Fluorine reaction + fluorocarbons

The Influence of Fluorine or Fluorocarbon Groups on some Reaction Centres... 

The Influence of Fluorine or Fluorocarbon Groups on some Reaction Centres Table 4.2 pKa values of some organic acids and alcohols [7]... 

In contrast, fluorine or fluorocarbon groups directly attached to the reaction centre have a much more pronounced effect [4] for example, the hydrolytic displacement of chloride from PhCHFCl appears to be activated with respect to benzyl chloride [10], although the situation is complicated by concomitant SnI and Sn2 processes. 

Two known synthesis routes were used to convert short-chained perfluoroalkylene dicarboxylic acid and diiodide intermediates to diaryl intermediates. The copper-catalyzed coupling of aryl and fluorocarbon iodides described by McLoughlin and Thrower (12) provided convenient synthesis of short-chained diphenylperfluoroalkylene compounds when appropriate fluorocarbon diiodides were available. The preparation of diaryl intermediates via aryl ketone synthesis and subsequent SF4 fluorination reaction provided a satisfactory alternative synthesis of lower-molecular-weight intermediates (13). 

This method is an extension of the monoester fluorination reactions reported earlier by Sheppard (1). Initial effort was placed on developing conditions that would result in high yields in the fluorination of the nitrophenyl ester of perfluoroglutaric acid. This was followed by fluorination of the nitrophenyl esters of the higher 1 1, 2 1, and 3 1 fluorocarbon ether oligomer acids. The products were the corresponding nitrophenoxy derivatives represented by IV where x + y = 1,2, and 3. 

Other experimental results [32] are also in agreement with the considered model. Thus, the chemical compositions of anode gases were established by means of chromatography and chemical analysis, and free fluorine and fluorocarbons were formed by the reactions (5.67) and (5.70). Noteworthy is the experimental dependence between current and temperature inside the graphite anode that is given in Fig. 5.18. One can see that it is almost exponential, as the Eq. (5.91) predicts. 

Cobalt(III) fluoride has been found to be a useful fluorinating agent in the production of fluorocarbons it can be used for a variety of fluorinating reactions as a substitute for elementary fluorine. While it is not possible to obtain elementary fluorine by heating cobalt(III) fluoride, it can be used to prepare higher-valent volatile fluorides that could not otherwise be obtained except by the use of elementary fluorine. The method of preparation described here is similar to that used by Ruff and his coworkers. ... 

Fluorinated Acids. This class of compounds is characterized by the strength of the fluorocarbon acids, eg, CF COOH, approaching that of mineral acids. This property results from the strong inductive effect of fluorine and is markedly less when the fluorocarbon group is moved away from the carbonyl group. Generally, their reactions are similar to organic acids and they find apphcations, particularly trifluoroacetic acid [76-05-1] and its anhydride [407-25-0] as promotors in the preparation of esters and ketones and in nitration reactions. 

The nonbonding electron clouds of the attached fluorine atoms tend to repel the oncoming fluorine molecules as they approach the carbon skeleton. This reduces the number of effective coUisions, making it possible to increase the total number of coUisions and stiU not accelerate the reaction rate as the reaction proceeds toward completion. This protective sheath of fluorine atoms provides the inertness of Teflon and other fluorocarbons. It also explains the fact that greater success in direct fluorination processes has been reported when the hydrocarbon to be fluorinated had already been partiaUy fluorinated by some other process or was prechlorinated, ie, the protective sheath of halogens reduced the number of reactive coUisions and aUowed reactions to occur without excessive cleavage of carbon—carbon bonds or mnaway exothermic processes. 

In early reaction systems (9,10,31,32) the vaporized hydrocarbon was combined with nitrogen in a reactor and mixed with a nitrogen—fluorine mixture from a preheated source. The jet reactor (11) for low molecular weight fluorocarbons was an important improvement. The process takes place at around 200—300°C, and fluorination is carried out in the vapor state. 

The breadth of reactions catalyzed by cobalt compounds is large. Some types of reactions are hydrotreating petroleum (qv), hydrogenation, dehydrogenation, hydrodenitrification, hydrodesulfurization, selective oxidations, ammonoxidations, complete oxidations, hydroformylations, polymerizations, selective decompositions, ammonia (qv) synthesis, and fluorocarbon synthesis (see Fluorine compounds, organic). 

Almost all of the biomedical research done in the 25 years following the liquid-breathing work was conducted with commercially available fluorocarbons manufactured for various industnal uses by the electrochemical Simons process (fluonnation in a hydrofluoric acid solution) or the cobalt fluoride process (fluori-nation with this solid in a furnace at about 200 C) These processes tended to yield many by-products, partly because they were, to some extent, free radical reactions and partly because it was difficult to easily achieve complete fluonnation Aromatic hydrocarbons gave better products with the cobalt tnfluonde [73] method, whereas saturated hydrocarbons yielded better products with fluonnation using diluted or cooled gaseous fluorine (Lagow) Incompletely fluormated matenal was either... 

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