Preparation of perfluoroalkyl

This study relates to a continuous process for the preparation of perfluoroalkyl iodides over nanosized metal catalysts in gas phase. The water-alcohol method provided more dispersed catalysts than the impregnation method. The Cu particles of about 20 nm showed enhanced stability and higher activity than the particles larger than 40 nm. This was correlated with the distribution of copper particle sizes shown by XRD and TEM. Compared with silver and zinc, copper is better active and stable metal. 

Industrially, the perfluoroalkyl iodides by telomerization are mostly made by a batch system using peroxide initiators. However, the difficulty of mass production, and the production of hydrogen-containing byproducts in the process are disadvantageous [4]. In this study, a continuous process for the preparation of perfluoroalkyl iodides over nanosized metal catalysts in gas phase and the effects of the particle size on the catalytic activities of different the preparation methods and active metals were considered. 

Perfluoroalkyl iodides reacted with trialkylsilyl chloride in DMF in the presence of zinc followed by hydrolysis with acid to give perfluoroaldehydes in good yields [55]. Recently, Hu reported a new preparation of perfluoroalkyl aldehydes via reaction of perfluoroalkyl halides and DMF, initiated by redox... 

The first preparation of perfluoroalkyl copper reagents was reported by McLoughlin and Thrower in 1969 [68]. Perfluoroalkyl iodides react with copper... 

Perfluoroalkanoic acids also undergo Hunsdiecker reactions, with the greatest utility for such methodology being the preparation of perfluoroalkyl iodides, bromides and chlorides [64]. 

The Grignard or lithium route is of limited value for the preparation of perfluoroalkyl derivatives. Much of the early work was concerned with the addition of silanes to fluorinated alkenes [88, 89], leading to the preparation of important fluorinated poly-siloxanes, manufactured by Dow Coming Co. (Figure 10.39). 

Contrasting its broad versatility, the method of Eq. (d) is unsuited to the preparation of perfluoroalkyl or perfluoroaryl borazines, giving products in poor yield and of unsatisfactory purity. These borazines can be prepared in good yields, however, by a transamination reaction between the appropriate amine and a preformed amine-borane complex ... 

Refluxing one equivalent of S2CI2 or SCI2 with two equivalents of the amino acrylates 133 in chlorobenzene gives pyrroles 137 in good yields, Scheme 34. Initial cyclization gives the 1,4-thiazines 135 from which sulfur is extruded via 136. This method is particularly useful for the preparation of perfluoroalkyl-substituted pyrroles, which are difficult to obtain by the Knorr synthesis (84JOC4780). 

Later on, it was found that in case of diazenes, the corresponding chlorides can be used as starting materials for regioselective preparation of perfluoroalkyl derivatives 75-77." The reaction can be carried out in the presence of 2,2 -bipyridyl catalyst, in CgFg and DMSO (or DMF) cosolvent (Fig. 7.27). 

Uno, H. Okada, S. Suzuki, H. Preparation of perfluoroalkyl azaarenes with a perfluoroalkyllithium-boron trifluoride system. Tetrahedron 1991, 47(32), 6231-6242. 

Several perfluoroalkyl derivatives of SF4 and SFg are known, but this appears to be the first report of the preparation of perfluoroalkyl derivatives of Sep4 and SeFg. 

Preparation of Perfluoroalkyl Iodides.—C2F4 + IF5-2I2 + MoFe (cat.) at 75 C - CsFsI CFal-CFal + HF + SbCU + SOzClz at 165—168 °CC2F5I CsFa + I2 + KF doped with K2CO3 in MeCN at 110 °C (CFs)2CFI 2 8 CaFa +... 

The Pechmann pyrazole synthesis has also found similar utility for the preparation of perfluoroalkylated heterocyclic phosphonates, as demonstrated by the Shen group. Reaction of EDAC (30) with trifluoromethyl alkynylphosphonate 32 resulted in the formation of regioisomers 33 and 34 in high yield. The two regioisomers, isolated in a ratio of 85 15 (33 34) could be separated by column chromatography. 

The most conunon synthetic procedure for the preparation of perfluoroalkylated 1,2,3-triazole derivatives is 1,3-dipolar cycloaddition of azides to diverse unsaturated dipolarophiles containing perfluoroalkyl substituents. Thus, in 1966 Carpenter et al. carried out the cycloaddition of benzyl azide to perfluoroalkyl substituted acetylene derivatives leading to the formation of trifluoro-methyl-l,2,3-triazolines and 1,2,3-triazoles [39]. In this paper a synthesis of l-benzyl-4,5-bistrifluoromethyl-l,2,3-triazole 31 from hexafluoro-2-butyne was described. 

Following the disclosures in the patent literature in 1968, a detailed paper has been published dealing with the preparation of perfluoroalkyl iodide di- and tetra-fluorides (RrlFa and RpIFa) via treatment of perfluoroalkyl iodides with fluorine, bromine tri- or penta-fluoride, or, preferentially,... 

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