Dipolar Aprotic Solvents Research Articles

Mode of hydrophilic and hydrophobic interactions of DL-Tyrosine, DL-Leucine, DL-Isoleucine and DL-Threonine in aqueous binary mixture of dipolar aprotic acetonitrile

The saturated solubilities of DL- Tyrosine, DL-Leucine, DL-Isoleucine and DL-Threonine in binary aqueous dipolar aprotic acetonitrile solvent were estimated by ‘formol titrimetry’ at nine equidistant temperatures under 0.1 MPa pressure. The chemical effects of the standard transfer energetics of these amino acids obtained after elimination of cavity forming, dipole-dipole and dipole-induced dipole interaction effect from the total, are useful to know about chemical stability of it in such system and solvent-solvent interaction therein. Hydrophobic and hydrophilic interactions of standard transfer Gibbs free energies and entropies, as obtained after subtraction of dispersion from chemical interaction are guided by the attached side chains.

Novel Non‐toxic and Non‐hazardous Solvent Systems for the Chemistry of Indoles: Use of a Sulfone‐containing Brønsted Acid Ionic Liquid Catalyst in Butyl Acetate

AbstractDipolar and aprotic solvents are often required in acid‐catalyzed reactions, however, many of them are listed in solvent selection guides as not‐recommended due to their toxicity or explosivity. A catalytically functionalized ionic liquid, namely a sulfone‐containing imidazolium‐based Brønsted acid ionic liquid, was synthesized. It alleviates the detrimental effect of classical dipolar aprotic solvents because this ionic liquid integrates the function of a dipolar aprotic solvent able to stabilize carbocation intermediates and the activating effect of a strong Brønsted acid on electrophiles. The use of this tailor‐made ionic liquid was exemplified in some transformation reactions of indoles, which proceeded with high yield and selectivity using a green and an industrially acceptable solvent, butyl acetate. The recyclability of the ionic liquid catalyst was also demonstrated.

Structure and Stereochemistry of Adducts of Tris(dipivaloylmethanato)europium(III), Eu(dpm)3, with Some Dipolar Aprotic Unidentate O-Donors

Single crystal X-ray structural characterisations are reported for adducts of the form [(L-O)Eu(O,O′-dpm)3] obtained by the crystallisation of tris(dipivaloylmethanato)europium(iii) (dpm=[HC(C(tBu).CO)2]−) from an array of dipolar aprotic oxygen-donor solvents L (L=N-methylpyrrolidinone (nmp), trimethylphosphate, (MeO)3PO, (tmp), hexamethylphosphoramide (hmpa), dimethylacetamide (dma), dimethyl sulfoxide (dmso), and the bidentate octamethylpyrophosphoramide (ompa). In all adducts, the resulting arrays contain seven-coordinate metal atoms, which adopt two different isomeric forms of the mono-capped trigonal prismatic stereochemistry, the L=dma and dmso adducts corresponding to one type, nmp and tmp the other. The adduct formed with ompa behaves as a pair of discrete metal environments bridged by the O-ompa-O′ ligand, thus; [(dpm-O,O′)3Eu(O-ompa-O′)Eu(O,O′-dpm)3], and is found in two forms, one in which both Eu environments is of the tmp type, the other of the dmso/dma type. In the hmpa adduct, the asymmetric unit of the structure is a disordered composite of both types. In none of the adducts is there any further solvation beyond coordination of a single L.

METHODS FOR SYNTHESIS OF POLYETHERIMIDES

The review summarizes and systematizes the currently known data on the synthesis of polyetherimides. Polyetherimides are a promising class of high-quality polymeric materials with a valua-ble set of properties that can be directed to the appropriate design of the polymer chain. Thus, to obtain polyetherimide with a lower glass transition temperature, as much as possible of ether bonds are introduced into the macromolecule, as well as m-phenylene fragments that increase the flexibility of the polymer chain. Polyetherimides of this structure are amorphous and soluble in a number of amide solvents and chlorinated hydrocarbons. Three main methods for the preparation of polyetherimide are discussed in detail: high-temperature polycondensation by nucleophilic substitution in solution, polycondensation in a melt, and production of polyetherimide directly during extrusion. The most promising method for today is the method of high-temperature polycondensation in solution by the reaction of nucleophilic aromatic substitution. As a halogen-containing monomer, chlorine or fluorophthalic anhydrides are used in the synthesis. The reaction of diamines with chlorophthalic anhydride proceeds at lower rates in comparison with the fluorine-containing analog. However, the use of fluorophthalic anhydride proved to be inexpedient from the economic point of view. The economic availability of the corresponding nitrosubstituted phthalic derivatives and high rates of displacement of nitro groups with the help of aryl oxide ions allow to product the commercially avail-able polymers. As solvents, aprotic dipolar (dimethylsulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc.), nonpolar organic (o-dichlorobenzene, methylene chloride, etc.) and phenolic solvents can be used. However, the increasing attention of researchers is attracted to the synthesis in the environment of o-dichlorobenzene.

Synthesis of cardo poly(arylene ether ketone amide)s by heterogeneous palladium-catalyzed polycondensation of aromatic diiodides, aromatic diamines containing cardo groups and CO

New cardo poly(arylene ether ketone amide)s were synthesized by heterogeneous palladium-catalyzed carbonylative polycondensation of aromatic diiodides with ether–ketone linkages, aromatic diamines bearing cardo groups, and carbon monoxide. Polymerizations were conducted in N,N-dimethylacetamide (DMAc) at 120 °C in the presence of a bidentate phosphino-functionalized magnetic nanoparticles-immobilized palladium complex [Fe3O4@SiO2-2P-PdCl2] and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), yielding a series of cardo poly(arylene ether ketone amide)s with inherent viscosities up to 0.77 dL/g. All the polymers were readily soluble in various dipolar aprotic solvents at room temperature. These polymers showed good thermal stability with the glass transition temperature of 223–289 °C, the temperature at 5% weight loss of 441–464 °C in nitrogen. These cardo poly(arylene ether ketone amide)s could afford transparent, flexible, and strong films by solution-casting with good tensile properties. These polymer films exhibited lower dielectric constants, lower water uptakes, and higher optical transparency. Furthermore, this heterogeneous palladium catalyst can facilely be separated from the reaction mixture by simply applying an external magnet and recycled at least eight times with almost consistent activity.

Studies About the Acylation of Starch in Dipolar Aprotic Solvents

Starch laurates with average degrees of substitution (DS) from 0.63 to 2.52 are obtained applying three equivalents lauroyl chloride per anhydroglucose unit (AGU). Different solvents, that is, N,N‐dimethylacetamide (DMAc), DMAc/LiCl, and N,N‐dimethylformamide (DMF)/LiCl are studied as reaction medium without and with a base. In the presence of pyridine, products of highest DS and degree of polymerization (DP) are accessible. Nuclear magnetic resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR) reveal the presence of acetate moieties that could be caused by O‐acyl‐dimethylacetiminium generated from DMAc in a side reaction. No side reaction is found to occur in the presence of triethylamine and triphenylphosphane. Furthermore, no side reactions are detected in DMF/LiCl as solvent.

Cu(0) Wire-mediated Single-electron Transfer-living Radical Polymerization of Oligo(ethylene oxide) Methyl Ether Acrylate by Selecting the Optimal Reaction Conditions

The efficient Cu(0) wire-catalyzed single-electron transfer-living radical polymerization (SET-LRP) in organic solvents and mixtures of the organic solvents with water has been thoroughly investigated. Oligo(ethylene oxide) methyl ether acrylate was used as an exemplar oligomer monomer to determine the optimum polymerization conditions for rapid, controlled, and quantitative production of well-defined polymers. The effects of Cu(0)-wire length (12.5 or 4.5 cm), ligand type (tris(dimethylaminoethyl)amine, Me6-TREN, or tris(2-aminoethyl)amine, TREN), and solvent type (dipolar aprotic solvents, cyclic ethers, alcohol, or acetone) on the polymerization have been evaluated. Kinetic experiments were performed for all polymerizations to assess the “living” behavior of each system employed. Importantly, TREN could be used as a replacement for Me6-TREN in Cu(0) wire-catalyzed SET-LRP of oligomer monomer, which probably provides the most economical and efficient methodology since TREN is 80 times less expensive than Me6-TREN. The high chain-end fidelity of resulting polymer was experimentally verified by thiol-Michael addition reaction at the α-Br chain end and subsequent chain extension with methyl acrylate.

Local structure and hydrogen bonding in liquid γ-butyrolactone and propylene carbonate: A molecular dynamics simulation

In this work we report a new potential model for classical molecular dynamics (MD) simulation of two dipolar aprotic solvents – propylene carbonate (PC) and γ-butyrolactone (GBL). Parameters for intramolecular interactions as well as the partial atomic charges were derived from quantum chemical calculations, while the OPLS/AA force field Lennard-Jones intermolecular parameters were adjusted to reproduce the experimental thermodynamic and the transport properties of these solvents in the wide temperature range. The comparison of new potential models with existing models for PC and GBL is given. Using the proposed models, the local structure of these solvents was studied in detail, paying special attention to packing ability, dipole-dipole orientation and hydrogen-bonding (H-bonding) interactions. Based on the results of MD simulations and QTAIM analysis, it was shown that H-bonds involving carbonyl oxygen atoms in PC and GBL are rather weak, while no H-bonds are formed with ester oxygen atoms. According to the present results, the mutual molecular orientation in PC and GBL varies with the distance, being above/below plane-parallel configuration for closest neighbors, and in-plane T-shaped configurations for farther neighbors. The nearest neighbors approach coupled with angular distribution functions was applied for the estimation of the Kirkwood factor in the framework of the Onsager-Kirkwood-Fröhlich theory. Our results shows that in order to reproduce the corresponding experimental values the Kirkwood factor it is necessary to take in account the mutual orientation of ~8–9 neighboring molecules for GBL and ~5–6 molecules for PC.

Front Cover Picture: A Sulfone‐Containing Imidazolium‐Based Brønsted Acid Ionic Liquid Catalyst Enables Replacing Dipolar Aprotic Solvents with Butyl Acetate (Adv. Synth. Catal. 14/2019)

Front Cover Picture: A Sulfone‐Containing Imidazolium‐Based Brønsted Acid Ionic Liquid Catalyst Enables Replacing Dipolar Aprotic Solvents with Butyl Acetate (Adv. Synth. Catal. 14/2019)

Enhanced elevations of hypo-osmotic shock-induced cytosolic and nucleic calcium concentrations in tobacco cells by pretreatment with dimethyl sulfoxide.

Dimethyl sulfoxide (DMSO) is a dipolar aprotic solvent widely used in biological assays. Here, we observed that DMSO enhanced the hypo-osmotically induced increases in the concentration of Ca2+ in cytosolic and nucleic compartments in the transgenic cell-lines of tobacco (BY-2) expressing aequorin.

N‐Methylcaprolactam as a Dipolar Aprotic Solvent for Iron‐Catalyzed Cross‐Coupling Reactions: Matching Efficiency with Safer Reaction Media

AbstractAlthough iron‐catalysis provides a powerful alternative to the more conventional palladium and nickel in the cross‐coupling arena, the major limitation is the necessity for carcinogenic N‐methylpyrrolidone as a co‐solvent in the vast majority of catalytic reactions. Herein, we introduce N‐methylcaprolactam as an efficient, non‐toxic and practical dipolar aprotic solvent for iron‐catalyzed C(sp2)−C(sp3) alkylative cross‐coupling of aryl chlorides and tosylates. The utility of this method is reflected by its wide substrate scope, high yields and capacity to cross‐couple challenging alkyl organometallics prone to b‐hydride elimination and homocoupling. Considering the broad utility of iron‐catalyzed cross‐coupling, we envision that N‐methylcaprolactam will find wide application as a substitute for carcinogenic NMP.

Interparticle interactions and dynamics in BmimBF4 and LiBF4 solutions in propylene carbonate: MD simulation

Ionic liquids have gained immense popularity in recent decades due to a combination of unique properties. Despite the widespread use of ionic liquids mixtures with aprotic dipolar solvents in electrochemistry, it remains relevant to predict their macroscopic, primarily transport, properties based on the microscopic picture of the entire set of interparticle interactions in such systems. The method of molecular dynamics simulation (MDS) is one of the most powerful tools for solving problems of this kind. However, one of the unsolved problems of the classical MDS of ion-molecular systems is the correct accounting of polarization effects. Recently it was proposed to use a variation of the effective ion charges in solutions to solve this task. This paper presents the results of the MDS structural and dynamic properties of 1-butyl-3-methylimidazolium (BmimBF4) and lithium (LiBF4) tetrafluoroborates solutions in propylene carbonate (PC) at 298.15 K in NPT ensemble using GROMACS and MDNAES software packages. The possibility of reproducing the experimental dynamic properties (diffusion coefficients of cations and solvent, viscosity, and electrical conductivity) of binary systems based on mixtures of ionic liquids with PC in a wide concentration range was shown. Polarization effects were taken into account by reducing the partial charges of the ion atoms. The structure of the solvation shell of cations was studied within the framework of radial distribution functions, distribution of coordination numbers and the presence of hydrogen bonds between the organic cation and solvent molecules. The results point to stronger and more structured solvation shell of the Li+ cation compared to Bmim+, which is consistent with the conclusions about the mobility of these cations. The reorientation times of propylene carbonate molecules and their lifetimes in the framework of the first solvation shells of the cations are several times higher for the lithium cation.

Twenty-five years of cellulose chemistry: innovations in the dissolution of the biopolymer and its transformation into esters and ethers

The anniversary of the journal “Cellulose” is an opportunity to review innovations that were introduced during the past 25 years. Of these, from our perspective, the development of solvents that dissolve cellulose physically, i.e., without formation of covalent bonds is most relevant. The reasons are that cellulose can be regenerated from these media in different shapes and transformed into many important derivatives. Twenty-five years is a long time-span! As the volume of information on the applications of the above-mentioned solvents in cellulose chemistry is extensive, we made choices to reach a balance between the amount of material covered and the length of the review. Consequently, we focus on cellulose derivatization under homogeneous reaction conditions to produce selected derivatives. We dwell on the latter because a comprehensive discussion was recently published on derivatization under heterogeneous and homogeneous conditions (Heinze et al. in Cellulose derivatives, Springer, Cham, pp 259–292, 2018a). The derivatives selected are esters of organic acids, ionic and nonionic ethers because of their tremendous commercial and scientific importance. Cellulose derivatization in homogeneous media is advantageous because of much better control of product properties relative to those obtained under the heterogeneous counterparts. These properties include degree of substitution in the anhydroglucose unit and along the biopolymer back-bone, and regioselectivity. Thus, novel cellulose derivatives were prepared that are not accessible under heterogeneous conditions. The requirement to dissolve cellulose physically is to disrupt hydrogen bonding and hydrophobic interactions. Thus, the solvents employed to dissolve cellulose are usually composed of strong electrolytes whose cations and anions interact preferentially with cellulose. These electrolytes are used pure or as solutions in water or dipolar aprotic solvents. Salient examples include LiCl/N,N-dimethylacetamide, tetra(n-butyl)ammonium fluoride·3H2O/dimethyl sulfoxide, ionic liquids, salts of quaternary amines and super-bases. We discuss briefly the essentials of each solvent in terms of its mechanism of cellulose dissolution and show the most relevant results regarding its application for obtaining esters and ethers and back the discussion with relevant references. This information is summarized at the end of the review. We hope that this historical perspective shows the innovations made since the first publication of “Cellulose” and points out to future possibilities—with potential industrial application—of this renewable raw material and its biocompatible and biodegradable derivatives.

Synthesis of amides from acid chlorides and amines in the bio-based solvent Cyrene™

Cyrene™ as a bio-alternative dipolar aprotic solvent: a waste minimizing and molar efficient protocol for the synthesis of amides from acid chlorides and primary amines in the bio-available solvent Cyrene™ is disclosed.

PREPARATION OF NEW POLYETHERPHTHALIMIDES BASED ON CHLORAL DERIVATIVES USING NUCLEOPHILIC POLYNITRO SUBSTITUTION REACTIONS

Non-previously described new bis (3-nitropthalimide) arylenes activated with two carbonyls and containing flexible “bridging” groups, in particular dichloroethylene and ketones between the phthalimide fragments of the dinitrocompounds were obtained. The reactivity of the dinitrophthalimides used is determined, first of all, by the position of (3 or 4) nitro groups, and not by the nature of the Ar residue; monomers containing nitro groups in position 3 are more reactive than systems containing nitro groups in position 4. The interaction of synthesized bis (nitropthalimide) arylenes containing central dichloroethylene and ketone groups between phthalimide fragments and bis-phenolate derivatives of chloral was carried out. Synthesis of polyetherphthalimides using the process of polynitro substitution was carried out under modified conditions with complete absence of moisture. In general, the reactions of polynitro substitution proceed rapidly under relatively mild conditions; when dipolar aprotic solvents or a mixture of them with toluene are used, relatively high molecular weight polymers are formed. It has been established that the rate of dissolution of monomers is an important factor affecting the reaction rate; this determines the possibility of the formation of relatively high-molecular polymers, even with some deviation from the equimolarity of the monomers. As the general conditions for the synthesis of polyetherphthalimides based on synthesized bis (3-nitropthalimide) arylenes and bis-phenols, the optimal conditions were: reaction temperature -60 °C, reaction time -1 h with equimolar monomer ratio and concentration of each of them 0.25 mol/l. The influence of moisture on the synthesis of polyetherimides using the reaction of nucleophilic polynitro substitution was studied. It is shown that the process in the maximally dry system in the DMSO medium or (DMSO / toluene) leads to the formation of polymers with hr at least 0.63 dl/g. All the polymers obtained are readily soluble in dipolar and aprotic solvents. The structure of all the obtained intermediates and monomers was confirmed by elemental analysis and IR spectroscopy. An analysis of the primary thermal characteristics of the polymers obtained showed that they are characterized by relatively high and near destruction temperatures was found that the largest oxygen index (CI) in polymers, where more macromolecules contain more dichloroethylene fragments, and the lowest CI in polymers with a high oxygen content. It is shown that the polymers obtained have satisfactory deformation-strength characteristics. A feature of synthesized polyetherphthalimides is a significant difference between the temperatures of intensive destruction and softening temperatures, which determines the possibility of their processing into products by injection molding.

Correspondence between Spectral-Derived and Viscosity-Derived Local Composition in Binary Liquid Mixtures Having Specific Interactions with Preferential Solvation Theory.

Local interactions between unlike molecules (1-2) in solution are commonly measured with spectroscopy and used to estimate local composition. Herein, a viscosity model based on preferential solvation (PS) theory is developed for aqueous and nonaqueous binary liquid mixtures containing a dipolar aprotic solvent that provides local composition considering the hydration or solvation shell around complex (1-2) molecules. Spectral-derived and viscosity-derived local composition distributions showed similar trends with bulk composition, and their correspondence is attributed to characteristics of the hydration or solvation shell. Viscosity-derived local compositions were consistent with literature molecular simulations, whereas spectral-derived local composition distributions contained artifacts. The PS viscosity model is also applicable to nonpolar-polar mixtures for which self-association occurs, and it can be used to estimate solvent mixture dipolarity/polarizability. Since the PS viscosity model only requires bulk viscosity, it may provide a means to estimate microviscosity or the solvent environment around biomolecules.

Effects arising from the replacement of aprotic dipolar solvents with ionic liquids in the nickel-catalyzed reduction of aryl chlorides

In the work on the example of liquid-phase catalytic processes of the aromatic CCl bonds activation occurring in the presence of nickel complexes under reducing conditions the main effects arising from the replacement of aprotic dipolar solvents with ionic liquids are analyzed. The features of the nickel-catalyzed reaction of aryl chlorides, related to the nature of the anion and cation of the ionic liquid, were observed. It was shown that a high concentration of cations and anions in the ionic liquid affects the process of reduction of the nickel complex to the catalytically active state. In addition, the presence of a reactive hydrogen atom in the imidazolium cation of ionic liquid causes the process of hydrodechlorination of aryl chlorides.

β-Elimination in 1,1,1-Trichloro-2,2-bis(4-nitrophenyl)ethane by the Action of Sodium Nitrite in Dipolar Aprotic Solvents

The kinetics of dehydrochlorination of 1,1,1-trichloro-2,2-bis(4-nitrophenyl)ethane with sodium nitrite in dipolar aprotic solvents have been studied. Quantum chemical simulation of the process has been performed, and its thermodynamic parameters have been determined. The effects of dissociation and solvation on the rate constant have been considered. The reaction mechanism has been identified as E2H.

Medium effect on the α-effect for nucleophilic substitution reactions of p-nitrophenyl acetate with benzohydroxamates and m-chlorophenoxide in DMSO–H2O mixtures as contrasts with MeCN–H2O mixtures: comparing two very different polar aprotic solvent components

A kinetic study is reported on nucleophilic substitution reactions of p-nitrophenyl acetate (1a) with three α-effect nucleophiles, benzohydroxamate (BHA–), p-methylbenzohydroxamate (MBHA–), and p-methyl-N-methylbenzohydroxamate (M2BHA–), and a reference nucleophile, m-chlorophenoxide (m-ClPhO–), in DMSO–H2O mixtures of varying compositions at 25.0 ± 0.1 °C. Second-order rate constants for the reactions with BHA– and MBHA– decrease upon addition of DMSO to the reaction medium up to 60 mol % DMSO and then increase thereafter only a little. In contrast, M2BHA– and m-ClPhO– become much more reactive as the DMSO content in the medium increases. Such contrasting medium effects on reactivity are consistent with the report that hydroxamic acids behave as OH acids in H2O but as NH acids in dipolar aprotic solvents (e.g., DMSO and MeCN). It has been concluded that BHA– and MBHA– form an equilibrium of a reactive form I with less reactive species II in DMSO–H2O mixtures and the position of the equilibrium is dependent on solvent compositions. BHA– and MBHA– exhibit the α-effect in H2O but not in in 90 mol % DMSO. In contrast, the α-effect yielded by M2BHA– increases steeply up to 70 mol % DMSO and then levels off thereafter.

Bio-available Solvent Cyrene: Synthesis, Derivatization, and Applications.

The development of green solvents is one of the key tenets of Green Chemistry as solvents account for the majority of waste stemming from the production of the chemicals on which we have all come to rely. An important class of solvents is the dipolar aprotics, which include N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP). In addition to being derived from non-renewable resources, these solvents are also under increased regulatory pressures that will limit their industrial applications. This Concept concerns the bio-available solvent Cyrene (dihydrolevoglucosenone) as a potential replacement for toxic dipolar aprotic solvents. An emphasis is placed on examining the strengths and weaknesses of Cyrene as a solvent and is accomplished by looking at the synthesis, derivatization, and application in synthetic protocols of Cyrene. With respect to the Twelve Principles of Green Chemistry, this Concept describes a bio-available solvent that should have a disruptive effect on the use of traditional industrial dipolar aprotic solvents.