Cellulose, acetylation nitration

The monosaccharide composition of the products of the alkalii saponification of cellulose tosylates containing tosyloxy groups at Cg has been established on the basis of data obtained from a study of the composition of the products of acetylation, nitration, and periodate oxidation, and from quantitative paper chromatography of the products of complete hydrolysis of the mixed polysaccharides synthesized. The content of 3,6-anhydroglucose units in the 3,6-anhydro derivatives of cellulose was found to be 50-70 mol.-% (10-13). 

The comparative reactivities of cellulose and other polysaccharides towards acetylation, nitration, hydrolysis, and etherification have been investigated. "... 

Cellulose acetate was initially employed as a replacement for the more flammable cellulose nitrate. The degree of acetylation of this ester can be varied the commercial product is 80 to 97% acetylated. Both films and fibers are made by the extrusion of solutions of cellulose acetate. The films and fibers are oriented in the direction of puli, and thus they have preferential strength in that direction. 

Clement and Riviere [59] also reported that cellulose acetate or a mixed ester — a nitrate-acetate — can be obtained by reacting cellulose nitrate with acetic anhydride, acetic acid, and sulphuric acid. According to more recent contributions, e.g. Wolfrom, Bower and Maker [60], the reaction should be performed as follows Cellulose nitrate is dissolved in the cold in a little sulphuric add and acetic anhydride, the surplus of acetic anhydride is then hydrolysed also in the cold, and cellulose acetate is extracted with a suitable solvent, such as chloroform. Other methods of acetylating nitrocellulose consist in reduction, for instance with zinc and hydrogen chloride, which entails denitration of the ester, followed by acetylation with acetic anhydride. All these reactions are carried out in the same vessel. Further, it is possible to synthesize mixed esters, cellulose nitrate-acetates, by subjecting cellulose to the action of a mixture that includes nitric acid, acetic add and acetic anhydride in the presence of sulphuric acid (Kruger [61]). The use of a large amount of nitric acid favours the formation of nitrocellulose only. Mixed esters are formed... 

Table 3 Relative Reactivities of Hydroxyl Groups in Tosylation (TS), Formylation (FO), Nitration (NT), Acetylation (AC), and Xanthation (XA) of Cellulose... 

Since iodide ion is a strong nucleophile, the action of iodides on cellulose tosylate, mesylate, and nitrate in ketones, and chlorodeoxycellulose in DMF or 2,5-hexanedione can generate iododeoxycellulose. In use of chlorodeoxycellulose, the chlorine substituents were almost completely replaced by iodide in 2,5-hexanedione. The iododeoxycellulose thus prepared was 6-dexoy-6-iodocellulose. lododeoxycelluloses having iodo substituents at C2 and C3 were also prepared by treating various sulfonates having a DS higher than 1.0 or 6-0-trityl-2(3)-p-nitrobenzenesulfonate of cellulose with sodium iodide in DMF. Ishii [134,135] succeeded in the almost quantitative preparation of 5,6-cellulosene acetate by the treatment of acetylated 6-deoxy-6-iodocellulose (DS 0.8) with 1,8-diazobicyclo [5,4,0]undec-7-ene in DMF. 

According to these data, an increase in the content of altropyranose units in the macromolecule of mixed polysaccharide (III) leads to a sharp fall in its acetylation rate as compared with cellulose. Similar results have been obtained for the nitration reaction of (III). An analogous relationship is observed for mixed polysaccharide (IV) upon acetylation preceded by the activation of the starting material. 

J) Acetylation and Nitration of Cellulose. Soak for a few minutes one gram of absorbent cotton in water. Press between fingers to remove the excess water, and finally between filter papers. Loosen the fibers and divide into two parts. 

The effect of the spatial arrangement of the hydroxyl groups of the repeating unit on reactivity has been investigated in comparative studies of the acetylation and O-nitration of cellulose and mixed polysaccharides (III) and (IV) (19,20). The data obtained are presented in Tables 4 and 5. 

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