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 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.-

Molecular interactions of polymer oleogelation

“…However, it has been shown that ethoxy substitution occurs first in the hydroxyl groups at C2 and C3. 5,26,27 The explanation lies on the fact that the OH groups in the primary position (C6) are more blocked through mutual hydrogen bonding and only when enough substitution in C2 and C3 has occurred, the chains are separated enough to allow for C6 substitution. 26 Hence, upon etherification, all the unsubstituted OH groups are mostly in the C6 position.…”

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

“…The first RO membranes were cellulose acetate based [ 309 ]. The primary C-6 and the secondary C-2 and C-3 hydroxyl groups on the D-glucose monosaccharide units allow a variety of reactive mechanisms to be employed [ 310 , 311 , 312 , 313 ]. To be used for water purification and treatment, cellulose has been modified using esterification [ 314 ], etherification [ 315 ], halogenation [ 316 ], phosphorylation [ 317 ], xanthation [ 318 ], oxidation [ 319 ], sulfonation [ 320 ], carboxymethylation [ 321 ], hydrolysis [ 322 ], nitro-oxidation [ 323 ], and polymer surface functionalization [ 324 , 325 ] methods.…”