Predict the products obtained when D-galactose reacts with each reagent.
(k) excess HIO₄

D-galactose is a six-carbon aldose sugar with a specific stereochemistry. It contains an aldehyde group at one end and multiple hydroxyl groups, which influence its reactivity. Understanding its structure is crucial for predicting how it will react with various reagents, including oxidative agents like HIO4.

Periodic acid (HIO4) is a strong oxidizing agent that cleaves vicinal diols and aldehydes. In the case of sugars, it can oxidatively cleave the carbon-carbon bonds adjacent to hydroxyl groups, leading to the formation of smaller aldehydes or ketones. This reaction is essential for understanding the products formed when d-galactose is treated with excess HIO4.

The reaction mechanism describes the step-by-step process by which reactants are converted into products. For d-galactose reacting with HIO4, the mechanism involves the formation of cyclic intermediates and subsequent cleavage of the sugar backbone. A clear grasp of these mechanisms helps in predicting the final products of the reaction.