Dear colleagues! I'm a student and our work is connected with certified materials for alcoholic drinks. According lots of preparations of standard solutions it was found that pure acetaldehyde (bought from Sigma-Aldrich) can easily polimerize with the creation of metaldehyde (4-membered cyclic compound according to GC-MS, 3-membered product is minor).
Earlier, we've made the distillation of acetaldehyde. During the experimental results it was found that:
1) Usual distillation overcomes hardly, even inspite of the fact, that the boiling point is 20.2 degrees, BUT the distillate is a high pure acetaldehyde without any traces of polymer;
2) Distillation with the addition of sulfuric acid overcomes easily and greatly, BUT distillate consists from acetaldehyde and it's polymer by a nearly 50/50 proportion.
3) Purified acetaldehyde cannot be stored for a long time even at the low temperature (-15), as polymer form begins to appear, and it's concentration is increasing all time.
Finally I'm looking for your help. I'll be gratefull for advices\links\literature sources you can give me. What can I do in order to receive pure compound? Self-made internet searches didn't give any success.