2-Oxetanone, 4-methylene- 2130-41-8 3-Buteno-beta-lactone 3-Butenoic acid, 3-hydroxy-, beta-lactone 4-Methylene-2-oxetanone 5-17-09-00115 (Beilstein Handbook Reference) 674-82-8 6842-10-0 ACETYL KETENE BRN 0104541 But-3-en-3-olide Diketene Diketene, inhibited [UN2521] [Poison] EINECS 211-617-1 Ethenone, dimer Ethenone, dimer (VAN) HSDB 2063 Ketene, dimer NSC 93783 UN2521 Vinylaceto-beta-lactone