text: 9-Crown-3, also called 1,4,7-trioxonane or 1,4,7-trioxacyclononane is a crown ether with the formula (CHO).  A colorless liquid, it is obtained in low yield by the acid-catalyzed oligomerization of ethylene oxide.  
  In contrast to larger crown ethers (12-crown-4, and 18-crown-6), 9-crown-3 has elicited very little interest, except from theorists.