N-Phthaloylated Chitosan as an Essential Precursor for Controlled Chemical Modifications of Chitosan: Synthesis and Evaluation

Abstract

ABSTRACT:In view of the importance of phthaloylated chitosan as a key intermediate that allows controlled modification reactions of chitosan, phthaloylation of chitosan was studied in detail to elucidate the substitution behavior and to establish a reliable method for preparing structurally well-defined N-phthaloyl-chitosan. The reaction of chitosan with phthalic anhydride in N,N-dimethylformamide resulted in N,O-phthaloylation, and the O-phthaloyl groups had to be removed through tritylation-detritylation, hydrolysis, or alcoholysis to afford N-phthaloyl-chitosan. In the presence of some water, however, perfect discrimination of the functional groups became possible, and selectively and quantitatively N-phthaloylated chitosan could be synthesized in a simple one-step reaction. The resulting N-phthaloyl-chitosan exhibited higher reactivity than N,O-phthaloylated chitosan as confirmed by tritylation and is promising as a precursor for C-6 substitution.

Synthesis and Characterization of Chitosan Biguanidine Hydrochloride under Microwave Irradiation

“…Thus, water soluble chitosan derivatives which are soluble in both acid and basic physiologic circumstances might be good candidates for a polycationic biocide. [6][7][8][9][10][11] Chitosan possesses primary amino groups in its structure and the number of these amino groups is related to its antimicrobial activity. The introduction of asparagine to chitosan oligosaccharide significantly improved the bactericidal activity and minimum inhibitory concentration; this probably indicates that the higher the number of amino groups, the higher the antimicrobial activity.…”

Synthesis of a new chitosan derivative and assay of Escherichia coli adsorption

“…Compound 2 (1.0 g) was dissolved in 20 mL aqueous hydrazine (3.4 mL 80% hydrazine) at 80 °C in a nitrogen atmosphere [22] . After 48 h of reaction with stirring, the solution was concentrated, washed several times with water and methanol, and then dried overnight in vacuo (compound 3,1.2872 g).…”

Synthesis and some properties of silylated chitins as key intermediates for chemical modifications

“…Chitin b-Chitin was isolated from squid pens [19,20], and the degree of deacetylation was 0.11 as determined by conductometric titration with a DKK TOA conductivity meter CM-20J [21,22]. After pulverization to 0.5 mm mesh with an ultracentrifugal mill Retsch ZM-1, it was selectively N-acetylated with acetic anhydride in methanol according to the reported method [23].…”