Low-molecular phosphorus-contg starch derivs

摘要

Low-molecular weight polysaccharide derivatives containing 0.3-3 weight % of combined phosphorus are prepared by reacting starch with a soln. of a phosphorus compound, with heating and dehydration. The preparation comprises a mixture of a (possibly pre-treated) starch and a solution which contains phosphoric acid and has a pH 5, is heated in an atmosphere where the oxygen content is such that the partial pressure of oxygen is lower than that of air. Heating is then continued under a still lower oxygen content, until condensation of the P compound with the starch occurs. The reaction mixture is then cooled under an atmosphere with a reduced oxygen content.