Methyl Isopropyl Research Articles

The recovery of gallic acid with triphenylphosphine oxide in different kind of solvents

In this study, gallic acid was separated by triphenylphosphine oxide in the presence of conventional solvents. Triphenylphosphine oxide is an organophosphorus extractant and highly selective towards carboxylic acids. Reactive extraction results were compared with physical extraction results. The extraction efficiencies reached up to 61, 76, 86, 67, and 84% in the presence of triphenylphosphine oxide with oleyl alcohol, dimethyl adipate, isobutanol, methyl isopropyl ketone, and methyl ethyl ketone, respectively. Further, the number of theoretical units and the solvent to feed ratio were calculated for the practical design of a liquid-liquid extraction column. Roughly 2 to 4 theoretical units were calculated to meet the targeted extraction efficiencies. This study is the first to investigate the reactive extraction of gallic acid by triphenylphosphine oxide, and include fundamental information for the recovery of gallic acid.

Experimental and modeling study of the low to high-temperature oxidation of the methyl isopropyl ketone in O2/N2/Ar and O2/CO2/Ar atmospheres

Few studies on the low-temperature combustion behavior of MIPK, being a promising fuel additive, have been conducted. In this work, ignition delay times (IDTs) of MIPK were measured in the temperatures ranging between 780–910 K and pressures of 20 and 25 bar using a rapid compression machine (RCM). Oxy-fuel combustion combined with biofuel could remove CO2 from the atmosphere. The IDTs of MIPK were measured in the temperatures ranging between 1125–1600 K under the O2/CO2 atmosphere at the pressures of 1 and 10 bar using a shock tube. A low to high-temperature MIPK kinetic model (HUST-MIPK model) was proposed, in which the low-temperature sub-model consists of 19 low-temperature reaction classes and was constructed by analogy-based method, the high-temperature sub-model was adapted from the works of Cheng et al.. The predictions of HUST-MIPK model are in good agreement with the present low-temperature IDTs, high-temperature O2/CO2 atmosphere IDTs, and the literature experimental data. The negative temperature coefficient (NTC) behavior was not observed in the temperature range from 790 to 910 K in the present RCM experiments, but was observed for methyl propyl ketone (MPK) and diethyl ketone (DEK) under similar conditions. The low-temperature chemistry of three pentanone isomers (MIPK, MPK, and DEK) was compared using the flux and sensitivity analysis. The comparison of the experimental high-temperature IDTs between O2/CO2 and O2/Ar atmospheres indicates the IDTs of MIPK under O2/CO2 atmosphere are longer than those under O2/Ar atmosphere at 1 bar, and the effects of CO2 are almost independent of the pressure. The physical and chemical effects of CO2 on the ignition were studied in detail.

Structure Identification for Force-Induced Reaction Using Single-Molecule Conductance Measurement

Structure Identification for Force-Induced Reaction Using Single-Molecule Conductance Measurement

Beating neat fuels by dedicated blending: Performance analysis of bio-hybrid fuel blends on a spark-ignition engine for passenger car applications

The alcohol fuel ethanol is well known for its favorable engine performance in terms of both high net indicated efficiency and low nitrogen oxide emissions. Other alternative neat fuels such as 2-butanone were not able to outperform ethanol in its engine performance. In addition, ethanol has lower production costs compared to 2-butanone, which makes ethanol even more attractive. To compete with neat fuels, model-based fuel design was introduced to tailor fuels by means of dedicated blending of neat alternative components. First, a blend consisting of ethanol, 2-butanone, cyclopentane, and cyclopentanone (EBCC) was defined. Second, a ketone–ester–alcohol–alkane (KEAA) blend consisting of methyl isopropyl ketone, methyl acetate, ethyl acetate, ethanol, methanol, and pentane was developed. Both blends were optimized regarding their production costs while simultaneously considering fuel properties such as the octane number, the oxygen content, and the enthalpy of vaporization. Although both blends showed promising fuel properties, their performance in an internal combustion engine was not evaluated in the fuel design process. This study presents investigations of both blends on a thermodynamic spark-ignition single-cylinder engine for passenger car applications with a compression ratio of 16.4. In particular, a variation of the engine load at an engine speed of 2000 1/min and two variations of the relative air/fuel ratio at the same engine speed and net indicated mean effective pressures of 6 bar and 15 bar were performed. The combustion behavior of the two blends was compared to that of neat ethanol, neat 2-butanone, and conventional gasoline pump fuel. In addition, 0D/1D simulations were performed to evaluate the efficiency losses during the combustion. EBCC achieved a maximum net indicated efficiency of 46.9% at a net indicated mean effective pressure of 15 bar and a relative air/fuel ratio of 1.7, exceeding ethanol’s maximum net indicated efficiency of 46.0% in the same operating point. KEAA achieved a lower net indicated efficiency than ethanol and was on the same level as neat 2-butanone, resulting in a maximum net indicated efficiency of 45.0% in the same operating point. This work shows that the combustion performance in an internal combustion engine should be considered in the fuel design process to better predict promising fuel candidates from an engine perspective.

Sevoflurane analysis in forensic cases using headspace-gas chromatography-mass spectrometry: A case study

The objective is to present a case study related to forensic analysis of Sevoflurane Using Head Space (HS)-GCMS. For qualitative detection of volatile substances, this methodology might be helpful in conducting forensic analysis of such substances. Sevoflurane is an ether inhalation general anaesthetic agent. Sevoflurane is a volatile nonflammable fluorinated methyl isopropyl ether inhaled anaesthetic, chemically related to desflurane and isoflurane (C. M. Rosales, J. Forensic Sci., 2007, 52, 1408–1410). The low solubility and the absence of pungency facilitate rapid mask induction. It has been used as an inhaled anaesthetic since 1985. Its major distribution is initially to areas of high blood flow (brain, heart, liver and kidney) and later to less perfused organs. Sevoflurane can cause cardio-respiratory depression, hypotension, and malignant hyperthermia (M. Adachi, J. Anaesth., 1992, 68, 214–215). Seizures (convulsions) can occur during anaesthesia with Sevoflurane but Sevoflurane related deaths are rare. Various studies have been conducted for detection and quantification of Sevoflurane in postmortem and toxicological studies. The case was submitted at PFSA (Punjab Forensic Science Agency) for analysis consisting of bottle of suspected narcotics. The bottle was recovered from accused committing offence of criminal intimidation, life threat and physically assaulting his ex-wife and children. He trespassed into house and sprayed her with some bottle in order to molest her. He also threatened her children and his father in-law with pistol. The suspected bottle of spray was analyzed qualitatively using HS-GC-MS with slight modification in already validated method. About 1–2 mL of liquid was taken in headspace vial and heated up to 50–60oC (for vaporization) and about 1–2 μL of headspace sample was injected manually in GC. A gas chromatographic system 7890B series (Agilent Technologies, Palo Alto, CA, USA) coupled to MS detector. Agilent HP-5MS Ultra Inert column (30 m length, 250 μm ID, with film thickness of 0.25 μm) (D. Bourdeaux, J. Chromatogr. B. Analyt. Technol. Biomed. Life Sci., 2010, 878, 45–50). was used for the separation of constituents. Injection volume of 1 μL was used in split mode in 20:1 ratio at 250 °C. Helium gas was used as carrier gas with 1 mL/min flow rate with inlet pressure 12.051 psi. Oven temperature for GC column at 50 °C upheld for 2 min and then gradually increased to 150 °C at 50 °C/min for 1 minute. The total run time was set up for 5 min. The temperature for MS source and MS Quad were 230 °C and 150 °C respectively. Scan mode for m/z from 43–220 was done. Agilent GC Chemstation was used for data analysis. Results were compared with reference book (C. Maffat, Clark's Analysis of Drug and Poisons. 3rd. London-Chicago: Pharmaceutical Press, 2004, 2, 1558–1559). This exceptional crime case of using sevoflurane bottle for threatening and attacking received in our lab was evaluated for the presence of suspected drug. The sample analyzed using HS-GCMS showed a single peak on chromatogram at 1.282 + 0.01 minutes and the MS ions were matched with reference MS spectrum showing Sevoflurane which is being used as inhalation anaesthetic. Various studies suggested that Sevoflurane could possible cause irreversible circulatory depression and hypoxia and may cause death. It is the new case of decapitation with sevoflurane. The reported method is quite short and efficient in detection of Sevoflurane using HS-GCMS.

Single-pulse shock-tube study on the pyrolysis of small esters (ethyl and propyl propanoate, isopropyl acetate) and methyl isopropyl carbonate

Single-pulse shock-tube experiments were used to study the thermal decomposition of selected oxygenated hydrocarbons: Ethyl propanoate (C2H5OC(O)C2H5; EP), propyl propanoate (C3H7OC(O)C2H5; PP), isopropyl acetate ((CH3)2HCOC(O)CH3; IPA), and methyl isopropyl carbonate ((CH3)2HCOC(O)OCH3; MIC) The consumption of reactants and the formation of stable products such as C2H4 and C3H6 were measured with gas chromatography/mass spectrometry (GC/MS). Depending on the considered reactant, the temperatures range from 716–1102 K at pressures between 1.5 and 2.0 bar. Rate-coefficient data were obtained from first-order analysis. All reactants primarily decompose by six-center eliminations: EP → C2H4 + C2H5COOH (propionic acid); PP → C3H6 + C2H5COOH; IPA → C3H6 + CH3COOH (acetic acid); MIC → C3H6 + CH3OC(O)OH (methoxy formic acid). Experimental rate-coefficient data can be well represented by the following Arrhenius expressions: k(EP → products) = 1013.49±0.16 exp(−214.95±3.25 kJ/mol/RT) s−1; k(PP → products) = 1012.21±0.16 exp(–191.21±2.79 kJ/mol/RT) s−1; k(IPA → products) = 1013.10±0.31 exp(–186.38±5.10 kJ/mol/RT) s−1; k(MIC → products) = 1012.43±0.29 exp(–165.25±4.46 kJ/mol/RT) s−1. The determination of rate coefficients was based on the amount of C2H4 or C3H6 formed. The potential energy surface (PES) of the thermal decomposition of these four reactants was determined with the G4 composite method. A master-equation analysis was conducted based on energies and molecular properties from the G4 computations. The results indicate that the length of a linear alkyl substituent does not significantly influence the rate of six-center eliminations, whereas the change from a linear to a branched alkyl substituent results in a significant reactivity increase. The comparison between rate-coefficient data also shows that alkyl carbonates have higher reactivity towards decomposition by six-center elimination than esters. The results are discussed in in the context of reactivity patterns of carbonyl compounds.

Experimental Study and Thermodynamic Modeling of Ternary Liquid–Liquid Equilibrium of Water + 2,2,2-Trifluoroethanol + Four Solvents at 298.2 K

For the separation of 2,2,2-trifluoroethanol in water, two alcohols and two ketones were chosen as extractants for experiments at 101.3 kPa and 298.2 K. The liquid–liquid equilibrium data for water + 2,2,2-trifluoroethanol + (4-methyl-2-pentanol, methyl isobutyl ketone, methyl isopropyl ketone, and benzyl alcohol) were measured under these conditions. The separation effects of the four solvents were assessed by the distribution coefficient (D) and the separation factor (S). Meantime, the interaction parameters were obtained by fitting the experimental data using NRTL and UNIQUAC models, and both values of AAD and rmsd were less than 0.43%. The GUI-MATLAB series of topological analysis tools were used to check the accuracy of the measured values with the binary interaction parameters.

Phosphorus accelerate the sulfur cycle by promoting the release of malodorous volatile organic sulfur compounds from Microcystis in freshwater lakes

Volatile organic sulfur compounds (VSCs) released by algae are of great significance in sulfur cycle, climate regulation and biological information transmission, and they also caused taste and odor in freshwaters. However, the categories, sources, and environmental regulatory factors of VSCs in freshwaters were less known. Here, we show that eight common freshwater cyanobacterium Microcystis, which bloom in freshwaters over the world, are found to be important producers of VSCs. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and isopropyl methyl sulfide (IPMS) are the main VSCs with the highest concentrations 184.81 nmol/L, 162.01 nmol/L and 101.55 nmol/L, respectively. The amount of VSCs released from those Microcystis varied greatly, M. elabens, M. panniformis and M. flos-aquae released the largest amount of VSCs (1260.52 nmol S/L, 1154.75 nmol S/L and 670.58 nmol S/L), and M. wesenbergii had the smallest release amount. We also found for the first time that phosphorus (P) was one of the important factors for the regulation VSCs from most Microcystis. P can elevate the release of DMS by promoting the biomass and DMS yields of most Microcystis in the range 0.05 mg/L to 0.5 mg/L. Similar results were also found in 16 lakes at three different spatiotemporal scales. Overall, we revealed that the common freshwater Microcystis were able to release diverse thioethers, and the major VSCs were significantly influenced by water P concentrations. In the context of global freshwater eutrophication and Microcystis bloom, freshwater cyanobacteria driven sulfur cycle and water odor will probably be further strengthened.

A rapid and environmentally friendly method for determination of parabens preservatives in flavors by supercritical fluid chromatography-tandem mass spectrometry.

A rapid method for determination of parabens preservatives (methyl paraben, ethyl paraben, isopropyl paraben, propyl paraben, isobutyl paraben, and butyl paraben) in flavors was established by using supercritical fluid chromatography-tandem mass spectrometry combined with dispersive solid-phase extraction. After adding methanol and primary secondary amine to the sample simultaneously, high extraction efficiency and good sample cleanup could be obtained by simple shaking. Parabens were well separated on a Chiralpak IG-3 column in 6min by gradient elution. Recoveries from spiked blank samples at 0.5, 1.0, and 5.0mg/kg were determined to be 88.3-106.6%with relative standard deviations less than 8.0%. All analytes achieved good linear relation (r ≥ 0.999 2). The limits of detection for all analytes ranged from 0.03 to 0.09mg/kg and the limits of quantification from 0.11 to 0.31mg/kg, respectively. A total of 20 actual samples were successfully analyzed by taking the proposed method. Being simple, rapid, green, and reliable, this method can be taken for the determination of parabens preservatives in flavors.

Growth, thermal and optical properties of r-2,c-6-bis(p-tolyl)-c-3,t-3-dimethylpiperidin-4-one – A new class of organic NLO material

An organic nonlinear optical crystal, r-2,c-6-bis(p-tolyl)-c-3,t-3-dimethylpiperidin-4-one (PT3DMPO), was synthesized using ammonium acetate, p-methyl benzaldehyde, methyl isopropyl ketone and ethanol. The PT3DMPO crystals were grown using slow evaporation method. Spectroscopic techniques like FTIR, UV – Visible, Powder XRD, 1H NMR, 13C NMR were employed to characterise the grown single crystals. The non-centro symmetric crystal was found to be orthorhombic system with Pna21 space group. Thermogravimetry and differential thermal analysis techniques were employed to analyse the thermal stability of PT3DMPO and found that the title compound is stable up to 375 °C. Using Kurtz – Perry powder method, the second harmonic generation efficiency was determined for the compound and found to have almost equal (0.95 times) efficiency as that of standard potassium dihydrogen orthophosphate (KDP).

Sevoflurane Promotes Neurodegeneration Through Inflammasome Formation in APP/PS1 Mice.

Sevoflurane (SEVO) is a highly fluorinated methyl isopropyl ether used as an inhalational anesthetic for general anesthesia. Previous studies have shown that SEVO may induce impaired memory and recognition ability and may be associated with neurodegenerative disease, e.g., Alzheimer’s disease (AD). However, the underlying mechanism remains unknown. Here, we used a mouse AD model, APP/PS1, to study the effects of SEVO on neurodegeneration occurring in AD. We found that SEVO exposure significantly impaired the spatial reference memory, sensorimotor, and cognitive function of the mice. Mechanistically, we found that SEVO induced formation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and its downstream caspase 1-mediated production of IL-1β and IL-18, which subsequently deactivated brain-derived neurotrophic factor (BDNF) to promote neurodegeneration. Together, these data suggest that NLRP3 inflammasome is essential for SEVO-induced AD.

Protein Modification at Tyrosine with Iminoxyl Radicals.

Post-translational modifications (PTMs) of proteins are a biological mechanism for reversibly controlling protein function. Synthetic protein modifications (SPMs) at specific canonical amino acids can mimic PTMs. However, reversible SPMs at hydrophobic amino acid residues in proteins are especially limited. Here, we report a tyrosine (Tyr)-selective SPM utilizing persistent iminoxyl radicals, which are readily generated from sterically hindered oximes via single-electron oxidation. The reactivity of iminoxyl radicals with Tyr was dependent on the steric and electronic demands of oximes; isopropyl methyl piperidinium oxime 1f formed stable adducts, whereas the reaction of tert-butyl methyl piperidinium oxime 1o was reversible. The difference in reversibility between 1f and 1o, differentiated only by one methyl group, is due to the stability of iminoxyl radicals, which is partly dictated by the bond dissociation energy of oxime O-H groups. The Tyr-selective modifications with 1f and 1o proceeded under physiologically relevant, mild conditions. Specifically, the stable Tyr-modification with 1f introduced functional small molecules, including an azobenzene photoswitch, to proteins. Moreover, masking critical Tyr residues by SPM with 1o, and subsequent deconjugation triggered by the treatment with a thiol, enabled on-demand control of protein functions. We applied this reversible Tyr modification with 1o to alter an enzymatic activity and the binding affinity of a monoclonal antibody with an antigen upon modification/deconjugation. The on-demand ON/OFF switch of protein functions through Tyr-selective and reversible covalent-bond formation will provide unique opportunities in biological research and therapeutics.

Computational comparison of oxidation stability: Sulfones vs. fluorinated sulfones

The oxidation stability and initial decomposition reaction of sulfones and fluorinated sulfones are compared through quantum chemical calculations. The fluorination of isolated sulfones does not always increase the oxidation potential, which is related to the fluorination position and molecular configuration. The effects of incorporating another solvent molecule/lithium salt anion (PF6−, FSI−) on oxidation stability are investigated. The addition of the solvent molecule slightly reduces the oxidation potential of sulfones or fluorinated sulfones. PF6− has a weak influence on the oxidation potential of sulfones, except for the branched methyl isopropyl sulfone. When the α-CH3 group of the sulfones is fluorinated to -CF3, PF6− is found to significantly reduce the oxidation potential of the solvent-PF6− complexes, while the effect is small on the fluorinated non-α-CH3 group. The greater impact on oxidation potential is due to the chemical reaction of sulfones or fluorinated sulfones with PF6− following the loss of electrons. Furthermore, although the oxidation potential of FSI− is lower than that of sulfones and fluorinated sulfones, the oxidation potential of most solvent-FSI− complexes is higher than that of isolated FSI−. This study provides important information for the design of electrolytes suitable for high-voltage applications.

Liquid-liquid equilibrium data measurement and thermodynamic modelling for ternary mixtures composed of water, diethylene glycol dimethyl ether and different solvents at 298.2 K

Liquid-liquid equilibrium (LLE) data for water + diethylene glycol dimethyl ether + {methyl isobutyl carbinol, methyl isobutyl ketone, methyl isopropyl ketone, methyl tert-butyl ether, n-octanol and 2-ethyl-1-hexanol} was measured at 298.2 K under 101.3 kPa. The effect of separating diethylene glycol dimethyl ether from water is evaluated by the distribution coefficient and the separation coefficient. The Othmer-Tobias and Hand equations were chosen to examine the experimental LLE data. Meanwhile, the data was correlated by the NRTL and UNIQUAC thermodynamic models with AAD% less than 0.55 and RMSD% less than 0.77. The separation performance of six solvents was compared using the σ-profile analysis via the exploration of the intermolecular interaction.

KINETICS OF QUATERNIZATION BETWEEN N, N-DIMETHYLANILINE AND BENZYL CHLORIDE IN POLAR SOLVENTS-A REVISIT TO MENSHUTKIN REACTION

This work reports an extension of Menshutkin reaction and involves the studies on kinetics of quaternization reaction between N,N-Dimethylaniline and benzyl chloride in acetone and in other various solvents at 300 K. The progress of the reaction was followed by measuring the conductance of the product formed at regular intervals of time. The effect of [benzyl chloride] and [N,N-Dimethylaniline] on reaction rate was studied under pseudo-first order condition and the rate showed first order dependence on both [benzyl chloride] and [N,N-Dimethylaniline]. The effect of dielectric constant of the medium on reaction rate was studied by employing various solvents such as methyl ethyl ketone, isopropyl alcohol, ethyl alcohol, methyl alcohol and acetonitrile and the rate is found to increase with increase in dielectric constant of the medium. The linear plot with a negative slope on plotting log k2 against 1/D where D is the dielectric constant of the medium indicates the existence of a highly charged or a polar transition state during the progress of the reaction. The quaternization reaction was also carried out at different temperatures so as to compute the various thermodynamic parameters like activation energy, enthalpy of activation, entropy of activation and Gibb’s free energy change. The higher value of activation energy is attributed for a slower reaction which is sterically controlled rather than thermodynamically controlled. The negative value of entropy of activation (ΔS*) indicates some sort of surrendering of disorder in the transition state on its formation which proves that it is highly ordered with sufficient charge separation and polar in character. The product after purification was analysed by melting point and infra-red spectral analysis and is proved to be N-Benzyl-N,N-dimethylphenylmethanaminium chloride. A plausible mechanism in accordance with the obtained experimental results is reported.

Formation and Cycloaddition Reactions of a Reactive Boraalkene Stabilized Internally by N‐Heterocyclic Carbene

AbstractThe synthesis of element−carbon double bonds is of great importance for the development and understanding of reactive π‐bonded systems in chemistry. The seven‐membered heterocyclic system 4 b is readily made by internal C−H activation at a pendent isopropyl methyl group of the respective [(IPr)C6F5BH]+ borenium ion. Subsequent deprotonation with the IMes carbene gives the neutral cyclic boraalkene system 5 b. The B=C double bond in compound 5 b adds carbon dioxide, CS2, sulfur dioxide, phenyl isocyanate, an acetylenic ester or two NO molecules to give the corresponding four‐membered ring annulated heterocycles. With sulfur or selenium 5 b gives the respective three‐membered ring systems. N2O reacts with 5 b to give a mixture of the related oxaborirane 18 and a unique [B]OH containing diazoalkane product 19.

Formation and Cycloaddition Reactions of a Reactive Boraalkene Stabilized Internally by N-Heterocyclic Carbene.

The synthesis of element-carbon double bonds is of great importance for the development and understanding of reactive π-bonded systems in chemistry. The seven-membered heterocyclic system 4 b is readily made by internal C-H activation at a pendent isopropyl methyl group of the respective [(IPr)C6 F5 BH]+ borenium ion. Subsequent deprotonation with the IMes carbene gives the neutral cyclic boraalkene system 5 b. The B=C double bond in compound 5 b adds carbon dioxide, CS2 , sulfur dioxide, phenyl isocyanate, an acetylenic ester or two NO molecules to give the corresponding four-membered ring annulated heterocycles. With sulfur or selenium 5 b gives the respective three-membered ring systems. N2 O reacts with 5 b to give a mixture of the related oxaborirane 18 and a unique [B]OH containing diazoalkane product 19.

Determination of eight organic residues in ion exchange resins by headspace gas chromatography

建立了功能食品加工用离子交换树脂中甲基异丙基甲酮、丁酸甲酯、3-戊酮、1,3-二乙基苯、1,4-二乙基苯、1,2-二氯乙烷、间二氯苯、甲基丙烯酸甲酯8种有机残留物的顶空气相色谱检测方法,研究了不同类型树脂中的有机残留物种类及含量,为食品和药品中安全使用离子交换树脂提供依据。优化了样品的提取溶剂和顶空气相色谱条件,样品经二甲亚砜超声萃取,应用DB-23色谱柱(60 m×0.32 mm×0.25 μm)分离,氢火焰离子化检测器(FID)检测,在顶空进样器平衡时间为30 min、平衡温度为80 ℃时有机残留物的分离和定量分析效果较好。色谱条件如下:柱温采用程序升温,初始温度60 ℃,保持16 min,再以20 ℃/min的升温速率升至200 ℃,保持2 min;进样口温度240 ℃, FID温度为300 ℃ ;载气为氮气,流速为1.2 mL/min;外标法定量。结果表明,在所考察的浓度范围0.02~200 mg/L内,8种有机物的线性关系良好,相关系数(R2)均在0.999以上,检出限为0.0050~0.0375 ng/g, 3个添加水平下的平均回收率为82.3%~109.2%,相对标准偏差为1.06%~4.16%(RSD, n=6)。用所建立的方法检测11种树脂样品,结果表明,树脂样品中均存在一定量的有机物,个别产品的残留量较高,其中苯乙烯类树脂Seplite LX-69B中甲基丙烯酸甲酯残留量达到470.8 μg/g。该方法不需要衍生,简化了样品前处理过程,操作简单,准确度和精密度良好,可同时检测离子交换树脂中多种有机残留物,能显著提高离子交换树脂中有机物的检测速率,该方法的建立对我国进出口离子交换树脂中有机残留物检验工作的开展具有重要意义。

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.