Coupling low-molecular substances to hydroxyalkyl starch

New conjugates of hydroxyalkyl starch (HAS) and small molecules comprise a covalent linkage between terminal aldehyde groups of the HAS, or functional groups formed by chemical conversion of the terminal aldehyde groups, and functional groups of the small molecule that are reactive with the aldehyde groups or derived functional groups. New conjugates of hydroxyalkyl starch (HAS) and small molecules comprise a covalent linkage between terminal aldehyde groups of the HAS, or functional groups formed by chemical conversion of the terminal aldehyde groups, and functional groups of the small molecule that are reactive with the aldehyde groups or derived functional groups. The bond formed as a direct result of the coupling reaction can be modified by a further reaction to produce the covalent linkage. Independent claims are also included for: (1) production of the conjugates by performing the coupling reaction in an aqueous medium and optionally modifying the resulting bond, and (2) selective oxidation of terminal aldehyde groups by reacting hydroxyalkyl starch with 2-20 molar equivalents of iodine in an aqueous basic medium or with a molar excess of stabilized copper (Cu 2+>) or silver (Ag +>) ions in an aqueous alkaline medium.