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

<i>N,N,N</i>-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 iod...

Full description

Bibliographic Details
Main Authors: Ellen B. Hemming, Anthony F. Masters, Alvise Perosa, Maurizio Selva, Thomas Maschmeyer
Format: Article
Language:English
Published: MDPI AG 2019-11-01
Series:Molecules
Subjects:
Online Access:https://www.mdpi.com/1420-3049/24/21/3986
Description
Summary:<i>N,N,N</i>-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 <sup>1</sup>H NMR spectroscopy and a functionally meaningful degree of quaternisation of 9% was demonstrated after a 12-h reaction time.
ISSN:1420-3049