Halo compounds, aromatic identification

Procedures for the identification of this class of compounds can be divided into methods for the identification of alkyl and cycloalkyl halogenides and methods for the identification of aromatic halo compounds. The type of bond between the halogen and the rest of the molecule is decisive for the choice of the identification procedure. While the procedures for the identification of halo compounds with halogen atom boimd to an aliphatic carbon are based on the exchange of a halogen by a suitable residue, the identification of compounds with halogen bound to an aromatic nucleus is generally carried out by additional substitution of the aromatic nucleus. 

One major reaction of aromatic compounds is electrophilic substitution and it was therefore natural to submit the present systems to electrophiles. Thus l,2-dihydro-2-methylbenz[e][l,2]azaborine (113 R = Me) is brominated and chlorinated in its 3-position to give compounds (186), of which (186 X = C1) was prepared authentically for identification, starting from w-chloro-2-aminostyrene. The main reaction was, however, deboronation to w-halo-2-aminostyrenes. 

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