(1)-4-Methyloxetan-2-one (I)-beta-Butyrolactone 2-Oxetanone, 4-methyl- 3-Hydroxybutanoic acid, beta-lactone 3-Hydroxybutyric acid lactone 3068-88-0 36536-46-6 4-METHYL-2-OXETANONE 4-Methyloxetan-2-one 43137-57-1 CCRIS 111 CCRIS 5988 EINECS 221-330-3 EINECS 253-093-7 Hydroxybutyric acid lactone beta-Butyrolactone beta-Butyrolakton [Czech]