1, 2-5, 6-Di-O-isopropylideneglucose-3-phosphate (IV) (Ba salt) was prepared by phosphorylation (POC13 in pyridine) of 1, 2-5, 6-di-O-isopropylideneglucose. 1, 2-O-Isopropylideneglucose-3-phosphate (V) and glucose-3-phosphate (VI) (Ba salts) were synthesized from IV by the partial and complete elimination of isopropylidene group respectively. In addition, a mixture of three types of phosphates (VII) (Ba salt) was obtained by phosphorylation (POCl3 in pyridine) of 1, 2-O-isopropylideneglucose. (1) Yields of IV, V, VI and VII from glucose were 13, 8, 4 and 23% respectively. (2) Purities of IV, V, VI and VII on the basis of organic phosphorus contents were 100, 103, 97 and 92% respectively. (3) On the paper chromatograms, IV, V, VI and VII showed 2, 2, 1 and 5 spots respectively. (4) From the pH titration curves, it was found that VII was dibasic (monophosphate ester), VI was monobasic (cyclic phosphate) and both IV and V were mixtures of mono- and dibasic phosphate. It was considered that the cyclic phosphate in IV and V was a secondary product during the desalting and condensing processes of the solution. (5) On the hydrolysis in the buffer solutions of various pH value, V and VI showed the similar behavior to glucose-6-phosphate . (6) Km values of a commercial alkaline phosphatase preparation for glucose-l-phosphate, glucose-6-phosphate, V and VI were almost the same (0.81 1.08 × 10_-3 mol/liter).

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This article is a comprehensive survey on the phosphorus in starch. It is focussed mainly on the structure and properties of the chemically bound phosphorus of native starches and is described under the following headlines. 1. Qualitative and quantitative aspects of the phosphorus. 2. Structure and analysis of chemically bound ester forms of the phosphorus. 3. Phosphorus in root and tuber starches. 4. Phosphorus in cereal starches. 5. Alteration of content and structure of the phosphorus by culture and storage conditions. 6. Behavior of the phosphorus for the actions of amylases.

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