Hydrolysis fluorinated compounds

Some small-ring compounds containing geminal fluorines suffer hydrolysis of fluorine only after initial opening of the ring For example, alkaline hydrolysis of... 

Various side reactions are possible. The solvent acetonitrile can also react as a nucleophilic agent to form, after hydrolysis, acetamides [R CH(NHAc)R2].23 Methanol as solvent results in a methoxylation product [R CH(OMe)R2].22 The selectivity of partial electrochemical fluo-rination depends on many different parameters, e.g. the type of solvent, the supporting electrolytes, the electrode materials, the electrochemical potential etc. The electrochemical potential can be measured by cyclic voltametry. Partially fluorinated compounds are particularly used in medical fields or as pesticides. 

Hydrolytic fission of a carbon chain which occurs with a,a,a-trihalo carbonyl compounds and which affords haloforms is observed with certain fluorinated compounds. Although R3C —F bonds are not broken, it is convenient to mention the process here. A special example is the hydrolysis of hexafluoro-2-phenylpropan-2-ol (5) in which two moles of trifluoromethane are liberated. 73... 

The synthesis of one of the agents begins with nucleophilic aromatic displacement of bromine by cyanide in the highly fluorinated compound 78. Acid hydrolysis of the nitrile (79), followed by esterification of the newly formed acid, affords ester 80. Base-catalyzed condensation of the intermediate with diethyl malonate leads to the tricarbonyl derivative 81. 

Sometimes fluorinated compounds have lower reactivity that is caused by the effect of fluorine. For example, oxetane acetals are compounds that are hydrolyzed easily when R=H, but hydrolysis is hindered when the group R=F. This is attributed to the decreased electron density of the proximal oxygen atom, resulting from the electron-withdrawing effect of the fluorine atom, and is also the result of suppression of cation generation at the carbon center ( ) (Scheme 1.3) [10],... 

The fluorine compounds of zirconium are insoluble or difficultly soluble in H2O. The other halide compounds are soluble but readily hydrolyzed. This hydrolysis goes so far that a solution of, e.g., ZrOCl2 may be diluted with H2O and the compound determined by titration of the liberated. Zirconium nitrate is readily soluble in H2O. 

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. 

Spectroscopic evidence indicates that protonation of 2-fluoro-and 2-chloro-quinoline is not appreciable in O.OlJf aqueous hydrochloric acid. Protonation becomes evident in more strongly acidic solution in the case of the chloro compound without any accompanying decomposition, but the fluoro compound hydrolyzes to carbostyril under the latter conditions. The hydrolysis is acid-catalyzed, but it is doubtful whether protonation on the heterocyclic nitrogen is responsible, owing to its low basicity (presumably below that for the chloro compound). An alternative explanation in this case would be hydrogen bond formation with fluorine, Ar—F. .. H-O+H2. 

The process of separating the intermediate products from the purified solutions, in the form of solid complex fluoride salts or hydroxides, is also related to the behavior of tantalum and niobium complexes in solutions of different compositions. The precipitation of complex fluoride compounds must be performed under conditions that prevent hydrolysis, whereas the precipitation of hydroxides is intended to be performed along with hydrolysis in order to reduce contamination of the oxide material by fluorine. 

Another way of applying the selective extraction method directly on the initial solution is to produce a solution of low acidity. This can be achieved by using the hydrofluoride method for fluorination and decomposition of raw material. As was discussed in Paragraph 8.2.2, the raw material is fluorinated by molten ammonium hydrofluoride yielding soluble complex fluorides of ammonium and tantalum or niobium. The cake obtained following fluorination is dissolved in water, leading to a solution of low initial acidity that is related for the most part to the partial hydrolysis of complex fluoride compounds. The acidity of the solution is first adjusted to ensure selective tantalum extraction. In the second step, the acidity of the raffinate is increased to provide the necessary conditions for niobium extraction. 

Modem refining technology uses tantalum and niobium fluoride compounds, and includes fluorination of raw material, separation and purification of tantalum and niobium by liquid-liquid extraction from such fluoride solutions. Preparation of additional products and by-products is also related to the treatment of fluoride solutions oxide production is based on the hydrolysis of tantalum and niobium fluorides into hydroxides production of potassium fluorotantalate (K - salt) requires the precipitation of fine crystals and finishing avoiding hydrolysis. Tantalum metal production is related to the chemistry of fluoride melts and is performed by sodium reduction of fluoride melts. Thus, the refining technology of tantalum and niobium involves work with tantalum and niobium fluoride compounds in solid, dissolved and molten states. 

As well as phenyl derivatives, other products have been prepared by hydrolysis of alkoxysilanes such as cyclohexenyl or naphthyl derivatives as well as heterocyclic compounds based on thienyl rings (Table 31, entries 28-33). Few practical applications have been reported for this type of compound, except for the styryl compound T81C6H4-A-CFI = CH2]s, and the fluorinated TslCeFsJs which have been used in polymer blending (Table 31, entries 13 and 28). ... 

MeCN, r.t., 24 h) gave, respectively, a mixture of fluorinated derivatives 287 (67%) and 290 (6%), and 290 (54%) and 287 (11%). In each case, the minor products were formed by C-5 epimerization of the starting compounds prior to the displacement, followed by fluorination. Reduction (NaBHJ of 287 and 290, followed by hydrolysis, gave an anomeric mixture of 5-deoxy-5-fluoro-L-idofuranose (from 287) and 5-deoxy-5-fluoro-D-glucofuranose... 

Hydrolysis of the oxaphosphetan (25) gave the phosphine oxide (26) which was converted into (27) by treatment with a mixture of thionyl chloride and pyridine. Treatment of (25) with HC also caused ring opening to (28) which was reversed on treatment with triethylamine. The chlorophosphorane (28) lost nexaxluoroiso-propanol on heating to give (27) which was fluorinated to give (29)27. All the compounds were characterised Dy 1H, 19F and 31P n.m.r. 

Cycloaddition of furans followed by a subsequent transformation is still adopted as a useful strategy to prepare fluorine-containing benzene derivatives and isoquinoline compounds <00SL550>. The cycloaddition adduct can also be converted to a trifluoromethyl substituted cyclohexanone compound via hydrogenation and hydrolysis. Examples of these transformations are illustrated below. 

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