Single-Step Methylation of Chitosan Using Dimethyl Carbonate as a Green Methylating Agent

Abstract

N,N,N-Trimethyl chitosan (TMC) is one chitosan derivative that, because of its improved solubility, has been studied for industrial and pharmaceutic applications. Conventional methods for the synthesis of TMC involve the use of highly toxic and harmful reagents, such as methyl iodide and dimethyl sulfate (DMS). Although the methylation of dimethylated chitosan to TMC by dimethyl carbonate (DMC, a green and benign methylating agent) was reported recently, it involved a formaldehyde-based procedure. In this paper we report the single-step synthesis of TMC from chitosan using DMC in an ionic liquid. The TMC synthesised was characterised by 1H NMR spectroscopy and a functionally meaningful degree of quaternisation of 9% was demonstrated after a 12-h reaction time.

A Promising Use of Trimethyl Chitosan for Removing Microcystis aeruginosa in Water Treatment Processes

“…The strong signal at c.a. 3.3 ppm in TMC corresponding to N-methyl groups is not observed in HMW chitosan, which reflects a high degree of N-methylation, a condition produced by the TMC [ 34 , 41 , 42 ].…”

Synthesis and Biological Evaluation of Three New Chitosan Schiff Base Derivatives

“…Drug resistance of microorganisms to antibiotics has encouraged researchers to search for new antibiotics to challenge this dangerous phenomenon. Many CS derivatives were synthesized to improve the antimicrobial effectiveness of CS, for example, SBs, via methylation, amination, etc. , In the present study, CS was extracted and used to prepare three new SBs of CS by reacting CS with 2-chloroquinoline-3-carbaldehyde, quinazoline-6-carbaldehyde, and oxazole-4-carbaldehyde. The structures of the prepared CSSBs were confirmed using 1H NMR, 13 C NMR, and FT-IR techniques.…”

Sustainable valorisation of renewables through dialkyl carbonates and isopropenyl esters

“…Under the optimized conditions (T = 90 °C, t = 12 h), TMC was obtained in 9 % yield and characterized by 1 H NMR. 161 The tuneable reactivity of DACs can be exploited for the chemical modification of biopolymers, developing novel, fully renewable-based functional molecules and materials. Alkylation and/or carboxyalkylation typically improve the overall biopolymers solubility in organic solvents: in the future, this should be combined with novel insights on the reactivity of asymmetric DACs and COCs in organic synthesis.…”