Radical Reactions of Carbohydrates

Volume II: Radical Reactions in Carbohydrate Synthesis

Chapter 24: Redox Couples

Chapter 24 is in a portable document file (pdf) and can be viewed by clicking the blue, Chapter 24 button below. The drawing underneath the button pictures a reaction brought about by a redox couple. Beside the drawing is a description of the reaction. Below the drawing and its description is a summary of Chapter 24.

Chapter 24: Redox Couples

This drawing shows a radical addition involving a redox couple.

Drawing Description

The drawing on the left (eq 1 in Chapter 24) pictures an addition reaction in which the adding radical is generated by reaction of a deoxyiodo sugar with a zinc–copper couple (Zn and CuI) suspended in an ethanol-water solution.

Summary of Chapter 24

A redox couple is a combination of a transition metal with an ion from another transition metal. These couples serve as electron donors in addition of halogenated carbohydrates to compounds with electron-deficient double bonds. There is some uncertainty as to whether a free radical or an organometallic compound is the intermediate in this type of reaction. Stereochemical evidence supports the radical pathway, but solvent effects indicate a more complicated situation.