Reaction with Iodine of Polysaccharides dissolved in Strong Calcium Chloride Solution

SEVERAL plant hemicellulose- B fractions, when dissolved in strong calcium chloride solution, have been separated into a more or less linear, galactose-free hetero-xylan and a highly branched galactose-rich fraction by treatment with iodine. The xylan is obtained as a heavy blue precipitate and the branched fraction remains in solution 1,2 . Apart from its value in hemicellulose fractionation this iodine precipitation appeared to be of wider interest as results with other polymers suggested that it separated linear (precipitated) from branched (not precipitated) polysaccharides 1 . Since this work was published, Morak and Thompson 3 have examined the reaction and shown that wood galactoglucomannans with a small number of single terminal branches along the main chain are precipitated but not those with many such branches.