rrkss - 11-2-2010 at 10:07
I'm going to attempt a synthesis of Cellulose Acetate over this weekend but don't have any Acetic Anhydride which is how I esterified cellulose in the
past. Anybody know if glacial acetic acid + sulfuric acid catylist and heat will be enough to esterify the cotton and give me the cellulose
tri-acetate?
On paper the reaction looks like it will work but reality could be quite different.
fractional - 12-2-2010 at 02:31
I have no experience with Cellulose Acetate with GAA but I have synthesised Acetanilide using GAA. Also here the standard acetylating reagent is
normally Acetic Anhydride. This gave a fairly good yield (about 65%) by using GAA in two-fold excess, and by refluxing the reaction mixture (aniline +
GAA) using an air-condensor in such a way as to hold back/condense the acetic acid, but allowing the product water to distill off. With other words
the temperature at the top of the air-condensor was kept at 100...105 degC for the duration of the reaction, until no more water came over.
Aniline serves also as a catalyst in this reaction. For the cellulose you will need the sulfuric acid to catalyse the reaction.
I could imagine that also other ways of removing the product water would do the trick (e.g. using molecular sieves or azeotropic distillation with
toluene).
[Edited on 12-2-2010 by fractional]
rrkss - 12-2-2010 at 11:50
Sounds interesting. I'm gonna try the reaction in a simple erlenmeyer flask in a hot water bath to control temperature. I'll report what happens.
Don't plan on doing any distillation or anything to remove water just want to see if the reaction is possible.
entropy51 - 12-2-2010 at 12:05
Adding some anhydrous NaOAc to the aniline and AcOH seems to improve the yield of acetanilide made as fractional describes. Just a thought.