VI. Summary

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The type of radical produced by reaction of a nitro group in a carbohydrate depends upon whether this group is bonded to a carbon or an oxygen atom. A nitro group bonded to an oxygen atom invariably fragments to produce an alkoxy radical, but a nitro group attached to a carbon atom either fragments to generate a carbon-centered radical, expels an oxygen-centered radical to form a nitroso compound, or abstracts a hydrogen atom.

The alkoxy radicals produced from O-nitro carbohydrates rapidly abstract hydrogen atoms either internally or from molecules present in solution. Competing with or, in some instances, superseding hydrogen-atom abstraction is carbon–carbon bond cleavage to give a carbonyl group and a carbon-centered radical.

The carbon-centered radicals derived from reaction of C-nitro carbohydrates form most readily if the radical being produced is tertiary. These radicals undergo typical replacement, addition, and cyclization reactions. Primary radicals are much less likely to form from C-nitro carbohydrates; instead, these carbohydrate derivatives usually produce nitroso compounds.