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It is an urgent problem to explore the explosion characteristics and self-suppression mechanism of R404A refrigerant, because R404A refrigerant is widely used in daily life, the combustion and explosion mechanism of it is more complex and the related explosion accidents gradually appear. Based on theoretical analysis and experimental research methods, the explosion characteristics of R404A refrigerant with the main components of trifluoroethane (C2H3F3), tetrafluoroethane (C2H2F4), and pentafluoroethane (C2HF5) under an oxygen-enriched condition under normal temperature and atmospheric pressure were revealed. The flammability limit, critical oxygen content and explosion characteristic parameters of R404A refrigerant under different oxygen content were further revealed. The evolution law of explosion parameters of R404A refrigerant in an atmosphere with different oxygen and nitrogen ratios was obtained, and the self-suppression mechanism of R404A refrigerant was explored. The results can provide some guidance for the safe use of refrigerants and the establishment of relevant industry standards.

Conventional lubricants decrease the wear and friction between rolling and sliding surfaces while raising environmental concerns. The thermodynamics and flow behavior of lubricants that contain environmentally friendly additives such as ionic liquids (ILs) are of interest to industries that require lubricants with superior tribological properties. Noncorrosive ILs are promising additives for conventional oil that not only further decrease friction but also create a less hazardous alternative to existing lubricants. In this study, thermodynamics, dynamics, and rheology of IL-oil mixtures are studied by using atomistically detailed molecular dynamics (MD) simulations. A combination of different imidazolium-based cations with linear ([CnC1Im]+[NTf2]-, n = 3, 7) and branched chains ([(n - 2)mCn-1C1Im]+, n = 3, 7) and bis[(trifluoroethane)sulfonyl]imide ([NTf2]-) anion are selected as the model IL which is suspended in bulk hexadecane. The effects of IL content, architecture, size of cation, and temperature are examined on the thermorheological and dynamics of the IL-hexadecane mixture. At equilibrium, ILs self-assemble and create clusters with different shapes and sizes and affect the dynamics and rheology of the mixtures. Mixtures show a significant deviation from ideal solutions behavior. Shear and extensional rheology simulations show that mixtures mostly show Newtonian behaviors at low and moderate rates which is followed by a weak thinning behavior at high rates. It is shown that a small addition of ILs (x=2% mole fraction) to oil significantly increases both the shear and extensional viscosity of the mixture by a factor of 3.

An unexpected substitution reaction of HCFC-123 with phenolates is reported. During the reaction, fluorine atoms in HCFC-123 are removed one by one in the presence of phenolates.

The volumetric and thermodynamic properties of fluorinated ethers such as trifluoromethyl-1-H-pentafluoroethylether, F-oxetane, 2-H-heptafluoropropane, pentafluorodimethylether, F-methyl methyl ether, perfluorodoxolane, pentafluorodimethoxymethane and HFCs such as trifluoroethane, heptafluoropropane, difluoroethane, pentafluoropropane, ethyl fluoride as alternatives to replace R134a have been predicted using SRK equation of state over the temperature range from − 25 °C to + 55 °C. Theoretical analysis is carried out using ten-point vapour compression cycle for screening of candidate refrigerants. The results of analysis have been used to ascertain standard refrigeration parameters in respect of each of the candidate refrigerants. The analysis indicates that the performances of difluoroethane, ethyl fluoride, pentafluorodimethylether and F-oxetane are better than that of R134a.

Remediation of electronic gas CF4 using commercially available technologies results in another kind of greenhouse gas and corrosive side products. This investigation aimed to develop CF4 removal at room temperature with formation of useful product by attempting an electrogenerated Cu1+[Ni2+(CN)4]1− mediator. The initial electrolysis of the bimetallic complex at the anodized Ti cathode demonstrated Cu1+[Ni2+(CN)4]1− formation, which was confirmed by additional electron spin resonance results. The degradation of CF4 followed mediated electrochemical reduction by electrogenerated Cu1+[Ni2+(CN)4]1−. The removal efficiency of CF4 of 95% was achieved by this electroscrubbing process at room temperature. The spectral results of online and offline Fourier transform infrared analyzer, either in gas or in solution phase, demonstrated that the product formed during the removal of CF4 by electrogenerated Cu1+[Ni2+(CN)4]1− by electroscrubbing was ethanol (CH3CH2OH), with a small amount of trifluoroethane (CF3CH3) intermediate.

Copper-mediated reaction of terminal 1,3-diynes with 1,1-dichloro-2,2,2-trifluoroethane (CF 3 CHCl 2 ) using ethanolamine as ligand gave trifluoroethylated unsymmetrical 1,3-diynes in moderate to good yields. The reaction were carried out under mild conditions, and were easy to operate. Aryl groups with weak electron-withdrawing group or electron-donating group, and alkyl substitutents at terminal 1,3-diynes were tolerated. Synthesis of a trifluoroethylated conjugated triyne by using this method was demonstrated. Further transformation of the trifluoroethylated unsymmetrical 1,3-diyne to provide trifluoroethyl-substituted 1,2,3-triazole and isoxazole as application examples were successfully realized.

Cu-promoted reactions of 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) with dialkyl phosphonates produced dialkyl (2,2,2-trifluoroethyl)phosphonates efficiently under mild conditions by successively activating the two inert C–Cl bonds in HCFC-123. These reactions can be efficiently carried out on a >30 g scale with moderate to good yields.

Ordered Cr2O3 nanorods (Cr2O3-R) and Cr2O3 nanoparticles (Cr2O3-P) were prepared by a hard template method with SBA-15 and a deposition–precipitation method, respectively. These catalysts were tested for the fluorination of 2-chloro-1,1,1-trifluoroethane (HCFC-133a) to synthesize 1,1,1,2-tetrafluoroethane (HFC-134a). It was found that both catalysts were very selective, with a HFC-134a selectivity of 98 %. However, the Cr2O3-R catalyst had an area specific reaction rate of 0.012 μmol m−2 s−1 at 320 °C, which was much higher than that on the Cr2O3-P (0.005 μmol m−2 s−1). The enhanced activity of the Cr2O3-R was attributed to its higher content of Cr(VI) species compared to that in the Cr2O3-P, which was evidenced by the hydrogen temperature-programmed reduction and X-ray photoelectron spectroscopy results. Besides, the Cr2O3-R catalyst had a higher surface acid density (0.076 mmol m−2) than the Cr2O3-P (0.068 mmol m−2), which could be another reason for its better performance.

Rh(I)-Catalyzed synthesis of 1,1-difluoro-2,2-diarylalkenes from trifluoromethylketone N-tosylhydrazones and arylboronates is presented in this communication. This new synthetic method is based on the Rh(I)-carbene migratory insertion followed by β-fluoride elimination. In one particular case the protonation occurs instead of β-fluoride elimination, affording 2,2-diaryl trifluoroethane product.

The title reaction provides a novel utilization of ozone-depleting/global-warming HCFCs as a new carbon–carbon cross-coupling model of various terminal alkynes by activating two inert C–Cl bonds successively. This protocol provided trifluoroethylated alkynes efficiently under mild reaction conditions and was compatible with a broad range of functional groups. An example of the synthesis of a terbinafine analogue is shown. Some mechanistic experiments including deuterated reagents and radical/SET inhibitors are described.

Pd-catalyzed fluoroarylation of gem-difluoroalkenes with aryl halides is disclosed. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derived from the nucleophilic addition of silver fluoride onto gem-difluoroalkenens, the present strategy bypasses the employment of strong base, thus enabling a mild and general synthetic protocol for the ready access of non-symmetric α,α-disubstituted trifluoroethane derivatives.

We report a facile method for the adsorption separation of fluorocarbon blends containing tetrafluoroethane (R134a), pentafluoroethane (R125) and trifluoroethane (R143a) refrigerants into their pure components using commercial 13X zeolite and pore-size modified 5A zeolite under ambient condition. Based on the measured R134a, R125, and R143a pure gas equilibrium adsorption isotherms, the adsorption capacity varies in the order of R134a > R143a > R125 on 13X zeolite. The mixed gas breakthrough experiments reveal that 13X zeolite selectively adsorbs R134a over R125 and R143a. By running two adsorption cycles, it is possible to obtain R134a with ultrahigh purity. Furthermore, through chemical modification of tetraethyl orthosilicate (TEOS), the pore size of 5A zeolite could be successfully narrowed to the extent to just adsorb R125 while excluding R143a. The modified 5A zeolite was utilized to separate refrigerant mixtures containing R125 and R143a into their pure components. © 2017 American Institute of Chemical Engineers AIChE J, 64: 640–648, 2018

Tp'Rh(PMe3)(CH3)H was synthesized as a precursor to produce the coordinatively unsaturated fragment [Tp'Rh(PMe3)], which reacts with benzene, mesitylene, 3,3-dimethyl-1-butene, 2-methoxy-2-methylpropane, 2-butyne, acetone, pentane, cyclopentane, trifluoroethane, fluoromethane, dimethyl ether, and difluoromethane at ambient temperature to give only one product in almost quantitative yield in each case. All of the complexes Tp'Rh(PMe3)(R)H were characterized by NMR spectroscopy, and their halogenated derivatives were fully characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. The active species [Tp'Rh(PMe3)] was also able to activate the alkynyl C-H bond of terminal alkynes to give activation products of the type Tp'Rh(PMe3)(C≡CR)H (R = t-Bu, SiMe3, hexyl, CF3, Ph, p-MeOC6H4, and p-CF3C6H4). The measured relative rhodium-carbon bond strengths display two linear correlations with the corresponding carbon-hydrogen bond strengths, giving a slope of 1.54 for α-unsubstituted hydrocarbons and a slope of 1.71 for substrates with α-substitution. Similar trends of energy correlations were established by DFT calculated metal-carbon bond strengths for the same groups of substrates.

The title reaction provides a novel utilization of ozone-depleting/global-warming HCFCs as a new carbon–carbon cross-coupling model of various terminal alkynes by activating two inert C–Cl bonds successively. This protocol provided trifluoroethylated alkynes efficiently under mild reaction conditions and was compatible with a broad range of functional groups. An example of the synthesis of a terbinafine analogue is shown. Some mechanistic experiments including deuterated reagents and radical/SET inhibitors are described.

The absolute configuration of the title acid 2 has been determined to be S by X-ray crystallography. Thus, decarboxylation of 2 produces ( S )-(+)-halothane with 99% retention of configuration. This behavior is compared to other stereoselective decarboxylation reactions of α-haloacids from the literature that also gave high degrees of retention of configuration when in the form of their quaternary ammonium salts, which contain one proton. The proton of the ammonium salt is necessary in order to protonate the anionic intermediate formed from decarboxylation. In the absence of this relatively acidic proton, we had previously found that using triethylene glycol (TEG) as both the solvent and proton source for the decarboxylation reaction of acid 2 caused poor stereoselectivity. This was in contrast to 1,2,2,2-tetrafluoro-1-methoxypropionic acid 6 , which showed a high degree of retention of configuration in TEG. In order to rationalize this differing behavior, we report DFT studies at PCM-B3LYP/6-31++G ∗∗ level of theory (the results were additionally confirmed with 6-311++G ∗∗ and aug-cc-pVDZ basis sets). The energy barrier to inversion of configuration of the anionic reaction intermediate 11 of acid 2 is 10.23 kcal/mol. However, we find that the anionic intermediate 10 from acid 6 would rather undergo β-elimination instead of inversion of configuration. Thus the planar transition state required for inversion of configuration is never reached, regardless of the rate of proton transfer to the anion.

This review provides an overview of several synthetic applications of the first fluorinated anaestetic, 1-bromo-1-chloro-2,2,2-trifluoroethane, leading to convenient preparation of numerous fluorine, and particularly, CF 3 group containing compounds via organometallic (Mg, Zn) and free radical “sulphinatodehalogenation” reactions.

The robust and efficient procedure is presented to calculate the transport properties, especially thermal conductivity coefficients, for gaseous state of difluoromethane (R32), pentafluoroethane (R125), 1, 1, 1, 2 tetrafluoroethane (R134a), 1, 1, 1 trifluoroethane (R143a) and 1, 1 difluoroethane (R152a) at zero density. The McLinden et al.'s1 approach of the extended corresponding states has been used for calculating the contribution of molecular degree of freedom to the thermal conductivity of these refrigerants. The Lennard–Jones 12-6 (LJ 12-6) potential energy function is used as the initial model potential required by the technique. The interaction potential energies from the inversion procedure reproduce the thermal conductivity coefficients commensurate to the best measurements.

This work presents experimental data of vapor−liquid phase behavior in the binary system of trifluoroethane (HFC-143a) + ethyl fluoride (HFC-161) with a single-phase circulation over the temperature range (253.15 to 303.15) K. The correlated results of the vapor−liquid equilibrium data with the Peng−Robinson (PR) equation of state (EoS), combined with the first Modified Huron−Vidal (MHV1) mixing rule and Wilson model, are presented. It is shown that there is a good agreement between the correlated results and the experimental data. The average and maximum absolute derivations of vapor mole fraction are within 0.0209 and 0.0437, respectively, and the average and maximum relative derivations of pressure are within 1.14 % and 2.88 %, respectively. In addition, from the correlation results, it is revealed that there is no azeotrope in the binary system, and the system exhibits from slightly negative deviations to slightly positive deviations when the temperature increases.

A new aromatic diamine, 1,1-bis(4-aminophenyl)-1-{4′-bis(4″-bromophenyl)amino}phenyl-2,2,2-trifluoroethane, is synthesized. Its interaction with various dianhydrides of aromatic carboxylic acids via high-temperature polycondensation yields a number of new functionalized poly(imides) combining high thermal and mechanical characteristics with solubility in organic solvents. The values of Tg vary from 208 to 230°C, and temperatures corresponding to 10% weight loss fall within the intervals 330–370 and 550–660°C (in air and argon, respectively). Spectroelectrochemical characteristics of poly(imides) are studied by cyclic voltammetry and UV-VIS spectrometry. Poly(imides) exhibit high reversible stability of electrochromic properties, and their color changes from colorless (the neutral form) to green (the oxidized form) as the applied potential is varied from 0 to 1.25 V.

A detailed reaction mechanism is developed and used to model experimental data on the pyrolysis of CHF 3 and the non-oxidative gas-phase reaction of CHF 3 with CH 4 in an alumina tube reactor at temperatures between 873 and 1173 K and at atmospheric pressure. It was found that CHF 3 can be converted into C 2F 4 during pyrolysis and CH 2=CF 2 via reaction with CH 4. Other products generated include C 3F 6, CH 2F 2, C 2H 3F, C 2HF 3, C 2H 6, C 2H 2 and CHF 2CHF 2. The rate of CHF 3 decomposition can be expressed as 5.2×10 13[s -1]e -295[kJmol -1]/RT. During the pyrolysis of CHF 3 and in the reaction of CHF 3 with CH 4, the initial steps in the reaction involve the decomposition of CHF 3 and subsequent formation of CF 2 difluorocarbene radical and HF. It is proposed that CH 4 is activated by a series of chain reactions, initiated by H radicals. The NIST HFC and GRI-Mech mechanisms, with minor modifications, are able to obtain satisfactory agreement between modelling results and experimental data. With these modelling analyses, the reactions leading to the formation of major and minor products are fully elucidated.

A novel aromatic diamine, 1,1-bis(4-amino-3,5-dimethylphenyl)-1-(3,4,5-trifluorophenyl)-2,2,2-trifluoroethane, containing a pendant polyfluorinated phenyl group, a trifluoromethyl group, and methyl groups ortho-substituted to the amino groups in the structure was synthesized and characterized. The diamine was polymerized with several aromatic dianhydrides, including 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, and 4,4′-hexafluoroisopropylidene diphthalic anhydride, via a high-temperature one-step procedure to afford four polyimides (PIs) with inherent viscosities of 0.47–0.70 dL/g. The PIs exhibited excellent solubilities in a variety of organic solvents. They were soluble not only in polar aprotic solvents but in many common solvents, such as cyclopentanone, tetrahydrofuran, and even toluene at room temperature. The tough and flexible PI films cast from the PI solutions exhibited good thermal stabilities and acceptable tensile properties. The glass-transition temperatures were in the range 312–365°C, and the 5% weight loss temperatures were all higher than 480°C in nitrogen. The films had tensile strengths in the range 76–99 MPa, tensile moduli of 2.2–2.8 GPa, and elongations at break of 5–8%. In addition, the PI films exhibited excellent transparency in the visible light region with cutoff wavelength as low as 302 nm and transmittance higher than 88% at the wavelength of 450 nm. The PI films showed low dielectric constants ranging from 2.50–2.68 and low moisture absorptions of less than 0.56%. The good combined properties of the PIs mainly resulted from the synergic effects of the different substituents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A novel fluorinated aromatic diamine 1,1′-bis(4-aminophenyl)-1-(3-trifluoromethylphenyl)-2,2,2-trifluoroethane (6FDAM) was synthesized in a simple procedure, which was then employed to prepare a series of fluorinated polyimides with commercial aromatic dianhydrides, such as pyromellitic dianhydride (PMDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane (6FDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4′-oxydiphthalic anhydride (ODPA). The polyimides exhibited good solubility in strong dipolar solvents such as NMP, DMAc, DMF and m-cresol as well as some of low boiling point organic solvents of THF and CHCl3, etc. Experimental results indicated the polyimides possessed low moisture adsorptions of 0.42–0.95%, low dielectric constant of 2.71–2.95 at 1 MHz, high dielectric strength of 92.0–122.6 kV/mm and good optical transparency with cutoff wavelengths of UV–vis at 330–375 nm. The polyimides also exhibited good mechanical properties as well as excellent thermal and thermo-oxidative stability. The fluorinated polyimides possessed better solubility, lower dielectric constant and water adsorption as well as higher optical transparency than the representative non-fluorinated polyimide derived from PMDA and 4,4′-oxydianiline (ODA).

Synthesis and Characterization of Novel Trifunctional Fluorine Containing Epoxy Resins Based on 1,1,1-Tris(2,3-epoxypropoxyphenyl)-2,2,2-trifluoroethane

Binary vapor-liquid equilibrium data were measured for the 1,1,1 -trifluoroethane (HFC-143a) + n-butane (HC-600) system at temperatures from (313.15 to 363.15) K. This experiment was carried out with a circulating-type apparatus with online gas chromatography. The experimental data were correlated well by Peng-Robinson-Stryjek-Vera equation of state with the Wong-Sandler mixing rules. The average absolute deviation of pressure and vapor composition between the measured data and the correlation was below 0.98 % and 0.0128, respectively.

In adsorption refrigeration, one of the key factors is the choice of the working pair. Therefore, the adsorption and desorption equilibrium data are very useful for designers and also for the analysis of the thermodynamic performance. In this paper, R-123 (2,2-dichloro- 1,1,1 -trifluoroethane) refrigerant with activated carbon adsorption cooling working pair is investigated. The adsorption is carried out with a thermogravimetric balance, and the equilibrium data are obtained. The Dubinin-Astakhov modified model is used to calculate the adsorption equilibrium parameters. The maximum adsorption capacity is obtained. The standard estimate error (SEE) between the experiment and the model result is evaluated. The results give a good agreement with the experiment data. The influence of the heterogeneity coefficient n to the adsorption capacity is presented. Desorption also is carried out to calculate the thermodynamic performance (refrigeration capacity) at different regeneration temperatures.

A novel fluorinated epoxy resin, 1,1-bis(4-glycidylesterphenyl)-1-(3′-trifluoromethylphenyl)-2,2,2-trifluoroethane (BGTF), was synthesized through a four-step procedure, which was then cured with hexahydro-4-methylphthalic anhydride (HMPA) and 4,4′-diaminodiphenyl-methane (DDM). As comparison, a commercial available epoxy resin, bisphenol A diglycidyl ether (BADGE), cured with the same curing agents was also investigated. We found that the BGTF gave the exothermic starting temperature lower than BADGE no mater what kind of curing agents applied, implying the reactivity of the former is higher than the latter. The fully cured fluorinated BGTF epoxy resins have good thermal stability with glass transition temperature of 170–175 °C and thermal decomposition temperature at 5% weight loss of 370–382 °C in nitrogen. The fluorinated BGTF epoxy resins also showed the mechanical properties as good as the commercial BADGE epoxy resins. The cured BGTF epoxy resins exhibited improved dielectric properties as compared with the BADGE epoxy resins with the dielectric constants and the dissipation factors lower than 3.3 and dissipation 2.8 × 10−3, respectively, which is related to the low polarizability of the C–F bond and the large free volume of CF3 groups in the polymer. The BGTF epoxy resins also gave low water absorption because of the existence of hydrophobic fluorine atom.

A novel trifluoromethyl-substituted bis(ether amine) monomer, 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane, was synthesized that led to a series of novel fluorinated polyimides via chemical imidization route when reacted with various commercially available aromatic tetracarboxylic dianhydrides. These polyimides were highly soluble in a variety of organic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, and most of them could afford transparent, low-colored, and tough films. These polyimides exhibited glass-transition temperatures (Tgs) of 227–269 °C and showed no significant decomposition below 500 °C under either nitrogen or air atmosphere. These polyimides had low dielectric constants of 2.87–3.17 at 10 kHz, low water uptake of 0.13%–0.58%, and an ultraviolet-visible absorption cutoff wavelength at 364–410 nm. For a comparative study, a series of analogous polyimides based on 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane were also prepared and characterized.

Hydrolysis studies of derivatives of molybdocene dichloride in which the two chloride ligands were replaced by 3,5-bis(trifluoromethyl)thiophenol, 3,5-bis(trifluoromethyl)benzyl thiol, and 2,2,2-trifluoroethane thiol ligands confirmed that the electron-withdrawing groups affect the lability of the Mo−S bonds and promote slow generation of the putative biologically active species “Cp2Mo2+”; the trifluoroethane thiol derivative underwent 50% hydrolysis in 14 h in 10% D2O/DMSO-d6. The structure of molybdocene bis(S-3,5-bis(trifluoromethyl)benzyl thiol) was confirmed by X-ray crystal structure analysis.

A novel fluorinated aromatic diamine, 1,1-bis(4-amino-3,5-dimethyl-phenyl)-1-(3,5-ditrifluoromethylphenyl)-2,2,2-trifluoroethane (9FMA), was synthesized by the coupling reaction of 3',5'-ditrifluoromethyl-2,2,2-trifluoroacetophenone with 2,6-dimethylaniline under the catalysis of 2,6-dimethylaniline hydrochloride. A series of fluorinated aromatic polyimides were synthesized from 9FMA and various aromatic dianhydrides, including pyromellitic dianhydride, 3,3'4,4'-biphenyl tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and 4,4'-hexafluoroisopropylidene diphthalic anhydride, via a high-temperature, one-stage imidization process. The inherent viscosities of the polyimides ranged from 0.37 to 0.74 dL/g. All the polyimides were quickly soluble in many low-boiling-point organic solvents such as tetrahydrofuran, chloroform, and acetone as well as some polar organic solvents such as N-methyl-2-pyrrolidinone, N,N'-dimethylacetamide, and N,N'-dimethylformamide. Freestanding fluorinated polyimide films could be prepared and exhibited good thermal stability with glass-transition temperatures of 298-334 °C and outstanding mechanical properties with tensile strengths of 69-102 MPa and elongations at break of 3.3-9.9%. Moreover, the polyimide films possessed low dielectric constants of 2.70-3.09 and low moisture absorption (

A novel fluorinated aromatic diamine monomer, 1,1-bis[4-(4′-aminophenoxy)phenyl]-1-[3″,5″-bis(trifluoromethyl)phenyl]-2,2,2-trifluoroethane(9FTPBA), was synthesized by coupling 3′,5′-bis(trifluoromethyl)-2,2,2-trifluoroacetophenone with 4-nitrophenyl phenyl ether under the catalysis of trifluoromethanesulfonic acid, followed reduced by reductive iron and hydrochloric acid. A series of new fluorine-containing polyimides having inherent viscosities of 0.96–1.23 dl/g was synthesized from the novel diamine with various commercially available aromatic dianhydrides using a standard two-stage process with thermal imidization and chemical imidization of poly(amic acid) films. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m -cresol, as well as some of low boiling point organic solvents such as chloroform and acetone. The polymer films have good thermal stability with the glass transition temperature of 223–225 °C, the temperature at 5% weight loss of 535–568 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 68–89 MPa, initial moduli of 2.14–2.19 GPa, and elongations at breakage of 3.2–10.5%.

A new series of fluorine-containing polyarylates were synthesized by interfacial or high-temperature solution polymerization of 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane with six aromatic diacyl chlorides. These polyarylates had inherent viscosities ranging from 0.47 to 1.37 dl/g that corresponded to weight-average and number-average molecular weights (by gel permeation chromatography) of 35,800–72,400 and 30,700–67,700, respectively. All polymers were highly soluble in a variety of solvents, and could afford tough, transparent, and colorless films via solution casting. The glass-transition temperatures of the polymers ranged from 209 to 271 °C. All of them did not show significant decomposition below 450 °C in both nitrogen and air atmospheres.

Sodium dithionite effectively promotes the addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to the exocyclic double bond of β-pinene. The reaction proceeded in an MeCN/H 2 O system to give almost quantitatively a 1:1 mixture of diastereoisomers of 4-(2-bromoisopropyl)-1-(2-chloro-3,3,3-trifluoropropyl)-cyclohexene ( 1 ). Dehydrobromination of 1 with pyridine gave a mixture of regioisomeric dienes 2 and 3 , while treatment with DBU at elevated temperature resulted in total dehydrohalogenation to give trienes 4 and 5 . Reduction of 1 with Bu 3 SnH gave 1-(2-chloro-3,3,3-trifluoropropyl)-4-(isopropyl)cyclohexene ( 6 ) which on dehydrochlorination with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) afforded conjugated diene, 4-isopropyl-1-( trans -3,3,3-trifluoropropenyl)-cyclohexene ( 7 ), with 50% overall yield. All the transformations proceeded with the retention of configuration at the carbon atom C-4 and the final compound 7 exhibited high optical activity.

We report a shock-tube, laser-schlieren investigation of the molecular dissociation of the title trifluoroethane, CF 3 CH 3 → CH 2 CF 2 + HF, over very high temperatures, 1600-2400 K, and a wide range of sub-atmospheric pressures, 15-550 Torr. The density gradients are well fit by a simple two-reaction mechanism and accurate dissociation rates obtained. The results are compared with a k ∞ calculated from a G3 TS for this molecular elimination, which is a superb fit to the available lower-T data and a reliable extrapolation of k ∞ to high temperatures. The derived rate constants show a very deep falloff from this extrapolation but surprisingly little variation with pressure. This peculiarity is so severe that RRKM calculations dramatically fail to account for the behavior. The dissociation seems to be a clear example of an intrinsic non-RRKM process (nonstatistical dissociation). This conclusion is strongly supported by the observation of double vibrational relaxation at both dissociating and nondissociating temperatures, an unambiguous demonstration of slow IVR. Using a simple model with division into two groups of states, the deep falloff is found to be consistent with a rate-controlling slow IVR, not with low collision efficiency. The model suggests an IVR rate of ∼10 8 s - 1 for dissociation energies.

Sodium dithionite initiated reactions of 1-bromo-1-chloro-2,2,2-trifluoroethane (1) with methyl and trimethylsilyl ethers of cyclopentanone and cyclohexanone enols (2a–d) in a MeCN/H2O system were investigated. 2-(2,2,2-Trifluoroethylidene)cyclopentanone (4a) and 2-(2,2,2-trifluoroethylidene)-cyclohexanone (4b), respectively, were obtained as the main products and isolated in reasonable yields. The reaction with a 1:1 mixture of 5- and 3-methyl substituted 1-methoxycyclohexenes, 2e and 2f, revealed strong influence of steric hindrance on the reaction rate; a mixture of 2-(2,2,2-trifluoroethylidene)-5-methylcyclohexanone (6) and 2-(2,2,2-trifluoroethylidene)-3-methylcyclohexanone (7) in a 9:1 ratio was formed. Ketones 4a and 4b were reduced to the corresponding alcohols 8 and 9 and the reaction of 4b with hydrazine gave an indazole derivative 10.

In the presence of KOH and Et 3 N, pyridinium and isoquinolinium N -ylides generated in situ from their bromides react with 1-chloro-2,2,2-trifluoroethane (HCFC-133a, bp 6 °C) or 1,1,1,2-tetrafluoroethane (HFC-134a, bp −27 °C) to give the corresponding 2-fluoroindolizines via 1,3-dipolar [3+2] cycloaddition at 80–100 °C in DMSO at atmospheric pressure in normal glassware.

1,1-Dichloro-2,2,2-trifluoroethane (HCFC-123) was evaluated as a substitute for trichlorofluoromethane (CFC-11), and it appeared that a permissible exposure limit of 50 ppm was justified. When HCFC-123 was introduced as a precision cleaning agent in a controlled operation, marked elevations in serum alanine transaminase and serum aspartase transaminase were noted in exposed workers. Sampling taken during start-up documented personal samples from 24-480 ppm (375 and 21 min, respectively) and area samples of 18-180 ppm (375 and 21 min, respectively). Personal and area samples collected after the liver abnormalities were identified ranged from 5-12 ppm. Exposure data were not available for the period when the abnormalities are suspected to have developed. Two models were developed to estimate exposure during the unmonitored period: (1) the entire plant as a homogenous box and (2) evaporation into smaller work zones. Modeling using the entire building estimated 8-hour time-weighted average (TWA) exposures of 10-35 ppm. Modeled estimates of work area and air exchange rates indicated that degreaser exposed workers could have experienced peak levels of 280-2,100 ppm (8-hour TWAs 252-1,630 ppm). Modeling of the work environment, estimated to be one-third of the volume of the entire open building, indicated peak exposures of 28-210 ppm (8-hour TWAs 25-163 ppm). These ranges estimate the minimum and maximum exposure levels. The best estimates, using 12 air changes per day, suggest peak levels around the degreaser of 635-2,100 ppm (8-hour TWA 499-1,630 ppm) and 63-207 ppm (8-hour TWAs 50-163 ppm) in the work area. These are the first estimates of exposure level associated with these hepatotoxic effects; all are significantly higher than personal and area samples collected for HCFC-123 after the liver abnormalities were identified.

A series of fluorinated polyimides were prepared from 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane with various aromatic tetracarboxylic dianhydrides via a conventional two-step procedure. These polyimides were amorphous in nature and afforded flexible and tough films. Some polyimides derived from less stiff dianhydrides were soluble in polar organic solvents. The glass-transition temperatures (Tg) of these polyimides ranged from 252 to 324 ○C, and softening temperatures (Ts) stayed in the 254∼322 ○C range. Decomposition temperatures (Td) at 10% weight loss all occurred above 569 ○C in both air and nitrogen atmospheres. For a comparative study, another series of analogous polyimides based on 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenylethane were also pepared and characterized.

Two series of novel fluorinated aromatic polyamides were prepared from 1,1-bis[4-(4-carboxyphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane with various aromatic diamines or from 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane with various aromatic dicarboxylic acids with the phosphorylation polyamidation technique. These polyamides had inherent viscosities ranging from 0.51 to 1.54 dL/g that corresponded to weight-average and number-average molecular weights (by gel permeation chromatography) of 36,200–80,000 and 17,200–64,300, respectively. All polymers were highly soluble in aprotic polar solvents, such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, and some could even be dissolved in less-polar solvents like tetrahydrofuran. The flexible and tough films cast from the polymer solutions possessed tensile strengths of 76–94 MPa and initial moduli of 1.70–2.22 GPa. Glass-transition temperatures (Tg's) and softening temperatures of these polyamides were observed in the range of 185–268 °C by differential scanning calorimetry or thermomechanical analysis. Decomposition temperatures (Td's) for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. Almost all the fluorinated polyamides displayed relatively higher Tg and Td values than the corresponding nonfluorinated analogues. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 420–431, 2003

Isothermal (vapour + liquid) equilibria were measured for (trichloromethane + tetrahydropyran or piperidine) at T = 333.15 K and {1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) + tetrahydropyran or piperidine} atT = 323.15 K with a circulation still. The results were verified by effective statistical procedures and used to calculate activity coefficients and excess molar Gibbs free energiesGmE . Excess molar enthalpiesHmE for these mixtures were determined at T = 298.15 K by means of an isothermal CSC microcalorimeter equipped with recently reconstructed flow mixing cells. Reliable performance of the calorimetric setup was proved by the good agreement of HmEfor (hexane + cyclohexane), (2-propanone + water), and (methanol + water), with the best literature results. The trichloromethane- or halothane-containing mixtures exhibit strong negative deviations from Raoult’s law and are highly exothermic, thus indicating that complex formation via hydrogen bonding is a governing nonideality effect. A close similarity in the behaviour of corresponding mixtures with trichloromethane and halothane is observed, but for halothane-containing mixtures,GmE and HmEare consistently more negative, confirming that halothane is a more powerful proton donor than chloroform.

The microwave spectrum of the 35 Cl and 37 Cl isotopic species of 1-chloro-1,1,2-trifluoroethane (HCFC-133b) has been investigated in the frequency region 10 to 50 GHz using a Stark modulation microwave spectrometer. A pulsed jet Fourier transform microwave spectrometer was also used for the measurement of hyperfine splittings. A least-squares analysis of the observed b -type Q - and R -branch transition frequencies gave rotational and centrifugal distortion constants and components of the chlorine nuclear quadrupole coupling constant tensors in the principal axes system as follows: A =4625.161 (3) MHz, B =2004.127 (2) MHz, C =1875.813 (2) MHz, Δ J =0.144 (9) kHz, Δ JK =1.0748 (8) kHz, Δ K =1.57 (1) kHz, δ J =0.01376 (4) kHz, δ K =−0.146 (4) kHz, χ aa =−57.958 (10) MHz, χ bb =21.231 (11) MHz, and χ cc =36.727 (11) MHz for 35 ClCF 2 CH 2 F species, and A =4607.684 (6) MHz, B =1960.565 (2) MHz, C =1834.823 (2) MHz, Δ J =0.106 (7) kHz, Δ JK =1.022 (3) kHz, Δ K =1.48 (1) kHz, δ J =0.0142 (2) kHz, δ K =−0.18 (2) kHz, χ aa =−46.268 (11) MHz, χ bb =17.319 (13) MHz, and χ cc =28.950 (13) MHz for 37 ClCF 2 CH 2 F species. The structural parameters are calculated from the observed six rotational constants by assuming the partial structure of ab initio calculation. The electronic properties of the C–Cl bond are evaluated from the observed nuclear quadrupole constants of chlorine. These molecular properties are compared with those of other related molecules.

Catalytic hydrolysis and ammonolysis of CF3CCl3 (CFC-113a) and CF3CH2Cl (HCFC-133a) and oxidation of CF3CH3 (HFC-143a) were studied as possible routes to produce trifluoroacetic acid (TFA), trifluoroethanol (TFE) or trifluoroethylamine (TFEA), respectively. Catalysts employed in this study included oxides/halides of Fe, Pd, Cs, Cu, Sn, supported on carbon, Al2O3, ZrO2, TiO2, sulfated zirconia and fluoride supports like β-AlF3, and MgF2, as well as modified lanthanum phosphates. The reaction temperatures were varied from 100 to 450 °C, under these conditions CF3CCl3 and CF3CH2Cl could be hydrolysed giving trifluoroacetic acid or trifluoroethanol, respectively, in moderate yields, however all other reactions yielded predominantly CF2CHCl. Optimum conditions were identified for obtaining TFA over Fe/C catalyst by hydrolysis of CFC-113a, and for TFE by hydrolysis of HCFC-133a over alkaline modified lanthanum phosphate.

Lewis acid-catalyzed deamination of aminal, 1,1-bis(dimethylamino)-2,2,2-trifluoroethane, using ZnI2 in ether, generates the 2,2,2-trifluoro-1,1-dimethylaminoethyl carbocation, which undergoes synthetically useful electrophilic reactions with alkynes, a variety of electron-rich alkenes, and TMS cyanide to form trifluoromethylated alkynylamines, homoallylic amines, alpha,beta-unsaturated ketones, and cyanoamines in fair to good yields.

A simple stereoselective three step synthesis of 2-fluoro- and 2-chloro-2,3-dideoxy arabinose derivatives from the readily available starting materials, (R)-glycidol and either 1,1,1,2-tetrafluoroethane (134a) or 1-chloro-2,2,2-trifluroethane (133a), is described. This compares very favourably with the multistep syntheses previously described in the literature. A mechanistic interpretation of the reaction via an unfavourable 5-endo-trig cyclisation is given.

The p–ρ–T relationships were measured for binary refrigerant mixtures by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 200 to 400 K, while pressures extended up to 35 MPa. Measurements were conducted on compressed gas and liquid samples with the following mole fraction compositions: 0.4997 R32+0.5003 R134a, 0.3288 R32+0.6712 R134a, 0.4996 R32+0.5004 R125, 0.5001 R125+0.4999 R134a, and 0.5000 R125+0.5000 R143a. Most published p–ρ–T data are in good agreement with this study. The uncertainty is 0.03 K for temperature and is 0.01% for pressure at p>3 MPa and 0.05% at p

Bubble-point pressures and saturated- and compressed-liquid densities of the binary R-125 (pentafluoroethane) + R-143a (1,1,1 -trifluoroethane) system have been measured for several compositions at temperatures from 280 to 330 K by means of a magnetic densimeter coupled with a variable-volume cell mounted with a metallic bellows. The experimental uncertainties of the temperature, pressure, density, and composition were estimated to be within ±10mK, ± 12 kPa, ±0.2%, and ±0.2mass%, respectively. The purities of the samples used throughout the measurements are 99.96 area% for R-125 and 99.94 area% for R-143a. Based on these measurements, the thermodynamic behavior of the vapor-liquid equilibria of this binary refrigerant mixture has been represented using the Peng–Robinson equation for the bubble-point pressures, a correlation for the saturated-liquid densities, and an equation of state for the compressed-liquid densities.

1,1-Bis(dimethylamino)-2,2,2-trifluoroethane is an excellent synthetic building-block replacement for trifluoroacetaldehyde in condensation reactions with ketones using 36% aqueous HCl catalysis. Moderate to good yields (43–68%) of trifluoromethyl carbinols are obtained with symmetric and unsymmetric methyl ketones, with the latter undergoing reaction mainly at the methyl group. Its reactions with silyl enol ethers under anhydrous conditions, catalyzed by ZnI 2 , lead directly to trifluoromethyl-α,β-unsaturated ketones.

The photodissociation dynamics of the title molecule at 157 nm has been studied using photofragment translational spectroscopy. The molecule was found to dissociate competitively via CHBrCF3 + Cl, CHClCF3 + Br, CHCF3 + Br + Cl, and CClCF3 + HBr channels with the branching ratio This result indicates that the stronger C−Cl bond breaks preferentially over the weaker C−Br bond, similar to the case of the photodissociation of CBrF2CHClF studied previously. Compared with the C−Cl:C−Br branching ratio for the photodissociation of CBrF2CHClF at 157 nm, this branching ratio indicates that a larger fraction of molecules dissociate via C−Br bond rupture in this case than in the case of CBrF2CHClF as a result of a higher transition probability from the initially excited nσ*(C−Cl) diabatic surface to the nσ*(C−Br) diabatic surface. This result is qualitatively consistent with the prediction from previous theoretical works that the transition probability from the nσ*(C−Cl) to the nσ*(C−Br) diabatic surface increases w...