Fluorinated olefins

Such relative lack of kinetic impact of olefinic fluorine substituents on alkyl radical addition reactions is consistent with Tedder s early studies on methyl affinities, the results of which are shown in Table 16, where the range of reactivities observed for the addition of methyl radical to ethylenes with varying fluorine content is seen to be relatively small [93,163],... 

Four-membered heterocydes are easily formed via [2+2] cycloaddition reac tions [63] These cycloaddition reactions normally represent multistep processes with dipolar or biradical intermediates The fact that heterocumulenes, like isocyanates, react with electron-deficient C=X systems is well-known [77d] Via this route, p lactones are formed on addition of ketene derivatives to hexafluoroacetone [777, 77S] The presence of a trifluoromethyl group adjacent to the C=N bond in quinoxalines, l,4-benzoxazin-2-ones, l,2,4-tnazin-5-ones, and l,2,4-tnazm-3,5-diones accelerates [2+2] photocycloaddition processes with ketenes and allenes [106] to yield the corresponding azetidine derivatives Starting from olefins, fluorinated oxetanes are formed thermally and photochemically [779, 720] The reaction of 577-1,2-azaphospholes with fluonnated ketones leads to [2+2] cycloadducts [727] (equation 27)... 

A number of interesting reactions of the dimer (66) with nucleophiles have been described. Addition of sodium methoxide in methanol yields dimethoxy-ether (71), by replacement of the olefinic fluorine atom and of an allylic fluorine, which in turn yields keten (72) by reaction with sulphur trioxide at 30—40 Diverse... 

Hexafluorobicyclo[2,2,0]hexa-2,5-diene has been carefully examined by gas-phase electron diffraction and its molecular structure, which has Cat> symmetry, has the parameters shown in Scheme 29 (bond lengths in pm). TheC-1—C-4 bond is not as long as that in the hexamethyl compound, being similar to the C-3—C-4 bond in perfluorocyclobutene, the angle between the planes of the two cyclobutene portions is 121.8 2.0°, and the olefinic fluorines lie some 7.5 2.0° below these planes. 

As an example of the complexity of the NMR spectra of polyfluorocompounds, Figure 2 shows expansions of the individual resonances of the olefinic fluorines from the spectrum of 6H-perfluorohex-l-ene (1)... 

Figure 2 Expansions of the individual resonances of the olefinic fluorines in the 564 MHz F NMR spectrum of 6H-perfluorohex-1-ene [I] in CDCI3 solution. On the left is shown the result of Fourier transformation of the raw data and on the right Is given the result of resolution enhancement. Assignments are FI (top), FI (center), and F2 (bottom).

The olefinic fluorines in octafluorobicyclo [2,2,0 ]hex-2-ene (20 X = F) may be displaced by methyl-lithium, sodium borohydride in (MeO CHj-CH2>20, or sodium methoxide in methanol, to give (20), where X — Me, H, or OMe. The last reaction also yields a methanol adduct, which gives the methoxyheptafluorobexene (21) when treated with KOH at 170 °C. All the bicyclohexenes yield the corresponding c clohexa-l,3>dienes (22) when heated. 

In the case where R = OEt, an Arbuzov reaction to give (CF3)2C CF-P(0)(0Et)F occurs in the absence of water, and when R = NMe or NEt2, exchange of the olefinic fluorine by chlorine occurs. Reaction of 1,2-dichlorohexafluorocyclopentene with phosphite esters yields phosphonic... 

Pyrolysis of the propyne and but-2-yne 1 1 adducts yields the benzenes (111). Certain of these adducts are more conveniently prepared by LLA1H reduction of the corresponding adducts of octafluorocyclohexa-1,3-diene, but the hexafluorobut-2-yne and 3,3,3-trifluoropropyne adducts give products (112) and (113), and (114) and (IIS), respectively,arising from addition-elimination at the CFa-substituted double bond. The ethylene adduct of octafluorocyclohexa-1,3-diene undergoes replacement of both olefinic fluorines by methyl... 

The process of chain generation in olefin fluorination undoubtedly is CnHgn +... 

Halogenation— This reaction incorporates one of the halogen elements, usually chlorine or fluorine into a compound. Halogen gas can be used, as in the addition of chlorine to benzene to form chlorobenzene. Copper chloride on various supports are also used to add CI2 or HC to olefins. Fluorine or HF can be added to olefins. 

Chloroacetate esters are usually made by removing water from a mixture of chloroacetic acid and the corresponding alcohol. Reaction of alcohol with chloroacetyl chloride is an anhydrous process which Hberates HCl. Chloroacetic acid will react with olefins in the presence of a catalyst to yield chloroacetate esters. Dichloroacetic and trichloroacetic acid esters are also known. These esters are usehil in synthesis. They are more reactive than the parent acids. Ethyl chloroacetate can be converted to sodium fluoroacetate by reaction with potassium fluoride (see Fluorine compounds, organic). Both methyl and ethyl chloroacetate are used as agricultural and pharmaceutical intermediates, specialty solvents, flavors, and fragrances. Methyl chloroacetate and P ionone undergo a Dar2ens reaction to form an intermediate in the synthesis of Vitamin A. Reaction of methyl chloroacetate with ammonia produces chloroacetamide [79-07-2] C2H ClNO (53). 

Other applications of zirconium tetrafluoride are in molten salt reactor experiments as a catalyst for the fluorination of chloroacetone to chlorofluoroacetone (17,18) as a catalyst for olefin polymerization (19) as a catalyst for the conversion of a mixture of formaldehyde, acetaldehyde, and ammonia (in the ratio of 1 1 3 3) to pyridine (20) as an inhibitor for the combustion of NH CIO (21) in rechargeable electrochemical cells (22) and in dental applications (23) (see Dentalmaterials). 

Certain CFCs are used as raw materials to manufacture key fluorinated olefins to support polymer apphcations. Thermolysis of HCFC-22 affords tetrafluoroethylene and hexafluoropropylene [116-15 ] under separate processing conditions. Dechlorination of CFC-113 forms chlorotrifluoroethylene [79-38-9]. Vinyhdene fluoride [75-38-7] is produced by the thermal cracking of HCFC-142b. 

The lowest members of the series of perfluoroalkanedicarboxyhc acids have been prepared and are stable compounds. They have been synthesized by oxidation of the appropriate chlorofluoroolefin as well as by electrochemical fluorination and direct fluorination. Perfluoromalonic acid is an oxidation product of CH2=CHCE2CH=CH2 (21). Perfluorosuccinic acid has been produced by oxidation of the appropriate olefin (see eq. 7) (5) or by electrochemical fluorination of succinyl chloride or butyrolactone (41) and subsequent hydrolysis. 

Chemical Hazards. Chemical manufacturers and employees contend with various ha2ards inherent ia productioa of evea commonplace materials. For example, some catalysts used ia the manufacture of polyethylene (see Olefin polymers) ignite when exposed to air or explode if allowed to become too warm the basic ingredient ia fluorocarboa polymers, eg, Tefloa (see Fluorine compounds, organic), can become violently self-reactive if overheated or contaminated with caustic substances (45,46) one of the raw materials for the manufacture of acryflc fibers (see Fibers, acrylic) is the highly toxic hydrogen cyanide (see Cyanides). 

Miscellaneous. 1,1,1-Trichloroethane reacts with olefins, CH2=CRR, in the presence of P(0)[(NCH2)]3 and FeCl2 at 130°C, to give compounds of the type CH2CCl2CH2CRR Cl (61). Fluorination of 1,1,1-trichloroethane with anhydrous hydrogen fluoride at 144°C gives both... 

Alkyl fluorides have been prepared by reaction between elementary fluorine and the paraffins, by the addition of hydrogen fluoride to olefins, by the reaction of alkyl halides with mercurous fluoride, with mercuric fluoride, with silver fluoride, or with potassium fluoride under pressure. The procedure used is based on that of Hoffmann involving interaction at atmospheric pressure of anhydrous potassium fluoride with an alkyl halide in the presence of ethylene glycol as a solvent for the inorganic fluoride a small amount of olefin accompanies the alkyl fluoride produced and is readily removed by treatment with bromine-potassium bromide solution. Methods for the preparation of alkyl monofluorides have been reviewed. ... 

Preparation and Application of Aliphatic Fluorine Compounds 1 Halides, Olefins Alcohols, and Cyclobutaiies Oer) Liebig H Ulm, K Chem Ztg 99, 477M85 ISO... 

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