The Relative Reactivities of the Hydroxyl Groups of Cotton Cellulose—A Progress Report1

Abstract

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 hy droxyl 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.