Some regularities in the nucleophilic substitution of various cellulose esters with halides

Deoxycelluloses and related structures

“…2a where X = ÐOTs or ÐOMs and Nu = a corresponding nucleophilic halide ion) in various solvents to yield the corresponding halodeoxycelluloses. As expected, a comparative study demonstrated that cellulose tosylate was a better leaving group than cellulose nitrate and that nucleophilic displacement to form halodeoxycelluloses increased in the order I b Br b Cl with optimum substitution occurring in solvents such as cyclohexanone rather than in aqueous solutions [5]. There are numerous earlier studies that describe the preparation of iododeoxycellulose by displacement of leaving groups such as tosylate [6] and later studies that describe its preparation by reaction of chlorodeoxycellulose with NaI in 2,5hexanedione [7].…”

“…A similar strategy was used to prepare 2,3-cellulosene; 2,3ditosyl-6-O-tritylcellulose was converted into 2,3diiododeoxy-6-O-tosylcellulose then reacted with methanolic KOH [55]. The most recent synthesis of 5,6-cellulosene claims preparation at the highest DS yet achieved (0.7) by conversion of 6-chlorodeoxycellulose into 6-iododeoxycellulose, subsequent acetylation of the 2-and 3-positions, then dehydrohalogenation under mild conditions with 1,8diazabicyclo [5,4,0]undec-7-ene (DBU) followed by hydrolysis of the ester groups [56].…”

Deoxycelluloses and related structures

“…2a where X = ÐOTs or ÐOMs and Nu = a corresponding nucleophilic halide ion) in various solvents to yield the corresponding halodeoxycelluloses. As expected, a comparative study demonstrated that cellulose tosylate was a better leaving group than cellulose nitrate and that nucleophilic displacement to form halodeoxycelluloses increased in the order I b Br b Cl with optimum substitution occurring in solvents such as cyclohexanone rather than in aqueous solutions [5]. There are numerous earlier studies that describe the preparation of iododeoxycellulose by displacement of leaving groups such as tosylate [6] and later studies that describe its preparation by reaction of chlorodeoxycellulose with NaI in 2,5-hexanedione [7].…”

“…A similar strategy was used to prepare 2,3-cellulosene; 2,3-ditosyl-6-O-tritylcellulose was converted into 2,3-diiododeoxy-6-O-tosylcellulose then reacted with methanolic KOH [55]. The most recent synthesis of 5,6-cellulosene claims preparation at the highest DS yet achieved (0.7) by conversion of 6-chlorodeoxycellulose into 6-iododeoxycellulose, subsequent acetylation of the 2-and 3-positions, then dehydrohalogenation under mild conditions with 1,8-diazabicyclo [5,4,0]undec-7-ene (DBU) followed by hydrolysis of the ester groups [56].…”