Dipropylene Glycol Dimethyl Ether Research Articles

The influence of molecular structure on the oxidation reactivity of long-chain ethers: Experimental observation and theoretical analysis

Long-chain ethers have been proposed as promising biofuels for advanced combustion methods, yet their low-temperature oxidation (LTO) characteristics remain poorly understood. In this study, the LTO reactivities of n-heptane and five long-chain ethers with different structures, including dibutyl ether (DBE), diethylene glycol dimethyl ether (DGM), polyoxymethylene dimethyl ethers (PODE), 1,2-dimethoxyethane (1,2-DME), and dipropyleneglycol dimethyl ether (DPGDE) are investigated using a cooperative fuel research (CFR) engine, which is closer to the actual internal combustion engine operating environment. Products formed from LTO of ethers and n-heptane are investigated over a wide range of compress ratios (CRs), and their relationship to the global oxidation reactivity is suggested based on the quantum chemistry calculation. The presence of oxygen atoms in long-chain ethers significantly enhances oxidation reactivity, with the global oxidation reactivity ranking as follows: DGM > DPGDE > 1,2-DME > DBE > PODE > n-heptane. The key intermediate species generated during the LTO of n-heptane include aldehydes, ketones, and cyclic ethers, while oxygen atoms in ethers facilitate the formation of acids. The species pathway analysis and quantum chemistry calculations reveal that (1,5) and (1,6) H-transfers of alkylperoxy radical (ROȮ) are critical chain-propagation channels, playing pivotal roles in the LTO process. The impact of oxygen on oxidation reactivity can be attributed to two primary factors: accelerating the H-abstraction of ȮH and H-transfer of ROȮ by weakening the neighboring C-H bonds, and enhancing the branching ratio of H-transfer of ROȮ. The arrangement of two oxygen atoms between every two carbon atoms (–OCH2CH2O–) is optimal for oxidation reactivity, while the arrangement of oxygen and carbon (–OCH2OCH2–) weakens the oxidation activity due to fewer available hydrogens for H-transfer. The methyl group in branching-chain, exhibit reduced oxidation reactivity due to the strength of C-H bonds. Additionally, for ethers with the same structure, a longer carbon chain allows for more available hydrogens, resulting in stronger oxidation reactivity.

Reaction kinetics of CO2 capture into AMP/PZ/DME solid-liquid biphasic solvent

The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol (AMP)/piperazine (PZ)/dipropylene glycol dimethyl ether (DME) features a high CO2 absorption loading, favorable phase separation behavior and high regeneration efficiency. Different with the liquid-liquid phase change solvent, the reaction kinetics of CO2 capture into solid-liquid biphasic solvent was rarely studied. In the present work, the reaction kinetics of CO2 absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor. The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism. The overall reaction rate constant (kov) and the enhancement factor (E) of CO2 absorption both increased with increasing temperature. The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading, so the higher reaction temperature was conducive to the absorption, and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.

Recycling of ammonia-cured epoxy resin by oxidative degradation of nitric acid assisted by swelling agent

Because of its high crosslinking density, compact structure and stable performance, epoxy resin is difficult to be degraded, which leads to serious environmental pollution problems. In this work, using dipropylene glycol dimethyl ether as swelling agent and nitric acid as oxidant, the degradation of amine cured epoxy resin was studied. Results are as follows: The degradation rate obtained by swelling agent assisted oxidation degradation method is much higher than that obtained by oxidation degradation method only. And the degradation rate of the epoxy resin even reached 100 % at 100 °C only in an hour under the condition of swelling agent assisted nitric acid. FT-IR and GC–MS showed that the degradation was mainly caused by that the CN bond in the molecular chain was gradually weakened and fractured finally. The molecular weight of the degradation product was relatively dispersive, which was composed of low molecular polymer and small fragments, and the molecular weight of low molecular polymer was about 2167. And the degradation products primarily contain 4-isopropylphenol and (allyloxy)benzene rings. This work provides a new way to solve the problem about the degradation, recycling and pollution of epoxy resin.

The regulated emissions and PAH emissions of bio-based long-chain ethers in a diesel engine

Catalytic etherification is a new and developing method for the upgradation of pyrolysis bio-oil into high performance bio-based long-chain ethers. In this work, the application of bio-based long-chain ether oxygenated additives in diesel engines have been checked by focusing on their regulated emissions and PAH emissions. Four bio-based long-chain ethers with similar structures, including: Polyoxymethylene dimethyl ether, diglyme, dipropylene glycol dimethyl ether and tripropylene glycol methyl ether have been blended with diesel fuel and tested in a small-duty diesel engine. The results showed that long-chain ethers were beneficial to the reduction of regulated emissions by comparing to pure diesel. Polyoxymethylene dimethyl ether and tripropylene glycol methyl ether showed best performance among the four tested ethers. Polyoxymethylene dimethyl ether could reduce 56% CO, 23% NO and 93% soot emissions, while Tripropylene glycol methyl ether could reduce 52% CO, 28% NO and 88% soot emissions. Besides, the particle sizes of soot particles from the blended fuels were also reduced. What's more, the addition of bio-based long-chain ethers could reduce particulate PAHs emissions by 39% ~ 67% and reduce gaseous PAHs emissions by 25% ~ 44%, and the PAHs toxicity was also reduced by 32% ~ 55%. This work proved that the structure of oxygen atoms evenly distributed in the chain could efficiently suppress the production of soot precursors and eventually reduce the soot emission

Applications of Lambert-Beer law in the preparation and performance evaluation of graphene modified asphalt

The main purpose of this paper is to develop high-performance graphene-modified asphalt (GMA) and characterize graphene occurrence in asphalt and examine its mechanism. The main research methods are: Based on Lambert-Beer law and dispersants dipropylene glycol dimethyl ether (DME) and polyvinyl pyrrolidone (PVP), the absorbance of dilute graphene mother liquor (GML) solutions at different concentrations were obtained via ultraviolet/visible spectrophotometry, and the concentration of dilute GML solutions were obtained via supernatant algorithms. The absorbance and concentration of dilute GML solutions were fitted via regression, which obtained the absorbance coefficient. Then, based on nominal graphene dosage (G) and dispersant and graphene proportion (D/G), respectively, the absorbance coefficients were fitted via regression to establish mathematical GML materials composition models which were solved via First Optimization (1stOpt) analysis software. Following the materials composition, DME-GMA and PVP-GMA was prepared, and the corresponding performance tests were carried out, and GMA was characterized via metallographic microscope and micro/nano-CT scanning to explore the morphology of graphene and mechanism in asphalt. The results are: Based on dispersants DME and PVP, respectively, the materials composition are G = 0.53%, D/G = 160%, and G = 0.26%, D/G = 190%. The penetration, non-recoverable creep compliance at 0.1 kPa and 3.2 kPa of DME-GMA and PVP-GMA (based on matrix asphalt) were decreased by 7.44 and 7.76%, 20.82 and 30.95% (0.1 kPa), and 8.63 and 18.88% (3.2 kPa), respectively. The softening point, maximum force at 5 °C, ductility at 5 °C, fracture energy at 5 °C, antirutting factors at 64 °C, and creep recovery rate at 0.1 kPa and 3.2 kPa were increased by 4.57 and 7.17%, 41.96 and 61.29%, 14.91 and 18.30%, 55.51 and 98.81%, 17.26 and 40.51%, 646.77 and 867.88% (0.1 kPa), and 128.62 and 153.53% (3.2 kPa), respectively. The high- and low-temperature stability of GMA are notably improved via uniformly dispersing graphene in asphalt materials, and graphene occurs as agglomerates in asphalt materials, and dispersants DME and PVP increase the graphene agglomerate dispersion effect in asphalt materials, changing its larger, irregular morphology to a smaller, regular one. The better the graphene dispersion effect is, the better the GMA performance is. PVP-GMA attains a better performance than DME-GMA.

TBAI-mediated sulfenylation of arenes with arylsulfonyl hydrazides in DPDME

Abstract An efficient TBAI (tetrabutylammonium iodide)-mediated C–H sulfenylation of arenes with arylsulfonyl hydrazides in dipropylene glycol dimethyl ether (DPDME) was described. Various electron-rich arenes were applicable in the reaction, such as naphthylamine, naphthol, aniline, indole, pyrrole, and imidaz o [1,2-a] pyridine. A wide range of the aryl sulfides were obtained with good functional group tolerance. This method features green reaction conditions (odorless and easily available sulfur reagent, recyclable TBAI, and DPDME as solvent), and broad substrate scope. The synthetic potential is demonstrated by gram-scale synthesis and downstream transformations. The mechanism studies show that the reaction is achieved through electrophilic substitution process, and diaryl disulfide may be the main intermediate.

Exploration of molecular interaction in binary liquid mixtures of dipropylene glycol dimethyl ether with methyl acetoacetate and ethyl acetoacetate at different temperatures using physicochemical approach

Density ρ, and speed of sound u, measurements have been carried out for the binary mixtures of dipropylene glycol dimethyl ether with methyl acetoacetate and ethyl acetoacetate at intervals 5 K, from temperatures T = (288.15 to 308.15) K and experimental pressure of p = 0.1 MPa. The entire ranges of composition have been measured using Anton-Paar DSA 5000 M densimeter i.e. density and speed of sound analyzer. Using experimental density data the excess molar volume, VmE has been determined. Isentropic compressibility along with excess molar compressibility have been determined from the experimental speed of sound. Deviations in intermolecular free length and deviations in acoustic impedance along thermal expansion coefficient have also been calculated. The variation of these parameters with composition and temperature have discussed in terms of molecular interaction in these mixtures. FT-IR studies of these mixtures have been also reported and obtained results have been used to analyze the mixing behaviour of the components.

Effect of repeated dry-cleaning process on physical properties of cotton, silk and wool fabrics

The present study is aimed at analyzing the effect of dry-cleaning solvent on the physical properties of cotton, silk andwool fabrics. The sourced fabrics are dry-cleaned with two different commercial solvents, namely mineral turpentine oil,and dipropylene glycol dimethyl ether. The fabrics are dry-cleaned separately for 5, 10 and 15 times with each solvent andanalysed for their performance. The results indicate that the dry-cleaned fabrics become thicker and bulkier, and hence theirair permeability, bending ability, crease recovery, tearing strength and abrasion resistance reduce. The water absorbency,stiffness and thickness of the fabrics are found to be increased significantly. The statistical analysis results confirm that thechanges in the fabric are significant with 95% confidence limit (p 0.05). Out of the selected dry-cleaning solvents,hydrocarbons are found to be more aggressive than the glycol ethers in terms of fabric deterioration, except tearing strength.The GC-MS analysis results confirm the presence of dry-cleaning solvents deposits on the fabric even after 24 h of airingout process.

Toward Environmentally Friendly Lithium Sulfur Batteries: Probing the Role of Electrode Design in MoS2-Containing Li–S Batteries with a Green Electrolyte

While lithium sulfur batteries (Li–S) hold promise as future high energy density low cost energy storage systems, barriers to implementation include low sulfur loading, limited cycle life, and the use of toxic electrolyte solvents. A comprehensive study of Li–S cells in the environmentally benign di(propylene glycol) dimethyl ether (DPGDME)-based electrolyte, using as-prepared MoS2 nanosheets derived from a facile aqueous microwave synthesis as polysulfide trapping agents, is reported herein for the first time. Conventional coated foil electrodes and binder-free electrodes (BFEs) with various structures are systematically generated and tested to correlate electrode design with the resulting electrochemical behavior. Significantly improved Li–S electrochemistry is demonstrated through the synergy of MoS2 chemistry and binder-free electrode engineering. In the coating configuration, the MoS2-containing cell evinced better rate performance and more stable cyclability than the cell without MoS2. In comparison with the coating counterparts, the BFE cells exhibited excellent cycle stability and superior rate capability (10-fold capacities and energy density per electrode weight with 20% higher retention rate) despite 2X higher areal sulfur loading. The BFE cell improvement can be attributed to the synergistic effect of the i) interconnected macroporous structure of CNT interlayers, providing a conductive framework, and ii) the efficient polysulfide trapping by the MoS2 nanosheets.

Mixing properties of binary liquid mixtures of dipropylene glycol dimethyl ether (DPGDME) with 2-propanol, 1-butanol and 2-butanol at different temperatures

Densities ρ and speed of sound u for the binary liquid mixtures of dipropylene glycol dimethyl ether (1) + 2-propanol (2), +1-butanol (2) and +2-butanol (2) have been measured at temperatures T = (288.15, 293.15, 298.15, 303.15 and 308.15) K and experimental pressure P = 0.1 MPa over the whole composition range. Experimental densities and speed of sound data has been used to determine excess molar volumes VmE, isentropic compressibility κS, molar isentropic compressibility Ks,m and their excess counterpart excess isentropic compressibility KS, mE at different temperatures. Thermal expansion coefficient along with its excess function has been reported. Deviations in intermolecular free length and deviations in acoustic impedance have also been reported. The variations of the parameters with concentration and temperature have been discussed t have insight into the intermolecular interactions prevailing in the mixtures chosen for the present study.

Thermodynamic and interaction studies of binary liquid mixtures on the basis of Flory's statistical theory and empirical relations

A number of important and useful thermodynamic properties of seven binary liquid mixtures namely DPGDME + methanol, 1-propanol, 1-pentanol, 1-heptanol at 298.15 K and oxolane + aniline, N-methyl aniline, N-ethyl aniline at 303.15 K, 313.15 K & 323.15 K have been computed on the basis of the most widely accepted Flory's statistical Theory (FST). The component DPGDME is basically dipropylene glycol dimethyl ether and oxolane known as tetrahydrofuran are the key ethereal liquids with which the interactions of popular solvents are analyzed. Also, some thermodynamics properties of aforesaid mixtures were calculated from the recently proposed empirical correlations using density and ultrasonic velocity. The theoretical results are compared with the experimental findings yielding quite satisfactory agreement. The results are discussed in the light of interactions operating in the systems.

Ionic liquid hybrids: Progress toward non-corrosive electrolytes with high-voltage oxidation stability for magnesium-ion based batteries

Magnesium – ion batteries have the potential for high energy density but require new types of electrolytes for practical application. Ionic liquid (IL) electrolytes offer the opportunity for increased safety and broader voltage windows relative to traditional electrolytes. We present here a systematic study of both the conductivity and oxidative stability of hybrid electrolytes consisting of eleven ILs mixed with dipropylene glycol dimethylether (DPGDME) or acetonitrile (ACN) cosolvents and magnesium bis(trifluoromethylsulfonyl)imide (Mg(TFSI)2). Our study finds a correlation of higher conductivity of ILs with unsaturated rings and short carbon chain lengths, but by contrast, these ILs also exhibited lower oxidation voltage limits. For the cosolvent additive, although glymes have a demonstrated capability of coordination with Mg2+ ions, a decrease in conductivity compared to acetonitrile hybrid electrolytes was observed. When cycled within the appropriate voltage range, the IL-hybrid electrolytes that show the highest conductivity provide the best cathode magnesiation current densities and lowest polarization as demonstrated with a Mg0.15MnO2 and Mg0.07V2O5 cathodes.

DNA-Based Asymmetric Catalysis: Role of Ionic Solvents and Glymes.

Recently, DNA has been evaluated as a chiral scaffold for metal complexes to construct so called 'DNA-based hybrid catalysts', a robust and inexpensive alternative to enzymes. The unique chiral structure of DNA allows the hybrid catalysts to catalyze various asymmetric synthesis reactions. However, most current studies used aqueous buffers as solvents for these asymmetric reactions, where substrates/products are typically suspended in the solutions. The mass transfer limitation usually requires a long reaction time. To overcome this hurdle and to advance DNA-based asymmetric catalysis, we evaluated a series of ionic liquids (ILs), inorganic salts, deep eutectic solvents (DES), glymes, glycols, acetonitrile and methanol as co-solvents/additives for the DNA-based asymmetric Michael addition. In general, these additives induce indistinguishable changes to the DNA B-form duplex conformation as suggested by circular dichroism (CD) spectroscopy, but impose a significant influence on the catalytic efficiency of the DNA-based hybrid catalyst. Conventional organic solvents (e.g. acetonitrile and methanol) led to poor product yields and/or low enantioselectivities. Most ILs and inorganic salts cause the deactivation of the hybrid catalyst except 0.2 M [BMIM][CF3COO] (95.4% ee and 93% yield) and 0.2 M [BMIM]Cl (93.7% ee and 89% yield). Several other additives have also been found to improve the catalytic efficiency of the DNA-based hybrid catalyst (control reaction without additive gives >99% ee and 87% yield): 0.4 M glycerol (>99% ee and 96% yield at 5 °C or 96.2% ee and 83% yield at room temperature), 0.2 M choline chloride/glycerol (1:2) (92.4% ee and 90% yield at 5 °C or 94.0% ee and 88% yield at room temperature), and 0.5 M dipropylene glycol dimethyl ether (>99% ee and 87% yield at room temperature). The use of some co-solvents/additives allows the Michael addition to be performed at a higher temperature (e.g. room temperature vs 5 °C) and a shorter reaction time (24 h vs 3 days). In addition, we found that a brief pre-sonication (5 min) of DNA in MOPS buffer prior to the reaction could improve the performance of the DNA-based hybrid catalyst. We have also shown that this DNA-based catalysis method is suitable for a variety of different substrates and relatively large-scale reactions. In conclusion, a judicious selection of benign co-solvents/additives could improve the catalytic efficiency of DNA-based hybrid catalyst.

Volumetric and Acoustic Studies of Binary Liquid Mixtures of Dipropylene Glycol Dimethyl Ether with Methyl Acetate, Ethyl Acetate and n-Butyl Acetate in the Temperature Range T = (288.15, 293.15, 298.15, 303.15, and 308.15) K

Densities and ultrasonic speeds have been measured over the whole composition range for binary liquid mixtures of dipropylene glycol dimethyl ether, CH3(OC3H6)2OCH3, with methyl acetate, ethyl acetate, and n-butyl acetate using an Anton Paar DSA 5000 M density and speed sound analyzer at T = (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure in order to evaluate the behavior of these binaries. From these data excess the molar volume, \( V_{m}^{\text{E}} \), and deviation in isentropic compressibility, ∆κS, have been calculated. These excess properties have been fitted with the Redlich–Kister type polynomial equation to get their coefficients and standard deviations which provide a base for discussing the forces operating in solutions.

Carbon Nanofoam-Based Cathodes for Li–O2 Batteries: Correlation of Pore–Solid Architecture and Electrochemical Performance

Freestanding, binder-free carbon nanofoam papers afford the opportunity to gauge the influence of pore size on the discharge capacity of Li–O2 cells. Four sets of carbon nanofoam papers were synthesized from resorcinol–formaldehyde sols, with pore size distributions in pyrolyzed forms ranging from mesopores (5–50 nm) to a size regime not represented in the literature for Li-O2 cathodes—small macropores (50–200 nm). The first-cycle discharge capacity in cells containing 0.1 M LiClO4 in dipropylene glycol dimethyl ether tracks the average pore size distribution in the carbon nanofoam cathode, rather than the specific surface area of the nanoscale carbon network or its total pore volume. The macroporous nanofoams yield cathode specific capacity of 1000–1250 mA h g−1 at –0.1 mA cm−2 discharge rate, approximately twice that of the mesoporous nanofoams (∼580–670 mA h g−1), even though the macroporous foams have lower specific surface areas (270 and 375 vs. >400 m2 g−1). The specific capacity of the cathode decreases as the thickness of macroporous carbon nanofoam paper is increased from 180- to 530-μm, which indicates that the interior pore volume is underutilized, particularly with thicker nanofoams. For the four pore–solid nanofoam architectures studied, the specific capacity is limited by pore occlusion arising from solid Li2O2 product that is electrogenerated near the outer boundaries of the nanofoams.

Prediction of the mutual solubility of water and dipropylene glycol dimethyl ether using molecular dynamics simulation

Molecular dynamics (MD) simulations were applied to investigate the liquid–liquid equilibria of water and dipropylene glycol dimethyl ether (DMM) based on all-atom OPLS force fields and simple point charge (SPC) water model. The default combining rules (geometric means) for describing interactions between water and ether molecules were modified by fitting hydration free energies of dimethyl ether and diethyl ether. The difference of Gibbs free energies (Δ G) was calculated using the thermodynamic integration (TI) method. Extensive simulations were carried out in order to reach high precision in the predicted free energies. The average uncertainties in calculated Δ G are 0.8 kJ/mol for DMM and 0.3 kJ/mol for water. From the calculated Δ G mix , the mutual solubility of the binary mixture was predicted using the double tangent method at four temperatures ranging from 283 K to 353 K and 1 atm.

Liquid–liquid equilibria of dipropylene glycol dimethyl ether and water by molecular dynamics

Abstract In the framework of the Industrial Fluid Properties Simulation Challenge 2010, liquid–liquid equilibria of dipropylene glycol dimethyl ether and water are determined by molecular dynamics simulation. A new force field for the ether was developed and combined with a water model from the literature (TIP4P/2005). According to the specifications of the competition, molar fractions of the components in the coexisting phases are predicted over a temperature range from 283 to 353 K.

Mutual solubilities study for binary mixtures of dipropylene glycol dimethyl ether and water via molecular dynamics simulation and AMOEBA polarizable force field

It is a challenging task to accurately compute the structures and physicochemical properties of partially soluble liquid mixtures using classical force field simulation methods due to the limitations of both sampling and intermolecular potential. In the present study, we employed replica exchange molecular dynamics in combination with the AMOEBA polarizable force field to simulate partially miscible liquid mixtures of dipropylene glycol dimethyl ether and water. We demonstrated that our strategy is promising in studying such complicated binary mixture systems without involving empirical fitting of any available experimental data of mixtures. We correctly predicted the trend of liquid concentration distribution as the function of temperature, and the concentration drifts found in the simulations are consistent with the concentration difference between experimental values and initial configurations. Based on self-diffusion coefficient analysis, the lower critical solution temperature of the system was identified at about 290 K, which is in satisfactory agreement with experimental evidence. Although accurate concentration prediction of such a partially miscible system using direct molecular dynamics method remains an intractable task, we expect that such atomistic simulations will play a more important role in future studies of liquid mixtures.

Gibbs ensemble Monte Carlo simulations for the liquid–liquid phase equilibria of dipropylene glycol dimethyl ether and water: A preliminary report

Configurational-bias Monte Carlo simulations in the isobaric–isothermal ensemble and in the canonical and isobaric–isothermal versions of the Gibbs ensemble were carried out to investigate the thermophysical properties of a 2-methoxy-1-(2-methoxypropoxy)propane/2-methoxy-1-((1-methoxypropan-2-yl)oxy)propane mixture and the mutual solubility of this dipropylene glycol dimethyl ether (DPGDME) mixture and water. The TraPPE-UA and TIP4P force fields were used for the DPGDME isomers and water, respectively. The TraPPE-UA force field yields satisfactory predictions for the specific density of the liquid phase and for the normal boiling point of the DPGDME mixture. Preliminary simulation data for the mutual solubility of the DPGDME mixture and water at T = 298 K pointed to an underprediction of the miscibility gap and, hence, simulations were carried out for variations of the TraPPE-UA DPGDME model with different partial charges for the ether moiety. Both the organic and the aqueous phase exhibit pronounced microheterogeneity and the persistence of very stable and large aggregates poses significant sampling challenges. The trajectories of independent simulations started from different initial compositions indicate either (i) that equilibrium has not yet been achieved, (ii) that composition fluctuations are sampled insufficiently over the current trajectory lengths, or (iii) that the system size is too small. Based on these preliminary simulation data, cautious estimates of the mutual solubilities at temperatures from 283 to 353 K are made using a model with modified charges. These predictions yield mean signed deviations from the experimental benchmark data for the mutual solubilities of +5% and −4% for the organic and aqueous phases, respectively.

Prediction of the temperature dependence of a polyether–water mixture using COSMO therm

As entry for the 6th industrial fluid property simulation challenge, the COSMO-RS method in its COSMO therm implementation has been used to predict the mutual solubilities of dipropylene glycol dimethyl ether (DPGDME) and water. The miscibility gaps and their unusual inverse temperature dependence have been qualitatively correctly predicted with COSMO therm standard procedure. For quantitative agreement some adjustments based on experimental data at 298 K turned out to be necessary. Fine tuning of the water and DPGDME areas led to a good quantitative agreement with experimental data with a maximum deviation of 5.4 mass percent points, which turned out to be the most accurate predictions within all challenge submissions.