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Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times.

Field sampling and testing were used to investigate the relationship between baseline geochemical and microbial community data and in situ reductive dechlorination rates at a site contaminated with trichloroethene (TCE) and carbon tetrachloride (CTET). Ten monitoring wells were selected to represent conditions along groundwater flow paths from the contaminant source zone to a wetlands groundwater discharge zone. Groundwater samples were analyzed for a suite of geochemical and microbial parameters; then push-pull tests with fluorinated reactive tracers were conducted in each well to measure in situ reductive dechlorination rates. No exogenous electron donors were added in these tests, as the goal was to assess in situ reductive dechlorination rates under natural attenuation conditions. Geochemical data provided preliminary evidence that reductive dechlorination of TCE and CTET was occurring at the site, and microbial data confirmed the presence of known dechlorinating organisms in groundwater. Push-pull tests were conducted using trichlorofluoroethene (TCFE) as a reactive tracer for TCE and, in one well, trichlorofluoromethane (TCFM) as a reactive tracer for CTET. Injected TCFE was transformed to cis- and trans-dichlorofluoroethene and chlorofluoroethene, and, in one test, injected TCFE was completely dechlorinated to fluoroethene (FE). In situ TCFE transformation rates ranged from less than 0.005 to 0.004/day. In the single well tested, injected TCFM was transformed in situ to dichlorofluoromethane and chlorofluoromethane; the TCFM transformation rate was estimated as 0.001/day. The results indicate that it is possible to use push-pull tests with reactive tracers to directly detect and quantify reductive dechlorination of chlorinated ethenes and ethanes under monitored natural attenuation conditions, which has not previously been demonstrated. Transformation rate estimates obtained with these techniques should improve the accuracy of contaminant transport modeling. © 2012 Wiley Periodicals, Inc.

The severely ozone‐depleting trichlorofluoromethane is still appearing in several recycling processes or industrial applications. A simple and selective supramolecular complex formation of per‐methylated α‐cyclodextrin (1) with the highly volatile trichlorofluoromethane (2) is reported. This interaction moreover leads to thermally stable crystals. Per‐methylated α‐cyclodextrin is successfully exploited as a reversible and selective adsorption material for liquid and airborne trichlorofluoromethane as well as an affinity material for the chemical sensing and detection of this particular volatile organic component.

The cover image depicts the hazard caused by chlorofluorocarbons such as CFC‐11, which are used, for example, as blowing agents for polyurethane foams, and the protective effect of the oligosaccharide, hexakis‐(2,3,6‐tri‐O‐methyl)‐α‐cyclodextrin, which is capable of binding CFC‐11 by supramolecular complexation and thus protecting the stratospheric ozone layer from the harmful trichlorofluoromethane. Further details can be found in article number 1800057 by Ralf Hellmann, Siegfried R. Waldvogel, and co‐workers.

A new general catalytic olefination reaction (COR) of aromatic and heteroaromatic aldehydes and ketones was applied to synthesise 2-chloro-2-fluorostyrenes. The two-stage procedure includes the transformation of carbonyl compounds into hydrazones followed by treatment with CFCl3 mediated by copper catalysis. Trichlorofluoromethane was used as a chlorofluoromethylene transfer reagent. The reaction proceeds stereoselectively and the target alkenes were obtained in high yield. A proposed mechanism for the reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Exposure of solutions of s-triazine in a trichlorofluoromethane matrix at 77 K to γ-radiation resulted in the formation of s-triazinyl radicals by deprotonation of the primary radical cations. The results indicate that neutral s-triazine molecules dissolve in an associated state in the Freon solvent. Copyright © 2001 John Wiley & Sons, Ltd.

Ozone depletion potential (ODP) represents the cumulative ozone depletion induced by a particular halocarbon relative to a reference gas (usually trichlorofluoromethane, CFC-11). We focus on ODP estimation for methyl bromide. Previous attempts at its estimation have assumed that components of the ODP equation are lognormally distributed. By considering a wide range of modeling scenarios, we show that this restriction (which is based on computational convenience rather than experimental evidence) has obscured the true uncertainty in the ODP value. Moreover, when publishing point estimates for the ODP value, previous authors have given either mean or median values. We submit that a more appropriate choice for a point estimate is the mode since the distribution of ODP is skewed and since the mode is by definition, the most likely value. For each modeling scenario considered, modal values are given. In general, we find these ODP point estimates are considerably lower than those published elsewhere.

A commercially available SRI gas chromatograph (model 9300B) has been adapted to enable the use of solid phase microextraction (SPME) as the sample preparation and introduction technique for fast GC separations in the field. SPME utilizes a small-diameter fused silica fiber coated with a polymeric stationary phase for extraction of organic analytes from aqueous or gaseous matrices. The analytes extracted are thermally desorbed in the injector of a gas chromatograph. Modifications to the instrument included a new injector and modifications to the PID detector. The injector enables very fast fiber heating rates (∼4000 °C/s), which produce narrow injection bands suitable for fast GC. Separation of BTEX (100 ppb each compound) within 15 s has been demonstrated with FID and PID detection. The precision of the results was very good. Separation of purgeables (trichlorofluoromethane, 1,1-dichloroethene, dichloromethane, 1,1-dichloroethane, trichloromethane, tetrachloromethane, trichloroethene, 1,2-dichloropropane, 2-chloroethyl vinyl ether, 1,1,2-trichloroethane, tetrachloroethene, dibromochloromethane, chlorobenzene; 200 ppb each compound) was accomplished in 2 min with good precision with the use of a dry electrolytic conductivity detector (DELCD). The instrument was tested in the field in the analysis of trichloroethylene in soil extracts. PID was used for detection because its dynamic range is better as compared to DELCD. Almost 500 samples were analyzed in 10 days without major problems. © 1997 John Wiley & Sons, Inc. Field Analyt Chem Technol 1: 277–284, 1997

A Penning ion source for volatile organic compounds is described. Design, operating conditions, and properties of the ions generated are reported. The source operates at pressures ranging from 10−5 to 10−3 mbar; a sensitivity of 1.4 × 10−4 A/mbar is achieved. Mass spectra of 4-methyl-2-pentanone, ethyl benzoatc, dimethyl sulfoxide, trichlorofluoromethane and 1,1,2-trichlorotrifluoroethane obtained at low discharge currents are almost identical with their corresponding electron impact spectra at 70 eV. Two different discharge modes, depending on pressure, were found. The average energy of the ions is proportional to the potential of the ion source (〈E〉 = 0.64U, energy given in eV). Multiply charged Ar ions, Arn+, up to n = 4, have been observed.

Following γ-radiolysis of dilute solutions of imines in trichlorofluoromethane at 77 K, EPR spectra of the corresponding radical cations were recorded. For PhCHNEt and PhCHNCHMe2 the primary 2A′ cations were formed, but in each case as a mixture of cations with different conformations of the alkyl group. The complex spectra were assigned with the aid of those for the deuteriated analogues PhCDNEt and PhCDNCHMe2. For Ph2CNEt, two cations differing by the confomation of the ethyl group were observed; for Ph2CNCHMe2, only a single conformer was evident. In an attempt to induce a σ/π‘crossover’, the compounds p-Cl–C6H4CHNBut and p-MeO–C6H4CHNBut were studied: the latter did indeed form a π-cation, while the former gave the normal 2A′ cation. The neopentyl derivatives PhCHNCH2But and Ph2CNCH2But gave only the distonic radical cations PhCH[graphic omitted]H–CH2C(Me2)CH2˙ and Ph2C[graphic omitted]H–CH2C(Me2)CH2˙, formed by an intramolecular hydrogen atom transfer. By studying the series of deuteriated compounds, PhCDNCH2CH2CH2CH3, PhCDNCD2CH2CH2CH3 and PhCHNCD2CH2CH2CH3, it is shown that, on radiolytically-induced single electron oxidation, PhCHNBu gives the distonic radical cation PhCH[graphic omitted]HCH2CH2ĊHCH3.

Catalytic oxidation can be an effecitve and economic alternative to thermal oxidation for the destruction of halogenated hydrocarbons (HHC) which are known to deplete stratospheric ozone. Existing oxidation catalysts, noble metal and metal oxides are expensive and can deactivate when treating pollutants containing halogens. Current operation of thermal and catalytic processes require downstream gas scrubbing to remove acidic by-products HCl and Cl2 as well as corrosion resistant materials of construction. In response to the need for a better treatment process, a catalyst—sorbent that simultaneously destroys the HHCs and captures the halogens is being developed, and our initial results are presented in this paper. In this catalyst—sorbent, copper and manganese oxides are supported on sodium carbonate. The metal oxides are responsible for catalyzing the oxidation reactions and sodium carbonate captures the chlorine by forming NaCl and releasing carbon dioxide. Powder X-ray diffraction results show a significant conversion of the carbonate occurs as chlorine is captured. X-ray photoelectron spectroscopy has verified that the change between fresh and used catalyst also occurs near the surface. Trichloroethylene (TCE), trichlorofluoromethane and toluene are shown to be completely converted at a space velocity of 6700 h−1, temperatures 250°–400°C, and feed concentrations 30–350 ppm of pollutants in moist air. A chlorine balance shows that more than 98% of the chlorine from converted TCE remains in the catalyst—sorbent. Comparisons of this catalyst with others in the literature show it is a viable catalyst for the treatment of low concentrations of air pollutants.

It was observed that the reaction of CFCl3 with thiophenoxide gave only 10% of the corresponding thioether. On the other hand, these thioethers could be prepared in excellent yield from diaryl disulfides and CFCl3 in the presence of sodium hydroxymethanesulfinate in aqueous DMF at 4 atm pressure of nitrogen. Dechlorination of the thioether (PhSCFCl2) with different reducing agents were studied. Most of the reducing agents eliminated both fluorine and chlorine functionalities or gave the hydrolyzed products. But its sulfone on treatment with Zinc in methanol gave monochlorofluoromethyl and fluoromethyl phenyl sulfone in good yields. Darzens reaction of these compounds was also studied.

The 19F solvent shifts of trichlorofluoromethane, fluorobenzene and methyl trifluoroacetate were measured with respect to an external reference in 48 solvents and solvent mixtures. The data were modelled using various linear and thermodynamic approaches. The models based only on the chemical composition of the solvent explain the results with a correlation coefficient of 0.95–0.96, corresponding to an r.m.s. value of 0.14–0.21 ppm. Including the refractivities improves the fit slightly in some cases.

The compound 1,1-dichloro--2,2,2-trifluoroethane (CFC-123) has been proposed as an industrial substitute for trichlorofluoromethane (CFC-11). The chemical destruction rates of CFC-123 by various processes is calculated here using a three-dimensional global model of the atmosphere, and it is confirmed that the chief sink of CFC-123 is destruction by OH radicals below 12 km, accounting for 88 percent of its loss. The calculated destruction rate is greatest in the equatorial region below 2 km. The calculated steady-state lifetime of CFC-123 is 1.5 years, much shorter than that of CFC-11, the destruction of which is largely confined to the stratosphere. For equal rates of CFC-123 and CFC-11 emission to the atmosphere, the molar content in the atmosphere and the injection rate of chlorine into the stratosphere are, respectively, 48 and 14 times greater for CFC-11 than for CFC-123 in steady state.

The minor neutral components present in a 1,2-propanediol-washed trichlorofluoromethane extract of a cider distillate have been examined by gas chromatography and gas chromatography-mass spectrometry. This led to the identification of ten alcohols, seven carbonyls, 52 esters and five other components, and to tentative evidence for the identity of a further 32 compounds. Fifty-five of these compounds have not previously been reported in ciders. Odour evaluation of the separated components as they were eluted from the gas chromatograph suggested that many of the esters contribute to the apple fruit character of this beverage.

Ethanol (95%) and glycerin were found to plasticize freeze-dried cubes of beef for reversible compression. Both are easily applied and plasticization appears to be rapid and effective. Appearance and texture of the reconstituted, compressed product compared favorably with that of noncompressed product and product plasticized by partial rehydration to 10% moisture; however, the glycerin and ethanol treatments gave a slight off-flavor. Vegetable oil and trichlorofluoromethane did not provide adequate plasticization. Polar liquids appear to be required for plasticization of dried beef for compression.

A model of the manufacture of rigid polyurethane foams by free rising is presented. The extent of cream and rise periods as well as the amount of blowing agent necessary to give the desired foam density are theoretically predicted. The rate of blowing agent evaporation is calculated from an experimental boiling temperature vs. composition curve. Experimental runs were carried out with a formulation consisting of a polymeric isocyanate, a polyether polyol based on sorbitol, a silicone-polyol block-copolymer as surfactant, dibutyltin dilaurate as catalyst, and trichlorofluoromethane as blowing agent. Mixing was performed in situ in the mold using a commercial foaming machine. Experimental results gave a satisfactory agreement with model predictions. A diagram containing all the relevant information may be theoretically built and used for the selection of adequate operating parameters for a given formulation.

Some of the propellants used in aerosols have the potential to produce bronchoconstriction, reduce pulmonary compliance, depress respiratory minute volume, reduce mean blood pressure, and accelerate heart rate. The most toxic propellant is trichlorofluoromethane (FC 11), which exerts all of these undesired effects except bronchoconstriction and a reduction of pulmonary compliance. Coincidentally, FC 11 is the most widely used low-pressure propellant. The least toxic propellant is difluoroethane (FC 152a), which is rarely used in aerosols. Additional investigation is needed to determine which toxic effects are the important ones in deciding on the future use of these propellants. It will also be necessary to examine the influence of pathological lesions in the heart and lung on the sensitivity of these organs to the various aerosols. 5 references, 2 figures, 1 table.

Separating funnel extractions of ethanolic solutions of esters and alcohols using pentane showed preferential removal of esters. Trichlorofluoromethane was less selective and ether showed no selectivity at all. The amounts of both alcohols and esters extracted by an equal volume of pentane decreased with increase in ethanol concentration, this decrease being most marked for alcohols. Increase in the amounts of components extracted by a fixed volume of solvent would, however, generally be expected from concentrating ethanolic solutions. Similar extractions, using pentane showed continuous extractors generally to be more efficient. Recoveries, and the ability to extract esters selectively in the presence of alcohols, were dependent not only on the ethanol concentration but also on the degree of purification imposed on the recycling solvent. The selective nature of pentane was lost in the process of increasing efficiency.

NMR evidence is presented for complex formation between nitromethane and sulfur trioxide in thrichlorofluoromethane as solvent according to . In addition, kinetic evidence for complex formation between nitrobenzene and sulfur trioxide in trichlorofluoromethane was obtained from sulfonation studies of that system.

Liquid polyols consisting ofthreo-orerythro-9,10-dihydroxystearic acid previously reacted with 1, 2, 4, 6 and 8 moles of propylene oxide were adjusted with triisopropanolamine to equivalent weight 100. Using trichlorofluoromethane as blowing agent and triethylenediamine as catalyst, the adjusted polyols were foamed by reaction with a prepolymer made from oxypropylated sorbitol and tolylene diisocyanate.

The analysis of minor volatile constituents in alcoholic beverages presents difficulties because of the relatively high concentrations of a few higher alcohols. Volatile components were extracted from a freshly prepared Riesling white table wine using the solvent trichlorofluoromethane, and analysed by combined gas chromatography-mass spectrometry. The higher alcohols were then removed from the trichlorofluoromethane extracts by treatment with propylene glycol, and the remaining components, mainly esters, were concentrated further. The final concentrate, whose volume represented about 0·01% of that of the wine, was analysed again, and in all, over 40 components were identified. Some of the esters observed, including the mixed ester, 3-methylbutyl ethyl succinate, have not been reported previously.

The ESR spectra of the radical cation of dimethyl ether, (CH/sub 3/)/sub 2/O/sup +/, which is isoelectronic with the dimethyl aminyl radical, (CH/sub 3/)/sub 2/N, are reported. The first- and second-derivative spectra were obtained from a ..gamma..-irradiated solid solution of dimethyl ether in trichlorofluoromethane at 97/sup 0/K. Analysis of the spectrum is discussed, and assignment of the spectrum to the oxygen-centered radical cation of dimethyl ether is felt to be unambiguous. (BLM)

Cation radicals of butene‐1, trans and cis butene‐2, isobutene, tetramethylethylene, cyclopentene, cyclohexene, butadiene, 1,3‐pentadiene, cyclopentadiene, 1,3‐ and 1,4‐cyclohexadienes have been produced mostly for the first time in γ‐irradiated frozen matrix of trichlorofluoromethane at 77 K. Well resolved ESR spectra at 77 K or at 130–155 K permit the determination of proton hyperfine coupling constants. Large hyperfine coupling constants of methylene and methyl protons adjacent to π electron systems indicate an extensive hyperconjugation in the cations. The following photoisomerizations are found: butene‐1+→butene‐2+, cyclopentene+→1,3‐pentadiene+, 1,4‐cyclohexadiene+→ 1,3‐cyclohexadiene+, 1,3‐cyclohexadiene+→1,3,5‐hexatriene+. The nonplanar cations of cyclopentene and 1,3‐cyclohexadiene undergo puckering motion in a limitedly warmed matrix. In the warmed matrix, where diffusions of the cation radicals toward unreacted hydrocarbon molecules proceed slowly, proton transfer reactions are induced. Decisiv...

The molecular structure and mean amplitudes of CC1 3 F have been determined by gas electron diffraction. General quadratic force constants have been derived from vibrational frequencies, Coriolis coupling constents, a centrifugal distortion constant and mean amplitudes. The zero-point average structure obtained by a joint analysis of electron diffraction and microwave spectroscopic data has been compared with structures given by molecular mechanics and ab initio calculations.

The microwave and millimetre-wave spectra of CF 35 Cl 3 have been measured in the ground and first excited doubly degenerate ( E ) vibrational states. Rotational, centrifugal distortion, and quadrupole parameters were obtained for both states. In the E state, strong l -resonance was observed, enabling some rotation-vibration parameters to be accurately determined. In addition, there was a splitting of the ( kl − 1) = ± 1 lines due to the asymmetry of the individual quadrupole coupling tensors with respect to the principal inertial axes.

Bridgehead carboxylic acids can be converted into their corresponding chlorides very efficiently under Barton halodecarboxylation conditions. Addition of the acid chloride to a suspension of the sodium salt of 1-hydroxypyridine-2(1H)- thione in boiling carbon tetrachloride under irradiation leads to excellent yields of the bridgehead chloride via the derived thiohydroxamic ester. In a useful modification for the synthesis of volatile halides, either 1,1,1-trichloro-2,2,2-trifluoroethane or trichlorofluoromethane can be employed as substitute solvents. It is found that the Barton procedure is applicable to the synthesis of labile bromides such as 1-bromobicyclo[3.1.1]heptane for which the usual Hunsdiecker reaction fails. For these, and other brominations , 2-bromo-2-chloro-1,1,1-trifluoroethane ('Halothane') is shown to function as an efficient solvent/bromine atom donor.

CCl 4 , HCCl 3 et FCCl 3 donnent l'ion hydrogenocarbonate; C 6 H 5 CCl 3 donne un melange de C 6 H 5 C(O)OO − et C 6 H 5 C(O)O − ; CF 3 CCl 3 et OHCH 2 CCl 3 donnent les anions carboxylates correspondants RC(O)O − ; et p,p'-DDT donne son produit de dechlorhydratation qui reagit avec O 2 − pour donner (p-ClC 6 H 4 ) 2 C=O