Cellulose trityl

Hall, D.M., Home, J.R., 1973, Model compounds of cellulose trityl ethers substituted exclusively at C-6 primary hydroxyls. J. Appl. Polym. Sci. 17 2891-28%. 

The primary OH group can be selectively blocked by the bulky triphenyl-methyl (trityl) moiety, followed by esterification at the secondary OH groups and removal of the protecting trityl group. Thus 2,3-di-O-acetyl cellulose has been obtained by this procedure. Moreover, regioselectively substituted mixed cellulose esters, acetate/propionate, were prepared by subsequent acy-... 

Usually, a gradient of ethanol is superimposed on the aforementioned salt gradient, to lessen the affinity of trityl-containing compounds for the cellulose derivative, but a drawback with this procedure is that flow rates then tend to decrease. Relevant fractions... 

Hydroxyl Reactivity. Tables 5 and 6 summarize the relative reactivities of hydroxyl groups observed in partial etherification of cellulose. Besides a distinctly high selectivity of the C6 OH group in tritylation, the relative reactivity of the 2-OH and 6-OH groups was considerably affected by the alkylation conditions, such as fiber swelling and the nature of etherifying conditions. 

Table 5 Relative Reactivities of Hydroxyl Groups in Tritylation, Alkylations, 2-Aminocthylation, Allylation, and Carbamoethylation of Cellulose... 

The reactivity of cellulose toward tri(p-toluenesulfonyl)methane chloride was recently examined [89]. The tosyl reagent is more reactive than trityl chloride, and the primary hydroxyl position exhibited 43 times more reactivity than the secondary hydroxyl groups. The products were used as intermediates in the synthesis of selectively modified cellulose derivatives [89]. As mentioned earlier, a high DS, organosol trimethylsilylcellulose has been prepared in DMAc/LiCl [10]. The condensation of polysaccharides with triphenyl-methyl (trityl) chloride proceeds generally with preference for the primary hydroxyl positions. The tritylation of cellulose occurs initially 58 times faster at the hydroxyl group at C6 than at either C2 or C3 [90]. 

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. 

A cellulose derivative with doubte bonds between the secondary carbon atoms of the repeating unit has been synthesized by dehydro-iodination of preparations of 2(3)-iodo-2(3)-deoxycellulose prepaid by the action of a solution of Nal in dimethylformamide on cellulose 6-0-trityl-2(3)-0-p-nitrobenzenesulph[Pg.108]

Trityl ethers of the higher polysaccharides are also known, the trityl ethers of cellulose, starch and glycogen " having been reported. 

Fig. 30. Plot of (nj/lnj of cellulose ether and ester solutions vs. refractive index of solvent ) 1 2-cyanoethyl-trityl-cellulose, 2 cellulose monophenylacetate, 3 ethyl ceBulose, 4 2-cyanoethyl-acetylcellulose and 5 cellulose benzoate...

Ionic liquids have also been used as solvents in other cellulose derivatisation reactions including etherification [166], carboxymethylation [160], phthalation [167, 168], sulfation [169], sulfonation [169], carbanilation [159, 162], silylation [170], succinylation [171], tritylation [172] and tosylation [173],... 

Harkness, B.R. Gray, D.G. Left- and right-handed chiral nematic mesophase of (trityl) (alkyl)cellulose derivatives. Can. J. Chem. 1990, 68 (7), 1135-1139. 

The earlier work on the use of such specific reactions as p-tolylsulfonyla-tion, tritylation, and oxidation by periodate and lead tetraacetate for distinguishing between unsubstituted primary and secondary positions in cellulose derivatives - was followed by more widespread applications of... 

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