Tetrachloroethylene Solutions Research Articles

Photo-on-Demand In Situ Synthesis of N-Substituted Trichloroacetamides with Tetrachloroethylene and Their Conversions to Ureas, Carbamates, and Polyurethanes.

N-substituted trichloroacetamides (NTCAs), which serve as blocked isocyanates, were synthesized in ∼97% yields by in situ photo-on-demand trichloroacetylation of amines with tetrachloroethylene (TCE). The reactions were performed by photo-irradiation of TCE solutions containing an amine under O2 bubbling over 70 °C with a low-pressure mercury lamp. TCE underwent photochemical oxidation to afford trichloroacetyl chloride having high toxicity and corrosivity, which then reacts in situ with the amine to afford NTCA. Compared with conventional NTCA synthesis with hexachloroacetone, the present reaction has the advantage of being widely applicable to a variety of amines, even those with low nucleophilicity such as amides, fluorinated amines, and amine HCl salts. NTCAs could be converted to the corresponding N-substituted ureas and carbamates through base-catalyzed condensation with amines and alcohols, respectively, with the elimination of CHCl3. The reaction may proceed by the initial formation of isocyanate and its subsequent addition reaction with the amine or alcohol. This photochemical reaction also enables the synthesis of fluorinated NTCAs, which accelerate the reactions, and realizes the synthesis of novel fluorinated chemicals including polyurethanes.

Photophysics of α-azinyl-substituted 4,4-difluoro-8-(4-R-phenyl)-4-bora-3a,4a-diaza-s-indacenes

A series of 15 compounds of the general formula 8-(4-R1-phenyl)-3-R2-5-R3-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, where R1 = NMe2, Me, Br, CN, or NO2, and R2, R3 = H, acridin-9-yl, or 6-phenyl-[1,2,5]oxadiazolo[3,4-b]pyrazyne-5-yl, have been synthesized and investigated for their fluorescence properties in tetrachloroethylene and benzene solutions. For tetrachloroethylene solutions of 8-(4-dimethylaminophenyl)-substituted compounds, bright fluorescence from a locally excited state has been observed. The same compounds in benzene show intramolecular charge transfer with an increased Stokes shift and greatly reduced radiative rate and fluorescence quantum yield. The rest of the compounds are characterized only by locally-excited fluorescence both in tetrachloroethylene and benzene. Their nonradiative rate constant knr obeys the equation ln knr = a + bnacr + cσp, where σp is the Hammett constant of the para-substituent, nacr is the number of acridine substituents; a, b, c are fitting parameters. The linearity of the formula implies an additive effect of the substituents on the activation energy of the nonradiative decay.

РЕФРАКТОМЕТРИЧЕСКИЕ СРЕДСТВА КОНТРОЛЯ ВОДНЫХ РАСТВОРОВ ТЕТРАХЛОРЭТИЛЕНА

The paper a refractometric device (URL-1) for measuring the concentration dependence of the refractive index in aqueous solutions of tetrachloroethylene is considered. The presented study is relevant and promising, since the identification of optical parameters in these media is important for chemical industries. The article the appearance of a laboratory refractometric installation, as well as technical and operational characteristics of refractometers used in measurements are presented. The results of measurements of the concentration dependence of the refractive index of the studied substances were obtained experimentally, which were compared with reference values from the scientific literature. The data of experimental measurements and reference values are compared with the results obtained on the K-Patents OY PR-03-M refractometer. The error of the experiment did not exceed k ≤ 0.4%.

Extraction of Strontium and Yttrium from Alkaline Carbonate Media with Functionalized Calix[8]arenes

The extraction of 90Sr and 90Y from alkaline carbonate media with tetrachloroethylene solutions of p-tert-butyl and p-isononylcalix[8]arenes with various substituents in the lower rim was studied. The dependences of the 90Sr and 90Y distribution ratios on pH of the aqueous phase in the interval from 11 to 14 were studied. Among the calixarenes tested, p-alkylcalix[8]arenes with a bridging group in the lower rim show the highest performance in the extraction of 90Sr and 90Y.

Cocaine detection by a mid-infrared waveguide integrated with a microfluidic chip

A germanium (Ge) strip waveguide on a silicon (Si) substrate is integrated with a microfluidic chip to detect cocaine in tetrachloroethylene (PCE) solutions. In the evanescent field of the waveguide, cocaine absorbs the light near 5.8 μm, which is emitted from a quantum cascade laser. This device is ideal for (bio-)chemical sensing applications.

Simultaneous and Sequential Photosonolysis of TCE and PCE

Aqueous solutions of trichloroethylene (TCE) and tetrachloroethylene (PCE) were treated in a flow-through reactor equipped with ultrasound and ultraviolet light sources. The reactor was operated as sonolysis (US), photolysis (UV), and simultaneous photosonolysis (UV/US) reactors; then as US, UV, and sequential UV/US reactors with the installation of a partition in the reactor. The reactor without the partition was simulated by using one continuously stirred-tank-reactor (1-CSTR) model, and the reactor with the partition was simulated by using the sequential CSTR model. Through model calibration, the decomposition rate constants and reactor efficiencies for the removal of TCE and PCE were evaluated. The results suggest that the combined effect of UV and US on the decomposition of TCE and PCE is synergistic in both the simultaneous and sequential UV/US modes, that the rate constants of sonolysis and photolysis are greater with the sequential combination than with the simultaneous combination, and that overall efficiency is higher for the reactor with the partition than for the one without it.

The relation between narrow-dispersed microcapsules and surfactants

Electric ink display is one of the prospect technologies in paper-like display. In this paper, electric ink microcapsules are prepared by means of an in situ polymerization and complex coacervation. In order to obtain the microcapsules in a uniform size distribution, this study focused on the inter-facial tension between tetrachloroethylene and water solution, the dispersion of the core droplets and the microencapsulation with different kind of surfactants. By measuring the inter-facial tensions between water and tetrachloroethylene, it is found that urea-formaldehyde (UF) pre-polymer presents certain surface activity due to the inter-facial tension descending from 43 mN m−1 to 35 mN m−1. Because the surface activity of pre-polymer is not valid, the water-soluble emulsifiers can occupy on the surface of the droplets and prevent the UF resin depositing there. The analysis of the size distribution shows that the UF microcapsules are multi-dispersed. Furthermore, the influence of anionic surfactant of SDS on the size distribution of the core droplets is also investigated. The average diameters of the core droplets prepared with 0.005 wt% and 0.012 wt% SDS are ∼50 µm and 28 µm, respectively. That reveals the existence of SDS not only decreases the droplet diameters, but also makes the size distribution centralized. Because the surface of the core droplets is charged due to the absorption of SDS anionic, the Gelatin and Gum Arabic (GA) coacervating layer is easy to form there. The size of the GA microcapsules prepared with 0.003 wt% SDS is ∼65 µm. Finally; the responsive behaviour of the microcapsules to electric field is also investigated.

Certified reference samples of tetrachloromethane, tetrachloroethylene, and chlorophenol solutions

A procedure was proposed for the metrological certification of reference samples (RS) of solutions of organic compounds. The procedure consists in the determination of performance characteristics of RSs using the developed and certified procedures for the determination of mass concentrations by gas chromatography with flame ionization detection using internal standards. The selection of the internal standards and calibration procedures and the calculation of the errors of determination are considered. Certified reference samples (CRS) of tetrachloromethane, tetrachloroethylene, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol solutions in ethanol are developed for the quality control of drinking water

Hydrogen isotope fractionation between methanol and diphenylphosphine or dimethylphosphine in the gas phase and in aprotic solvents

D/H fractionation factors between MeOH and Ph2PH in dilute solutions of tetrachloroethylene, benzene, tetrahydrofuran, pyridine, and acetonitrile and T/H fractionation factors between MeOH and Me2PH vapors were measured. The experimental results agree very well with values calculated from the statistical theory of isotope effects formulated by Bigeleisen and Mayer. There are correlations between observed fractionation factors and solvent polarity, and the interaction energy of methanol with the given solvent. Another correlation has been found between enthalpy of the exchange reactions and the interaction energy between methanol and the given solvent. Key words: isotope effects, fractionation factor, diphenylphosphine, methanol.

Free radical copolymerization in the presence of lewis acids—III: Alternating copolymerization of butyl acrylate and styrene in the presence of Al2Et3Cl3: Solvent effect

AbstractPhoto‐initiated alternating copolymerization of butyl acrylate (BA) and styrene (St) in the presence of Al2Et3Cl3 was investigated in tetrachloroethylene (TCE) and toluene (TOL) solution. The results showed that copolymers with equimolar compositions were obtained over a wide range of reactant composition. The 13C nuclear magnetic resonance spectrum confirmed their alternating structure. Solvent could greatly affect kinetic behaviour, in TCE solution, the optimum rate of copolymerization was observed near equimolar monomer ratio; while in TOL solution the rate of copolymerization increased rapidly at lower [BA], tended to a constant rate at higher [BA] and increased slightly with increasing [St]. Electron spin resonance spectra indicated that the St radical was the only one to be detected. The effect of solvent as well as Lewis acid on alternating mechanism is also discussed.

Chlorinated byproducts from the titanium oxide-mediated photodegradation of trichloroethylene and tetrachloroethylene in water

The degradation mechanisms of aqueous solutions of tetrachloroethylene (PCE) and trichloroethylene (TCE) have been studied in a 5.6-L recirculating photoreactor utilizing Pyrer-filtered xenon radiation (λ>290 nm) and a photocatalytic semiconductor (Degussa P25 TiO 2 ). Previously unreported byproducts from the photocatalytic degradation of each chloroalkene (CA) were observed. For PCE, at pH 8 and under an atmosphere of air, the major chlorinated byproducts were dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) (<15% based upon PCE degraded)

Dermal absorption of dilute aqueous chloroform, trichloroethylene, and tetrachloroethylene in hairless guinea pigs

Percutaneous absorption was measured in female hairless guinea pigs dermally exposed for 70 min to very dilute (∼ 10 to 100 ppb) aqueous solutions of 14C-labeled chloroform (CF), trichloroethylene (TCE), or tetrachloroethylene (PCE) in an airtight glass chamber containing no headspace. Similar experiments were conducted using aqueous solutions of TCE at 100,000 ppb. Dermal uptake was estimated by comparing the rate of radiolabel loss from chamber water in systems with and without experimental animals. After each low-concentration dermal-uptake experiment, radiolabel in total urine and feces excreted postexposure was measured and expressed as a fraction of corresponding estimated dermal uptake. For each of the compounds studied, the mean value of these fractions did not differ significantly from that obtained using animals injected with a known dose of that compound, indicating that our experimental system yielded accurate dermal-uptake estimates. The mean permeability coefficients obtained range from 0.13 cm/hr (CF) to 0.37 cm/hr (PCE); those obtained using low- vs high-concentration TCE are not significantly different. The value for CF is very close to one we calculate here from recently published data on CF uptake in human volunteers dermally exposed to aqueous CF while showering with normal tap water. Our results suggest that dermal absorption may be an important route of human exposure to chlorinated volatile organic compounds in domestic water supplies.

EXTRACTION OF Pu(IV) AND Th(IV) CHLORIDES WITH n-OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE IN TETRACHLOROETHYLENE∗

ABSTRACT The distribution of trace and macro amounts of Pu(IV) and Th(IV) chlorides between solutions of n-octyl(phenyl)-N,N-diiso-butylcarbamoylmethylphosphlne oxide in tetrachloroethylene and aqueous solutions of hydrochloric acid was studied. In extracting macro quantities of Pu(IV), the solvent can be loaded up to a Pu(IV)/extractant ratio of 1:2, but small amounts of a solid are formed which strongly retard phase disengagement. The disengaging problem can be overcome by using a phase modifier such as tributyl phosphate or dibutyl butylphosphonate. Both modifiers only slightly suppress the efficiency of the Pu(IV) extraction. Th(IV) is less extractable than Pu(IV) and a Th(IV) extractant ratio of only 1:3 can be reached even In the presence of excess Th(IV). Both Pu(IV) and Th(IV) form a third phase (second organic phase) at high concentrations of hydrochloric acid or in the presence of chlorides which salt-out hydrochloric acid from the aqueous phase.

Concentration dependence of Raman linewidth of isopropanol in aqueous solution

AbstractThe isotropic Raman linewidth of isopropanol at 818 cm−1 assigned to the CO stretching vibrational mode has been measured at a variety of concentrations in aqueous solution and in nonpolar tetrachloroethylene solution. On the basis of the concentration dependence of the linewidths observed in tetrachloroethylene solution, the isotropic Raman linewidth of the observed line is found to reflect the molarity of the hydrogen bonds of isopropanol. The unusual concentration dependence of the linewidths observed in aqueous solution, which shows a prominent maximum at a low concentration of isopropanol, has been examined in the light of these considerations. As a result, it is concluded that the concentration dependence of the linewidth is well explained in terms of the change in the partial molar volume of isopropanol, reflecting the change in the hydration structure in aqueous solution, and that the isotropic Raman linewidth of isopropanol is determined essentially by hydrogen bonding as an inhomogeneous broadening mechanism, other factors such as the vibrational dephasing being of less significance.

Raman linewidth study of hydration structure of p-dioxane in aqueous solution

Abstract The isotropic linewidth of the CO stretching Raman line of p-dioxane at 835 cm −1 has been measured at a variety of concentration in aqueous solution and in nonpolar tetrachloroethylene solution. The hydration structure of p-dioxane in aqueous solution has been investigated by a comparison of the experimental results obtained here with those for t-butyl alcohol in the preceding study. As a result, the present data prefer to the hydrogen-bond model rather than the clathrate model, proposed for the p-dioxane-water system.

Mechanism of alternating copolymerization of methyl methacrylate with styrene in the presence of diethylaluminum chloride

AbstractA kinetic study of the propagation mechanism of the alternating copolymerization of styrene (St) with methyl methacrylate (MMA) in the presence of a complexing agent (diethylaluminum chloride, DEAC) in bulk and in tetrachloroethylene solutions at a molar ratio DEAC/MMA = 0.5 has been carried out. It has been shown that the copolymerization is a chain radical process characterized by a short active‐center lifetime, bimolecular termination, and high rate of chain transfer to the complexed MMA. A kinetic scheme has been proposed for the propagation mechanism of alternating copolymerization in the presence of a complexing agent not requiring independent measurements of the equilibrium constant of complexation. It has been found that spontaneous and UV‐initiated copolymerizations in the system have different mechanisms of initiation and a common mechanism of propagation. The propagation proceeds by addition of single monomers as well as donor‐acceptor complexes of the comonomers to the propagation radicals, with the first mechanism being predominant. Inclusion of the monomers in the complex leads to an increase of the St reactivity and to a decrease of the MMA reactivity in propagation to the corresponding macroradicals in comparison with the reactivity of the free monomers. A number of kinetic and statistical parameters of the propagation reaction have been calculated.

Kinetics of alternating copolymerization of styrene with methyl methacrylate in the presence of diethyl aluminium chloride

A kinetic study was made of alternating copolymerization of styrene with methyl methacrylate in the presence of diethyl aluminium chloride, initiated by UV exposure in bulk and in tetrachloroethylene solutions. Molar ratios of methyl methacrylate: styrene = 1·2; [diethyl aluminium chloride]:[methyl methacrylate] = 0.5. It was shown that the rate of copolymerization is proportional to the intensity of initiating UV exposure to 0·5. Copolymer molecular weight remains constant up to 20–25% conversion. The reaction order with overall monomer concentration is 1·5. The average life time of active centres τ=0·65±0·32 sec was measured using the rotating sector method. It was shown that molecular weights of the copolymers formed are practically independent of reaction rate for the conventional range of rates of initiation because of strong chain transfer to the monomer. The constant of chain transfer to the monomer was calculated C m=(2·3±0·2)×10 −3 mole/l/·sec. It was established that copolymerization of the styrene-methyl methacrylate-diethyl aluminium chloride system is a radical chain process, characterized by a short life time of active centres, bimolecular chain termination, high rate of propagation and hig rate of self-transfer.

Association constants of substituted 2-acetylthiophenes with phenol

The association constants (Kass) of a number of substituted 2-acetylthiophenes and 3-acetylthiophene with phenol in tetrachloroethylene solutions at 25, 50, and 80° were determined by IR spectroscopy. It is shown that acetylthiophenes are stronger proton acceptors than the corresponding acetophenones. The thermodynamic characteristics (ΔH and ΔS) of the association were calculated, and the presence of a compensation effect was established. It is shown on the basis of correlation of the Kass values by means of the Brown, Yukawa-Tsuno, and Swain-Lupton equations that the thiophene ring is a better transmitter of the effect of substituents than the benzene ring because of the increased conductivity of the conjugation effect.

Effect of conditions of crystallization on molecular relaxation in polypropylene

It was shown that annealing “Moplen” isotactic polypropylene (PP) granules at temperature of 433–443°K and remelting reduced T g. Samples slowly cooled from melt have lower T g than quenched samples. By the crystallization of PP from 1% tetrachloroethylene solution samples were obtained with a ‘shish-kebab’ structure, which are characterized by a very low intensity β-maximum of radiothermoluminescence. Annealing ‘shish-kebab’ specimens at 433–453°K produces an intense β-maximum near 210°K. After heating these specimens to 455°K or higher temperatures spherulitic PP samples are obtained for which the shape of light emission curve agrees with that of the light emission curve of initial PP granules heated under the same conditions. It was shown that storing annealed PP speciments with a spherulitic structure at room temperatures is accompanied by a gradual increase of T g. It was assumed that the main cause of variation of T g of PP during heat treatment and storate is the formation of micropores and stressed sections in the amorphous phase of PP.

Ring-chain tautomerism of substituted hydrazones

The products of the condensation of 2- (N- phenylhydraz ino)-, 2- (N- p-tolylhydraz ino)-, and 2-(N-p-nitrophen ylhydrazino)etha nols with acetaldehyde, acetone, and pinacone exist in tetrachloroethyl ene solution in the form of tautomeric mixtures of N-aryl-N-(2-hydr oxyethyl)hydrazones and 4-arylperhydro-l ,3,4-oxadiazines . For the case of the pinacone derivatives, it has been shown that the equilibrium concentration of the cyclic form rises with an increase in the electron-accepti ng nature of the substituent in the para position of the aromatic radical. The position of the equilibrium between the tautomeric 4-alkylperhydro- l,3,4-oxadiazine s and the corresponding N-alkyl-N-(2-hyd roxyethyl)hydraz ones depends fundamentally on the spatial requirements of the N-alkyl substituent [2, 3]. Continuing our investigation in this field, we have turned to a study of the structure of derivatives of/3-(N-arylhydr azino) alcohols. Interest in these derivatives was due to the fact that in this case it was possible to determine whether the position of the equilibrium was influenced by the polar effects of substituents on the nitrogen atom, i.e., substituents not bound directly to the reaction center. It is known that in similar ring-chain tautomeric systems - products of the condensation of substituted benzaldehydes of/3- and y-amino alcohols - the equilibrium is shifted in the direction of the cyclic form with a rise in the electron-accepto r capacity of the substituent in the aldehyde fragment [4-6[. 2- (N- Phenylhydrazino) - and 2- (N- p-tolylhydrazino) ethanols (I and lI) were obtained by the nitrosation of 2-(N-arylamino)e thanols [7] followed by the reduction of the nitrosamines with lithium tetrahydroaluminate. The reduction of these compounds with zinc dust in acid [8, 9] or weakly alkaline [10] media