Solventless Method Research Articles

A simple and rapid method based on direct transfer of headspace vapor into the GC injector: application for determination of BTEX compounds in water and wastewater samples

A direct, inexpensive and solventless method based on headspace extraction coupled to gas chromatography-flame ionization detection (GC-FID) was developed for determination of benzene, toluene, ethylbenzene and xylenes (BTEX). In this method, volatile organic compounds are separated from the matrix and preconcentrated in the headspace of the sample solution. Then, the headspace vapor is transferred into the GC injector using a fused silica capillary tube. The parameters affecting the headspace extraction such as extraction time, extraction temperature, stirring rate, sample volume, transfer line tubing diameter, transfer line depth in the injector and salt addition were carefully investigated and optimized. The limits of detection (LODs) for the studied compounds ranged from 0.1 to 0.3 ng mL−1 for 15 mL sample solution with the relative standard deviations (RSDs) ranging from 3.34 to 7.18% (n = 5). Finally, the optimized method was successfully applied to water and wastewater as real samples.

Polymerization of N-methyl B-methyl amino borazine

Abstract A large quantity of high-quality poly[N-methyl B-methyl amino borazine] was synthesized via a solventless method from the monomer 1,3,5-trimethyl-2,4,6-tri(methyl amino)borazine. The thermal polymerization profile was investigated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), size exclusion chromatography (SEC), gas chromatography, and mass spectrometry. A polymerization mechanism involving the condensation reaction of two –N(H)CH3 groups releasing methylamine was proposed and compared with the literature. As a result of cross-linking via the amino­methyl moiety, the cured polymer exhibited a molecular weight Mn of 790 g mol-1, glass transition temperature of 64°C, high cross-link density, and thermal stability with a decomposition temperature of 165°C. Functionalized poly[N-methyl B-methyl amino borazine] with chemical stability was fully characterized by 1H, 13C, 11B nuclear magnetic resonance, FTIR, DSC, and SEC analyses. Ultraviolet absorption spectra evidenced changes in the structure of the aforementioned oligomers.

ChemInform Abstract: Synthesis, Cytotoxic Activity, and Thermal Studies of Novel N‐[(1,3‐Diphenylpyrazol‐4‐yl)methyl] α‐Amino Acids.

AbstractThis solventless method combines aldehyde (I), α‐amino acids (II), and sodium hydroxide in a mortar and aggregates the dry solid mixture until a powder is formed, thus accelerating the condensation reaction.

Organocatalyzed synthesis of ureas from amines and ethylene carbonate

A new solventless method for the synthesis of symmetrical and unsymmetrical ureas, starting from ethylene carbonate and amines, is reported. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene(TBD) and thioureas have been found to be efficient organocatalysts for this reaction.

Contribution of microwave accelerated distillation in the extraction of the essential oil of Zygophyllum album L.

The aerial parts of Zygophyllum album L. are used in folk medicine as an antidiabetic agent and as a drug active against several pathologies. In this work we present the chemical composition of Algerian essential oils obtained by microwave accelerated distillation (MAD) extraction, a solventless method assisted by microwave. Under the same analytical conditions and using GC-FID and GC-MS, the chemical composition of the essential oil of Zygophyllum album L. extracted by MAD was compared with that achieved using hydrodistillation (HD). The extracted compounds were hydrosoluble, and they were removed from the aqueous solution by a liquid extraction with an organic solvent. Employing MAD (100°C, 30 min), the essential oil contained mainly oxygenated monoterpenes with major constituents: carvone and α-terpineol. However, most of the compounds present in the hydrodistilled volatile fraction were not terpene species, with β-damascenone as a major constituent. The MAD method appears to be more efficient than HD: after 30 min extraction time, the obtained yields (i.e. 0.002%) were comparable to those provided by HD after 3 h extraction. MAD seems to be more convenient since the volatile fraction is richer in oxygenated monoterpenes, species that are recognised for their olfactory value and their contribution to the fragrance of the essential oil.

Functionalisation of cellulosic substrates by a facile solventless method of introducing carbamate groups

A facile method for the introduction of carbamate groups in cellulosic substrates is described. Woven cellulosic fabrics were padded with non-alkali treatment solutions containing PEG 2000, urea, and LiCl and heated at elevated temperatures to obtain cellulose carbamate fabrics. The introduction of carbamate groups was confirmed with FTIR-ATR and NMR spectroscopy, and the treated fabrics exhibited nitrogen contents of 0.10–2.04% (DS 0.01–0.25). There was a reduction in the viscosity-average degree of polymerization (DP v) of treated fabrics. However, the treatments did not significantly reduce mechanical properties (tensile strength, elongation at break and work of rupture) or thermal stability. The products were soluble in alkali solutions, but stable during storage at ambient conditions. Compared to the known carbamate processes reported in literature which can be applied only on wood pulp at the first state of fibre manufacture the advantages of this process are that not only this method can be employed on various cellulosic substrates at the latest state of the production but also the processing time can be reduced from hours to minutes. Moreover, the process is environmental friendly because it is a solventless procedure and employed less and non-toxic chemicals.

ChemInform Abstract: Microwave-Accelerated Crossed Cannizzaro Reaction Using Barium Hydroxide under Solvent-Free Conditions.

Abstract A solventless and expeditious method for the preparation of alcohols is described from aldehydes using barium hydroxide, Ba(OH)2.8H2O, and paraformaldehyde. A comparison of this microwave-accelerated Cannizzaro reaction to the one under conventional heating mode is also reported.

Synthesis and curing behavior of a novel benzoxazine‐based bisphthalonitrile monomer

AbstractA novel bisphthalonitrile containing benzoxazine units (BZ‐BPH) was synthesized via a solventless method from 4,4′‐dihydroxybiphenyl, paraformaldehyde, and 4‐aminophenoxylphthalonitrile. The chemical structure of BZ‐BPH was confirmed by 1H‐NMR and 13C‐NMR analyses. The curing behavior was investigated with DSC, FTIR, TGA, and rheology techniques. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the ring‐opening polymerization of benzoxazine moiety, and the second to the polymerization of phthalonitriles. Study about the effect of the catalysts including 4,4′‐diaminodiphenylsulfone and FeCl3 on the polymerization of BZ‐BPH was performed, and the result indicated that the addition of these agents could increase the curing rate and lower the curing temperature. Additionally, the cured product showed excellent thermal and thermo‐oxidative stability, the high char yield was 76.0% by weight at 800°C in nitrogen atmosphere and 81.2% by weight at 600°C in air, and temperature at 5% weight loss (T5%) in nitrogen and air was 477.9°C and 481.7°C, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Simple Procedure for Polystyrene-Based Nanocomposite Preparation by Vapor-Phase-Assisted Surface Polymerization

Polystyrene (PSt)-based copolymer/montmorillonite (MMT) nanocomposites were prepared by an in situ vapor-phase-assisted surface polymerization (VASP) as a solventless method using an organically mo...

Rapid, Solventless, Bulk Preparation of Metal Nanoparticle-Decorated Carbon Nanotubes

A rapid, solventless method is described for the decoration of carbon nanotubes with metal nanoparticles. The straightforward two-step process utilizes neither reducing agents nor electric current and involves the dry mixing of a precursor metal salt (e.g., a metal acetate) with carbon nanotubes (single- or multi-walled) followed by heating in an inert atmosphere. The procedure is scalable to multigram quantities and generally applicable to various other carbon substrates (e.g., carbon nanofiber, expanded graphite, and carbon black) and many metal salts (e.g., Ag, Au, Co, Ni, and Pd acetates). As a model system, Ag nanoparticle-decorated carbon nanotube samples were prepared under various mixing techniques, metal loading levels, thermal treatment temperatures, and nanotube oxidative acid treatments. These nanohybrids were characterized by a variety of microscopic and spectroscopic techniques. For example, X-ray diffraction and scanning electron microscopy indicated that the average size of the Ag nanoparticles has little to do with the thermal treatment temperature but can be easily controlled by varying the Ag loading. Raman spectroscopy illustrated both the metal-nanotube electronic interactions and the surface enhancement effect from the Ag nanoparticle attachment. High-resolution transmission electron microscopy captured the in situ salt-to-metal conversion events on the nanotube surface. The mechanistic implications from the characterization results are discussed.

An efficient solventless method for the synthesis of N,N-dialkyl sulfonamide derivatives

Aza-Michael addition of sulfonamides to α,β-unsaturated esters efficiently proceeds in the presence of catalytic amount of sodium hydroxide (NaOH) and tetrabutylammonium bromide (TBAB) as a phase-transfer catalyst (PTC) under microwave irradiation to afford N,N-dialkyl sulfonamides as biologically interesting compounds in good to excellent yields and short reaction times.

Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry

A simple, rapid, solventless method for the determination of trihalomethanes (THMs) (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in water samples is presented. The analytes are extracted from the headspace of the aqueous matrix into a 2μL drop of the ionic liquid 1-octyl-3-methyl-imidazolium hexafluorophosphate working at 30°C for 30min. The separation and detection of the target compounds is accomplished by gas chromatography/mass spectrometry owing to the use of an interface that efficiently transfers the analytes extracted in the ionic liquid drop to the gas chromatograph while preventing the ionic liquid from entering the column. The detection limits obtained are below the values compelled by the legislation, ranging from 0.5μgL−1 for chloroform and bromodichloromethane to 0.9μgL−1 for dibromochloromethane. The use of ionic liquid in the extraction procedure avoids the use of organic solvents and leads to relative standard deviations that range from 3.1% to 4.8%.

Microwave Irradiation as a Green Alternative to Phase Transfer Catalysis: Solid-Liquid Phase Alkylation of Active Methylene Containing Substrates Under Solvent-Free Conditions

An ecofriendly, microwave (MW) promoted and solventless method is described for the alkylation of diethyl malonate, ethyl acetoacetate and ethyl cyanoacetate by a variety of alkyl halides in the presence of K2CO3. In the solidliquid phase alkylation of active methylene containing substrates, it seems to be of general value that the phase-transfer catalyst, that is an onium salt in the present case, can be omitted and substituted by MW irradiation promoting the formation of the potassium salt of the substrate and its transfer to the organic phase. In certain cases, the use of triethylbenzylammonium chloride led to the formation of by-products under the conditions (∼160 ° C/∼12 bar) applied.

Routes to new hafnium(IV) tetraaryl porphyrins and crystal structures of unusual phosphate-, sulfate-, and peroxide-bridged dimers.

New routes for the synthesis of mono tetraaryl porphyrinato hafnium(IV) complexes, Hf(IV)Por(L)(2), are reported, where the secondary ligands, L, are determined by the method of purification. These synthetic routes cater to the solubility of the macrocycles and provide access to Hf(IV) complexes of meso tetraaryl porphyrins bearing diverse functional groups such as phenyl, tolyl, pyridyl, pentafluorophenyl, and carboxyphenyl. The latter three derivatives significantly expand the repertoire of hafnium porphyrinates. One route refluxes the porphyrin with HfCl(4) in 1-chloronaphthalene or in a mixed solvent of 1-chloronaphthalene and o-cresol. A second, solventless method is also reported wherein the porphyrin is mixed with Hf(cp)(2)Cl(2) and heated to give the metalated porphyrin in good yields. Simultaneous purification and formation of stable porphyrinato hafnium(IV) diacetate complexes, Hf(Por)OAc(2), is accomplished by elution over silica gel using 3-5% acetic acid in the eluent. Exchange of the acetate ligands for other oxo-bearing ligands can be nearly quantitative, such as p-aminobenzoate (PABA), pentanoate (pent), or octanoate (oct). Notably, we find that two to three of a variety of small multitopic dianions such as peroxo (O(2)(-2)), SO(4)(-2), and HPO(4)(-2) serve to bridge between two Hf(Por) moieties to form stable dimers. The crystal structures of this library of Hf(Por) complexes are reported, and we note that careful analysis of crystallography data reveals (Por)Hf(micro-eta(2)-O(2))(2)Hf(Por) rather than four bridging oxo or hydroxy ions.

The Solventless Syntheses of Unique PbS Nanowires of X-Shaped Cross Sections and the Cooperative Effects of Ethylenediamine and a Second Salt

Unique PbS nanowires with x-shaped cross sections, with diameters in the range of 300-800 nm with an average of 598 nm (sigma = +/-21.7% ), and lengths of up to several tens of micrometers, have been made by a solventless method. Such nanowires show high adsorptivities of the PbS nanooctahedra, which can be washed off by ultrasound. The suitable precursor is obtained from a Pb(NO3)2/octanoate/ethylenediamine/dodecanethiol molar ratio of 1:2:1:1.6, and the PbS nanowires are produced by the thermolysis of such precursors at 280 degrees C for 1 hour. The X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterizations of the products and the keys of the morphological control have been reported. For the formation of such products, two cooperative effects are found to be crucial, the roles of ethylenediamine and a second salt, lead octanonate.

Preparation and application of polybenzoxazine adsorption resin

AbstractThe synthesis and application of polybenzoxazine adsorption resin was studied. First, the precursor was synthesized by the solventless method. And then a kind of spherical and granular polybenzoxazine resin was obtained using reverse‐phase suspension polymerization technique in the process of solidification. Besides, the influence of dispersion medium, the volume ratio of precursor to medium, the solidification temperature, and the agitation speed were studied in detail in the process of polymerization. Second, the spherical shape of the polybenzoxazine resin was identified by scanning electronic microscope and the thermal stability of resin was measured by thermogravimetric analysis. Finally, the adsorption capacity of the spherical resin on pyridine was studied in cyclohexane systems. The correlation coefficient of Langmuir adsorption constant temperature line was bigger than 0.99, which indicated that the equilibrium sorption date was coincident with the Langmuir isotherm equation. And the saturated adsorptive capacity of dried resin achieved 222.2 mg g−1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Bis allyl benzoxazine: Synthesis, polymerisation and polymer properties

A bis benzoxazine monomer with allyl groups viz: 2,2′-bis (8-allyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Bz-allyl) was synthesized via a solventless method from 2,2′diallyl bisphenol-A, paraformaldehyde and aniline. The chemical structure of Bz-allyl was confirmed by FTIR, 1H NMR and 13C NMR analyses. The monomer manifested a two-stage thermal polymerisation pattern. The first stage was attributed to the polymerisation of the allyl groups and the second to the ring – opening polymerisation of benzoxazine moiety. The polymerisation profile was investigated with DSC, FT-IR, TGA and pyrolysis-GC techniques. A polymerisation mechanism involving the electrophilic addition of the propagating iminium cation on the aniline ring in lieu of the activated sites of bisphenol-A, (which are blocked by allyl and alkyl substituents) was proposed. Additional cross-linking was provided by thermal addition polymerization of allyl groups. As a result of altered cross-linking via the aniline moiety and the additional cross-linking via allyl groups, the cured polymer exhibited a T g of ca. 300 °C and high crosslink density. The thermal stability of this polymer was also substantially higher vis-à-vis that of the bisphenol-A based polybenzoxazine. The work focuses on the manipulation of benzoxazine monomer structure to alter the ring-opening polymerisation mechanism and cross-linking to derive polybenzoxazine with improved properties.

Identification of volatile degradants in formulations containing sesame oil using SPME/GC/MS

Solid-phase microextraction (SPME), in combination with gas chromatography/mass spectrometry (GC/MS), was used to identify an unknown degradant observed during stability studies of a pharmaceutical formulation containing sesame oil. SPME is a solvent-less, rapid, sensitive, and inexpensive extraction method that minimizes sample preparation. SPME combined with GC is a widely used technique in certain fields, such as food, environmental analysis, forensics, and consumer products, but has only rarely been used for the analysis of pharmaceutical formulations. Hexanal, octanal, 2-octenal, 2-decenal, 2-undecenal, and 2,4-decadienal can be detected and identified by GC/MS, but they cannot be detected by LC/MS due to their volatility and low ionization efficiency under atmospheric pressure ionization conditions. Combining the MS data from the GC/MS with LC/DAD data resulted in the identification of the unknown degradant in the formulation as 2,4-decadienal. The presence of this and other aldehydes was attributed to the oxidative degradation of the unsaturated fatty-acid component in vegetable oils.

Rapid Extraction of Volatile Compounds Using a New Simultaneous Microwave Distillation: Solvent Extraction Device

Simultaneous distillation–extraction (SDE) is routinely used by analysts for sample preparation prior to gas chromatography analysis. In this work, a new process design and operation for microwave assisted simultaneous distillation–solvent extraction (MW-SDE) of volatile compounds was developed. Using the proposed method, isolation, extraction and concentration of volatile compounds can be carried out in a single step. To demonstrate its feasibility, MW-SDE was compared with the conventional technique, SDE, for gas chromatography-mass spectrometry (GC-MS) analysis of volatile compounds in a fresh aromatic herb, Zygophyllum album L., a wild salty desert herb belonging to the family Zygophyllaceae. SDE method required a long time (3 h) to isolate the volatile compounds, and large amounts of organic solvent (200 mL of hexane) for further extraction, while MW-SDE needed shorter time (only 30 min) to prepare the sample, and less amount of organic solvent (10 mL of hexane). These results show that MW-SDE–GC-MS is a simple, rapid and solvent-less method for the determination of volatile compounds from aromatic plants.

Synthesis of Nanosized α-Fe and Enhancement of Magnetic Property

α-Fe magnetic nanoparticle was synthesized by using solventless thermal decomposition method. [1] It resulted in higher saturation magnetization (M s ) almost comparable to that of bulk Fe power (M bulk =210 emu/g). To prepare α-Fe nanoparticles, the Fe 2+ -oleate 2 ligand complex was annealed at 400 °C in pyrex tube under 0,3 torr for 2 hrs and reduced to α-Fe crystal structure at 700 °C with sodium chloride under Ar + 5% H 2 mixture gas atmosphere. [2] The crystallinity and structure of α-Fe nanoparticle was investigated by X-ray diffraction (XRD). The shape and size were confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with saturation magnetization (M s ) from hysteresis loop by vibration sample magnetometer (VSM).