Fluoromethane

FIGURE 7 2 M irror image forms of chlorodi fluoromethane are superimposable on each other Chlorodifluoro methane is achiral... 

FIGURE 7 6 Ball and spoke models [left) wedge and dash drawings [center) and Fischer projections [right) of the R and S enan tiomers of bromochloro fluoromethane... 

Amongst the catalysts used or the polymerisation-trimerisation reactions are alkali metal phenolates, alcoholates and carboxylates and compounds containing o-(dimethylaminomethyl)phenol subgroups. Fluorocarbons such as trichloro-fluoromethanes are used as the sole blowing agents in the absence of any isocyanate-water reaction. 

One of the most useful ways of introducing fluorine into organic compounds is the placement of the hydroxyl group in alcohols hydroxy compounds, and carboxylic acids Methyl alcohol reacts with anhydrous hydrogen fluoride at 100 500 °C in the presence of aluminum fluoride [60, 61], zinc fluoride [62] chromium fluonde [63], or a mixture of aluminum and chromium fluondes [64] to give a 20-78% yield of fluoromethane Attempted fluorinations of higher alcohols by this method failed [60]... 

Unfortunately, the thermodynamically favored reactions of trichlo-rolluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) with water do not proceed to a significant degree below 300 C and at least 200 atm (1 atm = 101.325 kPa) or greater [42] (equation 44) Even at 4000 atm randoimzation rather than complete hydrolysis occurs, leaving another chlorofluorocarbon, chlorotri-fluoromethane (CFC-13), which is also potentially harmful to the earth s ozone layer... 

A SET mechanism is involved also in the condensation with dichlorodi-fluoromethane that occurs under moderate pressure [55, 5S] (equation 50). 

The mtroducuon of a tnfluoromethanethio group into an aromatic nng has a synthetic importance The reaction of tnfluoromethanethio copper with aryl bro mides and iodides provides a convenient route to the synthesis of aryltn fluoromethane sulfides The reaction is not sensitive to the type of substituents or the aromahc nucleus Selectivity can be achieved accordmg to the type of halogen or the aromatic rmg, because iodides react at lower temperatures than bromides, whereas chlondes do not react [f J] (equation 12) (Table 5)... 

Both values are in excellent agreement with the experimental heats of formation. Note that the experimental value for fluoromethane is quite uncertain. ... 

Figure 17.4 then is a typical Hartree-Fock analytical derivative calculation on fluoromethane. 

Fluoromethane (CH3F, jj. = 1.81 D) has a smaller dipole moment than chloromethane (CH3C1, ix= 1.87 D) even though fluorine is more electronegative than chlorine. Explain. 

UV irradiation (A>300nm) of an argon matrix containing tetra-fluoromethane led to the formation of difluorocarbene CF2 (Milligan and Jacox, 1968a). It was shown that the IR spectrum of this species contains three bands at 1222 (i i), 1102 (v ), and 668 (i 2)cm . Some time later difluorocarbene was stabilized in a neon matrix at 4.2 K from the gas phase after vacuum flash pyrolysis (1300°C) of perfluoroethene (Snelson, 1970b). In this case the IR bands of CF2 differed from those in an argon matrix by less than 2 cm . ... 

Ammonia monooxygenase in Nitrosomonas europaea is able to oxidize fluoromethane to formaldehyde (Hyman et al. 1994). 

The bond dissociation energy of fluoromethane is 115 kcal mol , which is much higher than the other halides (C-Cl, C-Br and C-1, respectively 84, 72 and 58 kcal mol ) [6], Due to its strength, the carbon-fluorine (C-F) bond is one of the most challenging bonds to activate [7], A variety of C-F bond activation reactions have been carried out with different organometallic complexes [8], Among them, nickel [9] and ruthenium complexes have proven to proceed selectively under mild conditions [10],... 

Table 6. -Chemical shifts in a series of fluoro-methylcobalamins and fluoromethanes...

Tris(difluoroamino)fluoromethane See Tris(difluoroamino)fluoromethane Pentaborane(9)... 

---