigating CH2FCH(OCH3)CH3 showed nine conformers with the lowest global minimum configuration being studied. The results of this investigation showed that the atmospheric oxidation reaction of CH2FCH(OCH3)CH3 with the BrO radical proceeded in four (4) plausible reaction routes. The computed total theoretical rate of 7.95*〖10〗^(-11) M-1 sec-1, the first of its kind with BrO radical was recorded. The atmospheric lifetime/global warming potential of 1.35*10-2 days/72.8 were also reported. The potential energy surface (PES) for each reaction route with the BrO radical was constructed at absolute temperature of 298.15 K.