In organic chemistry, a glycosyl group is a univalent free radical or substituent structure obtained by removing the hydroxyl (−OH) group from the hemiacetal (−CH(OH)O−) group found in the cyclic form of a monosaccharide and, by extension, of a lower oligosaccharide. Glycosyl groups are exchanged during glycosylation from the glycosyl donor, the electrophile, to the glycosyl acceptor, the nucleophile.[1] The outcome of the glycosylation reaction is largely dependent on the reactivity of each partner.[2] Glycosyl also reacts with inorganic acids, such as phosphoric acid, forming an ester such as glucose 1-phosphate.[3]