production and Applications of acetic anhydride

acetic anhydride could be prepared by methyl acetate. Carbonylation of methyl acetate could prepared acetic anhydride.
Firstly, we will get methyl iodide and acetate as reaction product. Carbonylation of methyl iodide will get acetyl iodide and acetate. This reaction must to be in non-water environment because acetic anhydride is unstable in water.
acetic anhydride is mainly used for acetylations leading to commercially significant materials. Its largest application is for the conversion of cellulose to cellulose acetate, it is used in the production of aspirin, acetylsalicylic acid, which is prepared by the acetylation of salicylic acid. It is also used as a wood preservative via autoclave impregnation to make a longer lasting timber.
In starch industry, acetic anydride is used for the production of modified starches.