4-(N-Maleimido)benzyltrimethylammonium 4-(N-Maleimido)benzyltrimethylammonium iodide 40748-21-8 Benzenemethanaminium, 4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)-N,N,N-trimethyl- MPTA