Paraldehyde
（重定向自Paracetaldehyde）
![Skeletal formula](/Images/godic/202502/01/Paraldehyde.svg1028.png")
![Ball-and-stick model](/Images/godic/202502/01/Paraldehyde-3D-balls1028.png")
![](/Images/godic/202502/01/Paraldehyde_stereochemistry_21029.PNG")
![A 5ml glass ampoule of paraldehyde.](/Images/godic/202502/01/ParaldehydeAmpoule1029.jpg")
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 ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with most plastics and rubber.