1-Buten-3-yne, 1-methoxy- 1-Buten-3-ynyl methyl ether 1-Methoxybutene-1-yne-3 2798-73-4 But-1-en-3-ynyl methyl ether EINECS 220-531-3 Ether, 1-buten-3-ynyl methyl NSC 65436