Paraldehyde
Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in alcohol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with most plastics and rubber.
Read more about Paraldehyde.