video tutorial Acetic anhydride from phosphorus pentoxide and acetic acid

Name: video tutorial - Acetic anhydride from phosphorus pentoxide and acetic acid
Uploaded: 2025-12-11T09:03:43.869Z
Duration: 9 min
Description: We had read that it wasn't possible to produce acetic anhydride via the dehydration of acetic...But we wanted to test this so we got a small amount of phosphorus pentoxide in a beaker.

Goal: test if acetic anhydride can be made from acetic acid and phosphorus pentoxide (P2O5).
Experiment 1: P2O5 with glacial acetic acid; reaction caused rapid heating but was uncontrolled and yielded no useful product.
Experiment 2: propionic acid with P2O5; slower reaction, temperature rose, suggesting activity but unclear if anhydride formed.
Experiment 3: 80 mL dry dichloromethane with P2O5 and slowly added acetic acid; formed a sticky mass, mild reflux, then distillation yielded only about 10 mL acetic acid; contents carbonized; deemed a failure.
Experiment 4: P2O5 and valuminium chloride in mineral oil; added acetic acid gradually; observed HCl fumes and no distillate; failure.
Context: prior work suggested propiothenone formation from propionic acid in benzene with valuminium chloride and P2O5; attempts to isolate acetyl chloride produced HCl but no distillate; aluminum acetate may be active.
Conclusion: acetic anhydride from acetic acid with P2O5 is not supported by these experiments; acetyl chloride could not be isolated under these conditions; the mystery remains and the claim is deemed myth-busted.