Halogen s. a. individual

With this section, the classification in the Handbook of Heterocyclic Chemistry has been followed thus a general survey of the effect of rings on the reactions of substituents is followed by a survey of the effect of rings on reactions of individual substituents in the order fused benzene rings, C-linked, AMinked, <9-linked, S-linked substituents, halogens, and metals. Substituents attached to cyclic nitrogen and sulfur are dealt with as described below. 

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