Fluoroform

The corresponding fluorine compound is also known, and is a gas with a chloroform-like odor. 

This is the only tetra-halogen substitution product of methane which will be mentioned. It is produced when methane is chlorinated to its limit. It may also be made by further chlorination of chloroform. The reaction by which it is made industrially is, however, entirely different. It consists in chlorinating carbon di-sulphide in the presence of a carrier such as iodine. In this reaction, which probably takes place in several steps, the two sulphur atoms, in the carbon di-sulphide, are replaced by four chlorine atoms. 

Isomerism.—When we come to the di-substitution products of ethane we find two classes of isomeric compounds as was discussed briefly on page 53. The fact that in each class only one mono-substitution product of ethane is known has been given as proof that all of the hydrogen atoms in ethane are alike, i.e., ethane, like methane, is a symmetrical compound. When, however, two substituting elements or groups are introduced into ethane, two isomeric compounds result each having the composition C2H4CI2, in the case of the chlorine product. 

Uns3mimetrical Di-chlor Ethane.—These two compounds may also be prepared by other reactions which show us what their true constitution is. When acet-aldehyde, which we have previously proven has the constitution represented by the formula, CH3—CHO, is treated with phosphorus penta-chloride one oxygen atom is replaced by two chlorine atoms and the product is one of the two isomeric di-chlor ethanes. 

This reaction is entirely different from that of phosphorus penta-chloride on alcohol, in which the hydroxyl of the alcohol is replaced by one chlorine, and the mono-halogen substitution product of the hydrocarbon results (p. 81). If our ideas in regard to the constitution of aldehyde are correct, this reaction must mean, that, in the di-chlor ethane formed in this way, the two chlorine atoms are linked to the same carbon atom. Such a structure represents a compound which is plainly unsymmetricaL 

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Dubai H-R and Quack M 1981 High resolution spectroscopy of fluoroform Chem. Phys. Lett. 80 439-44... 

Maynard A T, Wyatt R E and lung C 1995 A quantum dynamical study of CH overtones in fluoroform. 

Depending on the ring substituent, trifluoromethoxyben2enes can be made by the sequential chlorination—fluorination of anisole(s) (351—354). A one-step process with commercial potential is the BF (or SbF2)-cataly2ed reaction of phenol with carbon tetrachloride/hydrogen fluoride (355). Aryl trifluoromethyl ethers, which may not be accessible by the above routes,may be made by fluorination of aryl fluoroformates or aryl chlorothioformates with sulfur tetrafluoride (348) or molybdenum hexafluoride (356). 

At 225—275°C, bromination of the vapor yields bromochloromethanes CCl Br, CCl2Br2, and CClBr. Chloroform reacts with aluminum bromide to form bromoform, CHBr. Chloroform cannot be direcdy fluorinated with elementary flourine fluoroform, CHF, is produced from chloroform by reaction with hydrogen fluoride in the presence of a metallic fluoride catalyst (8). It is also a coproduct of monochlorodifluoromethane from the HF—CHCl reaction over antimony chlorofluoride. Iodine gives a characteristic purple solution in chloroform but does not react even at the boiling point. Iodoform, CHI, may be produced from chloroform by reaction with ethyl iodide in the presence of aluminum chloride however, this is not the route normally used for its preparation. 

In the present work low temperature adsoi ption of fluoroform and CO, were used to characterize surface basicity of silica, both pure and exposed to bases. It was found that adsorption of deuterated ammonia results in appearance of a new CH stretching vibration band of adsorbed CHF, with the position typical of strong basic sites, absent on the surface of pure silica. Low-frequency shift of mode of adsorbed CO, supports the conclusion about such basicity induced by the presence of H-bonded bases. 

Alkanoyl chlorides and chloroformates can be treated with potassium fluoride and benzyItriethylammonium chloride to obtain the respective alkanoyl fluorides or fluoroformates [62]. 2-Amino-6-chloro-9-(2,3,5-tri-0-acetyl-P-D-ribofurano-syl)purine is converted to the 2-amino-6-fluoro product with potassium fluoride and trimethylamme in dimethylformamide under rigorously anhydrous conditions [65] (equation 37)... 

Fluorodediazoniation of alkyl carbamates in hydrogen fluonde/pyndine (70/30) represents a novel route to alkyl fluoroformates [6, 9] (equation 4)... 

Diazoalkanes react with ethyl fluoroformate [S7j and acyl fluorides [87, 55] to give ethyl ot-fluorocarboxylates and ot-fluoroketones, respectively (equation 22) Table 7 lists examples of hydrofluorination [6. 83, 89] and geminal difluori-nation [90] of aryldiazomethanes... 

Fluoroform is brominated to yield bromotnfluoromethane The reaction rate and yield are both enhanced by vanous catalysts, as summanzed in Table 7 [2J, 24, 25]. 

The adamantyl carbonate is prepared from Adoc2C03 (DMAP, CH3CN, >79% yield) or, in the case of electron-deficient phenols, the fluoroformate (THF, Pyr, 54-95% yield). It is somewhat more stable to TFA than the adamantyl carbamate. 

Tris(trifluoromethyl)germanium iodide is unstable in 3M base, however, and yields fluoroform quantitatively. All of the compounds showed good thermal stability (15). 

Fluoroform magnesium and copper at normal temperatures. Nickel and Monel at higher temperatures ... 

Table VIII. It is difficult to conceive of fluoroform, which is chemically and physiologically inert, having toxicity to moths unless it acts as a mechanical asphyxiant.

In most enzymatic syntheses of polyesters, the polymerization was carried out in organic solvents or bulk. Using supercritical fluoroform as solvent, the polymerization of bis(2,2,2-trichloroethyl) adipate and 1,4-butanediol was demonstrated [60]. The molecular weight increased as a function of the pressure. By changing the pressure, the low-dispersity polymer fractions were separated. 

The experimental 13C NMR chemical shift of the simplest member of the acylium ions, the formyl cation [HCO]+ was reported as S = 139.5 (measured under CO pressure of 85 atm) which compares well with the GIAO-MP2 calculated shift of S — 136ppm.116,117 The analogous fluoroformyl cation [FCO]+ and protonated fluoroformic acid [FC(OH)2]+ were characterized by 13C NMR spectroscopy, experimentally118 ((5=117.5 and 157.8 ppm, respectively) as well as computationally (S = 118.6 and 170.6ppm, respectively).119... 

Reactions that have led to other deoxyhalogeno sugars do not necessarily lead to deoxyfluoro sugars, as, for example, in the attempted decomposition of fluoroformates, the treatment of diazoketones and of 2-deoxy-2-diazohexonates with hydrogen fluoride, and the reaction of benzoxonium ions with halide ions. The reaction2281229 by which fluoroformates are thermally or catalytically decarbonylated to give alkyl fluorides has been applied to carbohydrates. Both thermal and catalytic treatment of 6-0-(fluoroformyl)-l,2 3,4-di-0-isopropylidene-... 

Dynamical Study of CH Overtones in Fluoroform. I. A Nine-Dimensional Ab Initio Surface, Vibrational Spectra and Dynamics. 

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