Readily hydrolyzable cellulose esters as intermediates for the regioselective derivatization of cellulose, 1. Synthesis and characterization of soluble, low‐substituted cellulose formates

A new procedure was developed for the synthesis of low‐substituted, soluble cellulose formates. In a mixture containing cellulose, formic acid, phosphoric acid and water, cellulose can be dissolved within several hours, and after 24 h cellulose formates with a DS of about 0.6 that are soluble in DMSO could be obtained. By adding sulfuric acid as a dehydrating agent to the formylating system, formates with DS‐values up to 1.2 that are soluble even in DMF and N,N‐dimethylacetamide are formed after a very short reaction time of 15 min. 13C‐NMR studies show a strongly preferred formylation of the primary hydroxy groups of cellulose. Furthermore, the extent of depolymerization during the formylation reaction was investigated for various cellulose materials.