Synthesis of novel adamantoyl cellulose using differently activated carboxylic acid derivatives

New adamantane carboxylic acid esters of cellulose (adamantoyl celluloses) were synthesized homogeneously in N,N-dimethylacetamide/LiCl using differently activated carboxylic acid derivatives. This includes the reaction of cellulose with 1-adamantoyl chloride and with adamantane-1-carboxylic acid after in situ activation with p-toluenesulfonyl chloride and with 1,1'-carbonyldiimidazole, which is a new and efficient tool. The degree of substitution (DS) has been determined by means of H-1 NMR spectroscopy using the perpropionylated adamantoyl cellulose samples. DS values as high as 2.1 were achieved. The reaction efficiency was 85% and the DS can be controlled by the molar ratio and the reaction conditions applied. The reaction occurs faster at the primary position compared to the secondary ones. The products are soluble in various organic solvents dependent on the DS. Preliminary results of subsequent modifications and properties of the adamantoyl celluloses are discussed as well.