Page 101 - PG 504-theoretical notes-phyto-1-2024-2025..

Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

2) Soda process:

Wood is cooked with sodium hydroxide solution.

3) Sulfate process:

Wood is cooked with a solution of sodium hydroxide and sodium sulfate.

The rest of lignin in the resulting pulp may be removed by chlorine.

o Removal of non-cellulose polysaccharides: Hemicellulose and other

polysaccharides may be removed by alkaline treatment (5% NaOH).

Cross and Bevan Method for fractionation of Crude cellulose:

Crude cellulose can be fractionated into -, - and -cellulose according to

solubility in 17.5 % NaOH solution. The insoluble part is -cellulose (true

cellulose). -Cellulose is precipitated from the alkaline solution containing - and

-cellulose by acidification. -Cellulose is still in the mother liquor.

Preparation of cellulose from cotton fibers:

The cotton fibers are extracted with organic solvents to remove fat and

waxes, then treated with dilute alkalis under pressure to remove non cellulose

polysaccharides, washed and finally bleached with hypochlorite, to yield standard

cellulose.

Purified cotton:

Cotton is first combed to remove short hairs, and then washed with dilute

alkali to remove fatty materials, bleached with chlorinated soda, washed with

weak acid then water, dried, packed and finally sterilized.

Use: In surgical dressing.

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