Major preceding studies of the distribution of substituents in cellulose have been reviewed. Over-all results indicate that the highest degree of reaction occurs at the hydroxyl group on C-2 in the case of the irreversible Williamson syntheses involving reagents of small molecular size. Pronounced preferential reaction occurs at the hydroxyl group on C-6 in the case of reversible reactions and with increasing molecular size of reagent.The relative reactivities of the hydroxyl groups on C-2, C-3, and C-6 of the D (1→4)-β-glucopyranosyl unit of cotton cellulose have been explored with three chemical agents.Predominant reaction of cotton cellulose occurs at the primary hydroxyl group on C-6 in the case of the reversible Michael addition of methyl vinyl sulfone (i.e., 2-0-: 3-0-: 6-0-= 0.20: 0.03: 1.00), at the hydroxyl groups on C-2 and C-6 in the case of the irreversible reaction with diethylaminoethyl chloride (1.27 : 0.35 : 1.00), and at the hydroxyl groups on C-6 and C-2 in the case of the irreversible Williamson synthesis with sodium allyl sulfate (0.7:0.2:1.0). The D -(1→4)-α-glucopyranosyl unit of dextrin (employed as a soluble model compound for cellulose) undergoes reversible esterification with formic acid most rapidly and to the highest equilibrium level at the primary hydroxyl group on C-6.-
Substituent group distribution in ally1 cellulose, resulting from the base-catalyzed condensation of sodium allyl sulfate with cotton cellulose and having a degree of substitution of 0.07, was found to be 0.7: 0.2:l.O in the 2-0-, 3-0-, and 6-0-positions of the anhydroglucose units. Several new glucose derivatives were prepared in the syntheses of the 2-0-, 3-0-, and 6-0-allyl-D-glucoses.Canadian Journal of Chemistry, 46, 667 (1968) Introduction As a part of a program to characterize the reactivities of the hydroxyl groups of the Dglucopyranosyl units of cotton cellulose toward mono-and polyfunctional reagents, we have studied the substituent group distribution resulting from the base-catalyzed condensation of sodium allyl sulfate with cotton cellulose. In order to identify the 2-0-, 3-0-, and 6-0-allyl-Dglucoses obtained from the hydrolytic cleavage of the molecular chain of the modified cotton cellulose, it has been necessary to synthesize and characterize several new derivatives of glucose. These were prepared by the nucleophilic substitution reaction on allyl bromide with the alkoxide group of a selected glucose derivative. Substituent groups on glucose hydroxyls which were stable to the conditions of the reactions, yet easily removed by acid hydrolysis after introduction of the allyl group, were employed to block all the hydroxyl groups which were to be free in the final product. The requirement of stable blocking groups in basic reaction media for the preparation of 2-0-, 3-0-, and 6-0-substituted
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.