Editing Synthesis of Tosyl-Chitosan

Chitin powder isolated from crab shells (Sigma, Lot. C7170) was<br>purified by stirring in a 5% NaOH aqueous solution for 3 days, recovered with<br>deionized water to pH 7 and dried at 50 o C.

<br>Preparation of chitin solution (1) and tosyl-chitin (2)<br>0.5g of Chitin (equiv. to 2.5 mmol of pyranose unit) and 1.3g of lithium chloride<br>(LiCl) dried respectively at 50 o C overnight and at 130 o C for 4h and cooled, and were<br>placed in a 100 ml three-necked flask fitted with rubber septa.<br>The flask was purged<br>with dry oxygen free nitrogen (OFN) and 26 ml of anhydrous DMAc was added via a<br>syringe.<br>The mixture was stirred at room temperature using a magnetic stirrer bar<br>until all solids were dissolved.<br>To the resultant chitin solution, was added Et 3 N (7.2<br>ml, 52mmol) followed by a solution of tosyl chloride (9.53g, 50mmol) in 12 ml<br>DMAc.<br>The reaction flask was transferred to the cold incubator and the reaction was<br>allowed to proceed at 8 o C for 24h at stirring speed of 250 rpm.<br>At the end of the<br>reaction, the mixture was filtered and the filtrate precipitated into 200 ml acetone,<br>washed with 300 ml methanol (100 ml × 3), 100 ml water (25 ml × 4) and 100ml<br>acetone.<br>The resulting product was freeze-dried to give 0.65g white color solid of<br>tosyl-chitin. The yield was 86.6%.<br><br>



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