Show the product you would obtain from the reaction of...

Show the product you would obtain from the reaction of cellobiose with the following reagents:
(a) $\mathrm{NaBH}_{4}$
(b) $\mathrm{Br}_{2}, \mathrm{H}_{2} \mathrm{O}$
(c) $\mathrm{CH}_{3} \mathrm{COCl},$ pyridine

Key Concepts

Reducing Sugars

Reducing sugars are carbohydrates that have a free anomeric carbon, typically able to exist in an open-chain form with a reactive carbonyl group. This functionality allows them to act as mild reducing agents and to participate in various transformations, making their reactivity a central topic in carbohydrate chemistry.

Sodium Borohydride Reduction

Sodium borohydride (NaBH4) is a mild reducing agent that converts carbonyl groups, such as the aldehyde at the reducing end of a sugar, into alcohols. In the context of carbohydrates, this reaction transforms the reactive carbonyl group into a stable primary alcohol, thereby converting the reducing sugar into a sugar alcohol.

Formation of Glycosyl Halides

Glycosyl halides are formed when the anomeric hydroxyl group of a reducing sugar is substituted with a halogen. Treatment with halogenating agents in aqueous conditions, such as a bromine-water mixture, leads to the formation of 1-halo derivatives. These species are important intermediates in carbohydrate synthesis and further functional group transformations.

Acetylation of Carbohydrates

Acetylation is a reaction where hydroxyl groups in a carbohydrate react with an acyl chloride (or anhydride) in the presence of a base like pyridine to form acetate esters. This reaction serves as a method both for protecting the hydroxyl groups during synthesis and for modifying the physical properties of the carbohydrate, facilitating structural analysis and further chemical manipulation.

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