Studies in chemically modified celluloses. IV. Lactones in chemically modified celluloses

Abstract

SynopsisCellulose has been modified by hydrolysis follow& by oxidation with chlorous acid t.o produce gluconic carboxyl groups, which can form only &la&ones. A method has been described for reducing these gluconic acid groups by sodium borohydride into alcoholic groups. Iodometric and alkalimetric methods were used fur estimating the carboxyl value of various chemically modified samples.

Relationship between Length and Degree of Polymerization of TEMPO-Oxidized Cellulose Nanofibrils

“…The NaClO 2 oxidation selectively converts the C6-aldehydes, which are formed as intermediates during the TEMPO-mediated oxidation, to C6-carboxyls (Figure S1 in Supporting Information). The NaBH 4 treatment can convert the C6-aldehydes and C2/C3 ketones to hydroxyls. − …”

“…An aliquot of the TOC (∼0.5 g) was further treated with 1% NaClO 2 (50 mL) at pH 4.8 and room temperature for 2 days to oxidize C6-aldehydes present in the oxidized cellulose to carboxyls and washed thoroughly with water. Another aliquot of the TOC (∼0.5 g) was treated with 0.5 g NaBH 4 in water (95 mL) for 2 days at room temperature and pH ∼9, which was adjusted by adding a 0.5 M NaHCO 3 solution to reduce C6-aldehydes and C2/C3 ketones to alcoholic hydroxyls, − and then washed thoroughly with water. The microcrystalline cellulose was oxidized by the TEMPO/NaBr/NaClO system at pH 10 and room temperature with NaClO of 10 mmol per gram of the cellulose.…”