Carbon disulfide xanthates, polysaccharides

Starch xanthate. A water-insoluble synthetic polysaccharide made by reacting starch with sodium hydroxide and carbon disulfide biodegradable. 

The modification of cellulose with alkaline carbon disulfide to introduce xanthate groups has been extensively exploited in the industrial production of viscose. Early work on the preparation and properties of starch xanthate has been discussed. Xanthate derivatives of cellulose and starch have been discussed with respect to general xanthate chemistry, and the xanthation of cellulose in homogeneous medium is known to be a second-order reaction. Cellulose xanthate shows some potential as a matrix for enzyme insolubilization, " and stable derivatives of this xanthate may be prepared by transesterification. Thermal decomposition of cellulose allyl- and benzyl-xanthates gives 5,6-cellulosene. Some thiocarbonyl derivatives of polysaccharides have been prepared. "... 

Polysaccharides react with carbon disulfide and sodium hydroxide to give dithiocarbonic acid esters known as xanthates ... 

The xanthate group appears to become preferentially attached to C-2 of D-glucose units in cellulose. Diazomethane replaces the xanthate groups with methyl groups so that subsequent hydrolysis yields 2-0-methyl-D-glucose (140). A high degree of xanthation is obtained when the polysaccharide is dispersed and esterified with carbon disulfide in tetraalkylam-monium hydroxide (I40). 

Polysaccharides react with carbon disulfide and sodium hydroxide to give dithiocarbonic acid esters called xanthates. The polysaccharide, such as cellulose, is first treated with 18% sodium hydroxide to give alkaline cellulose (reaction 7.4). The alkaline cellulose is usually aged several hours to achieve lower d.p. values. It is then reacted with carbon disulfide for 1-3 hr at 20-30°C (reaction 7.4). 

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