Automated Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectrometry Determination of N-methyl-2-pyrrolidone and its Metabolites in Urine and Plasma

A method for the simultaneous determination of N-methyl-2-pyrrolidone (NMP) and its metabolites 5-hydroxyl-N-pyrrolidone (5HNMP), N-methylsuccinimide (MSI) and 2-hydroxy-N-methylsuccinimide (2HMSI) in plasma and urine has been developed. Samples were purified by SPE using an ASPEC XL4. Analysis was performed using LC–MS equipped with an APCI interface. The analysis provided linear responses in the range of 0.125–12 μg mL⁻¹ for all of the analytes and up to 150 μg mL⁻¹ for 5HNMP and 2HMSI. The within day precision was in the range of 0.9–19.1% for plasma samples and 1.9–10.4% for urine samples whereas the between day precisions were 4.5–11.9% and 1.2–17.5%, respectively. The method was deemed to be suitable for monitoring the levels of NMP and its metabolites in the plasma and urine of occupationally exposed persons.     

Organic solid photochromism by photoreduction mechanism: Viologen embedded in solid polar aprotic polymer matrix

Reversible photocolor developments of viologens embedded in poly(N-vinyl-2-pyrrolidone) films, a typical polar aprotic solid matrix, were found to be affected by the kinds of viologen cation as well as the paired anion. The color developments in the corresponding low-molecular-weight solvents are connected closely to the solubility of viologens in these solvents; viologens are highly sensitive in the polar aprotic solvents in which they have poor solubilities, such as N-methyl-2-pyrrolidone and hexamethyl phosphoric triamide. These facts confirm the color-development mechanism consistings of electron transfer to the photoexcited viologen cation from the paired anion in polar aprotic solid matrices such as poly(N-vinyl-2-pyrrolidone).     

Protonation of polyaniline with lightly sulfonated polystyrene

Protonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such as dimethyl sulfoxide and N-methyl-2-pyrrolidone was investigated by UV-Vis absorption spectra. As the molar ratio of sulfonated polystyrene/polyaniline increases, the conversion from polyaniline base form to salt form is observed owing to increased protonation. The isosbestic point clearly shows that quinoid unit and semiquinoid unit are in equilibrium. They are functions of the sulfonic acid concentration and solvent media.     

Cellobiose as a model compound for cellulose to study the interactions in cellulose/lithium chloride/<Emphasis Type="Italic">N</Emphasis>-methyl-2-pyrrolidone systems

To investigate the solvent/solute interactions that take place during the dissolution of cellulose, cellobiose was employed as a model of the longer-chain cellulose molecule in a dissolution study of the cellobiose/LiCl/N-methyl-2-pyrrolidone (NMP) system, conducted using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), ¹³C, ³⁵Cl, and ⁷Li NMR spectroscopy, and conductivity measurements. For the LiCl/NMP system, FTIR and ¹³C NMR analyses of the NMP carbonyl moiety showed a strong dependence on the LiCl concentration, which suggested an association between the Li⁺ cations and the carbonyl groups of NMP. As the cellobiose molecules are dissolved in the LiCl/NMP solvent, the Li⁺–Cl^? ion-pairs in LiCl/NMP are dissociated. Strong hydrogen bonds are then formed between the hydroxyl groups of cellobiose and the Cl^? anions, resulting in breakage of the intermolecular hydrogen bonds of cellobiose. Meanwhile, the Li⁺ cations are further associated with the extra free NMP molecules. However, the NMP molecules do not directly interact with the dissolved cellobiose. Based on these results, we propose that our study is conducive to a more in-depth comprehension of the dissolution mechanism of cellulose in LiCl/NMP.     

Synthesis,characterization, and solution properties of new heterocyclic tellurium compounds based on 5,6-dimethyl-1,3-dihydro-2-telluraindene

The synthesis and characterization of a new range of heterocyclic tellurium compounds based on 5,6-dimethyl-1,3-dihydro-2-telluraindene are reported. Conductivity measurements of most compounds in dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF) showed considerable ionic character in both solvents. ¹H and ¹³C NMR studies indicated that the telluronium salts are stable to reductive elimination and no reaction between solute and solvent was observed. Benzyl and allyl telluronium salts are exceptional. Infrared and mass spectral data are reported and discussed.     

Volumetric Properties of Ternary–Pseudobinary Mixtures [(Styrene + Ethyl Acetate or Benzene) + (<Emphasis Type="Italic">N</Emphasis>-Methyl-2-pyrrolidone + Ethyl Acetate or Benzene)]

The densities of the ternary-pseudobinary mixtures [(styrene + ethyl acetate or benzene) + (N-methyl-2-pyrrolidone + ethyl acetate or benzene)], formed by adding the third component (ethyl acetate or benzene) to the binary system (styrene + ethyl acetate), have been measured as a function of composition by means of a vibrating-tube densimeter at atmospheric pressure at 298.15 K. The excess molar volumes V _m ^E were calculated from the densities and correlated using the Redlich–Kister equation to estimate the coefficients and standard errors. The experimental and calculated quantities are used to discuss the mixing behavior of the components. The results show that the third component, ethyl acetate or benzene, have quite different influences on the interaction between styrene and N-methyl-2-pyrrolidone.     

Synthesis and Characterization of Hyperbranched Polyesters Based on Isophthalic Acid and Trimethylolpropane

Hydroxyl-terminated hyperbranched polyesters (HBPEs) with aromatic/aliphatic structure were synthesized at three different monomer mole ratios (A₂/B₃=1, 0.9, and 0.6, respectively) by melt polycondensation of isophthalic acid and trimethylolpropane via A₂+ B₃ approach. Fourier transform infrared (FTIR) spectroscopy indicated that the expected HBPEs, which showed excellent solubility in a variety of polar solvents such as N, N-dimethyl formamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and terahydrofuran (THF), were produced without gelation during the polymerization. The weight-average molecular weight of HBPEs ranged from 7014 to 8306 and their inherent viscosities were varied from 0.17 to 0.34 dL/g. The degree of branching of the HBPEs was estimated to be 0.39–0.49 by¹H-NMR and ¹³C-NMR measurement. Their glass transition temperature measured by differential scanning calorimetry (DSC) was between 64 and 86°C. The thermogravimetric analysis (TGA) measurement revealed that HBPEs had ca 8.5% weight-loss at 300°C in N₂.     

Synthesis and characterization of novel aromatic polyamides from 3,4-bis(4-aminophenyl)-2,5-diphenylfuran and aromatic diacid chlorides

A new highly phenylated heterocyclic diamine, 3,4-bis(4-aminophenyl)-2,5-diphenylfuran, was synthesized in three steps from 4–-nitrodeoxybenzoin. The low temperature solution polycondensation of the diamine with various aromatic diacid chlorides afforded tetraphenylfuran-containing aromatic polyamides with inherent viscosities of 0.2–0.8 dL/g. Copolyterephthalamides were obtained from the diamine and 4,4′-oxydianiline. The polyamides were generally soluble in a wide range of solvents that included N,N-dimethylacetamide, N-methyl-2-pyrrolidone, pyridine, and m-cresol. Glass transition temperatures of the polyamides and copolyamides ranged from 302–342°C, and 10% weight loss was observed above 480°C in nitrogen.     

Synthesis of polybenzodipyrrolediones by thermal cyclodehydration of polyamides derived from dibenzylidenebenzodifurandiones and aliphatic diamines

A new class of polyheterocycles, polybenzodipyrrolediones (PBP), has been synthesized successfully by the two-step polymerization of dibenzylidenebenzodifurandiones with aliphatic diamines. New bislactone monomers, 3,5-dibenzylidene-3,5-dihydro-1H,7H-benzo[1,2-c:4,5-c′]difuran-1,7-dione and 3,7-dibenzylidene-3,7-dihydro-1H,5H-benzo[1,2-c:4,5-c′]-difuran-1,5-dione, were synthesized from pyromellitic dianhydride and phenylacetic acid. The ring-opening polyaddition reaction of the bislactones with aliphatic diamines in a polar solvent afforded novel polyamides having inherent viscosities of 0.1–1.0 in quantitative yield. The solution polymerization was almost completed within several hours at 80°C, while it required approximately a week to its completion at room temperature. Dimethyl sulfoxide and N-methyl-2-pyrrolidone were preferred solvents for the polymerization. The open-chain polyamides were subsequently cyclodehydrated by heating at 240°C to give PBP having high molecular weight. The aliphatic PBP were soluble in hot polar solvents such as N-methyl-2-pyrrolidone, m-cresol, and nitrobenzene. They began to decompose at about 400°C in a nitrogen atmosphere as determined by thermogravimetric analysis.     

Statistical evaluations of single-ion Gibbs energies of transfer

A statistical approach for the evaluation of single-ion Gibbs energies of transfer of the cations Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ba²⁺, Ag⁺, Tl⁺, Cu⁺, Zn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ into 40 solvents based on the principal component analysis is presented. It is shown that the Gibbs energies of transfer depend both on the nature of the cation and on the donor site of the respective solvent molecule. Correlation of the data for the investigated cations required separating the solvents into subgroups according to their donor atoms in the solvent molecule. Gibbs energies of transfer into oxygen donor solvents could be correlated with the Born term [N _L(z _i e ₀)²/(8πε₀ r _i )]. Several cation parameters were investigated with respect to the transfer data into nitrogen and sulfur donor solvents. No correlations were found. Thus the use of cation parameters derived from the statistical analysis are proposed to account for the Gibbs energies of transfer into nitrogen and sulfur donor solvents. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 1, pp. 9–17. The text was submitted by the authors in English.     

Conductance behavior of 1∶1 electrolytes in N,N-dimethylmethanesulfonamide

The conductances of eleven 1:1 salts have been measured at 50°C in N,N-dimethylmethanesulfonamide (DMMSA) for electrolyte concentrations of 1.2–55.0×10^–4 mol-dm^–3. The conductance data were analyzed using the equation of Lee and Wheaton. Calculations for different values of the distance parameter R indicate that all salts studied are only slightly associated in DMMSA. Association was somewhat greater for the trimethylphenylammonium halides than for the tetraalkylammonium salts. Ionic limiting molar conductances were estimated using the tris (isopentyl) butylammonium tetraphenylborate approximation. The markedly smaller value for _o (Na⁺) compared to the values for _o (Br^–) and _o (I^–) indicates that the sodium ion is probably more extensively solvated than the halide ion. In general, it appears that DMMSA (dielectric constant=80.31 at 50°C) is similar in its solvent properties to dipolar aprotic heterocyclic solvents such as 2-cyanopyridine and 3-methyl-2-oxazolidone which have similar dielectric constants.     

Carbon black/alumina gel composite: Preparation by sol-gel process in the presence of polymer-grafted carbon black and its electric properties

The preparation of a novel carbon black/alumina gel composite by sol-gel reaction of aluminum isopropoxide (AIP) was investigated. When sol-gel reaction of AIP was carried out in the presence of untreated carbon black, a thin film of alumina gel was hardly obtained, because of the presence of aggregated carbon blacks. On the contrary, in the presence of poly(N-vinyl-2-pyrrolidone)-grafted, poly(2-methyl-2-oxazoline)-grafted, and poly(N,N-diethylacrylamide)-grafted carbon black, a deep-black, thin film of alumina gel, in which carbon blacks were uniformly incorporated, was obtained. Carbon black was incorporated into an alumina gel matrix by the hydrogen bond between carbonyl groups of the grafted polymer and the residual hydroxyl groups in the alumina gel. Electric resistance of the polymer-grafted carbon black/alumina gel composite was very sensitive to the vapor of solvents of the grafted polymer chains on carbon black surface: the electric resistance of the composite drastically decreased in humidity and N,N-dimethylformamide vapor, but not in n-hexane vapor. The logarithm of electric resistance of polymer-grafted carbon black/alumina gel composite linearly decreased in proportion to relative humidity. In addition, the electric resistance of poly(N,N-diethylacrylamide)-grafted carbon black/alumina gel composite under humidity decreased drastically at 32°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3591–3597, 1999     

Expanded scope of heterocyclic biaryl synthesis via a palladium-catalysed thermal decarboxylative cross-coupling reaction

The palladium-catalysed decarboxylative cross-coupling of heterocyclic aromatic carboxylates and aryl halides is described. The cross-coupling proceeds under relatively mild conditions using catalytic Pd(0) and tetrabutylammonium bromide (TBAB). Utilizing a mixed solvent system consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), the cross-coupling system operated at temperatures ranging from 80 to 140 °C.     

Synthesis of poly(<Emphasis Type="Italic">N</Emphasis>-methylolacrylamide)/polymethylacrylamide hybrids via frontal free-radical polymerization

In this study, poly(N-methylolacrylamide)/polymethylacrylamide (PNMA/PMAA) hybrids were produced successfully by frontal free-radical polymerization at ambient pressure. In a typical run, the appropriate amounts of reactants (N-methylolacrylamide, NMA; methylacrylamide, MAA) and initiator (ammonium persulfate) were dissolved in dimethyl sulfoxide at ambient temperature. Frontal polymerization (FP) was initiated by heating the wall of the tube with a soldering iron, and the resultant hot fronts were allowed to self-propagate throughout the reaction vessel. Once initiated, no further energy was required for polymerization to occur. The dependences of the front velocity and front temperature on the initiator concentration, reactant dilution, and NMA/MAA components were thoroughly investigated. The front temperatures were between 69 and 116 °C, depending on the persulfate concentration. We have also investigated the FP of PNMA/PMAA hybrids with N-methyl-2-pyrrolidone as solvent. Results show that FP can be exploited as a means for the preparation of PNMA/PMAA hybrids with the potential advantage of higher throughput compared to the traditional mode.     

Direct synthesis and properties of polybenzodipyrrolediones from dibenzylidenebenzodifurandiones and various diamines

Aromatic and aliphatic polybenzodipyrrolediones have been synthesized directly by the solution cyclopolycondensation of two dibenzylidenebenzodifurandiones with four different diamines in refluxing m-cresol or o-phenylphenol in the presence of boric acid. The polymerizations proceeded smoothly in a homogeneous solution and afforded the heterocyclic polymers having inherent viscosities as high as 1.0 almost quantitatively. All the polymers were readily soluble in a wide range of solvents, including N-methyl-2-pyrrolidone (NMP), hot m-cresol, and hot pyridine. Tough, transparent, yellow films could be cast from NMP solutions of the polymers. Thermogravimetric analysis of the aromatic polybenzodipyrrolediones showed a 10% weight loss temperature of 460–500°C under nitrogen. The results also indicated that the aromatic polymers were somewhat less thermally stable than wholly aromatic polypyromellitimides.     

Synthesis of polyarylamines by vinylogous nucleophilic substitution polymerization of bis(4-chloro-3-nitrophenyl) sulfone with diamines

A series of new polyarylamines was prepared by the vinylogous nuclephilic substitution polymerization of bis(4-chloro-3-nitrophenyl) sulfone with both aromatic and aliphatic diamines. The synthesis involves the solution polycondensation in a polar aprotic solvent at elevated temperatures, a tertiary amine being used as an acid acceptor. Of these solvents, dimethyl sulfoxide and N-methyl-2-pyrrolidone were the most effective for the preparation of high molecular weight polymers. The polyarylamines having inherent viscosities in the range of 0.1–0.5 were all amorphous and highly soluble in polar aprotic solvents. Thermogravimetric analysis under both air and nitrogen atmospheres indicated that rapid decomposition began above 300°C for the polyarylamines from aromatic diamines.     

Colorimetric Solvent Indicators Based on Nafion Membranes Incorporating Nickel(II)‐Chelate Complexes

To develop solvent‐recognition films, Nafion membranes incorporating cationic nickel‐chelate complexes, that is, [Ni(L¹)(L²)]⁺ (HL¹=acetylacetone, 2,2,6,6‐tetramethyl‐3,5‐heptanedione; L²=N,N‐diethylethylenediamine, N‐butyl‐N,N′,N′‐trimethylethylenediamine), were prepared. Immersion of the films in various solvents effected the color changes varying from red to pale blue green depending on the donor number of the solvents. The color change is based on an equilibrium shift between square‐planar and solvent‐coordinated octahedral geometries of the cations. The degree of the color change depended on the affinity of the incorporated complex to the solvent molecules. The films were robust and exhibited a reversible solvent response. The films exhibited thermochromism when a small amount of appropriate solvents were incorporated and changed from pale blue green at low temperatures to red at high temperatures.     

Ion-molecular interactions and the equilibrium composition in the HCl-1-methyl-2-pyrrolidone-1,1,2,2-tetrachloroethane system according to IR spectroscopy data

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions of HCl in 1-methyl-2-pyrrolidone (N-MP) (0–43.4 % HCl) were studied in the 900–4000 cm^–1 range. Spectra were recorded for theN-MP-HCl-1,1,2,2-tetrachloroethane (TCE) ternary system at a TCE N-MP ratio of 1 1. Depending on the ratio between the components, complexes of the compositionN-MP · HCl (C-1),N-MP · 2HCl (C-2), and 2N-MP · HCl (C-3) are formed in the system. Complex C-1 has a quasiionic structure, (CH₂)₃N(Me)CO...H...Cl, formed by a strong quasisymmetrical H-bond between the carbonyl O atom and the Cl atom. The addition of anN-MP molecule to complex C-1 yields complex C-3, in which the quasiionic character of the bond betweenN-MP and HCl is retained. When excess HCl is present, the quasiionic structure is destroyed, theN-MP molecule is protonated, and the Cl^– anion interacts with HCl to give an ion with a strong symmetrical H bond (Cl...H...Cl)^–. Complex C-2 is an ion pair.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1757–1763, September, 1995.This work was carried out with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18356).     

Reaction of perfluoro-2-methyl-2-pentene with cycloalkanone oximes: new examples of the Beckmann—Chapman rearrangement

The base-catalyzed reaction of cycloalkanone oximes (la,b) with perfluoro-2-methyl-2-pentene (PFMP) initially affords the addition products,i.e., fluoroalkyl ethers (2a,b). In the presence of KOH, the latter undergoes dehydrofluorination to give perfluoroalkenyl ethers (3a,b). Thermolysis of ethers3a,b results in compounds of two types — pyrrolines (4a,b) andN-perfluoroalkenyl lactams (5a,b). The latter are also prepared from PFMP and the corresponding lactams. The structure ofN-[perfluoro-(2-methyl-2-penten-3-yl)]-2-pyrrolidone (5c) was established by X-ray diffraction study.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1073–1077, June, 1994.