Peracetates

Peracetates are acetyl esters in which all hydroxyl groups of a polyhydroxy compound have been converted to acetate esters. In carbohydrate chemistry, the term is commonly used for per-O-acetylated sugars, such as the full acetylation of all hydroxyl groups on a sugar to give penta-O-acetyl or hexakis-O-acetyl derivatives (e.g., penta-O-acetyl-D-glucopyranose).

Preparation typically involves acetylation with acetylating agents such as acetic anhydride in the presence of a base or catalyst (for example, pyridine, DMAP, or catalytic acid), often under dry conditions to drive complete conversion of hydroxyl groups to acetate esters. The resulting peracetates are usually less polar and more lipophilic than the parent polyhydroxy compounds and often crystallize as solids.

Properties of peracetates include stability under ambient conditions and hydrolytic lability under acidic or basic aqueous media, which allows selective deprotection when needed. Their lack of free hydroxyl groups also reduces hydrogen bonding, aiding purification and characterization in some contexts.

Applications center on protecting group chemistry in carbohydrate synthesis. Peracetylation stabilizes reactive sites and can improve the approach of selective glycosylations, enabling stepwise construction of complex carbohydrates. They are also used as intermediates in transformations where the free hydroxyls would be reactive, and as derivatives for analytical studies of sugar structures.

Example: glucose can be converted to 1,2,3,4,6-penta-O-acetyl-D-glucopyranose, a common peracetate used in synthetic sequences.