Pure Diethyl Ether Research Articles

Shock tube and comprehensive kinetic modeling study of ammonia/diethyl ether (DEE) mixtures

Ammonia (NH3) is a promising alternative clean fuel due to its carbon-free and high hydrogen content, along with the well-established infrastructure for storage and distribution. To overcome the issue of the low reactivity of NH3, a feasible strategy is co-burning ammonia with highly reactive fuels. Diethyl ether (DEE) is considered a promising alternative and biomass-oxygenated clean diesel substitute. Therefore, the NH3/DEE blend is also a promising carbon neutral alternative fuel. In this work, we measured the ignition delay times (IDTs) of NH3/DEE mixtures with DEE fractions (XDEE) of 0.05, 0.10, 0.30, and 1.00 at equivalence ratios of 0.5, 1.0, and 2.0, pressures of 1.75 and 10 bar, and temperature ranges from 1102 K to 1673 K in a shock tube. The DEE-NH3 model was proposed in this work, which included the DEE sub-model, NH3 sub-model, and some new cross-reactions between N-containing species and C-containing species. The DEE sub-model from Shrestha et al. (Fuel Communications, 2022) was modified in this work, NH3 sub-model was from our previous work (Reaction Chemistry & Engineering, 2023). The DEE-NH3 model was extensively validated by the IDTs, laminar flame speeds (LFSs), and species profiles (SPs) of NH3/DEE mixtures as well as pure DEE and NH3. The comparison of the prediction performance between the DEE-NH3 model and the Shrestha model was conducted for the ignition, flame propagation, and NH3 consumption. The effects of the cross-reactions on the NH3/DEE ignition and combustion were studied in detail.

Screening deep eutectic solvents as green extractants for oil from plant seeds based on COSMO-RS model

Deep eutectic solvents (DESs) have recently attracted considerable interest as eco-friendly alternatives for conventional solvents in many industrial separation processes. However, due to its vast number of possible combinations, reliable approaches for guiding the selection of task-specific DES remain limited. Using conductor-like screening model for real solvent (COSMO-RS), the solubility capacity was applied to screen 126 deep eutectic solvents to estimate their potential use as plant seed oil extractants. Moreover, DESs’ σ-profiles were matched to σ-profiles of linoleic acid and glutamine, representing oil and oil protective protein membrane, to evaluate their molecule interactions. Results of COSMO-RS revealed that the DESs with higher linoleic acid solubility capacity showed lower solubility capacity for protein and vice versa. Moreover, σ-profiles of representative DESs demonstrated this behavior by comparing the similarity of DESs to both linoleic acid and protein. Consequently, DESs with high linoleic acid solubility could be used as individual solvents, while DESs with high protein solubility could be used as co-solvents with organic solvents. However, the experimental results proved that the use of DESs having high protein capacity, as co-solvents with diethyl ether, n-pentane and n-heptane raised the extracted oil yield. Utilizing ChCl:Gly (1:2) as a co-solvent with diethyl ether produced the highest yield of 30.7% compared to pure diethyl ether, which produced 27.0%.

Aluminium nanoparticle modelling coupled with molecular dynamic simulation method to compare the effect of annealing rates on diethyl ether coating and oxidation behaviours

This study was conducted to examine the influence of annealing rates on coating and oxidation performances of Aluminium (Al) nanoparticle (ANP) by molecular dynamic (MD) simulations. Four levels of cooling rates were utilized on melted ANP to obtain annealed ANP models with different microstructures. Then those nanoparticles were placed into pure diethyl ether or oxygen gas environments to perform coating and oxidation simulations respectively. It was revealed that there was a relatively optimal annealing condition for ANP models to recover the initial microstructure of themselves as much as possible. The ether coating behaviour of annealed ANP model under this condition was better than other models. In contrast, the oxidation of all different models was almost the same. So, the factor of the annealing rate had little effect on the oxidation results. Along with the growth of the oxide layer, the core of ANP still kept its annealed microstructure.

Autoignition of diethyl ether and a diethyl ether/ethanol blend

Binary blends of fast-reacting diethyl ether (DEE) and slow-reacting ethanol (EtOH) are quite promising as renewable replacements for conventional fuels in modern compression ignition engines. In this work, pure diethyl ether and a 50/50 M binary blend of diethyl ether and ethanol (DEE/EtOH) were investigated in a shock tube and a rapid compression machine. Ignition delay times were measured over the temperature range of 550–1000 K, pressures of 20–40 bar, and equivalence ratios of 0.5–1. Literature reaction mechanisms of diethyl ether and ethanol were combined to simulate the reactivity trends of the blends. Species rate-of-production and sensitivity analyses were performed to analyze the interplay between radicals originating from the two fuels. Multistage ignition behavior was observed in both experiments and simulations, with peculiar 3-stage ignition visible at fuel-lean conditions. Kinetic analyses were used to identify the reactions controlling various stages of ignition. Reactivity comparison of DEE/EtOH and dimethyl ether/ethanol (DME/EtOH) blends showed that the oxidation of DEE blends is controlled by acetaldehyde whereas formaldehyde controls the oxidation of DME blends.

Molecular Dynamic Simulations of Diethyl Ether and its Mixture with Cellulose Dinitrate Tripolymer Molecules for their Thermal Diffusion Behaviors

In this paper, thermal diffusion states of pure diethyl ether and its mixture with cellulose dinitrate tripolymer were uncovered by LAMMPS-based Molecular Dynamic (MD) simulations. Those MD simulations were generally performed through specified ReaxFF reactive force field to obtain the properties of the chemical system such as molecular energy, density, mean square displacement (MSD) and molecular coordinate. The result of MD simulations presented the clear superheating phenomenon of pure liquid diethyl ether system in the studied environment. The obtained phase transition point was much higher than the reported one. The deviation between two temperatures was about 132.369[Formula: see text]K. It was also demonstrated that the transition process was associated with the sharp increment of potential energy, volume, diffusion coefficient and cohesive energy. However, the split of these diethyl ether molecules was not uniform. The cluster-like transition state was observed before the end of the vaporing process (460[Formula: see text]K). As for the addition of cellulose dinitrate tripolymer, these molecules were not agglomerated in the simulated organic mixture. However, the diffusion of cellulose dinitrate tripolymer was much weaker than those diethyl ether molecules. While the concentration of cellulose dinitrate tripolymer was higher, molecular interactions of this organic mixture were consequently improved, and this further limited the diffusion behavior of the entire chemical system. It could be concluded that the diffusion behavior of the entire organic system was decreased with more amount of cellulose dinitrate tripolymer molecules.

Studies on molecular interaction in binary mixtures of diethyl ether with some alkanols – an acoustic approach

The viscosity (η), density (ρ) and ultrasonic velocity (u) of pure diethyl ether (DEE) and three alkanols, namely methanol, n-propanol and n-butanol, and their binary mixture with DEE as a common component have been experimentally measured at 303.16 K under atmospheric pressure. The experimentally measured parameters were employed to compute the values of isentropic compressibility (β s), intermolecular free length (L f), molar volume (V m), acoustic impedance (Z), available volume (V a), free volume (V f), internal pressure (π i) and the viscous relaxation time (τ). Furthermore, the deviation functions such as were estimated in the entire range of DEE molefraction. The compositional variation of deviation functions were correlated to the Redlich–Kister-type polynomial equation. The sign and magnitude of deviation parameters have been interpreted in terms of H-bonding, proper interstitial accommodation in the structural process and the dipole–dipole type of molecular interactions between DEE and alkanol molecules. Theoretical values of ultrasonic velocity in all three binary mixtures have been estimated using five different empirical relations, such as Nomoto's relation, Junjie's relation, Rao's relation, Van Deal-Vageel's ideal mixing relation and impedance dependence relation. The relative merit of these relations with the measured values of ultrasonic velocity is discussed in this article.

Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes

Multinuclear NMR spectroscopic studies at low temperature (-110 to -150 degrees C) revealed that lithium p-fluorophenolate and the lithium enolates of cyclohexanone, cyclopentanone and 4-fluoroacetophenone have tetrameric structures in THF/Et(2)O and THF/Et(2)O-HMPA by study of the effects of the addition of HMPA. The Z and E isomers of the lithium enolate of 1,3-bis-(4-fluorophenyl)-2-propanone (5F-Li) show divergent behavior. The Z isomer is completely dimeric in pure diethyl ether, and mostly dimeric in 3:2 THF/ether, where monomer could be detected in small amounts. TMTAN and PMDTA convert Z-5F-Li to a monomeric amine complex, and HMPA converts it partially to monomers, and partially to lithiate species (RO)(2)Li(-) and (RO)(3)Li(2-). Better characterized solutions of these lithiates were prepared by addition of phosphazenium enolates (using P4-(t)Bu base) to the lithium enolate in 1:1 ratio to form triple ion (RO)(2)Li(-) P4H(+), or 2:1 ratio to form the higher lithiate (RO)(3)Li(2-) (P4H(+))(2)) (quadruple ions). The E isomer of 5F-Li is also dimeric in 3:2 THF/Et(2)O solution, but is not detectably converted to monomer either by PMDTA or HMPA. In contrast to Z-5F-Li, the E isomer is tetrameric in diethyl ether even in the presence of excess HMPA. Thus for the two isomers of 5F six different enolate structures were characterized: tetramer, dimer, CIP-monomer, SIP-monomer, triple ion, and quadruple ion.

Effect of Solvent on the Lithium−Bromine Exchange of Aryl Bromides: Reactions of n-Butyllithium and tert-Butyllithium with 1-Bromo-4-tert-butylbenzene at 0 °C

The outcome of reactions of 1-bromo-4-tert-butylbenzene (1), a representative aryl bromide, with n-BuLi or t-BuLi at 0 degrees C in a variety of solvent systems has been investigated. The products of reactions of 1 with n-BuLi vary significantly with changes in solvent composition: 1 does not react with n-BuLi in pure heptane; the exchange reaction to give (4-tert-butylphenyl)lithium, which is slow in pure diethyl ether, is virtually quantitative in heptane containing a small quantity of THF; and the reaction of 1 with n-BuLi in THF leads to considerable coupling. Lithium-bromine exchange is the virtually exclusive outcome of reactions of 1 with t-BuLi in every solvent studied except pure heptane: the presence of a small quantity of any of a variety of structurally diverse ethers (Et(2)O, THF, THP, MTBE) in the predominantly hydrocarbon medium affords (4-tert-butylphenyl)lithium, assayed as tert-butylbenzene, in yields exceeding 97%. The only side products observed from reactions of 1 with t-BuLi are small amounts of benzyne-derived hydrocarbons.

Modulation of tautomeric equilibria by ionic clusters. Acetylacetone in solutions of lithium perchlorate-diethyl ether.

Acetylacetone (2,4-pentanedione, 1) is a molecule whose tautomeric forms are in dynamic equilibrium. Concentrated salt solutions in nonaqueous solvents exert a remarkable influence on the keto-enol ratio of this beta-diketone. The keto content of 1 increases from 5% in pure diethyl ether to 84.5% in a 4.14 M lithium perchlorate-diethyl ether (LPDE) solution, a nearly 17-fold increase. The equilibrium expression, K = [keto]/[enol] = k(f)/k(r), exhibits a linear dependence on [LiClO(4)], with the formal order of participation of lithium ion in the equilibrium being 1.0. A kinetic analysis reveals that k(f) is independent of LPDE concentration, whereas k(r) displays an inverse dependence on salt concentration, indicating preferential coordination of the keto tautomer with Li(+). Although 1 exits as the enol in water only to the extent of 16%, the addition of lithium perchlorate further reduces this figure. In an aqueous 4.02 M LiClO(4) solution, acetylacetone enol accounts for only 4.6% of the total amount of 2,4-pentanedione present. It has also been found that acetylacetone itself is an excellent solvent for LiClO(4) as well as for NaClO(4) with solutions containing up to 7.5 M LiClO(4) attainable. The enol content of 1 decreases dramatically from 81% to 7.4% on going from the neat liquid to a solution of 6.39 M LiClO(4) in acetylacetone.

Molecular-Scale Desorption Processes and the Alternating Missing-Row Phase of Alkanethiol Self-Assembled Monolayers on Au(111)

The structural changes as a function of the immersion time of predeposited hexanethiol self-assembled monolayers (SAMs) chemisorbed on an Au(111) surface in diethyl ether at room temperature have been investigated by scanning tunneling microscopy (STM). High-resolution STM images show molecular-scale morphological changes of the monolayers resulting from the desorption of molecules from the surface and provide a significant implication for the stability of the monolayers in pure organic solvent. Defects in the ordered monolayer were mainly initiated at domain boundaries and around depressions, followed by molecular defects in closely packed domains. After the immersion of predeposited SAMs in pure diethyl ether for 10 days, the structure of the monolayer was completely changed to a disordered phase. Meanwhile, the recrystallization of the resulting disordered phase at 4 °C for 6 months gave rise to a well-ordered 6 × √3 structure having alternating missing rows in the nearest-neighbor direction, reflectin...

Determination of piroxicam and its major metabolite 5-hydroxypiroxicam in human plasma by zero-crossing first-derivative spectrophotometry

A zero-crossing first-derivative spectrophotometric method for the determination of piroxicam and its major metabolite 5-hydroxypiroxicam (5-HP) in human plasma is described. This technique permits the quantification of compounds with closely overlapping spectral bands without any separation step. The method consists of direct extraction of the less-ionised forms of piroxicam and 5-hydroxypiroxiam with pure diethyl ether. First derivative values at 343.5 and 332.5 nm for piroxicam and 5-HP, respectively, were obtained. The absolute recovery of the method was found to be 89.4% for piroxicam and 90.3% for 5-HP. Calibration graphs are linear ( r better than 0.9998), with zero-intercept, in the concentration range 0.5–12.0 μg ml −1 for both compounds. The limits of quantification attained according to the IUPAC definition were 0.29 and 0.27 μg ml −1 for piroxicam and 5-HP, respectively. The results obtained by the proposed method were in good agreement with those found by the high-performance liquid chromatographic method (HPLC).

Magnesium bromide in Grignard reagent formation

The progress of the reaction of magnesium with bromocyclopropane in diethyl ether at reflux varies with time in a sigmoid fashion, reflecting an initial induction period during which autocatalysis is evident. The initial addition of MgBr 2 to the medium greatly reduces or eliminates the autocatalytic induction period, suggesting that the autocatalysis in the initial absence of MgBr 2 is due to its formation. Magnesium does not react with either 1-bromo-2,2,3,3-tetramethylcyclopropane or bromopentamethylbenzene in pure diethyl ether. It reacts smoothly with either in 2.6 M magnesium bromide in diethyl ether, giving the corresponding Grignard reagents (2,2,3,3-tetramethylcyclopropylmagnesium bromide, 28%; pentamethylphenylmagnesium bromide, 49-80%). In the case of 1-bromo-2,2,3,3-tetramethylcyclopropane, by-products representing >44% solvent attack are formed. Magnesium bromide also has more subtle effects. In reactions of magnesium with bromocyclopropane in diethyl ether, the product distribution varies significantly with the initial concentration of the substrate. Initially-added MgBr 2 emulates the effect of higher initial concentrations of the substrate, suggesting that the substrate concentration effects are responses to the buildup of polar solutes (MgBr 2, RMgBr) as the reaction proceeds. The bromocyclopropane reaction contrasts with that of 5-hexenyl bromide, for which the extent of cyclization is not very sensitive to added magnesium bromide. The early turbidity that usually forms in reactions of magnesium with organic halides in pure diethyl ether is absent for reactions in 2.6 M MgBr 2. Turbidity not due to a precipitate (MgX 2, RMgX, or other) may be due to a separation of dilute and concentrated liquid phases of MgBr 2 solutions. There are many parallels between Grignard reagent formation and metallic corrosion in contact with aqueous solutions, suggesting that Grignard reagent formation, like aqueous corrosion, involves local galvanic cells.

Second-derivative spectrophotometric determination of naproxen in the presence of its metabolite in human plasma.

A second-derivative spectrophotometric method for the determination of naproxen in the absence or presence of its 6-desmethyl metabolite in human plasma is described. The method consists of direct extraction of the non-ionized form of the drug with pure diethyl ether and determination of the naproxen by measuring the peak amplitude (mm) in the second-order derivative spectrum at a wavelength of 328.2 nm. The efficiency of the extraction procedure expressed by the absolute recovery was 94.6 +/- 0.7% (mean +/- s) for the concentration range tested, and the limit of quantification attained according to the IUPAC definition was 2.42 mg l-1. The linear dynamic range for naproxen was 5.0-100.0 mg l-1, the correlation coefficient for the calibration graphs was excellent, r = 0.99993 (n = 6), the precision (Sr) was better than 4.58% and the accuracy was satisfactory (Er < 2.32%). The results obtained by the proposed method were in good agreement with those found by an HPLC method.

Addition of diazomethane and sulfur ylides to the oxo-group in derivatives of ketoses and aldoses : I. Reactions of 2,3-O-isopropylidene-D-glyceraldehyde

The reaction between 2,3-O-isopropylidene- D-glyceraldehyde and diazomethane, dimethylsulfonium methylide and dimethyloxosulfonium methylide has been studied. The sulfur ylides yield two epimeric epoxides, 1,2-anhydro-3,4-O-isopropylidene- D-erythritol and 1,2-anhydro-3,4-O-isopropylidene- D-threitol, with a slight preference for the erythro isomer. The reaction with diazomethane yields in addition to the epoxides a methyl ketone, 1-deoxy-3,4-O-isopropylidene- D- glycero-tetrulose. The relative yields of the three products have been discussed on the basis of mechanisms previously proposed for the reactions. The yield of methyl ketone was lowest when the reaction was carried out in pure diethyl ether solution. This solvent also gives the greatest preference for the erythro isomer of the two epoxides. Constitution and stereochemistry for the three products have been shown by synthesis.

The constitution of the Grignard reagent

AbstractExperiments are reported on the association number of magnesium bromide, diethylmagnesium, mixtures of these two compounds, the Grignard reagent prepared from magnesium and ethyl bromide and mixtures of this Grignard reagent with magnesium bromide, all dissolved in pure diethyl ether at concentrations from 10−3 to 10−2 molar and measured at the same temperature.No trace of the equilibrium: was observed.Only one magnesium atom is incorporated in the molecules of the Grignard reagent, even in the presence of a large amount of magnesium bromide.

An Unrecorded Constituent of Commercial Ethyl Ether

FOR anaesthetic purposes a pure diethyl ether is now generally recognised as a desideratum. An opportunity recently arose for carrying out some ex-periments on the bromine absorption of commercial anaesthetic ethers, a standard solution of bromine in glacial acetic acid being added, and light excluded to avoid direct substitution of the ether by bromine. The products from six manufacturers absorbed bromine to different extents, as is shown by the following figures:—A, 0.6; B, 2.5; C, 7.5; D, 11.6; E, 13.6; F, 15.9. These are the numbers of c.c. of deci-normal bromine absorbed by 100 c.c. of the different ethers in the dark in one hour, which in the absence of aldehydes give a measure of he degree of unsaturation of the ethers. On examination of the bromination products of 2250 c.c. of ether C, among other constituents which are being further examined there was identified, as a major product, αβ-dibromovinylethyl ether (1 gram), which must have arisen from vinylethyl ether, CH2: CH . O . CH2 . CH3, b.p. 35°.5, present in the original ether. Vinylethyl ether was also present to a similar extent in freshly prepared ether, direct from the manufacturing still, which had never been exposed to light. It doubtless owes its origin to vinyl alcohol (acetaldehyde) functioning in the same way as ethyl alcohol in the Williamson process.