Birch, acidic xylan from holocellulose

In an attempt to isolate a water-soluble 0-acetyl-(4-0-methylglucurono)-xylan from a birch chlorite holocellulose, Marchessault and coworkers kept the time of contact between the ammonia and the holocellulose at a minimum. Successive extractions of the pretreated holocellulose with water and methyl sulfoxide removed the xylan in yields of 7.1 and 14.6%, respectively, based on the weight of the original wood. The products still contained most of the iironic acid, but only one third of the 0-acetyl groups of the native xylan. 

The distribution of the 0-acetyl groups along the xylan chains has not been studied. The figures quoted above are very close to what would be expected if the acetate groups were distributed according to the laws of chance. An 0-acetylated xylan has also been isolated from the same birch wood by way of a peroxyacetic acid holocellulose. ... 

---