Azabenzenoid compounds

A general process has now evolved for the synthesis of highly fluorinated azabenzenoid compounds, involving (a) synthesis of the perchloro compound by further chlorination of partly chlorinated compounds with phosphorus pentachloride, and (b) subsequent reaction of the perchloro compound with potassium fluoride. The method is illustrated for per-fluoroquinoline [52] (Figure 9.22), but the technique has also been applied to other systems (Figure 9.22b). Thus, a novel field of heterocyclic chemistry is available that is still relatively unexplored. 

Perfluorobenzene and perfluorobenzenoid compounds have boiling points that parallel those of the corresponding hydrocarbons but, for perfluoropyridine and other perfluoro-azabenzenoid compounds, the values are significantly lower than for their hydrocarbon counterparts (Table 9.1). 

Pyridines and related nitrogen heterocyclic (azabenzenoid) compounds Polyfluoroaromatic nitrogen heterocyclic systems are all activated, relative to the corresponding benzenoid compounds, towards nucleophilic aromatic substitution. The magnitude of this activation is illustrated by the effects of a ring nitrogen, relative to C—F at the same position, for attack by ammonia [91] (Figure 9.32). 

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See also in sourсe #XX -- [ , ]

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