Fluorine fluoro

Fluor-, of or combined with fluorine, fluoro-, fluo-, fluoride of (see instances following),. ammonium, n. ammonium fluoride, -an-thenchinon, n. fluoranthenequinone. -anti-mon, n. antimony fluoride, -arson, n. arsenic fluoride, -baryum, n. barium fluoride, -benzol, n. fluorobensene, fluobenaene. -bor, n. boron fluoride. -borsMure, /. fluo-boric acid. -brom, n. bromine fluoride, -chrom, n. chromium fluoride, -eisen, n. iron fluoride. 

Peroxydisulfuryl Difluoride, S2OgF2, mw 198.14 colorless liq having extremely unpleasant odor, fr p —55.4°, bp 67-1° hydrolyzes in water. It ignites org materials immediately up on contact. It can be prepd by reaction of F with an excess of sulfur trioxide at 250° and by combination of fluorine fluoro-silicate with sulfur ttioxide (Refs 3 4)... 

Several partially and fully fluorinated aromatics have been further fluorinated. Fluoro- and 1,4-difluorobenzene give13 the same products as benzene over potassium tetrafluorocobalt ate(lll), in keeping with the current theory5 of fluorination. 

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATICCOMPOUNDS] (Volll) p-Fluoro-a,a-bis(trifluoromethyl)benzyl alcohol [2402-74-6]... 

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATIC COMPOUNDS] (Volll) 5-Fluoro-2,4-pyrimidinedione... 

Metahation of 2-fluoropyridine with lithium diisopropylamide (LDA) gives 2-fluoro-3-hthiopyridine, thereby providing entry to 3-substituted pyridines (388). This technique has been used to make fluorine analogues of the antitumor eUipticines (389). 

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). 

Synthetic procedures are available for the preparation of fluoro, chloro, bromo and iodo compounds from the corresponding lithio derivatives. Perchloryl fluoride (FCIO3), N-chlorosuccinimide, bromine and iodine are examples of reagents which can be used to introduce fluorine, chlorine, bromine and iodine, respectively. 

Fluorosilicones consist of PDMS backbones with some degree of fluoro-aliphatic side chains. The fluorinated group can be trifluoropropyl, nonafluorohexylmethyl, or fluorinated ether side group [78,28,79]. These polymers differ not only in substituent group, but also in the amount of fluoro-substitution relative to PDMS, the overall molecular weight and crosslink density, and the amount of branching. In most commercially available cases, these polymers are addition cure systems and the reactions are those discussed previously for silicone networks. 

The enamines, enol ethers and enol acetates of A -3-keto steroids provide important substrates for fluorination with FCIO3. Reaction of such A -enol ethers and acetates (6) with perchloryl fluoride results in 6a- and 6jff-fluoro-A -3-ketones (7) and (8), the latter representing the more abundant isomer. Tetrahydrofuran or dioxane-water mixtures appear to be particu-... 

In the course of synthetic efforts aimed at obtaining 6j5-fluoro steroids, Kirk and Petrow treated a 3)5-acetoxy-6-raethyl-5a,6a-epoxide with boron trifluoride etherate and unexpectedly obtained a fluorine-free acetoxy ketone." Later transformations established that the product was the A-homo-B-norsteroid (104). 

Fluorinatton of graphite with fluorine gives graphite fluorides that have interesting properties, as recently reviewed [63]. Pyridine and its derivatives add elemental fluorine to form unstable N-fluoro adducts [14, 26, 64, 65]. These may decompose to 2-fluoropyndines [65] or be stabilized by treatment with inflate salts to form useful electrophilic fluonnating agents [64]... 

Diazoketones react with trifluoromcthyl hypofluorite to give a mixture of a,a-difluoro ketones and o-fluoro-a-trifluoromethoxy ketones [70, 71] With elemental fluorine, two fluorine atoms replace the nitrogen in both diazoketones and unactivated diazo eompounds [70, 72, 73] (equation 9)... 

Selective fluonnation in polar solvents has proved commercially successful in the synthesis of 5 fluorouracil and its pyrimidine relatives, an extensive subject that will be discussed in another section Selective fluonnation of enolates [47], enols [48], and silyl enol ethers [49] resulted in preparation of a/phn-fluoro ketones, fieto-diketones, heta-ketoesters, and aldehydes The reactions of fluorine with these functionalities is most probably an addition to the ene followed by elimination of fluonde ion or hydrogen fluoride rather than a simple substitution In a similar vein, selective fluonnation of pyridmes to give 2-fluoropyridines was shown to proceed through pyridine difluondes [50]... 

Electrochemical fluorination of a-cyclohexenyl-substituted carboxylic (acetic, propanoic, butanoic, and pentanoic) acid esters (methyl, ethyl, and propyl) results in a series of both perfluoro-9-alkyl-7-oxabicyclo[4 3 OJnonanes and per-fluoro-8-alkoxy-9-alkyl-7-oxabicyclo[4.3.0]nonanes [<8S] (equation 19)... 

Many fluorinations by electropositive fluorine reagents produce a-fluoro carbonyl compounds as the final result An extensive review exists on the preparation of a-fiuorocarbonyl compounds [101 Also, electropositive reagents are used widely in the preparation of F-labeled radioactive materials required in positron etmssion tomography for biomedical research Excellent reviews are available on fluonne-18 labeling [//, 72]. 

Trimelhylsilyl enol ethers are effective substrates in fluorination with fluo-roxytrifluoromethanefor the preparation of a-fluoro esters, amides and aldehydes [J7] (equations 13-15)... 

The anions of malonaldehyde [106, 107] and of organophosphonates [108, 109, 110] are fluorinated in good yields to provide interesting fluorinated intermediates The At-fluoro compound B in Table 3a is also effective in the fluonnation of phosphonate anions [109] (equations 60 and 61). 

This topic has been reviewed [2, pp 94, 100-111, 130-134] All of the standard approaches to the synthesis of a compound like methyl 2-fluorostearate from methyl 2-bromostearate result mall yield of the 2-fluoro ester and the unsaturated esters. Although silver fluoride is not a new reagent, its use moist in wet acetonitrile to convert methyl 2-bromostearate to its fluoro ester is a departure from the traditional set of anhydrous conditions (Procedure 6, p 194) [71] In contrast, silver tetrafluoroborate converts a-chloroketones to their respective fluoroketones under anhydrous conditions. The displacement of less activated halogen groups by silver tetrafluoroborate to form their respective fluorides is novel Although silver tetrafluoroborate could not be used to convert an aliphatic terminal dichloromethyl or trichloromethyl group to its corresponding fluoro derivative, it is an effective fluorine source in other situations [72] (Table 8)... 

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)... 

Reactions of alcohols with sulfur tetrafluoride, because of decomposition and/or polymerization, usually do not give fluorinated products However, in the presence of a hydrogen fluoride scavenger like triethylamine or pyridine, even such sensitive substrates as benzylic alcohols [555], 2-phenylethanol, and 2-furylmethanol [554] can be fluorinated to give the expected fluoro derivatives (equation 73)... 

High-yield deaminative fluorination of a-atmnocarboxylic acids to a-fluoro-carboxylic acids can be effected with sodium nitrite in Olah s reagent [5, 6] (equation 3 and Table 2)... 

A more efficient agent than peroxy compounds for the epoxidation of fluoro-olefins with nonfluonnated double bond is the hypofluorous acid-acetomtrile complex [22] Perfluoroalkylethenes react with this agent at room temperature within 2-3 h with moderate yields (equation 13), whereas olefins with strongly electron-deficient double bond or electron-poor, sterically hindered olefins, for example l,2-bis(perfluorobutyl)ethene and perfluoro-(l-alkylethyl)ethenes, are practically inert [22] Epoxidation of a mixture of 3 perfluoroalkyl-1-propenes at 0 C IS finished after 10 mm in 80% yield [22] The trifluorovinyl group in partially fluorinated dienes is not affected by this agent [22] (equation 13)... 

An ipso attack on the fluorine carbon position of 4-fIuorophenol at -40 °C affords 4-fluoro-4-nitrocyclohexa-2 5-dienone in addtion to 2-nitrophenol The cyclodienone slowly isomenzes to the 2-nitrophenol Although ipso nitration on 4-fluorophenyl acetate furnishes the same cyclodienone the major by-product is 4 fluoro-2,6-dinitrophenol [25] Under similar conditions, 4-fluoroanisole pnmar ily yields the 2-nitro isomer and 6% of the cyclodienone The isolated 2 nitro isomer IS postulated to form by attack of the nitromum ion ipso to the fluorine with concomitant capture of the incipient carbocation by acetic acid Loss of the elements of methyl acetate follows The nitrodienone, being the keto tautomer of the nitrophenol, aromatizes to the isolated product [26] (equation 20) Intramolecular capture of the intermediate carbocation occurs in nitration of 2-(4-fluorophenoxy)-2-methyIpropanoic acid at low temperature to give the spiro products 3 3-di-methyl-8 fluoro 8 nitro-1,4 dioxaspiro[4 5]deca 6,9 dien 2 one and the 10-nitro isomer [2d] (equation 21)... 

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