Decomposition of 1,2‐dichloroethane in an RF plasma environment

A radio frequency (RF) plasma system has been used to decompose 1,2‐dichloroethane (DCE). Final products were identified by a Fourier transform infrared (FTIR) spectrometer. The main products of DCE decomposition in O₂/Ar plasma were CO₂, CO, and HCl. Other minor chlorinated products were CCl₄, C₂HCl₃, C₂H₃Cl, C₂Cl₄, CHCl₃, C₂HCl₅, and COCl₂. Nonchlorinated products were C₂H₂, C₂H₄, C₂H₆, and HCOOH. The plasma reactor with a brass electrode had a higher decomposition fraction of DCE [η, (C_in ? C_out)/C_in × 100%] than that obtained with other materials (Au, Ni, and Cr). Different electrode configurations (inner and outer) were also evaluated for the decomposition of DCE. Argon plus oxygen was found to be the most suitable carrier/auxiliary gas for DCE decomposition. In addition, operational parameters for DCE decomposition in RF plasma including concentration, operational pressure, and total gas flow rate were evaluated. Copyright © 2003 Society of Chemical Industry     

Combustion synthesis of hollow carbon fibers

Mixtures of calcium carbide with different oxidizers, such as C₂Cl₆, C₆Cl₆, (C₂F₄) _n , and (CF) _n , were investigated. Reactions between these substrates in the presence of sodium azide are exothermic enough to proceed in a high-temperature self-sustaining regime. Combustion of tested mixtures was performed in the presence/absence of ferrocene (Fc) as an agent catalyzing the growth of nanostructures. Heat effects accompanying the reactions were measured and solid reaction products were analyzed. SEM and TEM observations revealed the presence of multi-walled hollow carbon fibers in combustion products formed in the CaC₂/C₂Cl₆/NaN₃/Fc mixture. Exfoliated graphite was observed in solid combustion products when (CF) _n was used as an oxidizer. In others systems, a soot-like morphology was found to be predominant.      

Degradation of polymers subjected to radio-frequency discharges in SF6

Studies were conducted on the degradation reaction of polyethylene, poly(tetrafluoroethylene), and an expoxy resin resulting from the action of a 13.56-MHz radio-frequency (rf) discharge in SF₆. The curves showing the temperature variations of the samples during the experiment suggest that this degradation process occurs in two distinct stages: in the first, the heat released by the electric discharge causes the thermal degradation of the polymers, whereas in the second, the volatile degradation products react in the gas phase with the excited SF₆. Analysis of the reaction products shows consistency with this two-step degradation model. The main degradation products have been identified as C₂H₂, C₂H₄, SOF₂, and CS₂ in the case of polyethylene; as CF₄, C₂F₄, and SOF₂ in the case of poly(tetrafluorethylene); and finally as CO₂ and SOF₂ in the case of the epoxy resin. Furthermore, it is interesting to note the formation of polymers of the di(trifluoromethyl) polysulfane type, CF₃-S_n-CF₃, among the reaction products. The more volatile members, n = 2, 3, and 4, were identified by mass spectrometry, whereas the heavier members, identified by infrared spectrophotometry, often took the form of a whitish powder deposited on the walls of the reactor.     

Decomposition of ethoxyethane in the cold plasma environment

A radio frequency (RF) plasma system was used to decompose the ethoxyethane (EOE) contained gas. The reactants and final products were analyzed by using an FTIR (Fourier Transform Infrared) spectrometer. The effects of plasma operational parameters, including input power wattage (W), equivalence ratios (Φ), feeding concentration (C) of EOE and total gas flow rate (Q) for EOE decomposition were evaluated. In addition, the possible reaction pathways for EOE decomposition and the formation of final products were built up and are discussed in this paper. The mole fraction profiles of C₂H₅OC₂H₅, CH₃CHO, CH₄, C₂H₆, C₂H₄, C₂H₂, CO₂ and CO were detected and are also presented in this paper. At lower input power wattages, the creation of glow discharge is strongly dependent on the plasma production index ( PPI ). When input power wattages are smaller than 30 W, the minimum values of PPI to create glow discharge ranged between 18.2 and 19.0. The results of this study revealed that, in the RF plasma reactor, the decomposition fraction of EOE could reach 100% under most operational conditions. © 2000 Society of Chemical Industry     

Condensation products from imidobis(sulfuryl chloride)

A study of model compounds and polycondensation products derived from imidobis(sulfuryl chloride) (IBSC), HN(SO₂Cl)₂, has been carried out and their structures determined. The model compounds were reaction products of IBSC with aniline or ethyl alcohol. Polymeric products were obtained by polycondensations with (1) p-phenylenediamine and (2) 2,2-bis(4'-hydroxyphenyl)-propane. The products were characterized by elemental analysis, infrared, NMR, DSC, TGA, and viscometry data.     

Generation of Oxygen-Containing Radicals in the Aqueous Media of Mechanical Pulping

Mechanical treatments of veratrylglycerol-β-syringaldehyde ether (M) were conducted with a ceramic ball mill or a vibration ball mill in the presence of water and n-paraffin alcohols which were used as ·OH scavengers. Addition of 1% each of the alcohols to the milling process of Compound (M) greatly decreased the yields of the products, e.g. veratryl alcohol 2, vanillin 3, syringaldehyde 4, 3,5-dimethoxy-p-benzoquinone 5, 3,5-dimethoxy-p-hydroquinone 6 and others. Another addition of n-paraffin alcohols to aqueous media during the millings also significantly reduced the concentration of H₂O₂. When phthalic hydrazide (P) was treated in the mills in the aqueous media, triacetoxyphthalazine (1A), 3-acetoxyphthalic acid (2A) and other products were separated from the acetates of the reaction mixtures. Results mentioned above disclosed the generation of ·O₂H, ·OH, and ·H in the aqueous media during the mechanical treatments.     

Direct Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLA) using Gold Catalysts

Supported gold catalysts, e.g., Au on Al₂O₃, Fe₂O₃, CeO₂, MnO₂, TiO₂, ZrO₂, activated carbon, titanium silicalite TS‐1, were prepared and used for the isomerization of linoleic acid (cis‐9,cis‐12‐octadecadienoic acid) to conjugated linoleic acids (CLA) in the presence of hydrogen at 165 °C in a batch reactor. The best results were obtained using a catalyst with 2 wt % Au on TS‐1, which exhibits a high selectivity (78 %) towards CLA. The two biologically active target CLA isomers, i.e., cis‐9,trans‐11‐CLA and trans‐10,cis‐12‐CLA, were the main products. During the isomerization of linoleic acid to CLA, consecutive reactions also took place. These were the hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids and the further hydrogenation of monounsaturated acids to stearic acid. Thus, gold catalysts are capable of isomerizing linoleic acid to CLA and hydrogenating their double bonds to an extent that depends on the Au catalyst used.     

Thermal and chemical stability of Cu–Zn–Cr-LDHs prepared by accelerated carbonation

Layered double hydroxides Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O with different molar ratios of Cu/Zn/Cr were synthesized by accelerated carbonation. The products were characterized by XRD, SEM, FT-IR and TG-DTG-DSC-MS. The chemical stability was tested by the modified Toxicity Characteristic Leaching Procedure (TCLP). The results showed that the products were the mixture of Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O and (CuZn)₂(CO₃)(OH)₂, with similar thermal behavior. All products were chemically stable with reduced leaching at pH > 6 (Cu²⁺, Zn²⁺) or > 5 (Cr³⁺).     

Anodic dehalogenation of 1,2-dichloroethane in aqueous electrolytes

A solution of 0.1 M 1,2-dichloroethane in 1 M H₂SO₄ was anodically converted to CO₂, Cl₂ and HCIO₄ as the main products at smooth platinum. The current efficiency for CO₂ exceeds 60% at low current densities, while HClO₄ is obtained with about 20% current efficiency. Chlorinated products such as 1,2′,2-trichloroethane are formed in negligible amounts. Platinum plays a distinctive role as anode material and shows a reaction limited anodic prewave. Our experimental findings lead to a mechanism, whereby DCE is initially hydroxylated to form chloroacetaldehyde chlorohydrin which releases HCl and becomes rapidly further oxidized to monochloroacetic acid. The cleavage of the C? C bond proceeds via its anodic decarboxylation. Possible practical applications in the field of anodic water purification and in the direct electrosynthesis of vinyl chloride are discussed.     

Attempts to synthesize the framework nitrogen bearing zeolites

The attempts to synthesize the nitrogen bearing zeolite analogs have been conducted under conditions resembling hydrothermal synthesis of zeolite with SiCl₄, AlCl₃, AlN, or metallic Al, and NaNH₂, as principal substrates. Ammonolysis of the substrates (mostly SiCl₄) was always the first step of synthesis and yielded the amorphous, porous products showing very high surface area and well ordered mesopore system. Their further treatment with NaNH₂ in liquid NH₃ or in other aprotic solvents (i.e., crystallization) usually did not lead to crystalline, porous materials, whereas the porosity of the products declined markedly. The crystalline products have been obtained by ammonolysis of Al₂(SiF₆)₃, but the product showed a low thermal stability.     

Gaseous products of the thermolysis of brown coal impregnated with potassium hydroxide

The yields of gaseous products (H₂, CO, CO₂, and C _n H_2n + 2 at n = 1−4) from brown coal and brown coal-KOH compounds were determined under conditions of nonisothermal heating (4°C/min) to 800°C followed by an isothermal exposure (1 h, 800°C). It was found that, in the presence of the alkali, the yields of H₂, CO, C₂H₆, and C₃H₈ increased; the yields of CO₂ and CH₄ decreased; and the formation of isobutane was completely suppressed. Changes in the gas compositions were explained by the alkali degradation of C-C bonds in the organic matter of coal and by the thermally initiated dehydrogenation and dealkylation reactions of arene and alkane structural fragments, in which KOH molecules served as H-atom donors in the formation of H₂ and alkanes.     

Estimating Heats of Detonation and Detonation Velocities of Aromatic Energetic Compounds

A new method is introduced to predict reliable estimation of heats of detonation of aromatic energetic compounds. At first step, this procedure assumes that the heat of detonation of an explosive compound of composition C_aH_bN_cO_d can be approximated as the difference between the heat of formation of all H₂O CO₂ arbitrary (H₂O, CO₂, N₂) detonation products and that of the explosive, divided by the formula weight of the explosive. Overestimated results based on (H₂O CO₂ arbitrary) can be corrected in the next step. Predicted heats of detonation of pure energetic compounds with the product H₂O in the liquid state for 31 aromatic energetic compounds have a root mean square (rms) deviation of 2.08 and 0.34 kJ g⁻¹ from experiment for (H₂O CO₂ arbitrary) and new method, respectively. The new method also gives good results as compared to the second sets of decomposition products, which consider H₂, N₂, H₂O, CO, and CO₂ as major gaseous products. It is shown here how the predicted heats of detonation by the new method can be used to obtain reliable estimation of detonation velocity over a wide range of loading densities.     

Changes in Volatile Compounds of Black Cumin Oil and Hazelnut Oil by Microwave Heating Process

Black cumin and hazelnut oils were subjected to a heating process in a microwave oven for a duration of 2, 4, 6 and 8 min at a constant frequency of 2450 MHz and a power of 0.45 kW. The ultraviolet absorption and volatile products of the oils were investigated in detail during the processes. The experimental evidences obtained show that K₂₃₂ and K₂₇₀ parameters reach values of 4.69 and 1.30 for black cumin oil, 3.22 and 1.75 for hazelnut oil, respectively with the increment of heating time. The headspace SPME method was used to analyze volatile compounds extracted from black cumin and hazelnut oils being exposed to the microwave heating process. The SPME–GC/MS method allowed the detection of 17 identified volatile compounds (hexanal, α‐thujene, α‐pinene, sabinene, β‐pinene, 2‐heptenal, α‐terpinene, limonene, p‐cymene, γ‐terpinene, E‐2‐octenal, nonanal, 4‐terpineol, thymoquinone, E,E‐2,4‐decadienal, α‐longipinene and isolongifolene) in black cumin oils. Of the products, hexanal, 2‐heptenal, E‐2‐octenal, nonanal and E,E‐2,4‐decadienal were determined to be the predominant volatile oxidation products. In fact, the hexanal was found as a major volatile oxidation compound and reached a local maximum point of 7.41 × 10⁶ AU at the end of heating. On the other hand, only 8 volatile oxidation products (hexanal, heptanal, 2‐heptenal, nonanal, E‐2‐decenal, E,Z‐2,4‐decadienal, E,E‐2,4‐decadienal and E‐2‐tridecenal) were identified in hazelnut oils as a consequence of the heating process. Based on the experimental evidence observed, it is reasonable to conclude that the nonanal content dramatically increased at the end of heating and reached a value of 9.22 × 10⁶ AU.     

Studies on the hypohalogenation of long chain α,β-unsaturated acids

As a result of hypohalogenation, a series oferythro 2(3)-halo-3(2)-hydroxy derivatives of C₁₆, C₁₈ and C₂₂ α, β-unsaturated acids have been prepared. The structures of the individual isomers were established by chemical and spectral methods. The major products were shown to be 2-halo-3-hydroxy alkanoic acids. Unlike internal halohydrins, the isomeric mixture of these derivatives of long chain α, β-unsaturated acids was successfully resolved by column chromatography.     

NO x -Catalyzed Gas-Phase Activation of Methane: A Reaction Study

The catalytic effect of NO _x on methane oxidation in the absence of any solid catalyst has been investigated. The experimental results show that NO _x has very good catalytic activity in the partial oxidation of methane. The predominant products for reactions in a CH₄-O₂-NO _x co-feed mode are CO, CO₂, H₂O and H₂, CH₃OH, HCHO, and C₂H₄. Aromatics are also observed.     

Photocatalytic N-alkylation of benzylamine in microreactors

A photocatalytic process of N-alkylation of benzylamine in alcohol media was successfully observed by using microreactors with immobilized Pt-free TiO₂ as well as Pt-loaded TiO₂, while it has been reported that the N-alkylation did not occur by the irradiation of Pt-free TiO₂ in conventional batch reactors. The use of continuous-flow microreactor inhibited the formation of N,N-dialkylation products. These results suggest the possibilities of a catalytic microreaction system on organic photoreactions.     

Application of Statistical Physics on the Modeling of Water Vapor Desorption Isotherms

The sorption isotherms give information about the interaction of biopolymers with water vapor. These isotherms are extremely important in the modeling of the drying processes and in the prediction of the humidity changes during the product storage. An analytical expression for modeling of water vapor sorption isotherms of agricultural products was developed using the statistical physics formalism. The statistical model was further used to fit and interpret desorption isotherms of Tunisian olive leaves and some food products. In this model, five parameters in relation to the desorption process intervene, such as the number of water molecules per site n, the receptor sites density N _M , the energetic parameters a ₁ and a ₂, and the number of multilayers N ₂. The fitting results are discussed to explain the behavior of different parameters versus temperature. The statistical model was used to investigate thermodynamics functions that govern in the desorption mechanism, such as entropy, internal energy, and Gibbs free enthalpy.     

Novel carbonaceous coupling products containing sulphur

Summary The coupling of alkali ethynides with CSCl₂, SOCl₂, or SO₂Cl₂ results in new carbonaceous polymeric products; their structures were studied by FTIR and XPS spectra, and the assumptions on reaction mechanism were made with respect to the found elemental composition and model calculations. These macromolecular products, obtained in the yields of 80–92%, contain chlorine in the chain terminals, and alkyne sequences along with inserted C=S, S=O or SO₂ groups. These inserted sulphur groups contribute to the stability of alkyne sequences as evidenced by FTIR spectra. Soluble thioketone iPr₃SiC≡C–CS–C≡CSiiPr₃ (2) prepared by similar coupling of iPr₃SiC≡CLi (1) with CSCl₂ in the yield of 72%, was considered as a support of the suggested coupling mechanism. Similarly monomolecular sulfoxide iPr₃SiC≡C–SO–C≡CSiiPr₃ (3) was prepared by coupling of iPr₃SiC≡CLi (1) with SOCl₂ in the yield 75%.     

Glucamine-based gemini surfactants II: Gemini surfactants from long-chain <Emphasis Type="Italic">N</Emphasis>-alkyl glucamines and epoxy resins

Gemini surfactants were synthesized by reaction of long-chain N-alkyl glucamines with epoxy resins. Analogous to the synthesis of gemini surfactns from long-chain N-alkyl glucamines and α, ω-diepoxides (1), the reaction in methanol at 70°C could be used to convert the starting materials selectively and almost quantitatively. N-Octyl glucamine, N-decyl glucamine, and N-dodecyl glucamine were combined with several epoxy resins, mainly technical glycidyl ethers of diols. Syntheses involving equimolar amounts of amine resulted in quantitative conversion of the epoxy resins, and epoxide and products could be isolated quantitatively by removing the solvent. Gemini surfactants having hydrophobic or hydrophilic spacers were preparared according to their structures and the hydrophilic properties of the epoxy resin. Surface tensions were measured, and foaming propertiers were examined to characterize surface-active properties of these surfactants. The more hydrophilic products were of particularly high surface activity. Tensiometric studies showed a reduction of surface tension to 30–34 mN/m and critical micelle concentrations in the range of 2–35 mg/L. Comparison of gemini surfactants from long-chain N-alkyl glucamines and diepoxides of α,ω-diolefins (chain lengths: C₈, C₉, C₁₀, and C₁₄) with those based on epoxy resins showed similar or lower surface activities using hydrophobic epoxy resins and much better surface-active properties using hydrophilic epoxy resins (e.g., based on glycerol). This, together with the easier availability, makes the epoxy resin-based products interesting surfactants. Products having very good surface-active properties are available, especially using glycidyl ether of aliphatic diols or glycerol.     

RDX flame structure at atmospheric pressure

The chemical structure of an RDX flame at a pressure of 1 atm was studied using probing molecular beam mass spectrometry. The flame was found to contain RDX vapor, and its concentration profile was measured in a narrow zone adjacent to the burning surface. In addition to RDX vapor, ten more species were identified (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂ and NO₂), and their concentration profiles were measured. Two main chemical-reaction zones were found in the RDX flame. In the first, narrow, zone 0.15 mm wide adjacent to the burning surface, decomposition of RDX vapor and the reaction of NO₂, N₂O, and CH₂O with the formation of HCN and NO occur. In the second, wide, zone 0.85 mm wide, HCN is oxidized by NO to form the final combustion products. The composition of the final combustion products was analyzed from an energetic point of view. The measured composition of the products near the burning surface was used to determine the global reaction of RDX gasification at a pressure of 1 atm. Values of heat release in the condensed-phase calculated by the global gasification reaction and by the equation of heat balance on the burning surface (using data of microthermocouple measurements) were analyzed and compared. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 49–62, January–February, 2008.