Deacetylation of chitin or chitosan for production of material for use e.g. as a pharmaceutical excipient, involves heating with alkali solution, each heating stage being preceded by at least 6 freeze-thaw cycles under vacuum

摘要

A method for the deacetylation of chitin and/or chitosan by heating with concentrated sodium hydroxide solution under vacuum, in which each heating stage is preceded by at least 6 freeze-thaw cycles in each of which the reaction mixture is frozen solid, degassed under vacuum and then thawed out by heating. A method for the at least partial deacetylation of chitin and/or chitosan (I) involves heating, in one or more stages, a suspension of (I) in concentrated sodium hydroxide solution at up to 100[deg]C for 20-30 minutes under reduced pressure in the absence of oxygen, each heating stage being preceded by at least 6 freeze-thaw cycles, each cycle of which comprises (a) immersing the reactor in a refrigerating medium until the mixture freezes completely, (b) degassing the reactor to below atmospheric pressure and (c) heating the reactor until the mixture thaws out completely. Independent claims are also included for (1) chitin obtained by this method, using a single boiling stage (2) completely deacetylated chitosan with a mol. wt. of more than 450000 (as determined by steric exclusion chromatography), obtained by the above method followed by neutralisation to pH 8.5, washing several times with water (centrifuging after each wash), freezing and then freeze-drying. ACTIVITY : Antibacterial; Vulnerary; Antilipemic. MECHANISM OF ACTION : None given.