NEW SOLUBLE AND HYDROLYTICALLY CLEAVABLE INTERMEDIATE IN CELLULOSE FUNCTIONALIZATION - CELLULOSE DICHLOROACETATE (CDCA)

Cellulose dichloroacetates (CDCAs) have been prepared using a) a mixtu re of dichloroacetic acid (DCA) and partially hydrolyzed phosphorus ox ychloride (PO(OH)(1.5)Cl-1.5), and b) a mixture of DCA and dichloroace tic anhydride (DCAA). In case a) CDCAs with DStitr values (degree of s ubstitution determined by titration) of 1.6 were obtained by using 10 mol of PO(OH)(1.5)Cl-1.5 per mol anhydroglucose unit (AGU) after react ion times of 14 h. The samples contained traces of phosphorus and free DCA. They were soluble in DMSO, DMF, and pyridine. By means of C-13-N MR spectroscopy and HPLC of per methylated and depolymerized samples, a preferred dichloroacetylation of the O-6 unit was determined. Method b) yielded polymers with DStitr values of 1.9 by using acetylation mi xtures of DCA/DCAA with 20% anhydride. Reaction times up to 12 days we re necessary. The polymers were soluble in DMSO, DMF, and pyridine. St ructure analyses showed preferred esterification of the primary OH gro up. DP values (degree of polymerization) up to 270 were accessible. Th e synthesized polymers were thermally degraded starting from 280 degre es C but became insoluble after treatment at temperatures higher than 150 degrees C.