Ethane, fluorination

Mercury-photosensitised decompositions have been reported for fluorinated methanes , fluorinated ethanes , fluorinated ethylenes , perfluorocyclobu-tene and perfluorobuta-1,3-diene , chlorofluoromethane , dichloromethane (ref. 939), and octafluorobut-2-ene . Acetone has been used for sensitising the decomposition of 1,4-dichlorobutane , chlorobutenes , and allylic halides (the last to cyclopropyl halides) other studies have involved the use of hexafluoroacetone and benzene as sensitisers. 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

Formal replacement of one of the bulky halogens in polyhalogenofluoro-ethanes by nitrogen nucleophiles occurs through the intermediate formation of fluorinated olefins [91, 92] (see equation 47) (equation 79). 

The molecular ion is usually not observed in the mass spectra of aliphatic fluorinated compounds (>ethane). Common losses are F. HF, or CF3. Frequently observed ions lie at m/zs 31 (CF), 50 (CF2). and 69 (CF3). If mass 69 is intense, a CF3 group is present. The presence of a small m/z 51 peak indicates the presence of carbon, hydrogen, and fluorine. If a m/z 51 peak is intense, then CHF is present. The absence of m/z 51 and/or m/z 47 (without chlorine) suggests a perfluorinated compound. 

Fluorinated Silicon Oxide. The introduction of fluorine in the ratio of 2 to 14 at.% lowers the dielectric constant, which is reported as low as 3.0. This is a major factor in the design of dielctric films. The CVD of these fluorinated compounds is accomplished by plasma-CVD and usually with Sip4 as a fluorine source. Also available are fluorinated compounds, such as fluorotriethoxysilane (FTES), l,2bis(methyldifluorosilyl)ethane, and 2,5disilahexane.P2]... 

Particularly the chlorinated compounds have enjoyed range of applications vinyl chloride (chloro-ethene) as monomer for the production of PVC, tetra- and trichloroethenes as solvents for degreasing, and the insecticides l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and isomers of hexachlorocyclohexane (HCH) (benzene hexachloride). The biodegradation of fluorinated aliphatic compounds is generally different from the outlines that have emerged from investigations on their chlorinated, brominated, and even iodinated analogues. They are therefore treated separately in Part 4 of this chapter. 

Perfluoroalkyl)ethane thiols have been used as precursors to fluorinated surfactants and products for hydro- and oligophobic finishing of substrates such as textiles and leather (1). The synthesis of 2-(perfluoroalkyl)ethane thiol and a byproduct bis-(-2-perfluoroalkylethane)-disulfide (5-10%) has been practiced via the reaction of 2-(perfluoroalkyl)ethane iodide with thiourea to form an isothiuronium salt which is cleaved with alkali or high molecular weight amine as shown in Equation 1 for 2-(perfluorohexyl)ethane iodide (1). 

The olefin yields are higher with 2-(perfluoroalkyl) ethane iodides than their hydrocarbon analogues apparently because of the strongly electron withdrawing fluorine making the hydrogens more acidic and prone to elimination. 

The discovery of the phenomenal insecticidal activity of 1,1, l-trichloro-2,2-bis(p-chlorophenyl)-ethane (DDT), which occurred less than 10 years ago, opened up a new field of endeavor for the chemist, biologist, and toxicologist. The activity in this field is considerable, and a portion of it has been directed toward efforts-to locate useful insecticides among the fluorine-containing compounds. Some of the fluorine compounds known to be insecticidal were re-evaluated, other compounds were tested biologically for the first time, and new compounds were prepared to be subjected to such tests. 

Samples of l,l,l-trifhioro-2,2-bis(p-fluorophenyl)-ethane, and the corresponding bis-(p-chlorophenyl) derivative were obtained by applying Henne s fluorination method to DFDT and DDT, respectively. In both instances a mixture of the mono-, di-, and trifluoro compounds was obtained, but the desired trifluorinated material was separated by fractional recrystallization from methanol and cooling with a mixture of dry ice and acetone. 

More Heavily Fluorinated Compounds. The series of fluo-rinated ethanes in Scheme 3.18 indicates that the fluorine nucleus of a CH2F group is increasingly shielded as the number of P-fluorines increases, unlike the situation observed for an increasing number of P-chlorine substituents (Scheme 3.12). Note that as one accumulates fluorines at the P-position, the three-bond H—F coupling constant becomes progressively smaller. 

Few SF5-substituted saturated hydrocarbons have been reported. On the basis of the methane and ethane derivatives in Scheme 7.22, it appears as if the equatorial b-fluorines of the ab4 system are much more... 

The SF5 fluorines of SF5-ethane and SF5-ethylene are almost indistinguishable, but the respective 13C NMR spectra would certainly allow their distinction (Scheme 7.28). 

There is a remarkable difference in the ab4 systems of SF5-acetylenes as compared to the respective SF5-alkenes or SF5-alkanes. Most noticeably, the order of appearance of the ab4 signals switches for SF5-acety-lenes, with the four fluorine signals due to the equatorial fluorines appearing downfield of the one fluorine signal due to the axial fluorine (Scheme 7.31). Relative to SF5-ethane, the SF5-acetylene equatorial fluorines have shifted 20ppm downfield, whereas its axial fluorine is shifted 10ppm upfield compared to those of SF5-ethane. 

Murray, J. S., P. Lane, and P. Politzer. 1995b. Special Relationships of Fluorinated Methane/Ethane Boiling Points and Heats of Vaporization to Molecular Properties. J. Mol. Struct. (Theochem) 342, 15. 

Methane, ethane, and other alkanes react with fluorine, chlorine, and bromine. 

Figure 12. F cycle constant current charge curves of synthetic graphite LONZA KS 44 (i) using 1 MLiN(S02CF3)2 in EC.DME (dimethoxy ethane, CH3OCH2CH2OCH3) (3 2) as electrolyte. The measurement was stopped when the graphite was exfoliated, (ii) using 1 M LiN(S02CF3)2 in EC F-DME (partially fluorinated dimethoxy ethane, CH3OCF2CF2OCH3) (3 2) as electrolyte, i = 20 mA g1, cut-off = 0.0 V vs. Li/Li+ (adaptedfrom [12]).

Several fluorodinitro compounds of methane (1,1,1-) and ethane (1,2,2-) are described as explosive, sensitive to initiation by impact, shock, friction or other means [1]. Procedures for safe handling of fluorine and explosive fluoronitro compounds are detailed [2],... 

In this work, results of high level ab initio SOPPA calculations of vicinal fluorine-fluorine indirect nuclear spin couplings are presented for 1,2-difluoroethene, -propene, -ethane and -propane. The four contributions (OD, OP, SD, FC) and the total value of the coupling constant are analyzed. 

Keller. D.A., Roe, D.C., and Lieder, P.H. Fluoroacetate-mediated toxicity of fluorinated ethanes, Fundam. Appl. Toxicol, 30(2) 213-219, 1995. 

In this structure, five halogen atoms— three fluorines, one chlorine, and one bromine atom— replace five of the six hydrogen atoms of ethane. 

As pointed out above, neither methane nor its higher homologs (ethane, propane, hexane) can be effectively metalated. The introduction of a hetero-substituent changes this outset profoundly. Second-row and third-row elements (such as silicon, phosphorus and sulfur) will not be considered in this context as they are known to acidify hydrocarbons strongly due to d-orbital resonance (or polarization) effects. But also the first-row elements nitrogen, oxygen and fluorine can distinctly facilitate the deprotonation of paraffinic hydrocarbons. 

Let us try to extrapolate this correlation to the available experimental data on some of the two-carbon HCFCs, based on ethane instead of methane, which is shown in table 5.12. There are new considerations, as tetrafluoroethane can have two different forms one with three fluorine atoms on one carbon and one fluorine atom on the other carbon, and the other with two fluorine atoms on each carbon. Nevertheless, the boiling points of the 19 substances satisfy the correlation formula of... 

Technological applications have been found for the oxathietane 1,1-dioxides. Ethane ) -sultones (19) substituted with long, saturated hydrocarbon chains have been developed as foam-producing surfactants and detergents. Attention is being given to the fluorinated sultones (20), especially by Soviet... 

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