Method of fluonnation

The preparation of fluonnated acid anhydrides can be done by simple methods Phosphorus pentoxide removes a molecular equivalent of water from tnfluoroacetic acid and tnfluoromethanesulfonic acid and forms the mixed anhydride [Si] (equation 53)... 

A new thermal preparation ot fluorinated species is copyrolysis Copyrolysis of fluorinated compounds like perfluorobenzene, fluorinated aromatic anhydndes, and fluorinated heteroaromatics with tetrafluoroethylene or other fluonnated olefins is a useful method of preparing fluorinated olefins [88 89], functionalized fluoroaromatics [90 91 92, 93, 94, 95], fluonnated benzocycloalkanes [80, 96, 97, 98, 99, 700], fluorinated heterocycles [80, 93, 101, 102, 103], and fluonnated polycyclic compounds [104] (equations 19 and 20)... 

The modern electronic industry has played a very important role in the development of instrumentation based on physical-analytical methods As a result, a rapid boom in the fields of infrared, nuclear magnetic resonance (NMR), Raman, and mass spectroscopy and vapor-phase (or gas-liquid) chromatography has been observed. Instruments for these methods have become indispensable tools in the analytical treatment of fluonnated mixtures, complexes, and compounds The detailed applications of the instrumentation are covered later in this chapter. 

Novel Methods for Selective Fluorination of Organic Compounds. Design and Synthesis of Fluonnated Antimetabolites Kollonitsch, J hr J Chem 17, 53-59 50... 

The simplest method for obtaining selective fluonnation is to conduct reactions under conditions that invigorate the electrophilicity of fluorine In practice this method entails the creation of anionic or strongly nucleophilic reactive centers on substrate molecules while suppressing or reducing the tendency toward radical attack Numerous examples of seleetive fluorine attack on carbanionic, amido and carboxylato species are documented Especially abundant is alpha fluonnation of nitroalkanes in polar solvents [42 43, 44, 45 46] (equations 10-14)... 

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... 

One of the most useful ways of introducing fluorine into organic compounds is the replacement of the hydroxyl group in alcohols hydroxy compounds, and carboxylic acuis Methyl alcohol reacts with anhydrous hydrogen fluoride at 100 500 °C in the presence of aluminum fluoride [60, 61], zinc fluoride [62] chromium fluonde [63], or a mixture of aluminum and chromium fluorides [64] to give a 20-78% yield of fluoromethane Attempted fluonnations of higher alcohols by this method failed [60]... 

Fluonnations with DAST proceed with high chemoselectivity In general, under very mild reaction conditions usually required for the replacement of hydroxyl groups, other functional groups, including phenolic hydroxyl groups [112], remain intact This provides a method for selective conversion of hydroxy esters [95 97] (Table 6), hydroxy ketones [120, 121], hydroxy lactones [122, 123], hydroxy lactams [124] and hydroxy nitriles [125] into fluoro esters, fluoro ketones, fluoro lactones, fluoro lactams, and fluoro nitriles, respectively (equations 60-63)... 

Only a few reports of unsaturated fluonnated cadmium compounds have appeared The direct reaction of perfluoroalkenyl iodides or bromides with cadmium powder in DMF stereospecifically gives the vinylcadmium compounds [143] (equation 110) Table 5 shows several typical vinylcadmiums prepared by this method. 

Over the past 40 years fluorine nuclear magnetic resonance (19F-NMR) spectroscopy has become the most prominent instrumental method for structure elucidation of organofluorine compounds. Consequently the amount of spectral data published has grown almost exponentially Unfortunately NMR data for fluonnated compounds are not as well, or as easily, organized as proton data To facilitate retrieval of fluorine NMR information and comparison of data, acquisition parameters should be clearly defined Guidelines for publication of NMR data have been established by the International Union for Pure and Applied Chemistry (IUPAC) [7] The following niles for acquisition and reporting of NMR data should be strictly observed... 

Basic data coverage in this section commences with fluonnated methanes, ethanes, ethylenes, acrylates, aliphatic monofluondes (pnmary, secondary, and tertiary), and geminal difluondes (pnmary and secondary) The compilation continues with six categones of tnfluoromethylated compounds and finishes with aromatic fluondes 19F-NMR applications extend greatly beyond simple structure determination Six of these special topics are bnefly surveyed, including analytical NMR methods and biochemical NMR studies... 

Fifolt [ 130] reported this chemical shift additivity method for fluorobenzenes in two deuterated solvents d6 acetone and d6 dimethyl sulfoxide (DMSO) Close correlations between experimental and calculated fluorine chemical shifts were seen for 50 compounds Data presented in Table 18 result from measurements in deuterochloroform as (he solvent [56] Fluorine chemical shifts calculated by this additivity method can be used to predict approximate values for any substituted benzene with one or more fluorines and any combination of the substituents, to differentiate structural isomers of multisubstituted fluorobenzenes [fluoromtrotoluenes (6, 7, and 8) in example 1, Table 19], and to assign chemical shifts of multiple fluorines in the same compound [2,5 difluoroamline (9) in example 2, Table 19] Calculated chemical shifts can be in error by more than 5 ppm (upfield) in some highly fluonnated systems, especially when one fluonne is ortho to two other fluorines Still, the calculated values can be informative even in these cases [2,3,4,6-tetrafluorobromobenzene (10) in example 3, Table 19]... 

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