Potassium fluoride-oxygen

Potassium fluoride-Oxygen. a-HYDROXY KETONES Chromyl... 

The metal-ion complexmg properties of crown ethers are clearly evident m their effects on the solubility and reactivity of ionic compounds m nonpolar media Potassium fluoride (KF) is ionic and practically insoluble m benzene alone but dissolves m it when 18 crown 6 is present This happens because of the electron distribution of 18 crown 6 as shown m Figure 16 2a The electrostatic potential surface consists of essentially two regions an electron rich interior associated with the oxygens and a hydrocarbon like exterior associated with the CH2 groups When KF is added to a solution of 18 crown 6 m benzene potassium ion (K ) interacts with the oxygens of the crown ether to form a Lewis acid Lewis base complex As can be seen m the space filling model of this... 

In a caustic scmbbing system, caustic potash, KOH, is preferred to caustic soda, NaOH, because of the higher solubiUty of the resulting potassium fluoride. Adequate solution contact and residence time must be provided in the scmb tower to ensure complete neutralization of the intermediate oxygen difluoride, OF2. Gas residence times of at least one minute and caustic concentrations in excess of 5% are recommended to prevent OF2 emission from the scmb tower. 

Difluoropyridines. 2,4-Difluoropyridine can be prepared (26% yield) from 2,4-dichloropyridine and potassium fluoride in sulfolane and ethylene glycol initiator (403). The 4-fluorine is preferentially replaced by oxygen nucleophiles to give 2-fluoro-4-hydroxypyridine derivatives for herbicidal apphcations (404). 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

The reaction ot tormamides with sulfur tetrafluoride in the presence of potassium fluoride leads to replacement of both carbonyl oxygen and hydrogen with fluorine. The formyl group is directly converted into the trifluoromethyl group A-(trifluoromethyl)amines are formed in near quantitative yields [233] (equation 121)... 

It is, therefore, required that all initial compounds be dried properly prior to performing the reduction. This procedure is not at all trivial and refers, first of all, to the diluent salts, and especially to potassium fluoride, KF, which is characterized by a strong hygroscopic property and a tendency to form stable crystal hydrates. The problem of contamination due to hydrolytic processes can usually be resolved in two manners. The first is to apply another tantalum-containing complex fluoride compound that does not undergo hydrolysis. The second involves the adjustment of the reduction process parameters and use of some additives that will "collect" the oxygen present, in the form of water, hydroxyl groups or other compounds. 

The adduct (56) was hydrolyzed (CSA, CH3OH) to afford the unsaturated ketone 70. Finally, the unsaturated ketone 70 was regioselectively oxygenated by treatment with potassium fluoride (0.1 equiv) in methylsulfoxide under an atmosphere of air. This sequence generated the tertiary alcohol 55 in 48 % yield over three steps. 

In the presence of freeze-dried potassium fluoride, perfluoro-2-methylpent-2-ene reacts with activated methylene compounds to yield pyrans (81MI22400). The fluoride ion abstracts a proton from the methylene group and subsequent condensation of the carbanion with the perfluoroalkene affords a dienone (19) which ring closes to the pyran (20 Scheme 3). In the case of pentane-2,4-dione a divinyl ether (21) is also formed. This product is considered to arise from reaction of the alkene at the oxygen of the enolate ion. 

Hydrogen fluoride may be removed from fluorine by absorption over dry potassium fluoride or sodium fluoride or by passing the gas through a trap cooled with liquid oxygen. Probably the latter method is most effective. If one of the salts is used, it is necessary that it should be pure and dry. Moisture introduces oxygen into the fluorine, whereas chlorides will lead to contamination of the fluorine with chlorine. 

Ozone is produced during the electrolysis of neutral or alkaline solutions of potassium fluoride m consequence of the action of the fluorine momentarily produced at the anode upon the water in its vicinity.2 Electrolysis of aqueous hydrogen fluoride is stated to have yielded 3 ozonised oxygen containing from 0-475 to 3-48 per cent, of ozone by volume.4 With a saturated solution of potassium fluoride at 0° C. a yield of 0-65 per cent, ozone has been obtained for a short time, but the percentage of ozone tends to fall with the duration of the experiment. Variation of current density from 5 to 10 amperes per sq. decimetre does not appear to have any appreciable effect upon the yield.4... 

How can the electronegativity difference help you predict the type of bond By the end of this section, you will understand the aswer to this question. Consider three different substances potassium fluoride, KF, oxygen, O2, and hydrochloric acid, HC1. Potassium fluoride is an ionic compound made up of a metal and a non-metal that have very different electronegativities. Potassium s electronegativity is 0.82. Fluorine s electronegativity is 3.98. Therefore, AEN for the bond between potassium and fluorine is 3.16. 

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